ENERGY ANALYSIS OF SHRIMP MARICULTURE
Howard T. Odum and Jan E. Arding
Environmental Engineering Sciences
Center for Wetlands
University of Florida
Gainesville, Fl, 32611
Coastal Resources Center
University of Rhode Island
In 1988, H.T. Odum delivered a series of lectures at the University of Rhode Island. They
were stimulating, at times baffling. They suggested a set of concepts that might link in a single
framework the principals of ecology and economics as they apply to the processes that govern how
living systems function and change. Such insights are central to the work of an organization like the
Coastal Resources Center that is dedicated to formulation and testing of management strategies for
coastal environments. The need for better understanding the linkages between ecological and
economic processes is particularly urgent in developing tropical countries where the rate of change
brought to coastal environments by man is accelerating and the long-term implications of such
change to both ecosystems and the human economies they support are too often considered in a
cursory manner, if at all. The lectures and a review of some of H.T. Odum's writings convinced me
that the Coastal Resources Center needed to know more. One way to learn more was to apply
EMERGY analysis to a specific resource management problem for which we had data on hand and
that posed significant policy issues.
The Coastal Resources Center, through a Cooperative Agreement with the U.S. Agency for
International Development (USAID), had just completed a synthesis of the available information on
shrimp mariculture in Ecuador. The industry has, in a mere fifteen years, become Ecuador's second
largest earner of foreign exchange. It has also brought greater changes to the country's coastal
ecosystem than any other human activity. The industry has, with minor exceptions, transformed
every estuary by the construction of ponds in former salt flats and mangrove wetlands, channelizing
water flow and in some cases significantly altering water quality. Through the capture of seed
shrimp and egg-bearing females, the industry has increased the pressures on all estuarine fisheries.
It has also brought employment, and, to some, great wealth. This discussion paper is the result of
applying EMERGY analysis to these issues.
H.T. Odum contends that human free choices, given enough time and
sometimes after social turmoil and much wasteful destruction of natural resources, will through trial
and error find the means for maximizing public wealth (which includes symbiotic designs of the
economy with environmental systems). EMERGY evaluation, he suggests, by providing a means for
predicting what actions will maximize public wealth and produce sustainable economies, provides
policy makers with a means for short-circuiting the process and avoiding an otherwise slow and
wasteful evolutionary process. Odum argues that the market value of products and services is of
obvious importance to individuals and businesses but is largely irrelevant as a measure of the "true
wealth" of a society or a geographic area.
"A tank of gasoline drives a car the same distance regardless of what people are willing to pay
for it A day of summer sunlight generates so much corn growth regardless of whether a
human thinks it's free or not A nugget of copper concentrated by geological work will make
so much electric wire regardless of its price."
"When resources are abundant, wealth is great, standard of living is high, and money buys
more. But when resources are abundant, market values and prices are small. Prices are not a
measure of resource contribution to wealth."
"When resources are scarce, prices are high not only because shortages affect demand, but
because more human services are required to mine, transport, or concentrate scarce resources.
By the time the resources have been collected and used, the net contributions of the resource
have been diminished by the extra efforts to process the resources."
"In other words, prices are not only not a measure of the contribution of resources and
commodities to an economy, they are inverse, being lowest when contributions are greatest
EMERGY provides another measure for evaluating contributions to public wealth."
(Quotes from Part Two of this volume.)
EMERGY analysis does not propose to replace the free market as the system for setting prices
for human transactions. The price of lipstick, an art work, a piece of real estate or a commodity on
the future's market should continue to be set by what society is willing and able to pay and what
those who produce it are willing and able to make it for.
EMERGY analysis is offered as a tool for those charged with setting policy and attempting to
balance between short-term gains and long-term stability for a society. This is, after all, one of the
primary roles of government. If EMERGY analysis is based on sound perceptions of how
ecosystems-including their human component-function and respond, then it can provide powerful
insights when considering such questions as:
How much is a natural resource worth?
How great is the contribution of the unpaid environment to a commodity?
What is the wealth generating potential of the natural resources of a region or a country?
What substitutions can be made to the process of generating a product without changing the
productivity of a system?
How can taxes be used to effectively reinforce those levels and types of consumption that
benefit society without threatening the productivity of the economy?
How can we estimate quality of life and wealth in a non-monetary economy?
Questions such as these have long been the purview of economists. EMERGY analysis applies
the principals of system ecology to such questions and brings to bear observations on how
ecosystems function, and why, in competitive settings, certain systems prevail.
The conclusions offered by this analysis of shrimp mariculture and the recommendations
regarding public policy, and particularly the recommendations as they relate to international trade,
will be highly controversial. HT. Odum has been a difficult target for critics. His concepts have
been evolving rapidly and he freely admits that language and techniques he put forward in the past
were incomplete and have had to be improved. Yet there can be no doubt that his is a giant intellect.
He has played a central role in developing the science of systems ecology, performed much of the
pioneering work in the ecology of reefs, rain forests and other systems, and co-authored the classic
textbook on ecology with his brother. His 1971 book Environment, Power and Society has had a major
impact. In 1987 he received, with his brother, the Crafoord Prize, the equivalent in the biological
sciences of the Nobel Prize. For the past ten years he has devoted himself almost entirely to
developing, testing and refining EMERGY analysis. Few of his students have kept pace with the
evolution of his ideas. Some of the controversy it has triggered is summarized in a section of Part
Two of this volume.
This volume is being distributed as a Working Paper because the usual review process is
much complicated by the unfamiliarity and potentially far-reaching implications of this analysis.
The next objective is to use this document as the basis for a series of structured discussions that will
bring together economists, ecologists and those concerned with the policy of development to discuss
not only the potential usefulness of EMERGY analysis but the other analytical techniques available
to address the questions raised by this case study. Such discussion should address directly the
limitations of neoclassical economics that were so widely discussed at a 1990 workshop sponsored
by the World Bank entitled "The Ecological Economics of Sustainability: Making Local and Short-
Term Goals Consistent With Global and Long-Term Goals." As a participant at that workshop, it
appears to me that a conclusion was that neoclassical economics does not and cannot be relied upon
to reasonably set values for natural resources and ecosystem processes. The impression created at
that workshop was that no alternative analytical system as yet exists. These discussions should
explore whether EMERGY analysis helps fill the gap.
Director, The Coastal Resource Center
The University of Rhode Island
EMERGY Analysis of Shrimp Mariculture in Ecuador
Table of Contents
Theory of Maximum EMERGY Designs 1
Systems of Shrimp Production and Sale 1
Systems Diagrams and their Hierarchical Organization 9
EMERGY Analysis Procedures 9
EMERGY Benefit of Alternatives 11
Optimal Matching of Environmental and Economic Inputs 11
EMERGY Solutions to Other Questions 11
Report Organization 11
Microcomputer Simulation 12
(A) Detailed Energy Systems Diagram 13
(B) Aggregated Diagrams 14
(C) EMERGY Analysis Table 15
(D) EMERGY Indices 16
(E) Microcomputer Simulation 21
(F) Public Policy Questions 21
EMERGY Benefit of Alternatives 21
EMERGY Change Analysis 22
Uses of the EMERGY Investment Ratio 22
Significance of the EMERGY Exchange Ratio 22
NATIONAL SYSTEM OF ECUADOR 23
Energy Systems Diagrams 23
EMERGY Analysis of Annual Flows 23
Overview Indices for Ecuador 35
Different EMERGY in Exported and Imported services 35
National Comparisons 35
Regional EMERGY Investment Ratios 35
SHRIMP AND INTERNATIONAL EXCHANGE 37
High EMERGY of Currency of Ecuador in International Exchange 37
EMERGY Exchange with Foreign Sales of Shrimp 37
EMERGY Trade Balance for Ecuador 39
EMERGY Feedback Reinforcement of Environmental Work 39
Shrimp Culture Isolation from the Local Economy 39
Simulation of Price Effects on a Renewable Resource 41
SHRIMP ECOSYSTEMS OF COASTAL ECUADOR 47
Ecosystems Supporting Reproduction, Recruitment, and Growth of Shrimp 47
EMERGY Inputs to the Coastal System of Ecuador 47
EMERGY Inputs to the Mangrove Nursery Areas 53
EMERGY Evaluation of Daule-Peripa River Diversion 53
Evaluating Pelagic Fishery Landings 57
Evaluating Shrimp Trawl Landings 57
SHRIMP MARICULTURE DEVELOPMENT 59
Energy Diagram of Shrimp Pond System 59
EMERGY Inputs and Investment Ratio of Shrimp Pond Mariculture 59
Shrimp Transformities and System Efficiency 60
Pelagic Fish Meal Supplements to Shrimp Ponds 60
Net EMERGY of Shrimp from Ponds 66
Regional EMERGY Change Accompanying Pond Development 66
Comparison of EMERGY Benefit of Alternatives 67
Optimum Development for Maximum Benefit 67
SIMULATION MODEL OF SHRIMP PRObUCTION AND SALES 73
Simulation of Benefits as a Function of Developed Area
using MAXSHRMP.BAS 73
Calibration of MAXSHRIMP 73
Simulation Results 73
Effects of Adding More Shrimp Ponds 82
Sources of Hatchery Post Larvae 82
Data Limitations 82
General Recommendations for Maximum Success of Economic Development 83
REFERENCES CITED 85
Appendix: Principles of EMERGY Analysis for Public Policy - H.T. Odum 89
An EMERGY Glossary - Dan Campbell 113
This work has been funded in part by a Cooperative Agreement between the United States
.Agency for International Development, Office of Forestry, Environment, Natural Resources, Bureau
for Science and Technology and the University of Rhode Island Coastal Resources Center.
The opinions, findings, conclusions, or recommendations contained in this report are those of
the authors and do not necessarily reflect the views of the Coastal Resources Center or the Agency
for International Development
Marine Shrimp ponds (Figure 1) are being constructed in many developing tropical countries
selling shrimp on the international market to meet a large demand from the developed countries. In
Ecuador this new mariculture system is based on getting the young shrimp from the natural system,
which also supports an established trawl shrimp fishery. The shrimp example highlights recurring
problems with environmental development, international aid, and investment. Is the new
development sustainable? Is its development at the expense of other values? Does it help the home
country; does it help the consuming country? Is it likely to be economic in the long run? Is it a good
model for developing countries to emulate?
In this study the EMERGY method for evaluating environmental contributions was used to
evaluate the systems of shrimp production of Ecuador (Figure 2) and their relationship to the
national and international economies. EMERGY, spelled with an "M", is a scientific-based measure
of wealth, which puts raw materials, commodities, goods, and services on a common basis, the
energy of one type required to generate that item. EMERGY measures the real basis for economic
vitality in the long run. Sources of more explanation of EMERGY concepts and application are given
under separate cover: "Principles of EMERGY analysis for Public Policy".
Theory of Maximum EMERGY Designs
According to the theory, the pattern that maximizes EMERGY contributes more wealth.
Designs that draw more resources overcome more limitations, and displace alternatives. In general,
economically developed resources prevail over the undeveloped ones because the environmental
EMERGY contributions are augmented by additional resource inputs paid for from investments and
sales. Figure 3 shows the evaluation plan used in this study, comparing EMERGY of a new project
with EMERGY before development, with EMERGY of alternative investment, and with maximum
potential EMERGY for those resources. Selection of project plans for maximum EMERGY can
generate wealth according to an area's potential.
Systems of Shrimp Production and Sale
Understanding shrimp ponds, their estuarine basis and their relationship to the international
economy requires systems thinking and wealth evaluations at several levels of size: the pond
system, the regional economy, the national economy, international exchange and the world
economy. Ideally, a new development should contribute to the wealth of all these, without one at the
expense of another. Maximizing one does not maximize the whole system's wealth and
performance. Nor are such developments sustainable.
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Figure 1. Aerial view of shrimp ponds in Ecuador.
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--- 100m Depth Contour
0 100 200 km
0 50 100 150 miles
Figure 2. Map of Ecuador with Gulf of Guayaquil and offshore continental shelf that
supports shrimp reproduction and larval growth.
Figure 3. Diagram for comparing EMERGY benefit of a new environmental
use (P2) with an old system (P1), with typical alternatives in the region (PA),
and with maximum potential (PD) matching environmental EMERGY and economic
inputs according to the regional investment ratio R.
Figure 4. Energy systems diagram of the coastal system of Ecuador and the life cycle of shrimp between
inshore mangroves (below) and offshore shelf ecosystems (above). (a) Whole systems; (b) life cycle of
Figure 4 (continued)
Figure 5. Overview system diagram of shrimp culture ponds and their inputs.
Figure 6. Overview systems diagram of Ecuador and its foreign trade,
Systems Diagrams and Their Hierarchical Organization
The parts and processes of shrimp systems are conveniently represented with diagrams in
Figures 4-6, using the symbols in Figure 7. Diagrams drawn with energy systems language help
visualize causal relationships, set up analysis tables and simulation programs. Circles outside the
defined boundary frame are sources of external resources, goods, and services; tanks are stocks and
storage; pointed blocks are interactions of more than one commodity or factor in a productive
process. Diagrams of the larger system aggregate the the smaller systems, which are shown in more
detail in the diagrams of the smaller scale subsystems.
The environment and the economy are hierarchical. Many small products, rapidly turning
over are the basis for larger, longer-lasting products at a larger scale. Hierarchy within each diagram
is represented with small to large in positions on the paper from left to right
In some systems diagrams annual flows of solar EMERGY are written on the pathways to
help the reader visualize which pathways are more important.
Figure 4 is the old system of shrimp production in the coastal area off Ecuador, including
offshore waters at the top where shrimp reproduce and their tiny larvae start development. At the
bottom of Figure 4 is the inshore, mangrove-lined estuary (Figure 1) where the post larvae achieve
half of their growth. An inset (Figure 4b) shows the life cycle of the shrimp separated out from the
Figure 5 is a systems diagram of the new shrimp pond mariculture system. Estuarine waters
containing post larvae, shrimp food and fertilizer nutrients are pumped into the diked ponds. More
organic food is generated by the pond algae and other plants. The pond managers add additional
fertilizer, foods, post-larvae, utilizing goods and services, fuels, and electricity. Harvested shrimp
are sold and the money obtained is used to buy purchased items, pay interest, repay loans, with the
balance retained as profit
Figure 6 is an overview diagram of the shrimp production systems in their relationship to the
economy of Ecuador and international markets for shrimp. The national economy is heavily based
on the renewable resources, sun, wind, and rain on the left; the marine inputs of tide and species; the
geologic inputs of mountain-building, petroleum generation above; and the purchased goods and
services from abroad on the right. The shrimp production system is shown drawing on many
aspects of the national system, and the product being sold on the international markets.
EMERGY Analysis Procedures
Application of the EMERGY method starts with overview diagrams of national economy and
its international trade (Ecuador in Figure 6), the environmental systems on which shrimp trawl and
pond production depends (Figure 4), and the shrimp pond system (Figure 5).
Then the main pathways of necessary inputs are evaluated in EMERGY units. Each inflow is
expressed in solar emjoules per year. (A solar emjoule of a product is the solar energy previously
required directly and indirectly to generate that product). EMERGY contributions are determined
for nature's work, for purchased resources, and human services.
Old and new systems are compared to determine which contribute the most real value to the
public economies as measured by EMERGY flux. After inputs are evaluated in EMERGY units,
Energy circuit. A pathway whose flow is proportional to the
quantity in the storage or source upstream.
Source. Outside source of energy delivering forces according to a
program controlled from outside; a forcing function.
Tank. A compartment of energy storage within the system storing a
quantity as the balance of inflows and outflows; a state variable.
Heat sink. Dispersion of potential energy into heat that accompanies
all real transformation processes and storage; loss of potential
energy from further use by the system.
Interaction. Interactive intersection of two pathways coupled to
produce an outflow in proportion to a function of both; control
action of one flow on another; limiting factor action; work gate.
Consumer. Unit that transforms energy quality, stores it, and feeds it
back autocatalytically to improve inflow.
Switching action. A symbol that indicates one or more switching
Producer. Unit that collects and transforms low-quality energy
under control interactions of high-quality flows.
Self-limiting energy receiver. A unit that has a self-limiting output
when input drives are high because there is a limiting constant
quality of material reacting on a circular pathway within..
Box. Miscellaneous symbol to use for whatever unit or function is
Constant-gain amplifier. A unit that delivers an output in
proportion to the input I but changed by a constant factor as long as
the energy source S is sufficient.
Transaction. A unit that indicates a sale of goods or services (solid
line) in exchange for payment of money (dashed line). Price is
shown as an external source.
Figure 7. Symbols of the energy language used to represent systems (Odum, 1983).
different alternative investments and degrees of development are evaluated to find the optimum
pattern for maximum EMERGY production and use. Details on the diagramming and EMERGY
analysis procedure are given in the METHODS section below.
EMERGY Benefit of Alternatives
The concept of comparing EMERGY benefits of alternatives is shown in Figure 3. The diagram
includes the old system of trawling shrimp from coastal ecosystems (third unit), the new system of
shrimp pond mariculture (second unit), the typical alternative investments available in the region
(third unit), and the potential maximum benefit (lower unit). Each of the alternatives is shown with
environmental inputs (I) and purchased inputs feeding back from the economy (F). The solar
EMERGY produced for the combined economy of humanity and nature (P) was calculated for each
alternative as the sum of the solar EMERGY flows I and F.
Optimal Matching of Environmental and Economic Inputs
For any region there is an optimal matching of purchased inputs (F in Figure 8) with available
environmental inputs (I in Figure 3) that is economic. If too few inputs are purchased, the output is
less than competitors and others take the market. If too many inputs are purchased, costs are too
high to be competitive and opportunities to use the investments to get greater environmental
matching in other areas are lost. In any regional economy there is an average EMERGY investment
ratio (R in Figure 8), which is the ratio of the flux of EMERGY purchased to the free EMERGY flux
from the environment. An overly intensive economic investment has a higher investment ratio than
the average for its region and loses economic position. However, it may be competitive as part of
more intensively developed economies overseas that have higher ratios.
EMERGY Solutions to Other Questions
EMERGY indices derived from the evaluations help with other questions. For example, is
there a net EMERGY contribution to the economy? What intensity of environmental use maximizes
the economy where that environment is already providing contributions to the under-developed
economy? If the market value does not represent a product's value to the public economy as a
whole, what kind of microeconomic incentives would insure reinforcement to maintain resources
and local economies? What is the most appropriate use of investment? What are the benefits of sales
on the international market? Which benefits most from shrimp sales, buyer or seller? What is an
appropriate interest rate for the investments?
In the text that follows, more procedural details are given next in METHODS. Then comes the
EMERGY overview of Ecuador as a whole (Figure 2), and the EMERGY of foreign trade, which is
necessary when putting the shrimp systems in perspective. Next, we consider the coastal system
before shrimp ponds were developed and the various changes taking place with development Then
we consider shrimp pond development (Figure 3), and finally, the intensity of development that
may maximize values.
The time dimension is supplied by microcomputer simulation models with the same
complexity as public policy thinking. These minimodel simulations are like controlled experiments,
showing what would happen for the conditions given, with other factors held constant. A very
simple model PRODSALE is given first to show how environmental work and economic sales are
The model MAXSHRIMP simulates the coastal system with trawl fishery and shrimp pond
developments drawing on common resources and markets. Successive runs are made to find the
degree of development which maximizes yields and values.
In this study the environmental-economic system of Ecuador, the coastal system, and the
shrimp mariculture system were studied with a similar methodology as follows:
(A) First a detailed energy systems diagram was drawn as a way to gain an initial network
overview, combine information of participants, and organize data-gathering efforts.
(B) Next, an agaregated diagram was generated from the detailed one by grouping components
into those believed important to system trends, those of particular interest to current public
policy questions, and those to be evaluated as line items.
(C) An EMERGY analysis table was set up to facilitate calculations of main sources and
contributions of the system. Raw data on flows and storage reserves were evaluated in
EMERGY units and macroeconomic dollars to facilitate comparisons and public policy
(D) From the EMERGY analysis table EMERGY ndices were calculated to compare systems,
predict trends, to suggest which alternatives will deliver more EMERGY, which will be
more efficient, and which will be successful.
(E) For some systems a microcomputer simulation program was written to study the temporal
properties of an aggregated model. The program is used as a controlled experiment to study
the effects of varying one factor at a time. Insights on sensitivities and trends are suggested
from the computer graphs.
(F) Models, evaluations, and simulations were used to consider which alternatives generate
more real contributions to the unified economy of humanity and nature. In particular, what
are the relative contributions of shrimp mariculture and its optimal development obtained
by evaluating Figure 3.
(A) DETAILED ENERGY SYSTEMS DIAGRAM
For understanding, for evaluating, and for simulating, our procedures start with
diagramming the system of interest, or a subsystem in which a problem exists. This initial
diagramming is done in detail with anything put on the paper that can be identified as a
relevant influence, even though it is thought to be minor. The first complex diagram.is like
an inventory. Since the diagram usually includes environment and the economy, it is an
organized impact statement
The following are the steps in the initial diagramming of a system to be evaluated:
1. The boundary of the system is defined.
2. A list of important sources (external causes, external factors, forcing functions) is made.
3. A list of principal component parts believed important considering the scale of the
defined system is made.
4. A list of processes (flows, relationships, interactions, production and consumption
processes, etc.) is made. Included in these are flows and transactions of money believed
to be important
5. With these lists agreed on as the important aspects of the system and the problem
under consideration, the diagram is drawn on the blackboard and on large sheets of
Symbols: The symbols each have rigorous energetic and mathematical meanings
(Figure 7) that are given elsewhere (Odum, 1983). Examples of a system diagram
involving both nature and the human economy are given in Figures 5 and 6.
System Frame: A rectangular box is drawn to represent the boundaries that are
Arrangement of Sources: Any input that crosses the boundary is an energy source,
including pure energy flows, materials, information, the genes of living organisms,
services, as well as inputs that are destructive. All of these inputs are given a circular
symbol. Sources are arranged around the outside border from left to right in order of
their energy quality starting with sunlight on the left and information and human
services on the right
Pathway Line: Any flow is represented by a line including pure energy, materials, and
information. Money is shown with dasHed lines. Lines without barbs flow in
proportion to the difference between two forces; they may flow in either direction.
Outflows: Any outflow which still has available potential, materials more concentrated
than the environment, or usable information is shown as a pathway from either of the
three upper system borders, but not out the bottom.
Adding Pathways: Pathways add their flows when they join or when they go into the
same tank. Every flow in or out of a tank must be the same type of flow and measured
in the same units.
Intersection: Two or more flows that are different, but are both required for a process
are drawn to an intersection symbol. The flows to an intersection are connected from
left to right in order of their transformity, the lowest quality one connecting to the
notched left margin.
Counterclockwise Feedbacks: High-quality outputs from consumers such as
information, controls, and scarce materials are fed back from right to left in the
diagram. Feedbacks from right to left represent a loss of concentration because of
divergence, the service usually being spread out to a larger area.
Material Balances: Since all inflowing materials either accumulate in system storage
or flow out, each inflowing material such as water or money needs to have outflows
(B) AGGREGATED DIAGRAMS
Aggregated diagrams were simplified from the detailed diagrams, not by leaving
things out, but by combining them in aggregated categories. See example in Figure 6 for
Simplified diagrams show the source inputs (cross boundary flows) to be evaluated:
environmental inflows (sun, wind, rain, rivers, and geological processes); the purchased
resources (fuels, minerals, electricity, foods, fiber, wood); human labor and services; money
exchanges; and information flows. Exports are also drawn. Initial evaluations may help in
deciding what is important enough to retain as a separate unit in the diagram.
Inside components include the main land use areas; large storage of fuel, water, or
soil; the main economic interfaces with environmental resources, and final consumers.
Interior circulation of money is not drawn, but all the major flows of money in and out of
the systems are shown.
(C) EMERGY ANALYSIS TABLE
An EMERGY analysis table is prepared with 6 columns with the following headings:
1 2 3 4 5 6
Note Item Raw Data Transformity Solar EMERGY Macro-
If the table is for flows, it represents flows per wnit time (usually per year). If the table is for
reserve storage, it includes those storage with a turnover time longer than a year.
Column number one is the line item number, which is also the number of the footnote in
the table where raw data source is cited and calculations shown.
Column number two is the name of the item, which is also shown on the aggregated
Column number three is the raw data in joules, grams, or dollars derived from various
Column number four is the transformity in solar emjoules per unit (sej/joule; sej/gram; or
sej/dollar, see definition below.) These are obtained from previous studies.
Column number five is the solar EMERGY. It is the product of columns three and four.
Column number six is the macroeconomic value in macroeconomiic dollars for a selected
year. This is obtained by dividing the EMERGY in column number five by the
EMERGY/dollar ratio for the selected year. The EMERGY/dollar ratio is obtained
by dividing the gross national product by the total contributing EMERGY use by the
combined economy of man and nature in that country that year.
(D) EMERGY INDICES
The following are EMERGY indices used to draw inferences from EMERGY analyses.
The solar transformity of an object or resource is the equivalent solar energy that would be
required to generate (create) a unit of that object or resource efficiently and rapidly. Figure 8a shows
the solar transformity defined as the solar EMERGY required forone joule of another form of
energy, which is shrimp energy in the example.
The net EMERGY yield ratio is the EMERGY of an output divided by the EMERGY of those
inputs to the process that are fed back from the economy (see Figure 8b). This ratio indicates
whether the process can compete in supplying a primary energy source for an economy. Recently
the ratio for typical competitive sources of fuels has been about 6 to 1. Processes yielding less than
this are not economic as primary EMERGY sources.
The EMERGY investment ratio is the ratio of the EMERGY fed back from the economy to the
EMERGY inputs from the free environment (see Figure 8b). This ratio indicates if the process is
economical as utilizer of the economy's investments in comparison to alternatives. To be
economical, the process should have a similar ratio to its competitors. If it receives less from the
economy, the ratio is less and its prices are less so that it will tend to compete in the market. Its
prices are less when it is receiving a higher percentage of its useful work free from the environment
than its competitors.
However, operation at a low investment ratio matches attracted investment at a level below
what is possible. In other words, there is an unused potential available in the natural resources that
can be usefully applied when they are combined with more economic inputs. The tendency will be
to increase the purchased inputs so as to process more output and more money. The tendency is
towards optimum matching.
Thus, operations above or below the regional investment ratio will tend to change towards
the investment ratio. The ratio for an area is set by the state of development of the economy using
- Solar EMERGY = Direct and Indirect Solar energy required
Solar EMERGY required
18.6 E6 tolar emjoules
Figure 8a. Definition of solar Transformity applied to shrimp (Table 15).
EMERGY Investment Ratio = - R
Net EMERGY yield ratio = -
Figure 8b. Net EMERGY yield ratio for evaluating primary sources and EMERGY investment
ratio for evaluating whether matching of investments with environmental contributions is
competitive. J and F should both be in solar EMERGY units (Odum and Odum, 1983).
The EMERGY exchange ratio is the ratio of EMERGY received for EMERGY delivered in a
trade or sales transaction (see Figure 9). For example, a trade of grain for oil can be expressed in
EMERGY units. The area receiving the larger EMERGY receives the larger value and has its
economy stimulated more. Raw products such as minerals, rural products from agriculture,
fisheries, and forestry, all tend to have high EMERGY exchange ratios when sold at market price.
This is a result of money being paid for human services and not for the extensive work of nature that
went into these products.
E - E2
El-<---- -- ---- ---
EMERGY exchange ratio -
Figure 9. EMERGY exchange ratio of a transaction. (a) Trade of two commodities;
(b) sale of a commodity.
The EMERGY/dollar ratio for a country and a particular year is the ratio of the total EMERGY
used by the country from all sources divided by the gross national product for that year (see Figure
10). As the diagram shows, it includes EMERGY used in renewable environmental resources such as
rain, non- renewable resources used such as fuel reserves and soil, imported resources, and
imported goods and services. Rural countries have a higher EMERGY/dollar ratio because more of
their economy involves direct environmental resource inputs not paid for.
- The term macroeconomic value refers to the total amount of dollar flow generated in the
entire economy by a given amount of EMERGY input It is calculated by dividing the EMERGY
input by the EMERGY/dollar ratio.
The EMERGY amplifier ratio is the EMERGY increase produced in some process compared to
an EMERGY increase applied. In Figure 11, an increase in EMERGY input (dF) causes increase in
consumer service EMERGY (dY). The ratio is a measure of efficiency of the applied action. For
example, increasing health services for the working population to some optimum point will
maximize productive work hours
The alternative benefit ratios are used to make decisions between investment options (Figure
3.). Selecting different options for a given investment creates different systems within which each
can be evaluated. This ratio should be used in a two-step comparison. First compare the -
W k V EMERGY used -
A 4 ! I+F
. .. .. in equivalent
S "units of the
I - A GNP * same quality
- --.-.. . ------ E
Figure 10. overview diagram of a national economy. main flows of dollars
and energy; (b) summary of procedure for summing solar EMERGY inflows.
EMERGY AY Service Increase
ratio AF Investment increase
Figure 11. EMERGY amplifier ratio.
EMERGY contributions of the alternatives. In Figure 3, P is the sum of the free environmental
EMERGY, I, and the attracted investment EMERGY from the economy, F. In the diagram, P2 is
predicted to out compete, or prevail over P1 if its EMERGY is higher. PA is EMERGY from
alternative investments typical of the region in regard to investment ratio R. PD is the highest
benefit possible obtained by retaining all environmental inputs plus investment inputs.
A second comparison must then be made to assure that the investment that appears to be the
best alternative among a set of options considered is also reasonably attractive compared with the
average regional competitive investment ratio. In the United States the competitive investment ratio
for purchased goods and services (not source inputs) is about 7 to 1 (the ratio of F to I in Figure 8b).
This represents the fact that, in highly industrialized society, it requires about 7 units of paid goods
and services for every unit of environmentally contributed input to generate products in that
economy. The alternative which has the highest EMERGY contribution must also have an EMERGY
investment ratio comparable with that for the region in order to survive or succeed. Otherwise,
resources will gravitate to more productive options.
Ratios of EMERGY outputs (P's) are EMERGY benefit ratios.
Various EMERGY indices of an economy are useful for comparing states and nations. These
EMERGY flow per rson is a measure of the standard of living that includes free
environmental inputs, which may be large in areas of low population.
EMERGY flow per area is a measure of spatial concentration of an economy.
EMERGY caring capacity is the sum of the renewable environmental EMERGY flow plus
an attracted EMERGY flow from the economy equal to the competitive investment
ratio times the environmental flow, and is a measure of the total macroeconomic
activity that can be supported by the resources available to a region.
Fraction of total EMERGY that is indigenous is an index of self sufficiency.
(E) MICROCOMPUTER SIMULATION
For simulation, the models in the energy systems diagrams were aggregated further,
combining features that were unchanging, small, or belonging to a more general category. The main
source inputs, boundary flows of money, and the main features of production and consumption
were retained. A new simpler diagram resulted. Equations automatically implied by the
diagramming were written and placed in a BASIC simulation program.
Numerical values for flows and storage were written on the pathways and "tanks" of a copy
of the diagram and adjusted for steady states expected at carrying capacity. Coefficients were
evaluated with a spread-sheet template and entered in the simulation program. Graphs were
obtained from simulation runs for the base calibration. Then one variable was changed at a time to
study effects as a controlled experiment and for study of various changes.
(F) PUBLIC POLICY QUESTIONS
Various policy questions were examined by comparing EMERGY contributions of
alternatives. The alternatives with higher EMERGY flows represent solutions that will tend to
prevail because their contribution to the economy is richer. The presumption is that through trial
and error as well as through rational argument, alternatives are tried so that their utility can be
observed by the public decision process. Ultimately, people will come to accept the high EMERGY
alternatives because these succeed and survive. By doing the EMERGY analysis in advance, one is
able to predict what will eventually be the accepted policy.
EMERGY Benefit of Alternatives
To evaluate a new development using Figure 3, EMERGY analysis tables are evaluated for the
original system and the new system including the environmental inputs and the purchased inputs.
The new development is also compared with the typical alternative investment for that region. The
flux of environmental EMERGY typically matching purchased EMERGY is the regional investment
ratio defined in Figure 8. This ratio is 7 in the United States and less than one in many under-
developed regions. The EMERGY of a new development can be compared with typical
developments that are economic in that region by adding the purchased EMERGY (F) to the
environmental matching (F/R),
(Purchased EMERGY) F
Environmental Matching = I= = - sej/yr
(EMERGY investment ratio) R
A new development, to be a net EMERGY benefit, should have a higher annual solar
EMERGY yield than the previous system and/or be higher than typical alternative investments.
EMERGY Change Analysis
On comparing a development with the system it displaces, it may not be necessary to evaluate
all the resource inputs. An EMERGY change table can be evaluated, including in the table only those
items that have changed. Because a change table is smaller and simpler, it is easier for readers to
Uses of the EMERGY Investment ratio
Often in the development of environmental resources, early success is followed by over-
development which puts too much purchased EMERGY for the matching environmental input This
wastes economic potential and overloads the environmental resource. The EMERGY investment
ratio (Figure 8) is the index for determining the development intensity and the environmental
loading. The ratio should not exceed the regional investment ratio if the development is to be part of
Sustainability of a development is possible when its EMERGY yield is higher than alternatives
AND when EMERGY feedback from the economy goes to the environmental work processes (not to
humans) so as to reinforce their ability to compete with alternative ecosystems that tend to displace
the ones under environmental loading. Many fisheries of the world get little or no feedback
reinforcement and have crashed one after another, being displaced by other environmental species
and patterns not under economic use. Partly this was a result of failed policy based on optimum
catch calculations for only one species, ignoring the whole ecosystem. The tendency for an
environmental use system to be displaced is accentuated by supply and demand that causes rising
prices to sustain demand at the critical stage when an environmental system is overloaded. Public
policy should be designed to encourage sustainability with incentives or regulations for feedback
EMERGY reinforcement. Policy should consider EMERGY ratios.
Significance of the EMERGY Exchange Ratio
When products are exchanged or sold, the relative benefit is determined from the exchange
ratio (Figure 9). A local economy is hurt when the new development takes more EMERGY than it
returns in buying power. Keeping the product for home use raises the standard of those living at
NATIONAL SYSTEM OF ECUADOR
An EMERGY analysis overview was made of Ecuador including diagrams, annual EMERGY
analysis table, and indices of the national economy.
Energy Systems Diagrams
The aggregated diagram of the national system of Ecuador in Figure 6 is shown in more detail
in Figure 12, including the features prominent in the summarizing map (Figure 2). Major sectors are
the tropical rain forests of the Amazon Basin, the high Andes with their populations and agriculture,
and the coastal systems and fisheries. Oil from the Amazon is pumped up over the mountains and
down to a shipping terminal on the Pacific ocean for export. For the national analysis the coastal
boundary was taken as the edge of the continental shelf defined by the 100 meter depth contour
(Figure 2). The overview diagrams were used to identify the main resources contributing EMERGY
from within and from outside imports.
EMERGY Analysis of Annual Flows
Annual flows of EMERGY evaluated in Table 1 include renewable sources, indigenous non-
renewable resources, and economic imports utilized in 1986. Economic exports are in Table 2. Sorie
of the line items in these tables include others, and some are byproducts of common processes and
thus were not added in deriving total EMERGY use. Total EMERGY use of Ecuador is summarized
in Table 3 and Figure 13. EMERGY indices of the national economy are given in Table 4.
Summation of EMERGY inputs to a nation is made so as to avoid double counting two
inputs that come from the same process and same EMERGY originally. Items in Table 1 and 2,
identified by their line numbers, were summarized for Figure 13 and for a summary Table 3 as
Summation of EMERGY inputs to Ecuador
Renewable flows (Table 1):
8 Tide absorbed inshore 67.0 E20
7 Offshore area (Humboldt current) '33.0 E20
5 Rain over land (Chemical potential) 381.0 E20
Total renewable 481.0 E20
Nonrenewable uses (Table 1):
14 Wood from mature forests 5.7 E20
21 Soil loss 283.0 E20
19 Home oil used 121.0 E20
18 Natural gas 11.0 E20
Total non-renewable 420.7 E20
Total Annual EMERGY Use 901.7 E20
Exports (Table 2)
Without transformation & use
1 Oil 231.0 E20
2 Shrimp 31.2 E20
3,4,6,7Agricultural products 10.7 E20
6 Fish 2.6 E20
Total transformed 44.5 E20
Exported services (not included in those above)
9 Goods and services 38.7 E20
Figure 12. Main sectors of society and nature in Ecuador. See also Figure 6.
EMERGY Evaluation of Annual Environmental Flows for Ecuador in 1986
Note Item Raw Units Transformity Solar Emergy Macroeconomic*
J,gor $ Sej/unit E20 sej/yr E6 1989 US $
1 Sunlight 1.09E+21 1 10.90 545.000
2 Wind 2.72E+18 623 16.95 847.280
3 Mangroves 2.87E+16 14684 4.21 210.715
4 Rain, geopotential 3.28E+18 8888 29153 14576.320
5 Rain, chemical 2.47E+18 15444 381.47 19073.340
6 Rain, kinetic 1.31E+13 15444 0.00 0.101
7 Humboldt current 4.17E+14 8000000 3336 1668.000
8 Tide 2.85E+17 23564 67.16 3357.870
9 Waves 7.76E+16 25889 20.09 1004.493
10 Volcanic activity ?? - - ?? ??
11 Geological uplift ?? 4.93E+17 "29000 143.0 7148.500
12 Hydroelectrcity 6.30E+15 159000 10.02 500.850
13 Earthquake activity 5.29E+13 3.73E+07 19.73 986585
14 Wood consumption 1.64E+16 34900 5.72 286.180
15 Fishing yields 4.01E+15 131E+05 5.25 262.655
16 Shrimp trawl yields 2.08E+13 4.00E+06 0.83 41.600
17 Shrimp pond yields 1.68E+14 18.6E+06 31.25 1562.000
INDIGENOUS NON-RENEWABLE SOURCES:
18 Natural gas 2.27E+16 48000 10.90 544.800
19 Oil use 2.42E+17 53000 128.37 6418.500
20 Electricity 1.59E+16 159000 , 25.28 1264.050
21 Soil loss 453E+17 62500 283.13 14156.250
22 Gold (g) 3.13E+04 2.51E+12 <0.01 <0.01
23 Silver (g) 6.26E+04 251E+10 <0.01 <0.01
24 Copper (g) 8.00E+06 9.60E+07 <0.01 <0.01
25 .. Zinc (g) 1.48E+07 3.64E+07 <0.01 <0.01
26 Crude steel (g) 1.70E+10 1.78E+09 0.30 15.130
SERVICES IN IMPORTS (US $1986)
27 Fuels 8.20E+07 2.40E+12 1.97 98.400
28 Raw Material (Ag&Ind.) 6.77E+08 2.40E+12 16.26 812.880
29 Cap. goods (Ag&Ind) 4.00E+08 2.40E+12 9.59 479.400
30 Transport equipment 2.03E+08 2.40E+12 487 243.600
31 Construction materials 4.98E+07 2.40E+12 1.20 59.760
32 Consumer goods 2.19E+08 2.40E+12 5.26 262.800
33 Imported Services (US$) 9.54E+08 2.40E+12 22.90 1144.800
* Solar EMERGY divided by 2.0 E12 sej/$
Footnotes for Table 1
1. Sunlight Country area 283,561 E6 m2 (T. E. Weil et al., 1973); 18500 E6 m2 shelf, 6330 E6 m2
estuary; total 308361 E6 m2. Av. solar radiation 127 kcal/cm2/yr (assume .7 absorbed).
(308361 E6 m2X.7X127 E4 kcal/m2/yr)(4186 J/kcal) = 1.09 E21 J/yr.
2. Wind: 7.552 Ell kWh/yr potential (World Bank, 1981).
(7552 Ell kWh/yr)(3414 Btu/kWh)(105435 J/Btu) = 2.72 E18 J/yr.
3. Mangroves : area 18.2 E8 m2 (1984); 1E4 g/m2 density observed (Snedaker, 1986).
(1E4 g/m2)(18.2E8 m2)(3764 cal/g)(4.186 J/cal)(0.10/yr) = 2.87 E16 J/yr.
4. Rain, geopotential: mean elevation 741 m. (Area Handbook for Ecuador, 1973); average
rainfall 1603 nmm, 80% runoff.
(741m)(1.603 m)(.8)(E3 kg/m3)(9.8 m/s2)(281561 E6 m2) = 2.62 E18 J/yr.
5. Rain, chemical: Gibbs free energy of rainwater relative to seawater, 4.94 J/g.
(283561 E6 m2X1.603 m)(l E6g/m3)(4.94 J/g) = 2.47 E16 J/yr.
Rain on offshore area
(18500 E6 m2)(1.6 m/yrX1 E6 g/m3)(4.94 J/g)= 1.46 E17 J/yr
6. Rain, kinetic: (av.rainfal/yrXl/2)(density)(av.velocity)^2).
(160.3 cm/yr)(l E4 cm2/m2X6.91 E-6 Cal/nt3)(4.186 J/cal)(281561 E6m2) = 1.32 E13 J/yr.
7. Humboldt current - physical energy (see Table 14) 1.68 E4 J/m2/yr. Coastal system area
(Table 12) 24830 E6 m2.
(1.68 E4 J/m2)(24830 E6 m2) = 4.17 E14 J.
8. Tidal energy (assume 50% absorbed): coastal area 24830 E6 m2, av.height, 1.8 m.
(24.83 E9 m2)(05)(706/yr)(1.8 m)(1 m)(9.8 m/s2)(1.025 E3 kg/m3)
= 2.85 E17 J.
9. Waves: straight shore line 560 E3 m (av. h 1 m).
(560 E3 m)(.125)(1.025 E3 kg/m3)(9.8 m/s2Xl m2)^2 (9.8 m/s2 x 1.25 m)
(5) (3.154 E7 s/yr) = 7.76 E16 J.
10. Volcanic activity as hierarchical top of energy chain for which the base is some fraction ? of
the world annual EMERGY flow,8 E24 solar emjoules/yr manifest in solar and earth's deep
heat (Odum, 1988), 30 of world's 800 active in Ecuador.
(8 E24 sej/yr)(30/800X? fraction of earth process)= <<3000 E20 sej/yr
11. Geologic continental cycle: Stable area. 1 E6 J/m2/yr for 0.739 land area; active 5.26 J/m2/yr
for 0.261 land area in active mountains.
(261)(283561 E6 m2)(5.26E6 J/m2/yr) + (.739)(283561 E6 m2XlE6 J/m2/yr)
= 3.89 E17 + 1.04 E17 = 4.93 E17 J/yr.
12. Hydroelectricity: 1750 E6 kWh 1984. (Stat Abstracts of Latin America).
(1750 E6kWhX3414 Btu/kWh)(1054.35 J/Btu)(3.606 E6 J/kWh) = 6.30 E15 J/yr.
13. Earthquake activity E = Ke x a2 x f (cal/m2/y), where Ke = 4168 (constant), a = .2 % one g
acceleration, f = frequency/100 years; Ecuador earthquake activity assumed similar to
(4168X0.2)2(110/100)(4186 J/cal)(689 EIO m2) = 5.29 E13 J/yr.
14. Wood consumption (1985): 5879 E3 m3 (Europa Year Book, 1988 EYB).
(5879 E3 m3)(.7 E6 g/m3)(.25 DM)(38 kcal/g)(4186 J/g) = 1.64 E16 J/yr.
15. Fishing yield (1985) herring, sardine, anchovie, mackerel: 826.1 E3 mt (EYB).
(826.1 E9 g)(0.2 DM)(5800 cal/g)(4.186 J/cal) = 4.01 E15 J/yr.
Transformity from Table 14, footnote 9.
16. Shrimp trawl yield (McPadden, 1986) 3710 mt.
(3710 E6 g)(.2 DMX6.7 kcal/g)(4186 J/kcal) = 2.08 E13 J/yr.
Transformnity lower value from Table 15.
17. Shrimp yield (1986): 30,000 mt (Estadisticas de Importacion y Exportacion in Acuacultura
del Ecuador, July 1988).
(30 E9 g)(.2 DM)(6700 cal/g)(4.186 J/cal) = 1.68 E14 J/yr.
18. Natural gas consumption (1985XSouth America Economist, 1987- SAE) 21495 E6 ft3.
(21495 E6 ft3)(E3 Btu/ft3X105435 J/Btu) = 2.27 E16 J/yr.
19. Oil used 106E6 barrels/day
(106 E3 bbl/day)(6.28 E9 J/bblX365 d/yr) = 2.42 E17 J/yr.
20. Electricity: (SAE) 4400 E6 kWh.
(4400 E6 kwh)(3.606 E6 J/kwh) = 1.59 E16 J/yr.
21. Soil loss: Data by LA. Medina and E.Erraez C. for Guayas River basin, (mean of 79 stream
(283,561 E6 m2)(7080 g/m2X.01 organic)(5.4 Kcal/g)(4186 J/Kcal)
= 4.53 E17 J/yr
22. Gold (1984) (Statistical Abstract of Latin America, 1987): 1000
T.oz. (= 31300 g).
23. Silver (1984) (Statistical Abstract of Latin America, 1987):
2000 T.oz. (62600 g).
24. Copper (1983) (EYB): 7,960 kg.
25. Zinc (1983) (EYB): 14,820 kg.
26. Crude steel (1984) (SAE): 17000 mt.
27. Fuels & lubricants imports (EYB): 82 E6 US $.
28. Raw material (Ag and industry) (EYB): 677.4 E6 US $.
29. Capital goods (Ag and industry) (EYB): 3995 E6 US $.
30. Transport equipment (EYB): 203 E6 US $.
31. Construction materials (EYB): 49.8 E6 US $.
32. Consumer goods (EYB): 219 E6 US $.
33. Imported Services (EYB): 954 E6 US $.
EMERGY Evaluation of Annual Export Flows for Ecuador in 1986
Note Item Raw Units Transformity Solar Emergy Macroeco-
JL$ Sej/unit E20 nomic US $E6*
1 Petroleum-energy 435E+17 53E+04 23055 11527.50
Efficient equivalent 1.68E+14 4.0E+06 6.72 336.00
Resource used 1.68E+14 1.82E+07 31.25 1562.00
3 Bananas 1.20E+15 3.2E+05 3.84 192.00
4 Coffee (1985Xg) 9.60E+10 93E+05 31.25 0.04
5 Cocoa (1985)(g) 1.28E+11 93E+05 0.00 0.06
6 Fish products 2.00E+15 1.30E+05 2.60 130.00
7 Cocoa products (US $) 7.71E+07 8.70E+12 6.71 33539
8 Petroleum deriv. (US $) 7.01E+07 8.70E+12 6.10 304.94
9 Services (US $) 4.40E+08 8.70E+12 38.28 1914.00
Footnotes for Table 2
* dividing Solar Emergy values by 2.0 E12 sej/US. 1989 $.
U.S.Dollar values from Europa Yearbook(1988) are included in footnotes.
1. Petroleum exports (1986): 190 E3 b/d. (South America Economist, 1987).
(190 E3 b/d)(365 dX6.28 E9 J/b) = 4.35 E17 J. ($ 912 E6).
2. Shrimp exports: 100% production 1986 (30,000 mt).
(30 E9 g)(.2 DM)(6700 cal/g)(4.186 J/cal) = 1.68 E14 J. Dollar value $315 E6 (EYB, 1988).
The first value is the EMERGY minimum to make shrimp anywhere; The second value is the
resource used in shrimp pond exports. See Table 15.
3. Bananas: 2.3 E6 mt (Europa Year Book, 1988 - EYB).
(23 E12 g)(.25 DM)(5 kcal/g)(4186 J/kcal) = 1.20 E15 J. ($263.4 E6).
4. Coffee (EYB): 96 E3 mt.
($ 298.9 E6).
5. Cocoa (EYB): 128 E3 mt.
($ 71 E6).
6. Fish catch: (total yield herring, sardine, anchovies, mackerel) 826.1 E3 mt. (EYB, 1988).
(826.1 E9 g.5)(.2 DM)(5800 cal/gX4.186 J/cal) = 2.00 E15 J.
Export value of seafood products ($ 725 E6).
7. Cocoa products (EYB): $77.1 E6.
8. Petroleum derivatives (EYB): $70.1 E6.
9. Services exported (EYB): $440 E6. EMERGY/$ ratio for Ecuador is used here appropriate for
service of Ecuadorians.
Summary Flows for Ecuador, 1986; See Figure 13.
Letter Item Solar Emergy Dollars
E20 Sej/yr E9 $/y
R Renewable sources - rainfall, tide etc. 481
N Nonrenewable flows 652
NO Dispersed rural 289
N1 Concentrated use 132
N2 Exported without use 231
F Imported fuels and minerals 19.4
G Imported Goods 19.7
I Dollars paid for imports 258
P2I Emergy value of goods and services imports 61.9-
13 Dollars paid for imports minus goods '- 0.95
P2I3 Imported services 22.9
E Dollars paid for exports 2.62
PIE Emergy value of goods and services exports 228
B Exported products transformed within country 445
E3 Dollars in exported service 1.49
P1E3 Exported service 130
X Gross national product 11.13
U Total EMERGY use within Ecuador 964
P2 U.S. EMERGY/$ ratio used for imports 2.4 E12 Sej/$
P1 Ecuador EMERGY/$ ratio used for exports 8.5 E12 Sej/$
EMERGY/Sucre ratio 7.1 E10 Sej/Su
Footnotes for Table 3:
R Renewable sources (see Table 1): Rain, tides, and offshore current.
N Nonrenewable sources: NO + N1 + N2 = 641.
NO Dispersed rural Mangroves lost 0.6 E20, soil loss 283 E20 Sej, and wood consumption 5.72
N1 Concentrated use: (Table 1, E20 Sej/yr) hydroelectricity 10, natural gas 10.9,31 % of oil 111,
N2 Exported without use: 65% petroleum production 231 E20 Sej. $ services in N2, US $ 912 E6.
F Imported Fuels and materials: (Table 1, E20 Sej/yr) Fuels 1.97, Raw material for ag and
industry 17.45. Sum, 1942 E20 sej/yr; dollars in fuel, F, $82 E6. raw material (including
construction) $727.2 E6.
G Imported goods: (Table 1, E20 Sej/yr) capital 9.60, transport equipment 4.87, consumer 5.26.
Dollars in G: Capital $3995 E6, transport $203 E6, consumer $219 E6.
I Dollars paid for imports (Table 1): US $ E9 2.58.
P2I EMERGY value of goods and services imports: 258 E9 x 2.4 E12 Sej/$ = 61.92 E20 Sej.
13 Dollars paid for imported services: $ 0.95 E9.
P213 Imported services: 0.95 E9$ x 2.4 E12 Sej/$ = 22.75 E20 Sej.
E Dollars paid for exports: 2.62 E9 $/yr
PIE EMERGY value of goods and services exports:
(262 E9)(8.7 E12 Sej/$) =228 E20 sej/yr.
B Exported products transformed within country (see Table 2) (E20 Sej/yr) Petrol derivatives
7.92, Fish products 2.6, cocoa 10.8. Dollar values: petrol ,$70.1E6, cocoa products $77.1 E6,
seafood products $72.5 E6; total, $0.22 E9.
E3 Dollars paid for exports, 2.62 E9, minus dollars in goods (B) $ 0.22 E9, and raw exports $ 0.91
E9 = 1.49 E9.
P1E3 Exported services: (1.49 E9X8.7 E12 Sej/$) = 129.6 E20 Sej.
X Gross national products 1986:11.1 E9 $ = 1.366 E12 Sucre/yr.
U Line 5, Table 4
P2 U.S. EMERGY/dollar ratio (Odum & Odum1983): 2.4 E12 Sej/$.
P1 EMERGY/ /dollar ratio for Ecuador
EMERGY used (R+NO+N1+F+G+IP2) = U = 964 E20 Sej/yr
EMERGY/dollar ratio = U/CNP = 8.5 E12 Sej/$.
EMERGY/sucre ratio =964 E20 Sej/1.366 E12 sucre = 7.1 E10 sej/sucre.
EMERGY Indices for Ecuador based on Table 3 and Figure 13.
Item Name of index Expression Quantity
1 Renewable use R 481 E20 Sej/y
2 Use from indigenous nonrenewable reserves N 421 E20 Sej/y
3 Flow of imported EMERGY F+G+P2I3 62 E20 Sej/y
4 Total EMERGY inflows R+N+F+G+P2I3 1195 E20 Sej/y
5 Total EMERGY used, U NO+NI+R+F+G+P213 964 E20 Sej/y
6 Total exported EMERGY N2+B+P1E3 314 E20 Sej/y
7 Fraction of EMERGY used derived from
home sources (NO+NI+R)/U 0.92
8 Imports minus exports (F+G+P2I3)-(N2+B+P1E3) -252 E20 Sej/y
9 Ratio of exports to imports (N2+B+PIE3)/(F+G+P213) 5.0
10 Fraction used, locally renewable R/U 0.49
11 Fraction of use purchased (F+G+P213)/U 0.06
12 Fraction used, imported service P2I/U 0.06
13 Fraction of use that is free (R + NO)/U 0.80
14 Ratio of concentrated to rural (F+G+P213+N1)/(R+NO) 0.24
15 Use per unit area (2.8 Ell m2) U/area of country 3.4 Ell Sej/m2
16 Use per person (9.6 E6 population) U/population 10.0 E15 sej/p
17 Renewable carrying capacity at
current living standard (R/U)(population) 4.7 E6 people
18 Developed carrying capacity at
same living standard 8(R/U)(population) 37.6 E6 people
19 Ratio of use to GNP, EMERGY/$
(GNP: $ 11.13 E9 $/yr)) P1 = U/(GNP) 8.5 E12 sej/$
(GNP: 1.366 E12 Su/yr P1 = U/(GNP) 7.1 E10 sej/s
EMERGY Self Sufficiency and Exchange
EMERGY ENERGY received
Nation from within EMERGY exported
Netherlands 23 43
West Germany 10 4.2
Switzerland 19 3.2
Spain 24 23
USA 77 22
India 88 1.45
Brazil 91 0.98
Dominica 69 0.84
New Zealand 60 0.76
Poland 66 0.65
Australia 92 . 0.39
Soviet Union 97 0.23
Ecuador 94 020
Liberia 92 0.151
EMERGY Use and Population
EMERGY used Population EMERGY use
Nation E20 sej/yr E6 per person
U* E15 sej/person/yr
Australia 8850 15 59
USA 66400 227 29
West Germany 17500 62 28
Netherlands 3702 14 26
New Zealand 791 3.1 26
Liberia 465 13 26
Soviet Union 43150 260 16
Brazil 17820 121 15
Dominica 7 0.08 13
Switzerland 733 637 12
Ecuador 964 9.6 10
Poland 3305 34.5 10
Spain 2090 134 6
World 180000 5000 3.6
India 6750 630 1
* U, see example in Table 4, Line 5.
Concentration of EMERGY Use
Area Population* Empower
Nation E10 m2 density density#
people/km2 Ell sej/m2/yr
Netherlands 3.7 378. 100.0
West Germany 24.9 247. 70.4
Switzerland 4.1 154. 17.7
Poland 312 111. 10.6
Dominica 0.075 107. 8.8
USA 940. 24.2 7.0
Liberia 11.1 16.1 4.1
Ecuador 28.0 34. 3.4
Spain 50.5 685 3.12
New Zealand 26.9 115 2.94
Brazil 918. , 132 2.08
India 329. 192. 2.05
Soviet Union 2240. 11.6 1.71
Australia 768. 1.9 1.42
* Population from Table 6 divided by national area where 1 km2 = 10 E6 m2.
# Rate of EMERGY use (Table 6) divided by national area.
National Activity and EMERGY/$
ENERGY used/yr* GNP ENERGY/$
Nation E20 sej/yr E9 $/yr E12 sej/$
Liberia 465. 1.34 345
Dominica 7. 0.075 14.9
Ecuador 1029. 11.13 85
Brazil 17820. 214. 8.4
India 6750. 106. 6.4
Australia 8850. 139. 6.4
Poland 3305. 54.9 6.0
World 188000. 5000. 3.8
Soviet Union 43150. 1300. 3.4
New Zealand 791. 26. 3.0
USA 66400. 2600. 2.6
West Germany 17500. 715. 25
Netherlands 3702. 16.6 2.2
Spain 2090. 139. 1.6
Switzerland 733. 102. 0.7
* Calculated as in Table 4 line 5.
Overview Indices for Ecuador
Overview indices calculated for Ecuador in Table 3 and 4 used data from Tables 1 and 2.
Different EMERGY in Exported and Imported Services
Money is paid only to people, not nature. When payments in local currencies are expressed in
international dollars for a particular year, there may be large difference between the EMERGY that
was contributed to a dollar's services of one country compared to another. The total EMERGY used
per year in Ecuador was divided by the gross economic product in U.S. $ at the time to obtain the
EMERGY/$ ratio-also illustrated in Figure 13b.
For the period evaluated here, the EMERGY/$ for Ecuador was 8.7 E12 sej/$, almost four
times larger than that for the USA (24 E12 sej/$). For more rural nations, more of the basis for life
comes to people direct from nature without payments. Thus, more of the real wealth used to support
their labor is represented per dollar earned.
The pattern of environmental resources in Ecuador can be put in perspective with
comparisons to similar analyses of other countries (Odum and Odum, 1983; Pillet and Odum, 1986).
See various indices compared in Tables 5-9. As might be expected, Ecuador is similar in many
indices of development to Brazil, with high degree of self sufficiency (Table 5). Half of the economy
was based on renewable resources and half on non-renewable usages (fuels, soils, mature forest
wood). Non-renewable resources are those that are very slowly renewed by natural processes of
earth cycles, but are being used much more rapidly than they are being replaced.
The EMERGY use per person indicates a moderate EMERGY standard of living (Table 6),
even though the income per person is low. The concentration of EMERGY use per area is lower than
the developed countries (Table 7). People receive environmental products and services free.
Regional EMERGY Investment Ratios
The ratio of purchased EMERGY to free Environmental EMERGY within Ecuador (Table 9)
was only 0.09, much less than the values of 7 or more in developed countries. This ratio is a measure
of intensity of development. It indicates a high degree of environmental matching to investments,
typically. In part the very low value reflects the large areas of undeveloped Amazon forests.
For consideration of shrimp pond developments, an EMERGY investment ratio was
calculated for the coastal region only where populations are more concentrated. The coastal region's
investment ratio was 23, more than for the whole country but still less than in developed countries.
(50% of the nation's population is present in the region and was assumed to purchase half of the
national energy use and 75% of the imports.)
E20 solar emjoulesyr E9 US 1966 $
R. NOI N N2
E20 sayYr -
Figure 13. Aggregated summary diagram of the Ecuador national system used to calculate
national EMERGY/$ ratio for the year. (a) Flows from Table 1; (b) summary.
SHRIMP AND INTERNATIONAL EXCHANGE
Commercial shrimp production, mainly exported, constitutes 35% of the exports on a dollar
basis. Because of the high EMERGY content of exported oil, the shrimp export (Table 2) constitutes
only 10% of the total EMERGY exported. The export of oil and shrimp is very bad for the economy
of Ecuador compared to the development that would occur if these products were used internally.
Consider the inequity in real wealth of the exchange (Table 5) and the reasons.
High EMERGY of Currency of Ecuador in International Exchange
The EMERGY per international dollar converted from the local currency in sucres (Table 8)
was much higher than dollars converted from currencies in developed countries because more of the
EMERGY was consumed directly without market transactions. International US. dollars had much
higher buying power in Ecuador than in the United States (EMERGY/$ was 8.7 E12 in Ecuador and
only 2.4 E12 in the U.S.).
Typical of underdeveloped countries, the EMERGY/$ ratio of Ecuador (Table 3) is much
higher than that of the United states and other developed countries. This is because more EMERGY
of the environment is used directly without any money being involved. Thus, more of the basic
needs that are required for human service are free and thus the costs of labor are less. When money
is converted on international currency exchange, no credit is given for the free EMERGY
contributions to the labor and services. In effect, the buying power of international US. dollars in
Ecuador is many times higher than in the United states. The EMERGY/$ ratio in Ecuador was 8.7
trillion emjoules per dollar (TREMS/$) compared to 2.4 TREMS/$ for the U.S.A. for the same year.
The EMERGY/$ ratio of Ecuador in 1986 was 3.6 times that of the U.S in that year. The EMERGY
buying power of a dollar in Ecuador is 3.6 times that in the U.S.
If money is borrowed by Ecuador from the U.S. and used to buy products in the United states
and later paid back from Ecuadorian currency converted on international currency exchange, 3.6
times more buying power is paid back. This is equivalent to an interest rate of 360%. Little wonder
that investments by developed countries in underdeveloped countries have caused financial
depression in underdeveloped countries.
SIf the shrimp development projects are started with foreign loans, the effect of paying back
interest and principle is a huge drain of EMERGY from the local economy. In the EMERGY analysis
this is an additional EMERGY requirement of the system, but one not essential to the most efficient
production of shrimp.
EMERGY Exchange with Foreign Sales of Shrimp
Consider the EMERGY exchange due to sales of shrimp, even if no foreign investments, loans,
or debts are involved. Figure 14 shows the balance of EMERGY when the shrimp from Ecuador are
sold on the international market for US. dollars. The EMERGY in the shrimp going to foreign
buyers is 4 times more than the EMERGY they receive back in buying power of US. products. This
difference has two reasons. First, the commodity has large EMERGY of environmental work for
which no money is paid. Second, the human labor in Ecuador has more EMERGY per dollar because
Environmental and Economic Components of EMERGY Use
Environmental* Economic# Economic/
component, component environment
renewable EMERGY of EMERGY ratio
Nation E20 sej/yr E20 sej/yr
West Germany 193. 17300 90.
Poland 159. 2946 18.5
Holland 219. 3483 15.9
Switzerland 86.8 646 7.4
USA 8240. 58160 7.1
Spain 255. 1835 7.2
Dominica 1.75 -4.8 2.7
World 80000. 188000 235
Australia 4590. 3960 1.1
India 3340 3410 1.0
USSR -9110 9110 1.0
New Zealand 438. 353 0.8
Brazil 10200. 7600 0.74
Ecuador 891. 483 0.09
Liberia 427. 38 0.09
* As calculated for Tables 5 and 6.
# Total EMERGY (U in Table 4) minus renewable component = U-R-No.
more of the EMERGY to support a person comes directly from the environment without involving
money, as previously discussed. Drawing shrimp into international markets reduces their
contribution to the local economy in real terms, as measured by EMERGY, by 4 times. The effect on
the buying country is more than four times, contributing to the wealth and standard of living of the
developed country at the expense of the underdeveloped country.
EMERGY Trade Balance for Ecuador
Because of the export sale of raw fuels, shrimp, and other environmental products, much
more EMERGY goes abroad than is received in payment (Table 5). Five times more EMERGY was
sent abroad than received. Ecuador was contributing to the largesse of developed countries,
stripping its wealth from its own people, 75% from its non-renewable soils and oil, i.e. its future.
Equity might be arranged by balancing the higher EMERGY in the exported shrimp with feedbacks
to the shrimp-producing economy in some other products, services, or information.
EMERGY Feedback Reinforcement of Environmental Work
Because of the heavy drain of environmental resources for wild shrimp stocks and other
estuarine-dependent species by the highly intensive shrimp mariculture, the necessary nursery and
reproductive system is being diminished. The past history of exploitation of marine fisheries where
there has not been reinforcing feedbacks to the food chains of economic value has lead to their
displacement by other food chains not subject to economic use. The equity feedback of EMERGY
from the world economy needs to be passed on to the environmental processes if the system is to be
Where agriculture is successful and sustainable for an extended period, the environmental
processes of soil and plant production are aided by feedbacks of EMERGY from the economy, often
mislabelled "subsidies". For example, New Zealand provided fertilizer at government expense.
These feedbacks have been scarce in marine culture efforts.
Shrimp Culture Isolation from the Local Economy
As the configuration "shrimp ponds" in Figure 6 shows, the shrimp production system can be
operated as a branch of the international economy without much relationship to the local economy
of Ecuador if most of the money received from international sales is spent back in the developed
countries. The local economy is reduced to the extent that the EMERGY of the environmental
resources for the ponds is diverted from the previous local use. Local use of labor at local wage rates
subsidizes the product without returning much of the EMERGY to the local economy. The EMERGY
of old and new shrimp production systems is considered next.
Buying power to Ecuador
(3.15 E8 $/yr)(2.4 E12 sej.US 1986$) = 7.6 E20 se(jyr
Goods, services, fuel -
- . . >... - 7.6 E20 sej/yr
Shrimp 31.2 E20 sejyr
Shrimp from Ecuador:
(3 E10 glyr)(0.2 dry)(6.7 kcal/g)(4186 Jikcal)(18.2 E6 sejJ) = 31.2 E20 sej/yr
Figure 14. Diagram of the exchange of EMERGY and money with foreign sale of 30,000 metric tons
(fresh weight) of shrimp from Ecuador. Transfonnity benefit ratio to US. is 4.0..
Simulation of Price Effects on Sale of a Renewable Resource
The sensitivity of shrimp exports to foreign market prices is illustrated with a simulation
model. Figure 16 is a much aggregated interface model typical of the economic use of an
environmental production system. Environmental work is generating products on the left. At the
interface with the economy, more inputs of labor, materials, information, etc., purchased from the
economy interact to generate the economic product that goes for sale to the right. Depending on the
price, money is received that goes into storage of money on hand M. Money is then paid out for
inputs, some of which go to maintain the capital asset storage A.
In this model the environmental production is limited by its input energies, but there are no
competing units present to take over the resources when an economic load is placed. In other words,
this model has sustainability built into it It has carrying capacity limitations but cannot crash due to
displacement of alternative environmental species and systems. So long as the input energies are
held constant, the main variables are the market prices. It is an appropriate minimodel for isolating
the effects of exchange prices on a source limited product.
If the simulation starts at low state, the system grows in assets and money until it is limited by
the environmental production process, which is based on renewable, limited flow sources. Changing
the relative price of purchased inputs simulates the price of oil and oil-based products on the world
market, ultimately affecting how much one can stimulate the economic interface. For example, a
gradual increase in price in successive years (Figure 16a) causes fishermen's assets (boats, nets,
information) or pond assets to decline, eventually to a place where there is no net yield. At first,
however, there is little effect on the sales because there is compensation in rebound of the resource
availability (R) as the fishing intensity decreases. There is little to fear from less intensive
environmental use in this range of properties. See simulation in Figure 16a.
The simulation in Figure 16 held sales price constant. If the sales price is arranged to rise with
decrease in supply, the simulation in Figure 16b results, which has even more stable sales over wide
range in the purchased inputs. This system caused environmental loading to increase in spite of
decrease in resource when fuels and the goods and services on which they are based were becoming
cheaper. When fuels become more expensive, the environmental loading will become reduced
without affecting the sales over a wide range.
Spreadsheet Calibration Table Used to Calculate Coefficients of the
Simulation Model PRODSALE.BAS Using Numbers from Figure 15
Renewable Sources, J
Price of sale product, pi
Price of purchased inputs, p2
Unused source, R = J/(1 + kl*E*A)
Money on hand in $, M
Resources used, Kl*R*E*A
Money spent, K2*M
Goods, services to assets, K3*E
Assets into production, K4*A
Assets depreciation, K5*A
Table 11 BASIC Program PRODSALE.BAS for IBM PC. See Model in Figure 15
10 REM IBM
20 REM PRODSALE: PRODUCTION ON RENEWABLE SOURCE
40 SCREEN 1,0: COLOR 0,0
50 LINE (0,0)-(319,180),3,B
60 LINE (0,90)-(319,90),3
70 REM External sources:
80 J = 1: REM Environmental source
90 P1 = 1:REM Price of product
100 P2 -.5:REM Price of purchased inputs
105 PC = .1'P2:REM 1% price change
110 REM Starting conditions
120 A=.1: REM Assets
130 M - 200:REM Money
140 E = 100:REM Purchased Inputs
150 Y - 100:REM Product yield
160 REM Scaling factors for graph
170 AO = 20
180 MO -.6
190 TO = 3
200 DT - .5
210 K1 - 9.000001E-02
220 K2 = .1
230 K3 - .002
240 K4 = .01
250 K5 - .1
260 K6 10
270 REM Equations
280 REM Plotting instructions
290 PSET (T TO,180 - A AO),3
300 PSET (T * TO, 90 -JM * MO),1
310 LOCATE 2,23: PRINT "Sales, $/ha/yr"
320 LOCATE 13,23: PRINT "Assets,A"
325 REM Equations
327 P1 = 100/(Y +20)
340 R-J /(1+K1*E*A)
360 E K2 * M/P2
375 JM = P1*Y: REM sales, $
390 DM P1 Y-K2*M
420 M - M + DM * DT
440 REM Instruction to return and repeat
450 IF T * TO < 320 GOTO 270
460 P2 = P2+PC
470 T 0
480 X = X +1
490 IF X <15 GOTO 110
500 LOCATE 1,1
R - J1 + kV'E*A)
DA - W'E - K4*R" A - K5*A
DM - PY - K2*M -
Figure 15. Simple simulation model PRODSALE, an example of an economic interface calibrated for shrimp ponds.
0> Price, p2
o-c'l i..i- q ...,U.II I - .--o I ..... .....I .. ........
2 . -..-- ."-'. . -"...... .
..t-i-...... I*..." Incr.....
j~t .."-** .. ..-" ..-... .......--
.; ,; :- .. ....... ..................................
,iii ......;.::: . .::::...
Figure 16. Results of simulating the model of economic yield PRODSALE in Figure 15. Assets are
built up from sales income (without capital investment). (a) successive runms with price of purchased
inputsp2increased witheachrun;sales p constant;(b) sameas(a)exceptsalesprice responding
inversely proportional to yield, Y with inelastic it =5: p = 100(20 + Y)
Figure 16. Results of simulating the model of economic yield PRODSALE in Figure 15. Assets are
built up from sales income (without capital investment). (a) successive runs with price of purchased
inputs p2 increased with each run; sales pl constant; (b) same as (a) except sales price responding
inversely proportional to yield, Y with inelastic limit = 5: pl = 100/(20 + Y).
Figure 17. Energy systems diagram of the mangrove nursery ecosystem,
List of Figures
Figure 1. Aerial view of shrimp ponds in Ecuador. 2
Figure 2. Map of Ecuador with Gulf of Guayaquil, continental shelf, and pelagic
deep water ecosystem that supports shrimp reproduction and larval growth. 3
Figure 3. Diagram for comparing EMERGY benefit of a new environmental use (P2)
with an old system (PI), with typical alternatives in the region (PA),
and maximum potential (PD) matching environmental EMERGY with
economic inputs according to the regional investment ratio R. 4
Figure 4a. Energy systems diagram of the coastal systems of Ecuador and the life cycle
of shrimp between inshore mangroves (below) and offshore shelf ecosystems
(a) whole system; 5
(b) life cycle of shrimp only. " 6
Figure 5. Overview systems diagrams of shrimp culture ponds and their inputs. 7
Figure 6. Overview systems diagram of Ecuador and its foreign trade. For a more
detailed version, see Figure 12. 8
Figure 7. Symbols of the energy language used to represent systems (Odum, 1983). 10
Figure 8a. Definition of solar transformity applied to shrimp (Table 15). 17
Figure 8b. Net EMERGY yield ratio for evaluating primary sources and EMERGY
investment ratio for evaluating whether matching of investments with
environmental contributions is competitive. I and F should all be in
solar EMERGY units. 17
Figure 9. EMERGY exchange ratio of a transaction. (a) trade of two commodities;
(b) sale of a commodity. 18
Figure 10. Overview diagram of a national economy. (a) main flows of dollars and
energy; (b) summary of procedure for summing solar EMERGY inflows. 19
Figure 11. Energy amplifier ratio. 20
Figure 12. Main sectors of society and nature in Ecuador. See also Figure 6. 25
Figure 13. Aggregated summary diagram of the Ecuador National system used to
calculate national EMERGY/$ ratio for the year.
(a) flows from Table 1; (b) summary. 36
Figure 14. Diagram of the exchange of EMERGY and money with foreign sale of
shrimp from Ecuador. 40
Figure 15. Simple simulation model PRODSALE, an example of an economic
interface calibrated for shrimp ponds. 44
Figure 16. Results of simulating the model of economic yield PRODSALE
in Figure 14. Assets are built up from sales income (without
(a) Successive runs with price of purchased inputs P2 changed with each
run; sales price (P1) constant; 45
(b) same as (a) except sales price responding to inverse to supply
(yield, Y) with inelastic limit = 5: P1 = 100/(20 + Y). 45
Figure 17. Energy systems diagram of the mangrove nursery ecosystem. 46
Figure 18. EMERGY benefit comparison of original system with trawls (P1), new
system of ponds and trawls (P2), typical alternative investment (PA),
and potential development (PD). 68
Figure 19. Overview simulation model MAXSHRMP for determining the benefits of
production of shrimp for various areas of pond development Systems
diagram includes variables and coefficients, EMERGY flow designations,
and numerical values used for calibration. 72
Figure 20. Results of simulating the program MAXSHRIMP.BAS diagrammed in
Figure 19, graphing variables with time for 10% of mangroves
converted to ponds. 74
Figure 21. Results of simulating the program MAXSHRIMP.BAS (Figure 19) graphing
stocks and EMERGY flows as a function of mangrove area developed into
shrimp ponds. (a) Upper panel: yield of shrimp in ponds, Y; middle
panel, shrimp larvae, L; lower panel: shrimp in estuary, SH;
(b) upper panel, total EMERGY production of ponds and mangroves,
JE; middle panel, total sales of shrimp, JM; lower panel, yield
of shrimp from ponds, YP. 75
SHRIMP ECOSYSTEMS OF COASTAL ECUADOR
In order to evaluate the new shrimp pond systems in relation to the environment and
previous pattern, coastal systems supporting shrimp were examined including the inshore gulf and
estuary, the offshore pelagic waters, the mangrove nursery areas, and the shrimp ponds.
Ecosystems Supporting Reproduction, Recruitment, and Growth of Shrimp
Much of the coastal zone contributes to the environmental shrimp production including the
mangroves, the estuarine waters, the continental shelf and offshore waters which are productive
with phytoplankton due to upwelling (Figure 2).
The normal life cycle of the commerical shrimp starts with release of larvae from reproduction
out in the open sea. The microscopic larvae released into the open sea plankton ecosystem, grow into
post larvae (macroplankton) depending on the phytoplankton. Tides, currents, and the transport
generated by waves bring the post-larvae to shore, into the Gulf of Guayaquil, and into the
mangroves (Figure 1). Thus, the small shrimp are "recruited" into the shrimp fishery. The mangrove
areas generate shrimp food, organic matter and small organisms, much of it derived from the
mangrove production, so that the mangrove waters and adjacent estuary are called a "nursery."
Here, the shrimp reach half size, "bait shrimp size," # several months. Aided by the tides, they
migrate out into the open seas, growing to full size there, later reproducing and releasing larvae
The pattern of inshore and offshore reproduction and inshore nursery growth is used by some
species of crabs and fishes as well as several species of shrimp. The offshore plankton ecosystem
yields plankton-eating fish, pelagic herring, sardines, and anchovetta, especially in the upwelling
zones just off the shelf to the southwest Periodically, in some years, the upwelling and its
contribution to the productivity offshore is interrupted by the change in the worldwide east-west
wind-current regimes. Warm waters displace the cold, nutrient-rich regime and its species.
Traditionally, fisheries based on the shrimp, crabs, and fish supplied local and international
markets. Some of the half-size shrimp and fish were caught in the estuary and larger ones caught
offshore. The EMERGY in the fishery products high in the food chain was contributed by the several
kinds of energy driving the coastal system.
As of 1989, shrimp pond development was spreading through the coastal zone, often
displacing the mangroves and other ecosystems that contribute to the estuarine nursery. Even
though many of the ponds were built on former salterns, the briny, algal-dominated salt flats, these
also reduced the organic matter made there by algae and flushed into the estuary at time of floods.
.. The energy systems diagram of the coastal system (Figure 4) has the offshore plankton
ecosystem above and the inshore mangroves and estuarine ecosystem below. The new ponds are
included. The yields of shrimp and other products from ponds and from trawl fishing are on the
right. The sources of EMERGY are the resource inputs represented in the diagram by the external
circular symbol. Especially important are the high quality sources, the physical circulation energies,
rivers, and nutrients, which have high transformities (high solar EMERGY per unit energy).
EMERGY Inputs to the Coastal Ecosystems
The EMERGY inputs to the coastal ecosystems were evaluated with EMERGY analysis Table
12 as drawn in Figure 4. For the purpose of evaluating the coastal system used by the shrimp life
cycle, an offshore boundary was drawn to include the continental shelf out to 100 meters depth
contour (Figure 2).
Annual EMERGY Flows of the Coastal System of Ecuador. See Figure 4.
Note Item Raw Units Transformity Solar Emergy Macroeco-
J,g$ Sej/unit E20 nomic US $E6
Offshore - Contintental Shelf and Coast Area: 18500 E6 m2
Deepwater nutrient - N (g)
Deepwater nutrient - P (g)
Pelagic trawl - fuel used
Pelagic trawl - G & Services
Pelagic fishery landings
Shrimp trawl - fuel used
Shrimp trawl, goods,services
Shrimp fishery landings
Inshore - Estuaries and beachesArea: 6330 E6 m2
14 Sun 236E+19 J
15 Wind 2.29E+15 J
16 Waves 7.76E+16
17 Rainfall 5.00E+16 J
18 River - chemical potential 5.13E+17 J
19 River - total N (g) 1.29E+11 g
20 River - total P (g) 1.42E+10 g
21 River - Organic load (COD) 2.77E+16 J
22 Tide 727E+16 J
23 Inputs to Shrimp Ponds (Table 14)-
23 Shrimp pond yield
Minimum efficient value 1.68E+14 J
Resource used in ponds 1.68E+14 J
* Solar EMERGY divided by 2 E12 sej/$ for US.A.
Some of these are included in others.
Indices of Coastal Ecuador
Environmental EMERGY Inputs from Table 12a;
See Note 1, Table 12 about what to include:
Offshore EMERGY inputs: tide absorbed offshore and the largest of the dlimataic-oceanic system, the
Humboldt current (See Table 12,note 4): 33.6 E20 sej/yr (25.0 E20 + 8.56 E20 sej/yr)
Inshore EMERGY inputs: tide absorbed inshore and river water and detritus,
126 E20 sej/yr [(17.1 + 54.1 + 55) E20 sej/yr].
Indices of Offshore Fishery:
Sum of solar EMERGY of input fuels 0.017 E20 sej/yr) and goods and services (0.099 E20 sej/yr)
purchased by pelagic fishery: 0.116 E20 sej/yr. (Fuels underestimated? EMERGY of boat materials
Solar EMERGY of fishery landings, item 10. 5.4 E20 sej/yr
Environmental Input to pelagic fishery calculated by subtracting purchased input(fuels,0.29 E20 &
goods and services, 0.099 E20) from EMERGY of landings(item 10): (5.44 E20 - 039 E20) = 5.05 E20
EMERGY investment ratio of pelagic fishery:
(039 E20/5.44 E20) = 0.07 (very low).
Net EMERGY yield ratio of pelagic fishery (Yield divided by purchased):
(5.83 E20/039 E20) = 14.9 (very high).
Environmental input to coastal zone system including inshore and offshore EMERGY above: (33.6 +
126) E20 = 160 E20 sej/yr; offshore to inshore ratio = 3.8
EMERGY indices of shrimp trawl fishery:
EMERGY of yield (item 13) using minimum (efficient, low intensity) solar transformity from Table
15:0.832 E20 sej/yr
Purchased inputs to shrimp trawl fishery fuels (0.29 E20 + goods and services 0.315 E20) = 0.605 E20
Calculation of environmental inputs: (Yield minus purchased):
(0.832-.605) E20 = 0.227 E20 sej/yr -
EMERGY investment ratio (purchased over environmental):
(0.605 E20/0.227 E20) = 2.7
Regional investment ratio for comparison: 2.3
Footnotes for Table 12
Direct sun, rain, pacific circulation, wind, and waves are all mutual by-products of the same
EMERGY sources. Therefore one subtracts each from the largest before adding back to eliminate
Offshore - continental shelf to 100 m depth; see Figure 2. Area, 1.85 E10 m2.
1. Sunlight: area 18500 E6 m2, av. solar radiation 127 kcal/cm2/yr, .7 absorbed. (.7)(18500 E6
m2)(127 E4 kcal/m2/yr)(4186 J/kcal) = 6.88 E19 J.
2. Wind kinetic energy: using diffusion and gradient values for FL. (1000m)(1.23 kg/m3)(18500
E6m2) ((.5)(3.154 E7 sec/yr)(2.8)(2.3E-3)A2 + (5)(3.154 E7 sec/yr)(1.7)(1.E-3)^2) = 6.69 E15
3. Rainfall chemical energy: (1.603 m)(18500 E6 m2)(1 E6 g/m3)(4.94 J/g) = 1.46 E17 J.
4. Physical current energy transferred from the Pacific Ocean Circulation. The Humboldt
current sweeps over the continental shelf of the southern half of Ecuador half of the year
(Cucalo'n, 1988). See Figure 2; half of shelf areg: 9.3 E9 m2). Assume water current 03 m/s
with 10% absorbed.
Kinetic energy over the shelf during the half year:
(93 E9 m2)(50 m avg. depth)(1.025E3 kg/m3)(5)(3 m/s)(.3 m/s) = 2.14E13 J
Rate of replacement turnover from velocity and entry cross section:
(03 m/s)(1.55 E7 seconds/halfyear)((50 m)(100 E3 m)/(9.3 E9 m2)(50 m)
= 50 times per half year
Energy absorbed: (2.14 E13 JX50/yr)(.1 absorbed) = 1.07 E14 J/yr
Solar transformity that of!Mississippi River current at New Orleans
80 E5 sej/J (Odum, Diamond, and Brown, 1987)
5. Nutrients nitrogen inflowing from deepwater on half of the area half of the year: 0 .3
microg-at/m2/s av. flux, 40% exported (Carpenter and Capone, 1983).
(0.5)(.6))(3 ug-at/m2/sX14E-6 g N/u-at)(3.154 E7 sec/yr) = 39.7 g/m2-yr.
(39.7 g/m2/yr)(93 E9 m2) = 3.7 Ell g/yr.
Solar transformity of marine nutrient nitrogen, 9.0 E8 sej/g was derived from world annual
EMERGY flux divided by world oceanic nitrogen flux.
6. Nutrients phosphorus inflowing from deepwater on half of the area half of the year: P
values 1/8 of N values observed (Walsh, 1981), est. 0.0375 microgram-at/m2/s.
(0.5)(0.6)(.0375 ug-at/m2/sX31 E-6 g P/ug-at)(3.154 E7 s/yr) = 11 g P/m2/yr.
(11 g/m2/yr)(9.3E9 m2) = 1.02 Ell g/yr.
Solar transformity of marine phosphate phosphorus, 8.1 E9 sej/g was derived from world
annual EMERGY flux divided by world oceanic phosphorus flux. Nitrogen and Phosphorus
are cycle by-products representing the same EMERGY
7. Tidal energy: average height 1. m. (Twilley, 1986), 50% absorbed on shelf, 185 E10 m2 area.
(706/yr)(5)(9.8 m/s2)((1.025 E3 kg/m3X1.85 E10 m2)(0.5)(1.8 m)(1.8m) = 1.06 E17 J/y.
8. Pelagic trawl - fuel consumed (1986) (Banco Central del Ecuador, Div. Tecnica, 1988) 9.54 E6
Su (1975 prices adjusted). (9.54E6 Su)/(41.2 Su/gallon) = (231.5 E3 gallon)(137 E6 J/gal) =
3.17 E13 J.
9. Pelagic trawl - goods and services (1986) 138 E6 Su (as above 1975 prices adjusted). (138 E6
Su)/122 Su/US $ = US $1.13 E6.
10. Landings of Pelagic Fishery; 826 E3 tonne/yr; also see Calculon(1986);
(826 E3 tonne/yr)(1 E6 g/tonne)(.2 dryX6 kcal/gX4186 J/kcal)
= 4.15 E15 J/yr
Solar transformity for landed fish 3.36 E5 sej/J; see note 9, Table 14.
11. Shrimp trawl fuel consumed: see notes in Table 16; 4 E6 gallons diesel/yr.
(4 E6 gallons)(137 E6 J/gal) = 5.48 E14 J/yr.
12. - Shrimp trawl goods and services: 547,055 Sucre/mo per vessel (McPadden, 1986), 266
vessels, est. 3 months operations per year.
(547,055 Sucre/mo-vessel)(266 vessel)(3 months)/(122 Sucre/US) $ = US $ 3.58 E6.
13. Shrimp fishery landings in 1985 (McPadden,1986) 3710 tonne;evaluated with solar
transformity 4 E6 sej/J from other studies.
(3.71 E3 tonne/yrXl E6 g/tonne)(.2 dry)(6.7 kcal/g)(4186 J/kcal)
= 2.08 E13 J/yr
Inshore - estuaries and rivers:
14. Sunlight (6330 E6 m2)(127 E4 kcal/m2/yr)(.7)(4186 J/kcal) = 2.36 E19 J.
15. Wind kinetic energy: values as #2 above.
(6330 E6 m2)(1000 m)(1.23 kg/m3) ((.5)3.154 E7 sec/yr)(28)(23 E-3)^2 + (5)(3.154 E7
sec/yr)(1.7)(1.5 E-3)^2) = 2.29 E15 J/yr.
16. Waves: See Table 1, note 7.
17... Rain chemical energy (1.603 mX6330 E6 m2)(1 E6 g/m3)(4.94 J/g) = 5.0 E16 J/yr.
18. River chemical energy: 750 TDS (Ariaga, 1986). Gibbs free energy relative to sea water: 138.8
* In((1 E6 - 750)/965000) = 4.48 J/g.
Coastal river discharges: 115 E10 m3/yr
(4.48 J/g)(1 E6 g/m3)(11.5 E10 m3/yr) = 5.13 E17J.
Solar transformity is that of average world river flow.
19. River total N (Solorzano, 1986): 80 mg-at/m3 average concentration at surface. (80 mg-
at/m3)(.001 g-at/mg-at)(14 g/g-at)(11.5 E10 m3/yr) = 12.86 E10 g/yr.
20. River total P (Solorzano, 1986): 4 mg-at/m3 surface average.
(4 mg-at/m3)(0.001 g-at/mg-at)(31 g/g-at)(115 E10 m3/yr) = 14.22 E9 g/yr.
21. River organic load, 115 ppm organic matter (mean of 5 measurements of chemical oxygen
demand from Rio Chone: 21,28,10.6,308.6,212.9,21 mg/litre).
(115 mg/l)(l g/m3/mg/l)(5 kcal/g)(4186 J/kcal)(11.5 E10 m3/yr)= 27.65 E16 J/yr.
22. Tidal energy in estuaries: av. height 1.8 m, all absorbed:
(706/yr)(.5)(9.8 m/s2)(1.8 m)(1.8)(1.025 E3 kg/m3)(6330 E6 m2)= 7.27 E16 J/yr
23. Shrimp ponds, environmental and purchased inputs from Table 14.
24. Shrimp pond yield from Table 14. Two EMERGY values are used in estimating EMERGY.
The first uses the least transformity from less intensive systems (Table 15)-the ultimate
thermodynamic value; the second transformity is that used in the intensive and inefficient
shrimp ponds (Table 14).
The inshore system includes the beaches, estuarine waters, mangroves, and shrimp ponds.
Note the high EMERGY contributions for the tide, currents, the river fresh water, the river
organic matter, and the nutrients. Much of the extraordinary marine productivity of the area is due
to the converging contribution of so many resources, especially the river flows in wet season. The
sharp seasonal variation due to alternation of dry and wet seasons organizes and channelizes net
The high levels of detritus organic matter flowing into the coastal zone are apparent from
aerial reconnaissance. This is the EMERGY of land production, some from the past in erosion of soils
and some from current land production utilizing the rain that was transpired in the present. The
total value contributed by the rivers to the estuaries is very large, 19.1 billion US. $/year (sum of
$10533 E6 and $8626 E6 from items 18 and 21 in Table 12a).
If one adds tide and waves to river inputs, total annual macroeconomic $ value for the coastal
waters is about $21.4 billion/year. The EMERGY of the pelagic fishery and shrimp landings is
substantial but a small part of the total works of nature there.
EMERGY Inputs to the Mangrove Nursery Areas
In Table 13 are EMERGY evaluations of the inputs to the mangrove nurseries considered
separately. Shown in Figure 1, the system includes the mangrove forest, the waters within the
mangroves, and their tidal channels. It is these areas that are being displaced by pond construction
or diminished by diversion of the estuarine waters into the ponds. For the later calculations it was
convenient to evaluate this ecosystem separately. Figure 17 is an aggregated systems diagram of the
mangrove system and the input pathways evaluated in Table 13. The evaluation was made per unit
area and multiplied by the mangrove area for totals.
Some of the products generated as concurrent byproducts within the mangrove system
include live mangrove biomass, organic litter fall, and medium sized shrimp migrating out. The
solar transformities of these products were calculated by dividing the total EMERGY contributions
of independent sources by the energy flux of each item.
EMERGY Evaluation of Daule-Peripa River Diversion
A dam being filled at the time this report is written, will store some water from the Daule
tributary, making the wet season flow less and the dry season flow greater, divert water to
agriculture, inland growth and evaporation. Many highly productive shrimp ecosystems occur
where fluctuating or very high salinities reduce diversity and channel energy into a few species.
Examples are the white shrimp of the Mississippi delta and the brown shrimp of the briny Laguna
Madre of Texas. The main shrimp cultivated in the ponds of Ecuador, Penaeus vannamei, is a species
that is adapted to wide ranges in salinity and temperature. Evidence that the annual river surges
favor high shrimp production was the 1983 year when exceptional El Nino runoff was accompanied
by exceptional shrimp production and post-larvae.
The damming of the river will cause estuarine salinities to be higher and uniform. Higher
diversity marine organisms will displace many of the shrimp populations. In an analogous situation,
oysters based on wide salinity fluctuations develop diseases and disappear when salinities are made
uniform by human reduction of flood run-off.
Annual EMERGY Flows in the Mangrove Nursery System of Ecuador.
119500 Hectares. See Figure 17.
Note Item Raw Units Transformity Solar Macroeco-
J,g$ Sej/unit EMERGY onmic 1989
E18 sej/yr US E6$/yr
1 Solar energy 44 E+18 J 1 4.44 2.22
2 Wind energy 4.4 E+14 J 623 0.27 0.14
3 Mangrove transpiration 4.4 E+15 J 41068 179.06 8953
4 Rain chemical potential 52 E+15 J 15444 80.31 40.15
5 Tides 4.2 E+15 J 23564 99.91 49.96
6 Total solids from sewer 5.8 E+10 J 62400 0.00 0.00
7 Total N from sewers 4.2 E+08 g 9.0 E+08 0.38 0.19
8 Total P from sewers 5.15 E+07 g 8.1 E+09 0.42 0.21
9 Biomass growth 1.9E+16 J 14684 279.00 13950
10 Litterfall 2.1 E+16 J '- 13285 278.99 139.49
11 Shrimp produced 2.1 E+12 J , 2000000 4.20 2.10
12 Independent total - - 278.97 139.48
Footnotes for Table 13
1. Solar input 1195 E6 m2, 127 kcal/cm-yr average solar insolation.
(1195 E6 m2)(127 E4 kcal/m2-yr)(.7 absorbed)(4186 J/kcal) = 4.44 E18 J/yr.
2. Wind energy: 0.19 available inshore system reall ratio) - see Table 12, note #2.
3. Mangrove transpiration:
(2.5 mm/d)(365 d/yr)(1000 g/rmm/m2)(4.0 J/g)(1195 E6 m2) = 4.36 E15 J/yr
4. Rain chemical potential energy: Av. precipitation in Guayaquil 885 mm/yr (Twilley,
1986): (1195 E6 m2)(.885 m)(1 E6 g/m3)(4.94 J/g) = 5.2 E15 J/yr.
5. Tidal energy range absorbed in mangroves, 1.0 m;
(706/yr)(9.8 m/s2)(1.025 E3 Kg/m3)(11.195 E9 m2)(1.0 M)(1.m) = 4.23 E15 J/yr
6. Total suspended solids in sewer effluent: 6456 E6 g/yr. 0.2 of area;
(0.2)(6456 E6 g)(.002 organic)(5.4 kcal/g)(4186J/kcal) = 5.84 E10 J/yr.
7. Nitrogen concentration in sewer effluent 2.1 E9 g/yr; 0.2 of estuary area (Twilley, 1986).
(2.1E9)(.2) = 42E8 g/yr
8. Phosphate concentration in sewer effluent 2.58 E8 g/yr (Twilley, 1986); 0.2 area. (2.58 E8
g/yr)(2)= 5.15 E7 g/yr
9. Mangrove biomass growth: 2.8 g/m2-day (observation from Snedaker, 1986 and Sell,
(1195 E6 m2)(2.8g/m2-X365 d)(3764 cal/g)(4.186 J/cal) = 1.9 E16 J/yr.
Transformity:(279 E18 sef/yr in footnote 12)/(1.9 E16 J/yr) = 14684 sej/J.
10. Mangrove litter fall: 957 - 1032 g/m2-yr (Sell, 1977); av. 995 g/m2-yr. (995 g/m2)(1195
E6 m2)(4139 cal/g)(4.186 J/cal) = 2.1 E16 J/yr.
Transformity: (279 E18 sej/yr)/(2.1 E16 J/yr) = 13285 sej/J
11. Medium sized shrimp produced (70 individuals-tails per pound) Turner(1985): 10 kg
commercial yield of adults per hectare of vegetated nursery.
(10 kg/ha)(2.2 lb/kg)(.7 tailsX35 tails/lb) = 539 individuals/Ha
(539 ind./haX1195 E6 m2X/70 ind/lb)/(1 E4 m2/ha) = 92 E5 Ib
(9.2 E5 lbsX.2 dry)(454 g/lb)(6.0 kcal/g)(4186 J/kcal) = 2.1 E12 J/yr
Transformity for estuarine shrimp, half of larger offshore adults:
(0.5)(4 E6 sej/J in Table 15) = 2 E6 SEJ/j
12. Total omitting double counting: sum of transpiration and tide:
(179 + 100) = 279 E18 sej/yr
We did not do a full evaluation of the dam and its economic consequences, but only of its
effect on the estuary and the shrimp as follows. Data from Arriaga (1986) were used. The average
flow of the Guayas River is 974 m3/s (307 E8 m3/yr). The solar EMERGY of the water purity (Gibbs
free energy) was evaluated using solar transformity for average world rivers as follows:
(3.07 ElOm3/yr)(1 E6 g/m3)(5 Gibbs J/g)(41068 sej/J) = 63 E20 sej/yr
Add to this the EMERGY of organic detritus using 115 parts per million (=g/m3) (similar to
the calculation made for the coast as a whole in Table 12, line 21).
(3.07 E10 m3/yr)(115 g/m3X5 kcal/g org.)(4186 J/kcal)(62400 sej/J) = 46.1 E20 sej/yr
Dividing the sum, 109 E20 sej/yr (63 E20 +46 E20) by U.S. solar EMERGY/$ ratio gives
macroeconomic $ contribution:
Macroeconomic 1989 US $ = (109 E20 sej/yr)/(2 E12 sej/$) = 5.45 E9 $/yr
Similar evaluations are made in the text table below for the Daule-Peripa dam situation. The
reservoir area will be 27,000 hectares. If the evaporation rate is 6 mm per day there is a 2% loss/yr.
The new dam is reducing flow on the Daule River, one of the main tributaries of the Guayas
River. According to the plan, the annual discharge ofthe Daule river (333 m3 /sec) will be reduced
to 100 m3/sec, a 70% diversion.
EMERGY and macroeconomic dollar values for the diversion follow:
Annual Flows of Guayas River affected by Daule-Peripa dam Project
Name Flow Solar EMERGY/yr Macroeconomic $/yr
E8 m3/yr E20 sej/yr sej/yr E6 1989 US $*
Average flow 307 109 5,450
Evaporation 5.9 1.21 60
Diversion 73.5 26.1 1,305
Loss of wet season
river surge 78 27.7 1,385
* EMERGY divided by 2 E12 sej/1989 US. $.
These figures are tentative, since there were few data on organic detritus content. Figures
during flood are likely to be higher than those used in these calculations:
The mean flow in 6 months wet season is 599 m3/s and in 6 months dry season 68 m3/s.
The difference between the wet season and the future planned discharge is:
599 -100 = 499 m/s (78 E8 m3.yr)
This is the surge of freshwater that dominates the estuarine productivity, lowering diversity
and channelizing energy to the shrimp and other estuarine values. See EMERGY evaluation in text
table above with macroeconomic value of 135 billion US $ threatened by water diversion. This does
not include the $1.134 macroeconomic dollars in purchased inputs to the shrimp industry (Table 14)
which may be decreased with water diversion. The shrimp ponds are based on several sources of
detritus and on pumping in waters of variable salinity that keep the competitors and weed species
from becoming established. Diversion of the waters may bring on algal blooms, animal competitors,
carnivores, and diseases normally prevented by the river surge. The mangroves are also based on
the freshwaters and their productivity will be much reduced without as much freshwater to
transpire. Insect infestation has been observed there in 1990.
From Table 12a and 14 the shrimp systems, ponds and trawling, were EMERGY evaluated,
and an annual macroeconomic $ value was found of 1.5 billion U.S. $/yr ($1.06 E9 + $0.42 E9). The
diversion of the rivers and their surges is likely to remove much, if not most, of estuarine resource
and the shrimp industry. Whether the values transferred inland by diversion of the river can equal
the coastal resources lost was not analyzed in this study. The agricultural alternatives now being
developed should be evaluated in the same way urgently. Certainly, the principle used in this
development was wrong, destroying a developed system without bringing in competent knowledge
of what may be lost.
Evaluating Pelagic Fishery Landings
Relating the EMERGY of the oceanic production to the landings of pelagic fisheries from
offshore is difficult because the boundaries fished for the boats landings included in Ecuador
statistics are not known. Also, the estimates of physical energy inputs are very preliminary. Part of
the EMERGY basis is the colder upwelling ecosystem beyond the continental shelf south of 2
degrees south latitude (Figure 2). The web of energy transfers is not worked out to show how much
of these energies are in support of the pelagic fishery.
A tentative solar transformity for this fishery was estimated from food chain calculations by
Walsh (1981) in Table 14, note #9. The transformity is appropriate for consumers low in the
ecosystem trophic web. Based on this, the EMERGY content of the fishery landings (Table 12a, item
#10) is very high, with macroeconomic value of 272 million US $. From the data available, the
investment ratio was very low and the net EMERGY high. In other words, the landings appeared to
be high value for little input. Much more can be done with these fish than is the case now. These
indices need verification.
Evaluating Shrimp Trawl Landings
The trawl fishery for shrimp on the continental shelf and Gulf waters receives its
environmental support from the mangrove nursery, the shallow open water estuary and the
continental shelf. These, in turn, receive their EMERGY basis from the river, tides, and oceanic
currents sweeping the shelf as evaluated in Table 12a. The total solar EMERGY contributed by
offshore and onshore areas (Table 12b) is 160 E20 solar emjoules/yr with macroeconomic $ value of
8 billion $.
There is not a full energy web worked out for the interaction of the physical energies with
geologic and biologic processes in this complex estuary. Thus, it is not clear how much of the solar
EMERGY supports the shrimp food chain hierarchy.
Another approach was used. EMERGY of landings contains that from purchased inputs and
the environment By calculating the landings with a transformity from Table 15 and subtracting the
purchased EMERGY, the environmental component was estimated. From this an investment ratio of
2.7 was obtained similar to the regional ratio 23, as would be expected for an operation
economically viable in that local economy (see previous section: "Regional EMERGY Investment
Some part of the solar EMERGY of the coastal waters supports a food chain web of
populations converging to a few dominant larger species, including the Penaeid shrimp. The shrimp
and other larger species are byproducts of each other, feeding back their services to the food web,
continuously self re-organizing. The solar EMERGY per unit energy of one species (solar
transformity of that species) measures what was required with all the division of labor operating to
develop an efficient system, presumably of maximum production and utilization by consumer
When an economic interface is attached to such a system without a feedback from the
economy to augment the ecosystem, higher level consumers and their services are diverted and
basic production may be reduced. Then the ecosystem may reorganize with energies going into
other consumers of less human use. Development of the ponds diverted mangrove nursery areas,
waters, and post-larvae without feedback reinforcement to the wild system to compensate for the
resources drawn off for human consumption. The low proportion of the solar EMERGY of the
coastal ecosystem that is going into shrimp trawl landings under the 1986 conditions may be due to
the disturbances and diversions of the wild system'by the new developments.
SHRIMP MARICULTURE DEVELOPMENT
The many new marine shrimp ponds like those in Figure 1 are intensive developments based
on international sales of shrimp at high price. Shrimp ponds capture the'shrimp growth process
within the pond dikes. Everything has to be supplied. The growth is based on fertilized aquatic plant
production plus added shrimp food. The critical inputs which are now in short supply are the post-
Energy Diagram of the Shrimp Pond Systems
An overview energy systems diagram showing main inputs to the shrimp ponds is Figure 5.
Note the many more inputs that have to be purchased in the pond systems compared to the system
of natural shrimp production and trawl harvest in Figure 4. The system resembles intensive
agriculture with high levels of purchased inputs per area. Estuarine waters are pumped into the
ponds to keep up with evaporation and seepage. The estuarine waters are generally low enough in
salinity due to river inflows to keep the ponds from becoming too briny for optimum growth. Plans
to dam and divert the river upstream may affect this.
The pumps also transfer inorganic fertilizer elements, organic matter to support the food
chain, and some living components, as shown in Figure 5, from above. However, the pumps destroy
many organisms that would otherwise contribute to the estuarine nursery system. Post-larvae are
obtained from pumping in waters, from catching and transporting larvae, and from physiological
treatments of adult shrimp previously raised or captured. In some areas in dry weather, the ponds
mainly pump each others' waters around and around.
The food for the shrimp comes from the pumped-in waters containing detritus, from
purchased organic matter, and from the algal-based food chain stimulated by high levels of
nutrients. Nutrients are added by the pumps, especially when the outside waters are enriched with
wastewaters; other nutrients are purchased fertilizers. Thus, the ponds may have higher
concentrations of nutrients, organic matter, and shrimp post larvae than adjacent waters.
Considerable fuels, electricity, machinery, and goods and services are required, all relatively high
Shrimp are harvested and few get back to the estuary for reproduction. Ponds that receive
food and larvae from the wild environment have less costs than those with more purchased inputs.
EMERGY Inputs and Investment Ratio of Shrimp Pond Mariculture
EMERGY evaluations of typical pond inputs are given in Table 14a. The EMERGY of fuels,
services, and the post-larvae are largest Indices are given in Table 14b. Economic developments
displace undeveloped environmental resources, because development supplies additional EMERGY
resource use consistent with the maximum power principle that reinforces such arrangements
because it is a design principle of self organization.
The degree of development is measured by the EMERGY investment ratio defined as the ratio
of purchased EMERGY to local free EMERGY (Figure 8). See Table 9. An investment ratio is
normally between 1 and 7 during development, where fossil fuel based inputs are available to
interact and amplify environmental resources. The ratio for Ecuador as a whole is about 0.25 (Table
9) and for the coastal region about 2.3 (Table 14b), which is lower than the same index for the United
states, Texas, and Florida (7.0). Because undeveloped resources are more abundant in Ecuador, there
is more free resource available to match investments. More EMERGY of environmental resources
can be obtained for the same EMERGY investment. Developments require more free matching to be
The shrimp pond systems EMERGY investment ratio is 3.4, indicating more economic
purchased inputs than environmental ones. In contrast, the shrimp ponds are more intensive than
the preceding direct uses of the mangroves for fisheries, crabs, and shrimps, wood, etc., and more
typical of the developed countries to which they sell. The higher the investment ratio (the more
inputs are bought), the higher the costs and prices. An industry with higher investment ratio than
the general one for the region has products too expensive for local sale. '
With less intensive operations, less feeding, fertilizing, labor, pumping, etc., the yields would
be less but so would the costs (as indicated by the investment ratio). Less intensive shrimp
operations could be sold within Ecuador.
Shrimp Transformities and System Efficiency
The total resource required for a product is measured by the solar transformity in solar
emjoules per joule (Solar EMERGY/energy). We believe there is an ultimate lowest transformity
thermodynamically possible for conditions of maximum production. These lowest, most efficient
transformities may be approximated by low intensity,'long-standing utilization practices. The solar
transformities of commercial Penaeid shrimp calculated from other studies are given in Table 15 so
they can be compared with that of the new shrimp ponds. Values of less intensive ways of obtaining
shrimp are generally 4 to 8 E6 solar emjoules per Joule, similar to other protein foods such as mutton
The SOLAR transformity of the pond yields (13.0 E6 sej/J, Table 14b) is much higher than the
less intensive systems of harvesting from the coastal systems. This may indicate a wasteful process
that uses too much resources for the results obtained. It may mean the system is vulnerable to being
replaced by less intensive, older systems when prices vary.
The new shrimp system is using the older system for its reproductive (Figure 4), but
undermining its basis by displacing the mangrove nursery and removing the post-larvae from the
cycle that leads to continued reproduction.
Pelagic Fish Meal Supplements to Shrimp Ponds
In the more intensively managed ponds, fish meal from offshore fishing is added. The added
feed makes a big difference in efficiency where everything else has been provided. The fish-food
supplement containing 25% protein increases yields 2 to 5 times. The solar transformity is higher
(more resource required per unit shrimp) where fish meal is absent, indicating a low efficiency
situation. In Table 14b, the EMERGY amplifier ratio, the increased yield due to added fish meal, was
2.8. (See Figure 11.)
The fish meal has a moderately high transformity and increases the investment ratio from 2.6
(the regional value) to 3.4 making costs high for local consumption but still cheaper than food in
developed countries where investment ratios are higher.
The solar transformity of herring, sardines, and anchovettas used to make the meal, although
less than the shrimp, is high enough to be used as food. It may not make sense to divert a food
product just to make a lesser quantity of luxury food for enriching a foreign economy. Money
required to catch and process the fish is small relative to the EMERGY from the open seas upwelling
system that is contained in the fish.
Annual EMERGY Flows of Shrimp Pond Mariculture in Ecuador, 1986
53,000 Hectares; 1.5 m deep; see system diagram in Figure 5.
Note Item Raw Units Transformity Solar Emergy Macroeco-
J,g,$ Sej/unit E20 nomic US $E6
1. Sunlight 1.97 E18 J 1 0.0197 0.99
2. Rain 2.65 E15 J 15444 0.41 20.5
3. Pumped sea waters 7.33 E15 J 15444 1.1 55.
4. Post larvae 3.2 E9 ind 1.04 Ell 3.4 170.
Sum of Free inputs, direct sun omitted 4.92 246
5. Labor 132 E14 J 2.62 E6 3.79 189.
6. Fuel 2.34 E15 J 5.3E4 1.24 62.
7. Nitrogen fertilizer 1.14 E9 g 4.19 E9 0.048 2.
8. Phosphorus fertilize. 2.62 E8 g 2.0 E10 0.053 2.6
9. Feed protein 3.29 E15 J 1.31 E5 43 215.
10. Other services 356 E7 $ US 8.5 E12 3.0 151.
11. Costs of post-larvae 3.56 E7 $ US 8.7 E12 3.0 151.
12. Capital costs 1.93 E6 $ US 8.5 E12 0.164 8.2
13. Interest paid back in sucres or sucre-converted-to $
112 E6 $US 85 E12 .95 47.6
Sum of Purchased Inputs 16.9 845
Sum without organic feed 12.7 635
Sum of all Inputs 2182 1092
Sum without organic Feed 17.6 880
14. Shrimp yield using organic feed
Efficient value 1.68 E14 J 4.0 E6 6.72 336
Resource used 1.68 E14 J 13.0 E6 21.80 1092
15. Shrimp yield without organic feed
Efficient value 0.93 E14 J 4.0 E6 3.72 186
Resource used 0.93 E14 J 18.9 E6 1758 879
Table 14b. Indices from Table 14a
EMERGY investment ratio:
With organic feed = (16.9 E20 sej/yr)/(4.92 E20 sej/yr) = 3.4
Without organic feed = (12.7 E20 sej/yr)/(4.92 E20 sej/yr) = 2.6
For comparison, regional EMERGY investment ratio = 23
Solar transformity of Shrimp from shrimp ponds:(Input EMERGY)/(yield energy)
= (21.82 E20 sej/yr)/(1.68 E14 J) = 13.0 E6 sej/J.
Solar transformity in ponds without organic feed
= (17.6 E20 sej/yr)/(9.3 E13 J) = 18.9 E6 sej/J.
For comparisons, Peneid shrimp transformities elsewhere = 4 - 8 E6 sej/J (Table 15).
Net EMERGY yield ratio (Yield EMERGY/Purchased EMERGY):
With organic feed = (21.82 E20 sej/yr)/(16.9 E20) = 13
without organic feed = (17.6 E20)/(12.7) E20) = 1.4
EMERGY amplifier ratio explained in Figure 11; using an average transfonnity before and after
amplifying production, 16 E6 sej/J.
EMERGY increase due to feeding with fish meal
16.0 E6 sej/J * (1.68 -.93) E14 J/yr 12.0 E20 sej/yr
amplifier ratio = = 2.8
EMERGY in added fish meal (Table 14a) 43 E20 sej/yr
Footnotes for Table 14a
1. Direct solar energy.
(127 E4 kcal/m2/yr)(4186 J/kcal)(0.7 absorbedX530 E6 m2) = 1.97 E18 J/yr
2. Rain into ponds:(1 m/yrX530 E6 m2)(1 E6 g/m3)(5 J/g) = 2.65 E15 J/yr
3. Pumped sea water to maintain water levels and salinity; evaluated freshwater content:
.(0.1 vol/d)(365 dX15m)(538E5 m2)(.08 fresh)(1E6 g/m3X3 J/g)=7.4 E15 J/yr
4. Input of post-larvae estimated from pond yield 3.0E4 tonne (Aquacultura de Ecuador, 1988):
(30 E6 kg)(2.2 lbs/kg).70 tails))(35 tails/lb)/(5 mortality) = 3.2 E9 ind./y
Larvae can be thought about as information packages with little energy. When a shrimp
releases many larvae, this represents a split of the EMERGY. Each tiny new individual carries
an information copy. If the population is at steady state the larvae grow and are depleted in
number by mortality eventually replacing two adults. This is a cosed life cycle dependent on
all the inputs necessary for the whole sequence. The EMERGY per individual is a transformity
that grows reaching a maximum with the reproducing individuals. For a mortality
commensurate with growth of the surviving, post-larvae with 50% further mortality
represents 2 individuals that will finally restore 1 adult. Thus a transformity for the post-
larvae is half that of the reproducing adult before harvest (.5 * 4 E6 sej/J). On an individual
basis the solar transformity is:
(05)(4 E6 sej/J)(10 g/ind)(.2 dry)(6.2 kcal/g)(4186 J/kcal) :
= 1.04 Ell sej/ind
5. Transformity of Labor in Ecuador estimated as national EMERGY/person/yr from Table 6.
Energy/person = (2500 kcal/d)(365 d/yr)(4186 J/kcal)(4186 J/kcal) = 3.82 E9 J/yr.
Solar transformity = (10 E15 sej/ind/yr)/(3.82 E9 J/ind/yr) = 2.62 E6 sej/J
90,000 fisherman 5 days a month; 20,000 people full time
(12.7 E6 person-days)(2500 kcal/person-day)(4186 J/kcal) = 132 E14 J/yr
6. Fuel: estimated as a percent of operating cost of pumped pond; price (Aquacultura del
($.10/lb shrimp)(26.4 E6 kg/yr)(2.2 lbs/kg)/($.34/gal fuel) = 17 E6 gal//yr
(17.1 E6 gal/yr)(137 E6 J/gallon) = 2.34 E15 J/yr
7. Nitrogen fertilizer for each 6 month start; 13 g/m3 N;
Volume: (1.5 m deep)(2.91 E8 m2) = 4.365 E8 m3
(4365 E8 m3)(13 g/m3)(2/yr) = 1.135 E9 g/yr
8. Phosphorus fertilizer for each 6 month start 03 g/m3;
(4365 E8 m3)(03 g/m3)(2/yr) = 2.62 E8 g/yr ,
9. Feed; Fish meal from offshore herring, sardines; See text figure.
Total feed = sum of 23,600 Ha of semi-extensive'ponds, fed for last 60 days.
(45 kg/ha/d)(l E3 g/kg)(2.36 E4 ha)(60 d)(5.7 kcal/g)(4186 J/kcal) = 1.52 E15 J /yr
and 5500 Ha of semi-intensive ponds, fed for 300 days:
(45 kg/ha/d)(1 E3 g/kg)(5500 ha)(300 d)(5.7 kcal/g)(4186 J/kcal) = 1.77 E15 J/yr
Total feed supplement (1.52 + 1.77 = 3.29 E15) J/yr
Much of the fish meal came from herring, sardines, etc mostly beyond the continental shelf. A
solar transformity was estimated using organic carbon per square meter in herring sardines
and anchovettas yield from the pelagic upwelling system published by Walsh (1981) divided
by the solar EMERGY of the current. EMERGY of direct solar energy, and chemical energy of
rain were also evaluated, but were less than the physical energy of the Humboldt current. As
lesser by products of the world weather system direct sun and oceanic rain were omitted to
avoid double counting.
Fish yield was 6.71 grams Carbon/m2/year with energy content
(6.71 g C/m2/yr)(2.5 g org./g C(5.7 kcal/g)(4186 J/kcal) = 4.00 E5 J/m2/yr.
Solar Emergy input per square meter of pelagic ecosystem generating this meal includes
.direct sun, rain, and the physical energy being used from the several sources driving the
Humboldt current, the waves, and upwelling. The circulation of the east Pacific gyral
includes wind energy transferred from the large scale circulation of the atmosphere wind plus
large scale pressure gradients maintained by density differences due to temperature and
salinity differences. In this pelagic system unlike the inshore ones, the tidal absorption and
river contributions are less. The physical energy was estimated by assuming a fraction of 1%
of the kinetic energy used up per day in steady state with the sources. As the calculations
below show, the EMERGY of the direct sun and direct rain are small by comparison.
EMERGY of direct solar Energy under offshore stratus::
(1 m2)(1.00 E6 kcal/m2/yr)(4186 J/kcal)(l sej/J = 4.19 E9 sej/m2/yr
Physical energy (tentative pending better sources);
(05)(.3 m/sec)(.3 m/sec)(100 m deep)(1 m2)(1025 kg/m3)(.01/day)(365 d/yr)
= 1.68 E4 J/m2/yr physical energy
EMERGY flux using solar transformity of river current at New Orleans: (4.67 E4 J/m2/yr)(80
E5 sej/J) = 1.34 Ell sej/m2/yr
Rainfall chemical energy on the open sea:
The solar transformity of rain falling over the ocean is different from that over land. Land is at
a higher level in the geological hierarchy in which the solar energy falling on the seas is part
of the basis for converging atmospheric processes to interact with continent building
processes to generate rain on land. Solar transformity of rain over land was calculated as the
quotient of the earths annual EMERGY divided by the Gibbs free energy of the rain over land
relative to sea water. Rain over the sea is a necessary by-product feedback lower in the
hierarchy with larger volume for the same earth EMERGY budget. Rain over ocean was
assumed 71/29 of 1.05 E14 m3/yr rain over land in proportion to the ocean/land areas.
Solar transformity 8.1 E 24 sej/yr/earth
of oceanic rain = 6380 sej/J
(257 E14 m3/yr)(1 E6 g/m3)(4.94 J/g)
(1.0 m)(l m2)(1 E6 g/m3X4.94 J/g) = 4.9 E6 J/rh2/yr
Solar Emergy: (4.9 E6 J/m2/yr)(6380 sej/J) = 3.13 E10 sej/m2/yr
Solar transformity of the fish meal based on 1 m2 of pelagic offshore; see Figure. EMERGY
sum ( 1.34 +. 014 = 1.35) Ell
(5.24 E10 sej/m2/yr)/(4.00 E5 J/m2) fish meal = 131 E5 sej/J
Costs (services) of feed supplement for 1986 from Camara de Productores de Camaron (1989)
EMERGY value added in fishmeal preparation:
(17% cost for supplementary feedingX150 E6 $) = 25.5 E6 $
(8.7 E12 sej/$)($25.5 E6) - 2.2 E20 sej/yr
10. Operating costs given as $2.70 (1986 US. $) per kilogram of shrimp yield.
($2.70 US /kg)(26.4 E6 kg/yr yield) = 71.2 E6 US.$;
Half of this is for post larvae (note 11) and half for other services:
(0.5)(71.2 E6 US $) = 35.6 E6 US $.
For evaluating EMERGY, use 8.7 sej/$ within Ecuador calculated in Table 3.
11. Costs of post larvae: 50% of total operating cost (note 10): 35.6 E6 US $.
12. , Capital costs: (235 E3 sucre/ha)(2.91 E4 Ha)/(122 sucre/$)= 58 E6 $US
Assume 30 year life of ponds; annual cost = 58 E6 $US/30 yr = 1.93 $US/yr
13. Interest on loans for capital investment at 20% of principal
(2)(58 E6 $US/30 yr) = 11.6 E6 $US. Whether aid to an investor within Ecuador or one in the
U.S., the sucres when converted to international $ represent EMERGY according to the
Ecuadorian EMERGY/$ ratio (85 sej/$).
14. Yield: 30,000 tonne/yr:
(3.0 E10 g/yr)(0.2 dry)(6.7 kcal/g dry)(4186 J/kcal) = 1.68 E14 J/yr
15. Yield without organic feed: 598 Ib/Ha (Camara de productores de Camaron, 1989)
(53 E4 HaX598 lb/Ha)(454g/lb)(.2 dry)(6.7 Kcal/g dry)(4186 J/kcal)
= 9.28 E13 J/yr
Solar transformity 5.24 sej 1.31 E5 seyJ
of helping: 4.0 J
Figure for footnote 9, Table 14.
4.0 E5 J
~r ~---- - - ~---- --- -- -- --- --- - �� - -�-
Comparisons of Solar transformities of Penaeid Shrimp
Location and Source Solar transformity
Shrimp, Gulf of Mexico (Fonyo, 1983) 3.77 E6
Shrimp Panga, Sea of Cortez, Mexico
(Brown, Tennenbaum and Odum 1989) 3.99 E6
Upper consumers, Mississippi River delta
(Odum, Diamond, and Brown, 1987,
data from Bahr, Leonard, and Day, 1982) 8.0 E6
Ecuador shrimp ponds with organic feed, Table 14b 13.0 E6
Ecuador shrimp ponds without organic feed, Table 14b 18.9 E6
Neither costs nor market prices of environmental resources measure their ability to generate
gross economic product dollars. Line 9 of Table 14a evaluates the contribution to the economy if the
pelagic fish landings are used appropriately at home (215 E6 $/yr).
Net EMERGY of Shrimp from Ponds
The net EMERGY yield ratio of the shrimp from the ponds (13, Table 14b) indicates little
contribution beyond what is required for its processing. Adding feed had little effect.
Compared to fuels or shrimp processed with low intensity means, pond shrimp cannot
stimulate an economy much more than they do already. One would not expect a food to be much
net EMERGY since food is one of the things an economy does with the net EMERGY it gets from its
primary energy source, currently fossil fuels.
Regional EMERGY Change Accompanying Pond Development
The EMERGY evaluation of the present coastal systems supporting shrimp production in
Tables 12 and 13 included some of the older natural pattern of producing shrimp in the sea and
some new ponds. To simplify the comparison of the original system and the system after shrimp
pond development, an EMERGY "change table" was prepared (Table 16), omitting those items not
mu=h changed by the development This table was used to evaluate the benefits of alternatives
shown in Figure 1 and 18. Since many inputs continue unchanged, the EMERGY change Table 16
has fewer line items than the general analysis. Included are totals for the EMERGY diverted from
Ecuador to the U.S.
The ponds have a big contribution to the outside developed economy and a heavy negative
drain on the local economy (Table 16), partly because of the differences in EMERGY/$ ratios of
undeveloped and developed economies. On a worldwide basis there is a net increase in rate of
generating EMERGY because the economic development of Ecuadorian resources draws on the
available fuels and other resources.
Comparison of EMERGY Benefit of Alternatives
The concept of comparing the EMERGY benefit of alternatives was shown in Figure 3. This
diagram was evaluated (Figure 18), comparing the natural shrimp production and trawl harvesting
with the present shrimp pond system still based on post-larvae from the natural cycle. Also included
is the EMERGY produced when the same amount of purchased EMERGY is invested in an
alternative with the typical regional matching of environment. The best possible alternative is
evaluated fourth, the original environmental contribution plus the EMERGY of purchased inputs
matched at the regional investment ratio. (More matching is not economical.)
Optimum Development for Maximum Benefit
In any environmental development there is an optimal intensity which generates maximum
EMERGY, part from the environmental work and part from purchased inputs. There are several
maxima of concern:
1. The development intensity that maximizes pond shrimp yield and profit.
2. The development intensity that maximizes the region's shrimp yield including trawls and
3. The development intensity that maximizes the total EMERGY availability to the home
4. The development intensity that maximizes the EMERGY of investing countries.
5. The development intensity that maximizes the total EMERGY production and use
Table 16 showed that shrimp pond developments contributed to developed economies by
diverting resources of Ecuador without receiving payments of equal buying power.
Figure 18. EMERGY benefit comparison of original system with trawls (PI), new system of ponds and
trawls (P2), typical alternative investment (PA) and potential development (PD). E0 se/
Environmental inputs to trawl fishery (0.227 E20 in Table 12B and
environmental later displaced (9.1 E20 in Table 16:
Environmental inputs to ponds (Table 14A, line 1-4):
Purchased inputs to trawl fishery(Table 12a, line 11,12):
Purchased inputs to ponds (Table 14a 16.9) and trawls:
11 = 93
F1 = 0.61
F2 = 17.5
Old shrimp system (trawls and local fishing): PI = II + F1 = 9.9
New shrimp system (trawls and ponds) P2 = 12 + F2 = 22.4
Alternative regional development where
investment ratio R = 23 PA = F2 + F2/R = 25.1
Potential development, matching original I1 PD = I1 + I1 * R = 30.7
Change in Annual EMERGY Flows of Coastal System with Shrimp Pond Developments
Item Solar EMERGY Macroeconomic $
E20 sej/yr E6 US 1989 $/yr*
Change in purchased inputs for pond development:
1 Pond Labor and services added +9.95
2 Pond fuel use added +1.24
3 Debt & profit lost -0.71
Changes in environmental resources to develop shrimp ponds:
4 Loss of Mangrove area -0.04
5 Lost Areas of organic runoff -0.22
6 Shrimp Post-Larvae diverted -3.4
7 Estuarine Waters diverted - -1.1
8 Fish diverted to feed shrimp -4.3
9 Shrimp Trawl decrease -0.046
10 Environmental losses (items 4-9) = -9.1
11 Exported pond shrimp = -215
12 Purchased gains & losses (items 1,2 & 3)
(+10.17+1.24 -.71 E20) = +10.7
13 Buying power from exported pond shrimp +7.56
14 Net benefit to the local region: -12.04
(7.56 +10.7- 9.1 - 215 E20)
15- Net benefit to foreign economies: +14.2
(21.2+58 -7.56 E20)
16 EMERGY increase for the planet +12.1
(21.2 - 9.1 E20)
17 Developed potential (U.S. level) +9.4
18 Sustainable potential (Long range) +3.86
Footnotes for Table 16
*Solar EMERGY change in sej/yr divided by 2 E12 sej/U.S. 1989 $
1 Labor, new services, costs of post-larvae, and capital costs in Table 14.
items 5, 10, 11, & 12 (3.79 + 3.0 + 3.0 + 0.164)= 9.95 E 20 sej/yr
2 Fuel, item 6 in Table 14.
3 Interest and profit assumed to leave the local area; item 13, Table 14.
4 Mangrove loss: 6000 hectares; Transpiration rate, 2.5 mm/day
(2.5 mm/d)(365 d/yr)(1000g/m2/mm/d)(4.8 J/g)(6.0 E7 m2 Ioss)(15444 sej/J)
= 4.05 E18 sej/yr
5 Organic runoff diverted by 46,600 hectares ponds on salterns and other areas contributing
organic matter. 1 g/m2/day net production
(1 g/m2/d)(365 d/yr)(4.6 E8 m2 Iost)(5 kcal/g) (4186 J/kcal)(6000sej/J) = 0.22 E20 sej/yr
6 Post larvae diverted: item 4 Table 14
7 Estuarine water (its fresh water content) diversion, item 3, Table 14.
8 Shrimp feed, item 9, Table 14.
9 (2000 pounds less/boat-McPadden, 1986)(249 boats) = 498,000 pounds
(4.98 E5 lb/yr)(454 g/lb)(2 dry)(6.2kcal/g) (4186 J/kcal)(4 E6 sej/) = 4.68E18 sej/yr.
10 Items 4-9 are losses from the environmental system but transferred for the most part to the
pond system, thus being retained in the area. However, their use here is grossly inefficient,
generating one fourth of the EMERGY yield compared to the environmental and purchased
inputs utilized. See Table 15.
11 Shrimp pond yield, item 14 Table 14.
12 Interest and profit removes EMERGY, especially if financed from the developed countries
with much smaller EMERGY/$ ratio. See section on "Shrimp and International Exchange".
13 Shrimp exports item 2 Table 2. Buying power of US $, with US EMERGY/$ ratio
(315 E6 US $/yrX2.4 E12 sej/US $ in 1986) = 7.56 E20 sej/yr
14 Buying power earned from shrimp sale plus purchased inputs of EMERGY used minus
environmental losses minus the EMERGY of exported shrimp.
15 Benefit to foreign developed economy from shrimp received plus EMERGY of Ecuador's
EMERGY/$ value of interest and profit (assuming half financed from developed country)
minus purchases made with shrimp earnings.
16 Change in annual rate of EMERGY production and use considered on a world basis without
regard to where it goes or is used or where the money goes:
Shrimp Pond production (which includes EMERGY in new fuel use and new items purchased
from fuel-based economy (items I & 2) and some environmental inputs) minus environmental
loss (item 10).
17 Temporary potential to developed economy using investment ratio of 7 (U.S.A.). For
calculations in footnote 18.
18 Sustainable contribution was estimated as the sum of the renewable environmental input plus
the economic development for the present regional investment ratio 2.3 which is similar to the
The environmental EMERGY input(Table 13) per unit coastal area is:
(279 E18 sej/yr)/(1.195 E9 m2) = 233 Ell sej/m2/yr
The environmental EMERGY input for the coastal area is calculated as if all that shrimp pond
area was calculated as if all converted into tidal mangroves even that which was originally
(2.33 Ell sej/m2)(5.3 E8 m2) = 1.17 E20 sej/yr
Investment ratio 23 multiplied by environmental EMERGY is
(23)(1.17 E20 sej/yr) = 2.69 E20 sej/yr)
Environmental and sustainable economic matching:
(1.17 E20 + 2.69 E20) = 3.86 E20 sej/yr
IRF- .2 (Ecuador)
wnronmental -- x
per area A R Ha\s \
y / ^RP \ \
Finputs . O SHO f d t b o p
OF 20 Y Jl
AM w 20o lX 100Sal"
shrimp for various areas of pond development. Systems diagram includes variables and
Sfl desi is, d Lavaesse
K20 S K1rimp K4 100
Mmrnmentl S1 X K1 K1
Inputs SHU x EC
Natural shrimp production
Figure 19. Overview simulation model MAXSHRIMP for determining the benefits of production of
shrimp for various areas of pond development Systems diagram includes variables and
coefficients, EMERGY flow designations, and numerical values used for calibration.
A SIMULATION MODEL OF SHRIMP PRODUCTION SYSTEMS
In order to study the effect of increased development of ponds on the shrimp production of
the region as a whole, a model of two linked subsystems was prepared as shown in Figure 19. At the
bottom is the original shrimp production system including estuarine and mangrove nursery. This
includes offshore Shrimp using offshore resources for growth and generating larvae, some of which
are exchanged back to shore and swept into the estuaries with the tide.
Figure 19 is an aggregated version of the more detailed systems overview in Figure 4. Table 17
contains the equations for this model and its program in BASIC is Table 18. Figure 19 also has the
three alternatives to be compared arranged from top to bottom as in Figure 18.
At the top of Figure 19 are shrimp ponds which pump larvae from natural water where they
grow on a food chain from solar energy and environmental inputs of waters and purchased inputs
of food, fertilizers, and management by pond managers as already diagrammed in Figure 5.
Simulation of Benefits as a Function of Developed Area Using MAXSHRIMP.BAS
To study the way the shrimp system generates maxima, a BASIC microcomputer program
MAXSHRMP.BAS was developed to simulate the model in Figure 19 with old and new shrimp
production systems and the interfaces with markets abroad.
The program also calculates the EMERGY flows by multiplying the flows of energy, materials,
or energy by the appropriate solar transformity. Figure 19b identifies the letter abbreviations for
various categories of EMERGY that the program calculates during the simulation. The model is very
sensitive to the rate of production of larvae (K14). More larval availability causes much wider
oscillations in magnitudes.
Calibration of MAXSHRMP
Data on storage and flows used for calibration of MAXSHRMP are given in Table 20.
Calibration numbers for flows and storage per square meter in Figure 19 were obtained from data
assembled for EMERGY analysis (coastal area in Table 12 divided by 1.2E9 m2 area of mangrove
nursery, and shrimp ponds in Table 14 divided by 53 E8 m2 area). Environmental inputs into the
subsystems are represented by solar EMERGY S1, S2, and OF in solar emjoules per square meter.
Money from sales is shown spent on inputs from the economy.
. n this calibration, shrimp in the greater coastal area were represented per unit of mangrove
nursery area that produced them. Then, when proportions of the mangroves are assigned to ponds,
there is a proportionate loss of freshwater coastal shrimp and larvae. The pond and the undeveloped
area parts of the model were both calibrated as if the mangrove nursery area was 100% in original
mangroves or ponds, respectively.
For the calibrated conditions and pond area, Figure 20 has the results of the simulation
graphed with time. When the program is run and variables graphed with time (Figure 20), the
system builds up to its carrying capacity and levels off, after some oscillation. Fluctuations of market
prices from the larger economic system would cause additional oscillations, but were not included
in these runs.
Yield, Y, and
Figure 20. Results of simulating the program MAXSHRIMP.BAS Diagrammed in Figure 19,
graphing variables with time for 10% of mangroves converted to ponds.
Yield, Y, I
Ponds and I I
[i I I II
Larvae, L I
Ii I I
Percent in Ponds
I I i
0 Percent in Ponds 100
Figure 21. Results of simulating the program MAXSHRIMP.BAS (Figure 19), graphing stocks
and EMERGY flows as a function of mangrove area developed into shrimp ponds. (a) Upper
panel: yield of shrimp in ponds, Y; middle panel: shrimp larvae, L; lower panel: shrimp in
estuary, SH (b) upper panel: total shrimp EMERGY production of ponds and mangroves, JE;
Middle panel: total sales of shrimp, JM; lower panel, yield of shrimp from ponds.
Equations for Simulation Program MAXSHRMP.BAS for the model in Figure 19.
Available environmental resources not used
in the intertidal area RM = Sl*AM/(1 +KI*L*OF)
Available environmental resources not used
in the ponds RP = S2*AP/(1 + K2*L*FP)
Shrimp stock in estuary and outside waters DSH = K3*RM*L*OF -K4*SH - K5*SH*FA
Shrimp stock in ponds DSP = K13*RP*FP -K17*SH - K18*SP
Shrimp larvae DL = K14*SH - K7*RM*L*OF - K9*L -K8*RP*FP
Fishing input efforts FP = K16*MP/PP
Pond processing FA =K15*MP/PP
Shrimp caught YF = K10*SH*FP
Pond shrimp yield YP = K18*SP
Total shrimp yield Y = YP + YF
Total shrimp sales JM = PS Y
Shrimp pond money DMP = PS*YP - K16*MP
Fishing money DMA = PS*YF - K15*MA
EMPOWER use JE = TRS*(Kl*RM*L*OF) +TRS*(K2*RP*L*E)
+TRA*K11*E +TRA*K2*F +TRM*PP*
(K15*MA + K16*MP)
Rather than use a spread sheet, this program has the calculation of coefficients in the front part of the
program. See Table 18.
BASIC Program MAXSHRMP.BAS for the Model in Figure 19.
10 REM IBM
20 REM MAXSHRMP (Optimum land use for maximum EMPOWER)
40 SCREEN 1,0: COLOR 0,1
50 LINE (0,0)-(319,180),3,B
70 X = 1 :REM x=0 for time graph; x=1 for variables with area as abscissa
75 E = 0:REM E=0 and z = 0 for yields,larvae,and coastal shrimp with area
76 REM E=1 and Z=0 for total empower, sales, and pond yield with area
78 Z = 0:REM Z - 1 for alternative investment and overall investment ratio
80 LINE (0,120)-(320,120),3
90 LINE (0,60)-(320,60),3
100 REM Outside sources for calibration
110 Sl = 2.34E+11
115 S2 = 2.8E+11
120 PS = 1.88E-06:REM $/j
130 PP = 1 :REM service effort expressed in $ per year cost
135 OF = 1
150 RP 8.2E+10
200 REM Calibration values
210 SH =8000
215 SP = 7000001
230 AM = 1
240 AP = 1
250 FP =.14
260 FA = .001
285 MA .1
290 MP = 11
300 REM Coefficients
310 K1 = 0.1*S1*AM/RMI/OF
320 K2 = 0.9*S2*AP/RP//FP
330 K3 = 8000/RM/UOF
340 K4 = 4000/SH
350 K5 = 2000/SH/FA
360 K6 = 4000/SH
370 K7= 100/RM/UOF
375 K8 - 20/URP/FP
380 K9 = 100/L
385 K10 -866/SH/FA
387 K11 = 40000001/FP
390 K12= 4000001/FA
395 K13 - 1660000/RP//FP
397 K14 = 200/SH
400 K15 = .001/MA
410 K16 =.14/MP
420 K17 = 8000001/SP
430 K18 = 800000!/SP
440 K19 = 1.9E+10/RM/UOF:REM Shrimp use of offshore EMERGY
450 K20 = 0.8*S1*AM/RM/OF:REM Other species use of Mangrove EMERGY
460 K21 = 1.5E11/RM/OF:REM Other species use of offshore EMERGY
500 REM Solar transformities: sej/J
515 TRM = 8.7E+12: REM Sej/$ for Ecuador
525 TRA = 500001: REM sekcal/kcal for fuel
600 REM External Sources
610 OF= 1
630 YP - 8000001
640 YF - 866
650 PP 1
660 PS = 1.88E-06
665 S1 = 4.4E+11:REM sejyr
670 S2 = 8.6E+11:REM sej/yr
690 IRE = 2.5: REM Investment ratio-Ecuador
700 REM Starting storage
705 TA = 1
710 AP = .02*TA
720 AM = TA-AP
725 L = 200
755 PP = 1
760 MA .01
770 MP = .01
780 SH = 500001
790 SP = 500
800 REM Scaling factors
805 DT = .03
810 TO = .15
820 SHO = 1000
830 LO= 10
840 YO = 10000
850 JEO = 2E+11
860 JMO= .04
870 SPO = 30001
880 YPO = 200001
890 REM Equations
900 FP K16*MP/PP
905 AM = TA-AP
910 FA= K15*MA/PP
920 RM= S *AM / (1 + K1 * L*OF+K20)
930 RP = S2*AP/(1 +K2*L*FP)
940 DSH= K3 * RM* LOF - K4 SH- K * SH*FA-K6*SH
950 DSP = K13*RP*L*FP- K17'SP - K18*SP
960 DL = K14 * SH- K7 * RM*L*OF -K8*RP*L*FP-K9*L
970 DMA = PS*YF - K15*MA
980 DMP - PS*YP -K16*MP
1000 REM EMERGY flows:
1005 ESIAM = S1*AM
1007 ES2AP - S2*AP
1010 SHU-KI*RML*OF:REM Inshore resource use by shrimp
1020 ES2 = K2*RP**FP:REM ponds
1030 SHO = (K19*RMOF*L):REM part of offshore resource used by shrimp
1035 OTH = K21*OF*RM:REM Other nursery species use of offshore resource
1040 EA = TRA'(K11*FP +K12*FA):REM Fuels
1050 EGS = TRM*(K15*MA +K16*MP):REM Service
1052 F2 = TRA*K11*FP +TRM*K16*MP:REM Ponds purchased
1055 EAV = F2 + F2/IRE:REM Alternate Investment
1058 EP = ES2AP +F2:REM Ponds total emergy
1060 JE = ES1AM +ES2AP +SHO +EA +EGS +OTH:REM Empower total (ponds &
1070 IRF = (TRA*K12*FA +TRM*K15*MA)/(SHU+SHO):REM Fishery investment ratio
1075 IRP = F2/ES2:REM Ponds investment ratio
1080 IR = (EGS +EA)/(ES1AM +ES2AP +SHO):REM Overall investment ratio
1100 REM Change equations
1110 SH= SH+ DSH*DT
1120 SP =SP+DSP*DT
1130 IF SH < .0001 THEN SH = .0001
1140 L=L + DL *DT
1150 IF L<.00001 THEN L= .00001
1160 MA= MA+DMA*DT
1170 MP =MP+DMP*DT
1180 YF = K1*SH*FA
1200 Y=YP +YF
1210 JM PS*Y
1220 REM Plotting
1230 IF X =1 GOTO 1295
1240 PSET (T/ T,180 - SH / SHO),1
1250 PSET (T / T0,120 - (L / L)),2
1260 PSET (T/ TO, 60- Y / YO),3
1270 PSET (T/TO, 60 - JM/JMO),1
1280 PSET (T/TO, 180 - SP/SPO),3
1290 IFX= 0 GOTO 1410
1292 IF T/TO < 300 GOTO 1410
1295 IF Z = 1 GOTO 1350
1296 IF E=1 GOTO 1310
1297 PSET (320*AP/TA, 60-Y/YO),3
1299 PSET (320*AP/TA, 120-LJLO),2
1302 PSET (320*AP/TA, 180-SH/SHO),1
1304 IF E = 0 GOTO 1400
1310 PSET (320*AP/TA, 120- JM/JMO),1:REM Tolal sales
1320 PSET (320*AP/TA, 60- JE/JEO),2:REM Total EMERGY (ponds and freewater)
1330 PSET (320*AP/TA, 180 - YP/YPO),3:REM Pond yield of shrimp
1340 IF Z=0 GOTO 1400
1350 PSET (320*AP/TA, 60 - EAV/JEO),2:REM Altemative investment of F2
1370 PSET (320*AP/TA, 120 - IRP),3:REM overall EMERGY investment ratio
1400 IF T/TO >310 GOTO 1440
1420 IF T / TO < 320 GOTO 890
1430 IF X =0 THEN END
1440 T 0
1442 MA-.01: MP =.01
1450 IF AP > TA THEN GOTO 1490
1460 AP = AP +.*1TA
1470 IF AP > TA GOTO 1490
1480 GOTO 890
Calibration of the Simulation Program MAXSHRMP in Table 18
STORAGES (state variables):
(SP) Pond shrimp storage per unit area estimated:
(50,000 ind/1E4m2)*(.5 survival)*(454g/70 ind)*(5.7 kcal/g)(4186 J/kcal) = 0.7 E6 J/m2
(SH) Shrimp storage in mangroves per unit areas (539/ ind./1 E4 m2)(454 g/70 ind)(5.7
kcal/g)(4186 J/kcal) = 8000 J/m2
(L) Plankton stage individuals free in coastal waters (Order of magnitude from Guzman
de Peribonio et al, 1981) 10 ind/m3 * 10 m = 100 ind/m2 coastal area;
(MP) Cash on hand for pond operations equivalent to 5 times annual costs; per area of
shrimp ponds (5)*($111 E6)/(5.3 E8 m2) = $1/m2
(MA) Cash on hand for trawl operations per unit area of nursery mangroves (5 * $ 2.58
E6)/(1.19E9 m2) = $.01/m2
(A) Total area of mangroves & ponds = 1.0
SOURCES & FLOWS: For environmental Inputsannual solar EMERGY was used.
(S1) Mangrove area (279 E18 sej/yr)/(1.19E9 m2) = 2.31 Ell sej/m2/yr.
(S2) For ponds: (1.5 E20 sej/yr)/(5.3 E8 m2) - 2.8E11 sej/m2/yr;
(OF) Offshore environmental availabilities set at unity (1.0)
(FP) same as (K16) pathway, $.14/m2/yr
(PS) ($315 E6/m2/yr)/(1.68 E14 J/m2/yr) = 1.88 kE-6 $/J
(PP) = 1.0; Money and costs both in $ units
(RM) Residual unused environmental availability to mangroves, 10% of S1
(RP) Residual unused environmental availability to ponds, 10% of S2
(YF) Trawl yield per area of mangrove nursery: (2.08E13 J/yr)/(2.4E10 m2) = 866 J/m2/yr
(YP) Mariculture yield per area of ponds: (1.68 E14 J/yr)/(5.3 E8 m2) = 316,981 J/m2/yr
(K1) 10% of Sl*mangrove area
(K2) 90% of S2*pond area
(K3) Shrimp produced, one year replacement time: 8000 J/m2/yr
(K4) Shrimp used to make larvae as 1/4; 4000 J/m2/yr
(K5) Shrimp harvested as 1/4: 2000 J/m2/yr
. (K6) Depreciation as half of turnover: 4000 J/m2/yr
(K7) Larvae metamorphosing in Mangroves: 100 lnd/m2/yr
(K8) Post-larvae used or killed by ponds (100,000)/(1 E4 m2)/0.5 year) = 20 ind/m2/yr
(K9) Larval mortality: 100 ind/m2/yr
(K10) Trawl yield--see YF 866 J/m2/yr
(K11) Fuel, ponds:(2.39 E15 J/yr)/(5.8 E8 m2) = 4 E6 J/m2/yr
(K12) Fuel, trawls: (5.4E14 J/yr)/(1.2 E9 m2) = 4 E5 J/m2/yr
(K13) Pond shrimp production, 6 month replacement: 1.6 E6 J/m2/yr
(K14) Larval production, half year replacement: 200 ind/m2/yr
(K15) Trawl costs, goods-services: $1.3E6)/(1.2 E9 m2) = $ .00108
(K16) Pond costs,goods-services: (25.5 +35.6+2.0+5.8+5.8 - 72.7 E6 $/yr)/(5.3E8 m2) =
(K17) Pond Shrimp mortality, half of production: 0.8 E6 J/m2/yr
(K18) Pond shrimp harvested, half of production: 0.8 E6 J/m2/yr
(K19) SHO Shrimp use of coastal EMERGY from Table 12b: (0.227 E20 sej/m2/yr)/(1.19 E9
m2) = 1.9 E10 sej/yr
(K20) Drain of other species on coastal shrimp availability, 80% of S1 = 3.5 E11 sej/m2/yr
(K21) Loss of offshore EMERGY use by other nursery species (8 * SHO). See coefficient
At the top is the combined yield of shrimp from the new ponds and the old system of fishing
in natural waters. The total sales Jm are plotted also. The lower part of Figure 20 has the growth and
leveling off of shrimp post-larvae L, shrimp in the environments SH and in the ponds SP. A run with
time shows up as a vertical bar. Then the program increases F, the development intensity and runs
again, plotting another bar, and so on. The results are graphs of variables as a function of
development area. Increasing numbers of ponds reduce the areas supporting the wild populations,
reduce the stocks and food supplies in the wild. Costs of operating ponds increase. Shrimp caught in
the wild decrease.
Effects of Adding More Shrimp Ponds
Figure 21 has the results of simulations plotted as a function of the area of shrimp ponds
developed. First is the total EMERGY use in the system calculated as the sum of the solar EMERGY
in environmental inputs S, in the fuels use in the purchased operations and in the goods and services
input. The graphs include total EMERGY, sales and yield. In Figure 21 as development increases, the
maximum EMERGY benefit and sales of trawl and pond shrimp together for the region as a whole
decline because resources are diverted as fast as purchased inputs are added.
The lower panel shows that an intermediate developed area produces maximum yields. The
lower panel of the graph is the yield for the ponds only. The maximum for the ponds alone is further
to the right than the maximum contribution to the economy of the region. If one continues pond
development so as to maximize profit to the shrimp operators, regional economy suffers.
In some runs where environmental resources available to the wild populations were restricted
and larvae were adequate, a maximum was found for the EMERGY and regional sales.
Sources of Hatchery Post Larvae
At the time of the study, the shrimp ponds of Ecuador depended on the natural life cycle of
the P. Vannemei to generate post larvae or to provide gravid females caught offshore. Hatcheries
were in extensive use, but female shrimp that supply up to 300000 eggs each were obtained from the
natural population off shore. Since the hatchery post-larvae tend to be clones of a few adults, and
not subject to the selective processes of the wild cycle, questions were raised about whether the
hatchery post larvae were as viable as those captured during their migration into the estuary. The
selection process of natural environment may be an important EMERGY contribution to genetic
viability. Culture methods include antibiotics with unknown effects on larval stamina.
In some Asiatic shrimp pond culture, penaeid shrimp have grown to reproduction size in
ponds and used to seed the hatcheries. In other words, it is possible to close the life cycle of shrimp
aquaculture without the wild system. However, this increases the inputs required in time, labor,
feeding, fuels, etc. for the same output. The Ecuador system uses the environmental system to do
half the work. An EMERGY analysis of a system that closed the cycle without use of the
environmental work would show whether it could be economic or whether the additional inputs
would make too-high ratio of purchased to free inputs to compete.
There are several numbers for which the calculations are tentative for lack of good data or
confidence in the aggregation. These include the EMERGY evaluation of the contributions of the
offshore Peru current More data are needed on the trawl fishery costs and fuel requirements, and
evaluation of the geological components of the national system. However, refinements are not
expected to change main conclusions.
List of Tables
Table 1. EMERGY Evaluation of Annual Environmental Flows for Ecuador in 1986. 26
Table 2. EMERGY Evaluation of Annual Export Flows for Ecuador in 1986. 29
Table 3. Summary Flows for Ecuador, 1986. 30
Table 4. EMERGY Indices for Ecuador Based on Table 3 and Figure 13. 32
Table 5. EMERGY Self Sufficiency and Exchange. 33
Table 6. EMERGY Use and Population. 33
Table 7. Concentration of EMERGY use. 34
Table 8. National Activity and EMERGY/$. 34
Table 9. Environment and Economic Component of EMERGY Use. 38
Table 10. Spreadsheet Table Used to Calibrate Coefficients of the Simulation Model
PRODSALE.BAS Using Numbers for Source, Storage, and Flow in Figure 14. 42
Table 11. BASIC Program PRODSALE.BAS for IBM PC. See model in Figure 14. 43
Table 12a. EMERGY Inputs to the Coastal System of Ecuador. See Figure 4. 48
Table 12b. Indices of Coastal Ecuador. 49
Table 13. EMERGY Evaluation of Annual Inputs to the Mangrove Nursery
System of the Gulf of Guayaquil, Ecuador. 54
Table 14a. EMERGY Evaluation of Shrimp Pond Mariculture System in Ecuador. 61
Table 14b. EMERGY Indices for Pond Mariculture. 62
Table 15. Comparison of Solar Transformities of Harvested Peneid Shrimp. 66
Table 16. Change in EMERGY Flows in the Coastal System of Ecuador Before and
After Shrimp Pond Developments. See Figure 4. 69
Table 17. Equations for the model in Figure 19 and its Simulation Program
MAXSHRIMP.BAS in Table 18. 76
Table 18. Listing of Microcomputer Simulation Program MAXSHRMP.BAS
diagrammed in Figure 19. 77
Table 19. Calibration of the Simulation Program MAXSHRMP.BAS in Table 18. 80
This report includes EMERGY evaluation of shrimp ponds and the mangrove bordered
estuaries in Ecuador, the role of shrimp in the economy of Ecuador and its foreign trade, simulation
models of shrimp ponds and their interface with the economy, and public policy recommendations
for maximizing sustainable economic use of the environmental resource. These studies illustrate the
methodology for evaluations and developing recommendations for sustainable development of
environmental resources and economically vital foreign aid.
In the absence of any public policy on managing environmental resource for the public good,
the free market economy causes the mangroves and shrimp previously supporting the public
generally, to be brought into private shrimp business, the products going overseas with much less
real wealth returning in the small buying power of the money received. Those in the shrimp
industry in Ecuador become part of the overseas business enterprises with overseas money no
longer contributing much to the local economy. Thie pattern also applies to oil exports. If the pelagic
fish, mangrove, river, oil, and shrimp products were utilized within Ecuador, prices would drop,
standards of living rise, inflation decrease and more buying power would remain in Ecuador.
The pattern of selling a valuable raw product abroad produces a very large drain from the
underdeveloped county because of the differences ind EMERGY/$ ratio, because of the large,
previously unevaluated contributions of the environment to shrimp, because of over-intense
developments of some of the ponds, and because valuable pelagic fish landings are being used as
auxiliary shrimp food.
In the rush to develop ponds and agriculture, contributions of coastal environmental systems
have diminished. Measures to help the environment generate more wealth could include:
decreasing channelization; returning some of the Peneus vannanme to the estuary at time of pond
harvest to insure larval stocks; returning the coastal areas to mangroves, and changing inland dam
development plans to return some of the seasonal flood of the Duale-Peripa river to the estuary.
Decreasing the intensity of pond operation may lower yield but will reduce costs, lower
shrimp prices, allow local consumption and generate more net benefit to the region. Using the high
EMERGY pelagic fish landings for local food contributes more to the standard of living than feeding
shrimp to profit foreign markets.
The simulation of models showed maximum benefit to Ecuador occurs with less area
developed in shrimp ponds than that which maximizes shrimp pond profits. In order to substitute
home use of products for unequal trade abroad, some existing ponds may be converted to other
To keep environmentally produced wealth within Ecuador to stimulate its own economy,
requires that there be less borrowing from developed currencies, less sales to countries with higher
EMERGY/$ ratio, keeping intensity of developments from exceeding the local investment ratio,
using high EMERGY products for high quality purposes, and matching environmental EMERGY
with purchased inputs without diversion of destruction.
General Recommendations for Maximum Success of Economic Development
Guidelines for development that reflect the principles illustrated by these studies on shrimp in
Ecuador include the following:
* Value of environmental areas and products should be determined with EMERGY
measures and then related to currency and international dollars on a national basis rather
than using market values which mainly cover human services, often a small part of
environmental products from nature.
* Density of development and amount of area developed should be that which maximizes
regional EMERGY and thus direct and indirect contributions to the whole economy.
Maximizing market value and profit of the environmental industry may detract from the
general economy, especially if there is no feedback from that industry to reinforce the
input processes of the environmental systems.
* Intensity of development as measured with investment ratio should not be greater than the
typical intensity for the region as measured with EMERGY investment ratio.
* Contribution of an environmental area before and after development should be compared
with EMERGY evaluation and these compared with the potential development that has the
national EMERGY/$ ratio. Evaluation is made as shown in Figure 18.
* Sales of products should be made to the local economy. If international sales are made,
arrangements should be made to obtain equal EMERGY value in exchange for the
environmental products or services. This may require that sales agreements include other
compensations such as information, service, and military protection. To some extent these
exchanges have been part of the exchanges between less developed and highly developed
countries, but there has not been an adequate basis for determining equity. Perhaps the
EMERGY method provides the means.
* An Emdollar may be defined as the basis for exchange equity with the conversion between
each country's currency and the emdollar based on the EMERGY/currency ratios.
Manipulations of currencies and exchange rates should be evaluated with EMERGY
We are grateful for the opportunity provided by the Coastal Resources Center to apply new
methods of environmental and macroeconomic evaluation. Data were supplied by Gordon Foer,
Bruce Epler, Lynne Hale, and John Walsh. Dan Campbell read and criticized the manuscript.
We acknowledge the stimulating leadership of Stephen Olsen in connecting scientific
initiatives with critical problems of the world's economy.
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PRINCIPLES OF EMERGY ANALYSIS FOR PUBLIC POLICY
Howard T. Odum
Environmental Engineering Sciences
University of Florida
This paper explains EMERGY concepts for maximizing public wealth, and gives explanations
for why the principles are valid. The viewpoint is that the world economy, the nations, and states
increase their real wealth and prevail according to these principles.
A new quantity, the EMERGY, spelled with an "M" measures real wealth. Here we are using
"wealth" to mean usable products and services however produced. Maximizing the EMERGY is a
new tool for those making public policy choices among alternative programs, resources, and
appropriations. Choosing actions and patterns with the greatest EMERGY contribution to the public
economy maximizes public wealth. EMERGY analysis is not advocated as a tool for estimating
market values. This paper explains EMERGY evaluation and its use to improve public policies.
Human Choices Consistent with Maximum Sustainable Wealth
Many if not most people of the world assume that the economy is not subject to scientific
prediction but is a result of human free choices by businesses and individuals motivated by their
individual needs. A different point of view is that the human economy, like many other self-
organizing systems of nature, operates according to principles involving energy, materials,
information, hierarchical organization, and consumer uses that reinforce production.
If those human choices that lead to successful, continuing wealth fit principles of larger scale
self organization, then the economy ultimately uses human choices to follow the scientific laws. The
human free choices are the means for finding the maximum public wealth by trial and error. Choices
that do not contribute to the public wealth are not reinforced in the larger scale. Eventually patterns
that do develop more wealth take over and are sustained.
However, if the designs of society that maximize wealth can be determined from scientific
principles, then better choices are possible with less trial and error. EMERGY evaluations and
designs based on unchanging physical measures may provide an efficient and predictable means for
achieving public wealth and sustainable economic patterns.
Scientific Basis for Economic Vitality
More in the education of scientists and engineers than in that of journalists and business
people is the recognition that resources and products are wealth. An economy is vital when it has
abundant goods and resources and uses them to reinforce productivity. Energy, minerals, and
1 Chapter 1. from "EMERGY AND POLICY," J. Wiley
information are the real wealth. It takes energy to concentrate the minerals needed by an economy. It
takes energy to maintain and process information. When resources are abundant and cheap, there
can be abundant wealth and a high standard of living. If resources and basic products are imported
cheaply, abundant wealth is imported.
The Irrelevance of Market Prices to Wealth
Although the market value of products and services is important to individuals and business
budgets, it is largely irrelevant as a measure of wealth. A tank of gasoline drives a car the same
distance regardless of what people are willing to pay for it. A day of summer sunlight generates so
much corn growth regardless of whether a human thinks it's free or not A nugget of copper
concentrated by geological work will make so much electric wire regardless of its price.
When resources are abundant, wealth is great, standard of living is high, and money buys
more. But when resources are abundant, market values and prices are small. Prices are not a
measure of resource contribution to wealth.
When resources are scarce, prices are high not only because shortages affect demand, but
because more human services are required to mine, transport, or concentrate scarce resources. By the
time the resources have been collected and used, the net contributions of the resource have been
diminished by the extra efforts to process the resources.
Figure 1 shows the economic interface between a typical environmental process that generates
the resources and the human economy. Money circulates through the people involved in processing
the resources, but no money goes to the works of the environment. The money paid is not a measure
of the wealth that comes from nature's work on the left. In other words, prices are not only not a
measure of the contribution of resources and commodities to an economy, they are inverse, being
lowest when contributions are greatest. Another kind of measure is required for evaluating
contributions to public wealth.
in p uct User, $
human-paid economic production process. Notice absence of reinforcement from user to
EMERGY of a product is the work which went into making it expressed in units of one type of
energy. The unit of EMERGY measure is the emjoule.
For example, a cubic meter of rain water over land has a solar EMERGY content of 7.5 E10
solar emjoules. This means that 7.5 E10 solar joules directly and indirectly were involved in bringing
this much rainwater to the land.
EMERGY and Sustainable Uses
Because EMERGY measures what went into a product, it is also a measure of what that
product should contribute to the economy if its use is to justify its production.
In the self organizational process of economies and of environmental systems, products that
require more work in their manufacture either contribute more to the system commensurate with
what was required to make them, or the production is discontinued.
Thus, EMERGY is not only a measure of what went into a product, it is a measure of the
useful contributions which can be expected from that product as an economy self organizes for
EMERGY goes with a product as it is processed and transported. It is like a memory, since it
records what went into that product.
Reinforcement of Production Required for Sustainable Uses
Whereas'individualistic human-centered concepts of economic benefit view production as
directed to benefit the human consumer, real self organizing systems develop with a different
consequence. All uses (by consumers) reinforce production processes or are displaced by those
which do. Economies which allow allocation of resources to wasteful luxuries are not sustainable,
being displaced by those with better reinforcement of their productive basis. This viewpoint
contrasts with the economic view that any expenditure of money is good whether it be for
unnecessary products and services or not.
Consumers that use products without contributing to production processes elsewhere in the
system divert resources, reducing the wealth of the system below its potential. For example,
consumers that use larger cars than necessary for their maximum service to the economy reduce the
potentials for economic reinforcement inherent in the products they consume.
Consumers that use products of nature's production such as fisheries without contributing
some reinforcement to the natural production process cause that production system to be displaced
by alternative systems which are not so exploited. Because marine fisheries have rarely reinforced
their stock production processes, many have been displaced. In contrast, most sustainable systems of
agriculture apply extensive reinforcement to their soil production processes by applying various
fertilizers and other soil improvements. Figure 2 compares sustainable systems that reinforce with
an unsustainable design that does not reinforce.
Figure 2. Comparison of consumers which reinforce production with those that don't. (a)
Environmental production and consumption with consumer outputs of materials and services
that don't reinforce; (b) economic production and consumption with consumer output
- Some of the production processes are those of environmental work such as that of forests,
farms, fisheries, and mineral forming processes (geological processes). Other production processes
are those within the human economic system of industries. Both kinds of production processes
require reinforcement with services and other inputs from the consumers to be sustainable. For
example, means for reinforcing fisheries production include release of hatchery stocks, fertilizing
food chains, selective removal of competing species, and chumming with extra food supplements.
The circulation of money helps insure that human producers receive reinforcement for their
contributions, but the production processes of nature cannot accept money. As Figure 1 shows,
money paid to humans to process environmental products with market pricing does not lead to
reinforcement. Maximizing human incomes does not include any reinforcement to the
environmental systems necessary for sustainable production.