EVALUATION OF ORGANIC CARBON ACCUMULATION IN A RECLAIM ED MANGROVE SEAGRASS ECOSYSTEM By TRACEY B . SCHAFER A THESIS PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUI REMENTS FOR THE DEGREE OF MASTER OF SCIENCE UNIVERSITY OF FLORIDA 2016
Â© 2016 Tracey B . Schafer
3 ACKNOWLEDGMENTS I thank the entire Osborne lab for their help and support throughout this endeavor . I would like to thank Leah Laplaca, Lorae Simpson, Jacob Johansen, and Ashley Peterson, whom were all willing to assist me in the field. I would also like to thank Rex Ell is for gathering previous data and information from my study site and helping me navigate through the mangrove thickets of SL 15. I would especially like to thank Dr. Osborne, my advisor, for taking me on as a graduate student and supporting me every step of the way. Thanks to Ramesh Reddy, Mark Clark, and Christine Angelini for being a part of my committee and helping to make me a better scientist. I would like to thank my parents, Marci Ade l s ton Schafer and Robert Schafer, for supporting me the past 27 years no matter where in the world I am and what I am undertaking. Also, thanks to all of my friends that have helped me stay positive throughout the process, and especially to Emily Dabe for inviting me to come to Florida for a two week vacation that tur ned into two years of graduate school.
4 TABLE OF CONTENTS page ACKNOWLEDGMENTS ................................ ................................ ................................ .. 3 LIST OF TABLES ................................ ................................ ................................ ............ 6 LIST OF FIGURES ................................ ................................ ................................ .......... 7 ABSTRACT ................................ ................................ ................................ ..................... 8 CHAPTER 1 INTRODUCTION ................................ ................................ ................................ .... 10 2 LITERATURE REVIEW ................................ ................................ .......................... 14 Source and Origin Determination of Organic Carbon to Estuaries .......................... 15 Accumulation Rates of Organic Carbon in Estuaries ................................ .............. 17 Decomposition Rates of Organic Carbon in Estuaries ................................ ............ 18 Interactions of DOC and POC ................................ ................................ ................. 19 Sources of and rates of movement of organic carbon in the Indian River Lagoon .. 21 Sources of Organic Carbon to the IRL ................................ ................................ .... 21 Seagrasses ................................ ................................ ................................ ...... 22 Seston (Phytoplankton and Detritus) ................................ ................................ 23 Mangroves ................................ ................................ ................................ ........ 23 Organic Carbon Loading in the IRL ................................ ................................ ........ 24 Water Quality Issues in the IRL ................................ ................................ .............. 25 3 SEDIMENT ORGANIC CARB ON ACCRETION OVER A TEN YEAR PERIOD IN A RESTORED MANGROVE AND SEAGRASS SYSTEM ................................ . 27 Introduction ................................ ................................ ................................ ............. 27 Description of Study Site/Field Methods ................................ ................................ . 29 Analytical Methods ................................ ................................ ................................ .. 30 Bulk Density ................................ ................................ ................................ ..... 30 Microbial Biomass Carbon, Microbial Bioma ss Nitrogen, and Extractable Organic Carbon ................................ ................................ ............................. 30 Organic Matter Determination ................................ ................................ .......... 31 Total Organic Carbon (% weight and isotopic C 13) ................................ ........ 32 Total Nitrogen (% Weight and Isotopic N 15) ................................ ................... 34 Statistic al Analyses ................................ ................................ .......................... 35 Results ................................ ................................ ................................ .................... 35 Mangrove Planter ................................ ................................ ............................. 36 Seagrass Bed ................................ ................................ ................................ ... 38 Discussion ................................ ................................ ................................ .............. 41 Mangroves ................................ ................................ ................................ ........ 4 2
5 Seagrasses ................................ ................................ ................................ ...... 44 Synthesis ................................ ................................ ................................ .......... 46 4 BLUE CARBON ACCRETION IN MANGROVE AND SEAGRASS VEGETATION OVER A TEN YEAR PERIOD ON A CONSTRUCTED SPOIL ISLAND ................................ ................................ ................................ ................... 58 Introduction ................................ ................................ ................................ ............. 58 Methods ................................ ................................ ................................ .................. 60 Site Description ................................ ................................ ................................ 60 Vegetation Assessment ................................ ................................ .................... 60 Mangrove above ground allometri c equations ................................ ........... 61 Mangrove biometric equation for seedlings ................................ ................ 62 Mangrove below ground allometric equations ................................ ............ 62 Mangrove area calculations for total g carbon ................................ ........... 62 Seagras s biomass measurements ................................ ............................. 62 Results ................................ ................................ ................................ .................... 63 Mangrove Planter ................................ ................................ ............................. 63 Seagrass Beds ................................ ................................ ................................ . 63 Discussion ................................ ................................ ................................ .............. 64 Mangroves ................................ ................................ ................................ ........ 64 Seagrasses ................................ ................................ ................................ ...... 65 Synthesis ................................ ................................ ................................ .......... 67 5 TOWARDS A MORE ACCURATE INTERPRETATION OF COASTAL MANGROVE AND SEAGRASS RECLAMATION ................................ ................... 80 Objective 1: Assessing Organic Carbon in Mangrove Sediments ........................... 80 Objective 2: Assessing Organic Carbon Accretion in the Seagrass Habitat ........... 81 Objective 3: Evaluating Vegetative Co mmunity Evolution ................................ ....... 81 Objective 4: Evaluating Trajectories of Recovery in Mangrove and Seagrass Habitats ................................ ................................ ................................ ............... 82 Conclusions ................................ ................................ ................................ ............ 83 LIST OF REFERENCES ................................ ................................ ............................... 85 BIOGRAPHICAL SKETCH ................................ ................................ ............................ 96
6 LIST OF TABLES Table page 3 1 Equations used to estimate % organic carbon in mangroves and seagrasses at SL 15. ................................ ................................ ................................ ............. 48 3 2 P values generated from Microsoft Excel using t tests assuming unequal variances for comparisons among years and chemical parameters on SL 15 and reference sites. ................................ ................................ ............................ 49 4 1 Allometric equations used to calculate the g/kg C for each measured mangrove according to species and height. ................................ ....................... 68 4 2 Allometric equations used to calculate kg C for below ground biomass of mangroves at SL 15 and the reference site. ................................ ....................... 69 4 3 Above and below ground biomass (gm 2 C) per plot on the SL 15 mangrove planter as calculated by allometric equations. ................................ .................... 70 4 4 Area calculations for total grams of C per polygon for both above ground biomass and below ground biomass. ................................ ................................ . 71 4 5 Results of reference plot approximately 100 m outside of SL 15. ....................... 72 4 6 Values for above ground and below ground biomass across the globe divided by location and forest type and age are shown above. .......................... 73 4 7 A few above and below ground biomass values of seagrasses in other systems are shown above in grams dry weight mass/ m 2 . ................................ . 74
7 LIST OF FIGURES Figure page 1 1 Evolution of SL 15 over time on Google Earth ................................ .................... 13 3 1 Location of SL 15 site north of Ft. Pierce Inlet. ................................ ................... 50 3 2 P lots created on SL 15 in 2005 and proximity to reference sites . ....................... 51 3 3 Mangrove sediment anal yte values for bulk density, organic matter, extractable organic carbon, and total nitrogen . ................................ ................... 52 3 4 Microbial biomass carbon traje ctories in the mangrove planter. ......................... 53 3 5 10 year trajectory on SL 15 for organic carbon accretion in the mangrove planter. ................................ ................................ ................................ ............... 54 3 6 Seagrass sediment anlyte values for bulk density, organic matter, extractable organic carbon, and total nitrogen . ................................ ................................ ..... 55 3 7 Microbial biomass carbon trajectories in the seagrass embayment .................... 56 3 8 10 year trajectory on SL 15 for orgnaic carbon accretion in the seagrass embayment ................................ ................................ ................................ ......... 57 4 1 Location of SL 15 near Fort Pierce, FL near the inlet of the Indian River Lagoon. ................................ ................................ ................................ .............. 75 4 2 Plots established at SL 15 and proximity to reference sites . .............................. 76 4 3 Averaged above ground biomass across SL 15 plots and the refer ence site . .... 77 4 4 Averaged below ground biomass across SL 15 and reference sites. ................. 78 4 5 Map of SL 15 divided into polygons representing 16 sections used for area calculations in ArcGIS. ................................ ................................ ....................... 79
8 Abstract of Thesis Presented to the Graduate School of the University of Florida in Partial Fulfillment of the Requ irements for the Degree of Master of Science EVALUATION OF ORGANIC CARBON ACCUMULATION IN A RECLAIMED MANGROVE SEAGRASS ECOSYSTEM By Tracey B . Schafer May 2016 Chair: Todd Z. Osborne Ph.D. Major: Soil and Water Science
9 Mangrove forests, seagrass meadows, and other vegetated coastal habitats sequester significant amounts of carbon in biomass and sediments, which has come to be known as the blue carbon pool. By using allometric equations to calculate blue carbon biomass s torage of mangrove and seagrass habitats at SL 15 (21445 m 2 restored spoil island in Fort Pierce, F) and comparing these values to those of a natural reference system, the current status and full potential for biomass carbon storage on the island was deter mined. The total above ground biomass C of mangroves was 10,445 gm 2 C in comp arrison to an average of 129,801 gm 2 C across the reference site. Below ground biomassses showed the same trend, as the averag e for SL 15 values were 5,997 gm 2 C, which w as much less than 183,736 gm 2 C at the reference site . Spatial patterns of mangrove height were also observed across the island due to salinity stress from poor site construction. Seagrass biomass was almost entirely absent in the constructed seagrass bed at SL 15, so biomass C storage was not calculated in seagrases and is essentially zero. Seagrass absence was attributed to site construction and/or water quality issues.
10 CHAPTER 1 INTRODUCTION Spatial area of coastal habitat is decreased every year by environmental degradation and human development. Globally, between 1 and 4% of original mangrove area is lost each year (Valiela 2001), and approximately 7% of original seagrass area (Waycott 2009 ). These ecosystems provide a wide variety of ecosystem services, including sequestration of carbon for greenhouse gas reduction that is important for global ecosystem health and sustainability ( Mcleod 2011 ; Lavery 2013). Due to this large decline in coa stal habitat, preservation efforts may themselves not be enough, and restoration of degraded coastal ecosystems is becoming necessary to aid in the return of these habitats and the services they provide. Ecosystem reclamati on is a common practice employed for mitigation and increased sustainability purposes across the United States. There are many different te chniques for implementing recl a ma tions and an equal number of ways of monitoring and asses sing the success of these reclamations. Reclam ation projec ts must take location and environmental factors into account and cater their practices to each individual system. Macroclimate and oxygen concentration, as well as source lability, determine accretion and decomposition rates of organic matter that drives many biogeochemical processes ( Meentemeyer 1978; Chapin et al. 2002). In addition, w etland systems must be considered differently than upland ecosystems. Due to the anaerobic conditions in wetland systems, organic matter is accreted over time as vegetati on recovers and produces biomass that eventually senesces and slowly decomposes (Reddy and Delaune 2008). One method of monitoring wetland systems is
11 to measure organic matter (or more specifically carbon) accretion over time and formulate a trajectory to determine reclam ation and recovery success. This technique is being used to formulate an organic carbon trajectory on the restored spoil island of SL 15. SL 15 is located in the Indian River Lagoon (IRL) and was restored as a mitigation site in 2005 by th e Florida Department of Transportation (FDOT). The island was originally created in the 1950s from dredging of the Atlantic Intracoastal Waterway (ICW) in St. Lucie County, FL. Before reclam ation, the island was primarily vegetated by exotic species of p lants with only a small na tive mangrove fringe. Reclam ation of the island involved removing excess fill, removing exotic vegetation, and reforming the island topography to create an area for a mangrove forest plateau and an embayment for seagrass bed dev elopment (Figure 1 1). Seven tidal channels were cut through the embayment area to allow tidal flushing and natural recruitment of local seagrass species. Determining the full potential of SL 15 and the overall reclam carried out throu gh studying the following research objective s: (1) assessing organic carbon in the mangrove habitat, (2) assessing organic carbon in the seagrass habitat, (3) evaluating vegetative community evolution , and (4) evaluating trajectories of recovery in mang ro ve and seagrass habitats. For this study, the foll owing hypotheses were test ed : (1) carbon accre tion in sediments will increase measurably after ten yea rs, (2) vegetation establishment on SL 15 occurs along a different and more rapid temporal trajectory than funct ional recovery , (3) functionality of carbon dynamics is still impaired after ten years and has not met background conditions . Reclamatio difficult term to define, as success is subjective and determined by the specific
12 objectives set by each restoration project. SL 15 may not be fully recovered, functionally or vegetatively, after only 10 years, but it is expected to show some level of carbon accretion and vegetat ive growth. This study attempts to evaluate the structural and functional aspects of the SL 15 mangrove and seagrass habitats and use carbon sequestration potential as a measure of the reclamation 15.
13 Figure 1 1. Evolution of SL 15 over time on Google Earth . A. SL 15 before reclam ation . B. SL 15 directly after reclama tion at time point zero . C. SL 15 three years post reclam ation. D. SL 15 fiv e years post reclam ation . E. SL 15 about 10 years post reclam ation. A . B. C . D . E.
14 CHAPTER 2 LITERATURE REVIEW Organic carbon (OC) is important in global biogeochemical processes. It can be reactive, mobile, and can be found in several different forms (Reddy and Delaune 2008) . In estuaries, where there is a great deal of mixing and movement of water from the ocean, river, and surface runoff, and it is possible to transport OC from a sizable area into the estuary . As the OC moves toward the estuary, it can bind with other molecules, accumulate within the estuary, and be stored un til decomposition releases the bound molecules. Estuaries are highly dynamic and unique systems and each one functions differently with regard to OC accumulation, decomposition, and reactivity (Bianchi 2007) . Organic carbon can be found in estuaries in se veral forms, mostly consisting of dissolved organic carbon (DOC) and particulate organic carbon (POC). Autochthonous sources of organic carbon within estuaries consist of decomposing vegetation, macroalgae, plankton, and detritus. A wide array of allocht honous sources of OC can enter into these systems from various water sources running into the estuary (Savoye 2012). Estuaries tend to accumulate OC at higher rates than uplands since anaerobic conditions slow rates of decomposition; however, estuaries ca n be either sources or sinks of organic carbon, depending on adjacent water sources and flow rates (Jespersen 2007). Rivers are key sources of water and nutrients to estuaries and can carry an estimated 0.9 Gt of total carbon per year, about 40% of which is thought to be OC (Maybeck 1993). In many estuaries with high flow rates and short residence times, most of this OC is carried through the estuary and deposited into the ocean (Winter
15 1996). In other environments, high residence time can lead to the se ttling and storage of OC within the estuary. Organic carbon is highly significant in estuarine systems because of its ability to bind with other molecules. This binding can either make nutrients unavailable for vegetative and microbial uptake, or it can shield the system from harmful toxins and contaminants. Forms of nitrogen and phosphorus, as well as pesticides and metals, are known to easily bind with DOC and POC and then be transported to new locations or become buried within the sediment. As OC dec omposes, many of these bonds are broken, releasing nutrients for plant and microbial uptake and/or possible environmental contamination (Reddy and Delaune 2008). Within the Indian River Lagoon Estuary (IRL) , the exchange loading rate of water within the I ndian River Lagoon has been shown to be as much as 150 cm day 1 , allowing high volumes of OC movement into and out of the estuary (Martin et al. 2006). Sources of OC in the Indian River Lagoon have differing carbon concentrations and levels of quality tha t initiate various processes based on OC source and placement (Lewis et al. 2014). This creates a unique system of OC movement, exchange, and storage, making it a significant consti tuent of the IRL and wetlands within the lagoon, such as SL 15. Source and Origin Determination of Organic C arbon to Estuaries Water runs into estuaries from terrestrial and marine sources and is the mixing point from oceans and rivers. Many of these terrestrial and riverine hydrologic sources carry forms of organic carbon in dissolved and particulate fractions. The five sources of globally important OC to estuaries includes terrestrial biomass, soil humus, fossil
16 kerogen, marine organic matter, and autochthonous estuarine primary production (Bauer and Bianchi 2011). Rivers are a significant carrier of allochthanous carbon to estuaries, wherein the amount of OC transported is dependent upon location, flow, and seasonality. River size and flow determine the amount of erosion that occurs along banks and amount of DOC and POC t hat is displaced. It has been suggested that 40% of total river transported 1996; Dagg et al. 2004). A study done on two of these rivers, the Yellow River and the Changjia ng River, measured the temporal variations in OC transport and determined that 36 44% of total DOC and 72 86% POC are transported through the rivers to the East China Sea within the rainy season of only two to three months (Wang et al. 2012). As the Yello oads, estimated at 1x10 9 t y 1 , these seasonal percentages can be quite significant in terms of global carbon transport (Milliman and Syvitski, 1992). Another one of the top ten largest rivers, the Amazon, i s estimated to carry 36.1 Tg OC yr 1 (Richey et al 1990) of the total 500 x 10 12 g OC transported to the oceans through rivers each year (Spitzy and Ittekkot, 1991). Estuaries are the passageway between rivers and oceans, consequently all of this OC is moved through estuaries at some point or another. When studying organic carbon fl ow through riverine to estuarine systems, determination of OC origin can be extremely important and very difficult. One way of doing this is to establish the distribution of OC, N, and stable C and N isotopes throughout a sediment profile to determine the original sources (Zhang et al. 2009). For example, different OM sources have unique isotopic ratios of C 13 that can help
17 determine where they came from. Atmospheric CO2 that generates OM terrestrially has an isotopic C 13 value between 27% and 14% fo r C3 and C4 plants, and OM created by aquatic bicarbonate algae has an isotopic C 13 value between 22% and 20% (Meyers 1997; Jia and Peng 2003). By determining these C 13 values throughout a sediment profile along with Pb 210 readings (or other radionuc lide readings) to determine age, where and when sources of OC originated can be determined (Zhang et al. 2009). Accumulation Rates of Organic Carbon in Estuaries Estuaries across the United States and around the world all accumulate OC at varying rates tha t are dependent upon the original sources of organic carbon and their varying levels of lability. Some studies done in estuaries with macrophyte dominated sediment organic carbon (SOC) pools have shown that there is a lag time between macrophyte establish ment and when they begin contributing to the SOC pool (Morgan and Short 2002). These accumulation rates differ from those that are constructed in estuaries with seston dominated SOC pools, which do not have a lag time between establishment and SOC pool co ntribution (Cammen 1975). Even though the source of OC is one of the major factors in determining OC accumulation rates, there are many other factors that need to be taken into account, including: temperature, residence time, turbidity levels, etc. A cou ple of studies exploring OC accumulation rates in different estuaries have been outlined below as examples. However, these rates are specific to each individual estuary and assumptions cannot generally be made that rates of one estuary will be similar to those of another. One study by Zhu and Olsen in 2014, explored the differences in organic carbon burial and sedimentation between the Yangtze River and Hudson River Estuary. The
18 burial rate in the Yangtze River Estuary was approximately 1.6 4.9 x 10 12 g C yr 1 and the rate in the Hudson River Estuary was around 1.8 3.6 x 10 10 gC yr 1 . The Hudson River has been continuously dredged, so erosion within the estuary is common, leading to much higher accumulation rates than solely those that were measured fro m inputs into the estuary (Zhu and Olsen 2014). Another study done in Mobile Bay, Alabama, showed total c arbon accumulation per year to be 0.09g cm 2 in the centr al part of the estuary, 0.361 g cm 2 at the head, and 0.564 g cm 2 at the mouth. TOC ranged from 11.6 to 16.6 mg g 1 that was shown to be approximately 20% of total carbon in the estuary (Smith and Osterman 2014). In a time serie s sketch of TOC preservation found in sediments taken from b ox core sampling , correlation coefficients between time and TOC levels were determined . The orientation of sampling location was from north to south (left to right) across shipping channels within the estuary. All correlations between TOC and years were negative with relatively high correlation coefficients, but no spatial reasoning was available for why correlations were slightly higher in some sampling areas than in others. This demonstrates how different OC accumulation patterns can be within different sites of a single estuary. Decomposition Rates of Org anic Carbon in Estuaries Decomposition of organic carbon in estuaries is dependent on the source, temperature, and oxygen concentrations (Chapin et al. 2002). Nutrient limited systems will also show slower decomposition rates, as lack nitrogen, phosphoru s, and other necessary nutrients can potentially slow microbial enzyme production necessary to break down large molecules (Keuskamp 2015). Systems that are surrounded by a lot of woody (and more recalcitrant) vegetation will show much slower rates of deco mposition
19 than estuaries that are mainly dominated by macroalgae, seagrass, and other more labile vegetation that have a low C:N ratio (Reddy and Delaune 2008). Similar to accumulation, decomposition rates are also specific to each estuary and individual areas within the estuary. A study from the Jiul ongjiang estuary in China used litter bags with Kobvata mangrove litter and found varying levels of C decomposition depending on the season. Decomposition rates were based on average values of half time (T50 ) of leaf litter decomposition based on season. These values are 29.8 days in spring, 18.7 days in summer, 23.9 days in autumn, an d 47.7 days in winter. According to seasonal climatic changes and temperature patterns, these were expected ratios (Li and Y i 2014). However, other factors can also change the seasonality of decomposition rates. A study done in the turbidity maximum in the Changjiang Estuary showed release of CO 2 from the estuary to range fro m 9 mmol m 2 d 1 in May to 16 mmol m 2 d 1 in Augu st to 5mmol m 2 d 1 in November and February. This showed organic carbon decomposition to make the estuary a CO 2 source in winter, and phytoplankton production made the estuary a CO 2 sink in summer . More carbon is fixed and converted to forms of OC in sum mer, but once cold temperatures kill off vegetation in winter decomposition rates increase (Li et al. 2015) . Interactions of DOC and POC Reactive organic carbon can be found in estuaries in the forms of DOC (dissolved organic carbon) and POC (particulate o rganic carbon). Autochthonous sources of both forms of OC are from decomposing vegetation, macroalgae, plankton, and detritus. Allocthonous OC can originate from rivers and many terrestrial sources, most of which eventually enter riverine systems through runoff (Savoye 2012). DOC
20 and POC are both reactive and tend to interact with other nutrients within the system through adsorption and chemical interactions (Reddy et al. 2008). DOC mostly a ffects interactions taking place within the water column. DOC a ffects the pH of water and imparts color that helps protect micro organisms from UV radiation. It can bind with various metals, affecting toxicity and mobility levels (Porcal 2009). Binding of these compounds can decrease bioavailability, but degradation of DOC can release those compounds back into the system and make them bioavailable again (Wang et al 2000). A study done in the Yangtze Estuary examined levels of EOCs (emer ging organic compounds) and show ed that DOC was p ositively correlated with a p= 0.042 and R = 0.77 to several EOCs. EOCs are compounds that are beginning to be seen in research studies as potentially environmentally problematic, but sufficient proof is still lacking in order for restrictions and regulat ions to be enacted. DOC has also been positively correlated to antibiotics in aquatic systems, as well as other harmful and potentially harmful contaminants (Yan 2015). POC concentrations are dependent upon resuspension events and concentrations tend to b e higher when suspended par ticulates are less than 20 to 30 mg L 1 (Bianchi et al. 1997). POC is composed of plant biomass from riverine, marine, and terrestrial sources that are degraded into particulate matter by physical and chemical weathering. Micr obial processes and trophic interactions are some of the major controls on POC cycling within estuarine systems (Wetzel 1995; Bianchi 2007). Many times POC is eventually broken down to DOC through microbial activities, grazing, and other physical degradat ive interactions (Reddy et al. 2008).
21 Sources of and rates of movement of organic carbon in the Indian River Lagoon All estuaries have varying nutrient concentrations, sediment loads, location, climate, flow rates, and other characteristics that effect con centrations and movement of OC within systems, so this section will specifically focus on the Indian River Lagoon Estuary where SL 15 is located. The Indian River Lagoon is 156 miles long and runs from Ponce de Leon Inlet to Jupiter Inlet, which covers a total of 40% of the east coast of Florida. The IRL watershed is 2,284 square miles and contains portions of seven Florida counties. There are five inlets between the lagoon and the Atlantic Ocean. The IRL is comprised of three smaller lagoons, including Mosquito Lagoon, Banana River, and the Indian River. The lagoon is estimated to contain 685 fish species, 370 bird species (and is also along the Atlantic flyway), 2100 plant species, and 2200 animal species. The IRL is a major fishery with an economic value estimated at $3.7 billion (St. services to the state of Florida; however, it has been shown to have various issues associated with ecosystem health. Extensive literatur e specifically relating to organic carbon mov ement within the IRL is sparse. However, from a combination of information from the first half of this review on general nutrient interactions and information collected on the characteristics of the IRL, a pict ure of possible sources and movement of OC in the IRL will be assessed, along with the associated potential effects on water quality. Sources of Organic C arbon to the IRL There are many potential sources of autochthonous and allochthonous OC within the In dian River Lagoon. The Smithsonian Marine Station located in Fort Pierce, Fl has a database that shows the green algae, red algae, brown algae, mangroves, and sea
22 grasses seen in the IRL (Smithsonian Marine Station). There is a total of 3500 species of p lants, animals, fungi, and protists that can all contribute to SOC pools in the lagoon. Nearby terrestrial plants and urban runoff can also contribute allochthanous OC during storm and flood events. Below some of the largest contributors to the SOC pool in the IRL are discussed. Seagrasses Seagrasses are one of the major SAVs (submerged aquatic vegetation) seen in the Indian River Lagoon. There are seven known species of seagrass in the Indian River Lagoon, including Halodule wrightii, Syringodium filifo rme, Thalassia testudinum, Ruppia martimia, Halophila englemanii, and Halophila johnsonii (Dawes et al. 1995). A study in from 1995 by Fletcher and Fletcher, showed changes in sea grass species and abundance in the IRL between 1940 and 1992 that was done by looking at aerial photographs. Coverage was seen to be about 31,800 ha between 1970 and 1976, 33,700 ha 1984 1986, and 28,400 in 1992. (Fletcher and Fletcher 1995). Most of the seagrass loss in the IRL is believed to have been caused by light limitat ions (Virnstein et al. 2002). Light limitation effects each species of seagrass differently based on individual light and depth tolerances. Halodule wrightii is a species that can survive deeper waters, but this is where most seagrass lost has occu r red a s light becomes more of a limiting factor (Steward 2005). Seagrass is an important player in organic carbon accumulation and movement within the IRL. They both create organic carbon themselves and trap OC from other sources, helping to reduce resuspensi on. One estimate proposes that seagrass contributes approximately 50% of the sediment organic carbon pool, and between 41 and 66 gC m 2 yr 1 originates from seagrass production itself. Globally, it is estimated
23 that carbon burial in seagrasses is between 48 and 112 Tg yr 1 (Kennedy et al. 2010). Even with taking into account seagrass loss over the past fifty years, it cannot be ignored as one of the major sources of organic carbon to the IRL system. Seston (Phytoplankton and D etritus) According to the di and including both living organisms (such as plankton and nekton) and nonliving matter (such as plant debris or suspended so il particles (Merriam Webster). Even though the concentrations and composition varies between and within estuaries, seston is seen in some form in every estuary. Although isotopic compositions vary, seston is generally extremely labile with a low C: N ratio that makes it an important food source. A study by Laursen et a l. (1996) determined that food quality is based upon existence and quality of proteins in the seston . Even though OC values vary greatly in seston, its contribution to trophic webs and degradability makes it an important source of labile OC to POC and DOC pools. Mangroves There are three species of true mangroves present in the IRL: Rhizophera mangle (red mangrove), Avicennia germinans (black mangrove), and Lagunculeria racemosa (white mangrove) (Smithsonian Marine Station) . Mangroves build up organic ma tter and carbon, by expanding root biomass (Alongi et al. 2003). Mangroves cover barely 0.1% of the globe, but they have been shown to contribute as much as 10% of terrestrially derived DOC (Dittmar et al. 2001, 2006). Annual export of DOC from mangrove s in the Amazo n has been estimated as 30 x 10 9 mol/yr, which is only 1 3% of total Amazon fluxes (Dittmar et al 2001). A study in the Zhangjiang Estuary showed sediment derived organic matter from K. candel mangrove origins (TOC and TN) to be
24 6.36%, and A . marina A.corniculatum to contribute up to 21.95% and 36.88% of estuarine sediment O.M. (Xue 2014). These values are very regionally specific and differ according to location, climate, and other associated characteristics. Current literature on exact OC values from mangrove origin in the Indian River Lagoon is sparse, but the other studies mentioned above show that even in differing conditions mangroves do play some role in organic carbon cycling. Organic Carbon Loading in the IRL A study done by Kim et al. in 2002 assessed the effects of land use on the amount of runoff at the John F. Kennedy Space Center in the Indian River Lagoon watershed. By using a Long term Hydrologic Impact Analysis Model and Geographic Information System based Soil Conservati on Service curve, it was estimated that between 1920 and 1990, the average annual runoff at KSC increased as much as 49% , and the runoff in the IRL increased by almost 113% (Kim et al. 2002). This land use change has drastically changed flow intensities within the IRL that can pave the way for various other system changes including nutrient transport. As more OC runs into the estuary, degrades, and interacts with other nu trients, it can result in various ecosystem and water quality issues. However, OC may not always be extremely mobile within the estuary. The IRL has constituent subterranean parts that are connected to the surface estuary through a 25m wide seepage face. Across this face, DO concentrations were shown to remineralize 2.8 mg day 1 of OC, and iron oxides in this system were shown to remineralize 5.34x10 2 mg cm 2 yr 1 of OC. Iron oxides are believed to be the primary terminal electron acceptors in this system. The average amount of OC buried in the subterranean estuary is estimated to be approximately 35 kg per 1 m long strip across
25 the 25 m wide face. These values indicate that this portion of the IRL is an overall sink of OC (Roy et al. 2010). Water Quality Issues in the IRL As the Indian River Lagoon area has experienced rapid changes over the past several years and the area surrounding the lagoon has been converted to suburban and agricultural land (Di erberg 1991), large loadings of nitrogen, phosphorus, and other nutrients have been flowing into the estuary. These loadings occur mostly during storm events when runoff rates are high. A study by Dierberg (1991) showed that 1/3 of total Nitrogen, Â½ of p hosphorus, and Â¼ of annual DOC (dissolved organic carbon) exported from these new systems along the lagoon were from runoff into drainage channels leading to the lagoon. Most of this runoff was amassed within a six week period, during which the IRL water shed experienced three major storm events. All of these loadings can have a major effect on hydrologic and nutrient cycles within the IRL that have caused many issues over the past several years. There are currently many programs looking at estuarine res earch and improvement. By using seagrass as an indicator, the IRL seagrass area was measured as 62,000 acres in 1943 and only 58,000 acres in 1992, where losses were mainly surrounding urban areas. This was most likely due to discharge from wastewater tr eatment plans amounting to 39 million gallons of treated wastewater per day that included 1.7 million lbs of nitrogen, 400,000 lbs of ph osphorus, and 1.5 million lbs of suspended solids to the IRL. Since then, laws have been enacted, so treatment plants a re currently only discharging 23 million gallons per day into the IRL. The seagrass populations have started to rebound in recent years , to about 70,000 acres in 2006 and 2007, assuming the water quality in the IRL has shown improvement (EPA).
26 Since POC and DOC adsorbs and interacts with forms of nitrogen, phosphorus, metals, pesticides, and other contaminants, POC and DOC play roles in movement and storage of these elements within the Indian River Lagoon system. These affects exacerbate water quality i ssues by varying degrees based on concentrations and interactions within the estuary . Organic carbon has significant impacts on the movement and cycling of nutrients in estuarine systems. It is present in both dissolved and particulate forms that come fr om a variety of autochthonous and allochthonous sources and interact differently in every estuary based on lability, presence of other nutrients and contaminants, and anthropogenic alterations. The Indian River Lagoon has seen many of these anthropogenic alterations take place, which has caused changes in nutrient loadings and flow patterns. All of these other changes can cause large fluctuations in OC sources, interactions, and movement within the IRL that can exacerbate present water quality issues. Th ese issues can greatly effect accretion and movement of organic carbon, and therefore restoration success across the IRL and SL 15.
27 CHAPTER 3 SEDIMENT ORGANIC CARBON ACCRETION OVER A TEN YEAR PERIOD IN A RESTORED MANGROVE AND SEAGRASS SYSTEM Introduction When assessing restoration success in coastal ecosystems, often the fact that ecosystem aspects recover along differing temporal trajectories is ignored. In many cases, vegetation will regrow quickly, but important biogeochemical and ecologic al functions take decades longer to fully recover (Zedler 2000). For various reasons, in this study, organic carbon accretion was used as the primary measurement for est ablishing functional reclamation . Organic carbon (OC) plays a vital role in driving m any reactions in the global carbon cycle. In addition, OC makes up approximately 40 to 50% organic matter in coastal ecosystems (Howard et al. 2014), depending on the original plant sources contributing to the organic matter pool and the surrounding envir onment. Original sources and environmental factors affect quality and stabilization of organic matter at a variety of ecosystem levels (Melilo et al. 1982; Balesdent 1988), which in turn affect the system as a whole and determine overall ecosystem health (Young et al. 2008). Organic matter (OM) provides nutrients for microbial and plant growth, as well as a source of electron donors for redox reactions carried out in microbial respiration and nutrient cycling (Reddy and Delaune 2008). OC specifically pl ays a role in many global biogeochemical processes and can be highly reactive, mobile, and found in several different forms (Bianchi 2007). Reactive organic carbon can be found in the forms of DOC (dissolved organic carbon) and POC (particulate organic car bon) that originate from decomposing vegetation, macroalgae, plankton, and detritus (Savoye 2012). DOC
28 and POC can interact with other nutrients within the system through adsorption and chemical interactions (Reddy and Delaune 2008). Ecosystems accrete OC at different rates, and as such, estuaries and wetlands have been shown to accumulate OC at much higher rates than uplands (Savoye et al. 2012), primarily due to anaerobic conditions slowing rates of decomposition and organic matter turnover (Reddy and Delaune 2008). Significant amounts of OC present in coastal ecosystems in Florida can originate from mangrove and seagrass vegetation, though accretion rates and cycles can vary greatly depending on location and other environmental factors (Twilley et al. 1992; Mcleod 2011 ; Greiner et al. 2013;; Smoak et al. 2013; Breithaupt et al. 2014). Reclaimed or constructed systems accrete carbon and nutrients at different rates from natural systems. For example, after twenty years, constructed mangrove systems st ill tend to have lower soil organic matter and total carbon than natural counterparts (Osland 2012), and even after fifty years of development, these levels may still not be functionally equivalent to natural counterparts ( Ballanti ne et al. 2009). Reclama t ion / restoration projects create a disturbance in the system that may require decades for functionality to return to levels consistent with nearby natural systems (Zedler 1999). By using organic carbon as an indicator of functional recovery, an early det ermination of reclam ation success was made at the restored spoil island SL 15 in Fort Pierce, FL . After SL density, % total organic carbon (TOC), microbial biomass carbon (MBC), extractable organi c carbon (ExOC) and % total nitrogen (TN) were measured over a two year period . By comparing these values in a time series between 2006 and 2015 data, three
29 objectives were determined: (1) trajectories for total organic carbon accretion and return of func tionality were created and evaluated, (2) carbon fractions, including microbial biomass carbon (MBC) and extractable organic carbon (ExOC), as well as total organic matter and total nitrogen measured in SL 15 sediments were statistically compared to 2006 v alues, and (3) determination of current functionality within the two habitat types (mangrove and seagrass) present on the island area were assessed overall. Description of Study Site/Field Methods SL 15 is an reclaim ed spoil island located in the Indian River Lagoon (IRL) across from the IRL boat ramp o ff of US Route 1 that was reclaim ed as a mitigation site in 2005 by the Florida Department of Transportation (FDOT). The island was originally created in the 1950s from dredging of the Atlantic Intracoastal Waterway (ICW) in St. Lucie County. Before the restoration, the island was primarily vegetated by exotics with only a small native mangrove fringe. Reconstruction of the island involved removing excess fill, eradica ting exotic vegetation, and reforming the island to create an area for seagrass bed development. Seven tidal channels were cut around the edge of the wetland area to allow tidal flushing and natural recruitment of local seagrass species Beginning with ini tial clearing of the island, 16 plots were established in the mangrove planter and ten within the seagrass bed (Figure 2 2). Two reference plots (one for mangrove and one for seagrass) were also established at nearby locatio ns within the lagoon (f igure 2 3 ) . Each plot consists of a 2m x 2m area, and the plots marked in green demarcate the plots where sediment cores were taken. Four sediment cores (7 .5 cm diameter) were taken in polycarbonate tubes (Osborne and Delaune 2013) randomly within each plot and brought back to the lab for analysis (Lab methods
30 are de scrib ed in the next section). Ten centimeter deep cores were taken and divided into 0 5 cm and 5 10 cm layers , bagged, and stored on wet ice for transport. Roots were removed from cores taken from the mangrove planter and analyzed separately, but roots in cores taken from the seagrass beds were analyzed with the sediment sample as there were not have enough root material to separate the roots from the sediment. Roots from mangrove reference site co res were also analyzed with the sediment samples d ue to the percentage of roots being too large to separate them from the sediment. Analytical Methods Bulk Density Soon after collection, sectioned core samples were weighed wet and total bag weight was rec orded. Then, subsamples of soil were placed in pre weighed aluminum dishes were put in a drying oven for 72 hours at 105 C. Once dry, the dishes were weighed again and the dry weight was recorded. Then, bulk density was calculated by the following equat ion: ((dry wt. subsam ple/ wet wt. subsample)*soil wt.)/ soil volume This yielded a set of subsample values in gcm 3 that were used for t test compa risons with 2006 and reference site data for further analyses. Microbial Biomass Carbon, Microbial Biomass Nitrogen, and Extractable Organic Carbon Microbial biomass carbon (MBC), microbial biomass nitrogen (MBN) and extractable organic carbon (ExOC) were determined by using a fumigation extraction procedure (Vance et al. 1987; Joergensen and Mueller 1995). M icrobial biomass carbon was determined by placing subsamples of approximately 10g of soil into
31 centrifuge tubes and placing the tubes into a vacuum desiccator. Approximately 20 mL of chloroform was added to a 50 mL beaker with boiling chips and placed int o the desiccator. The desiccator was evacuated with a vacuum pump and the samples were fumigated in chloroform vapor for 24 hours. removed in the fume hood, allowing the chloroform to evaporate for several minutes before adding 25 mL of 0.5 M K2SO4 to each centrifuge tube. The centrifuge tubes were then placed on a shaker table for 24 hours. Another set of 10 g subsamples of sediment are weighed and placed into centrifuge tubes with 25 mL of 0.5 M K2SO4 w ithout chloroform fumigation to assess the extractable fraction of O.C.. All samples were filtered on a vacuum system through Whatman #1 filters and acidified before analysis. All samples were then analyzed on a Shimadzu TOC V analyzer (Shimadzu Corpora tion, Kyoto, Japan) and A2 (Astoria Pacific, Clackamas, OR) for total nitrogen (TN). R esults were then converted from mgL 1 to kg C or N /m 2 for 0 5 cm and 5 10 cm depths. Extractable fraction values were subtracted from the chloroform fumigated values then multiplied by a 2.22 correction factor to get MBC (Wu et al. 1990). TOC subsamples were averaged for further analyses and statistical comparisons. TKN values were not further analyzed as values were at or barely above the practical quantitation lim it (PQL) and were not useful in statistical analysis. Organic Matter Determination L oss on ignition method (LOI) was used to determine total organic matter in all SL 15 samples (SSSA 1996). Five to ten gram sediment subsamples were air dried t 105 degree s C, weighed , and combuste d in a muffle furnace at 400 degrees C for 4 hours, and then taken out and allowed to cool in desiccators for 20 minutes. After 20
32 minutes, the samples were reweighed. Loss on ignition/percent organic matter was then calculated by using the following equation: 100*( dry soil wt. combusted soil wt.)/ ( d ry soil wt. ) These values were separated by depth for further analyses and statistical comparisons. Total Organic Carbon (% weight and isotopic C 13) Air dried subsamples were taken and put through a 1 mm sieve to remove root, wood, rock, and shell materials. Several techniques were attempted for getting accurate results for total organic carbon in SL 15 sediments. Filtration of subsamples over Whatmann # 40 filters on a vacuu m filtration system was first attempted. 1.0 M HCl was squirted with a squirt bottle over the sample and filter with the vacuum on until bubbles had stopped forming (assuming all inorganic carbon had been off gassed as CO 2 ). Then, the samples were rins ed off with DDI, rinsed off of the filter onto tin plates, and dried in a drying oven at 105 C for at least 24 hours. Samples were then milled in a ball mill for 5 minutes or until sediment was a fine powder . Samples were weighed into Al capsules between 5 mg and 250 mg (depending on plot and reference samples), then ru n on an elemental analyzer (ECS 4010, Costech Analytical Technologies, Valencia, CA) linked through a Thermofinnigan EA3 to a mass spectrometer (Thermofinnigan Delta Plus XL, Waltham, MA). Peach leaves were used as a calibration standard and sucrose and an internal soi l standard for quality control. The filtration technique used was believed to have caused losses of organic matter through constant rinsing. Therefore, a second technique w as attempted that involved directly acidifying samples in silver capsules (Hedges and Stern 1984; Harris et al. 2001). This was the technique used to analyze samples from SL 15 in 2005 and 2006. The sieved sediment
33 was dried in a desiccator for two weeks , placed in scintillation viles, and ball mill ed until the sediment was a fine powder. 20 mg of powder for the reference samples and 60 mg for SL 15 samples were weighed into 9 x 5 mm silver capsules (CE Elantech, Lakewood, NJ). The capsules were placed o pen in a 96 count well plate in a glass desiccator with a beaker of 20 mL of HCl. After HCl fumigation, the well plate was placed in a sealed box with desiccate for five days. After five days, the capsules were closed, rolled, and placed back into the b ox with desiccate until being run on an elemental analyzer (ECS 4010, Costech Analytical Technologies, Valencia, CA) linked through a Thermofinnigan EA3 to a mass spectrometer (Thermofinnigan Delta Plus XL, Waltham, MA). Unfortunately, all HCl did not eva porate from samples before being run, all yielding poor results. A third technique was then attempted, measuring total carbon and total inorganic carbon, and using subtraction to determine the difference as the organic fraction. A small subsampled of sedi ment was placed in aluminum tins and treated with 30% hydrogen peroxide. The peroxide treated samples were allowed to sit in a fume hood until bubbling stopped, then the samples were placed in a drying oven at 65 C until dry, placed in scintillation viles , and milled in a ball mill. These sediments were thought to be representative of the inorganic carbon fraction. The same sieved and milled sediment was used from the previous technique attempted for the total carbon measurements. Both sets of samples w ere w eighed at 6 mg into 5 x 9 mm Al capsules (C E Elantech, Lakewood, NJ) and ru n on an elemental analyzer (ECS 4010, Costech Analytical Technologies, Valencia, CA) linked through a Thermofinnigan EA3 to a mass spectrometer (Thermofinnigan Delta Plus XL, W altham, MA). Subtraction of the
34 inorganic carbon fraction from the total carbon fraction yielded calculated O.C. values that were over 60 % negative. Too much variability within samples, poor quality control during preparation, or too high of an inorganic carbon signature could have caused the poor results. Determination of why results were poor was difficult, so these results are also not used in this paper. Due to difficulty in determining percent and isotopic signatures for TOC using all the previous t echniques, an estimate was calculated from the % organic matter values by using the equations found in the Coastal Blue Carbon Manual (Howard et al. 2014) (table 2 1). The correction factors generally associated with correcting for loss of inorganic carbo nates was removed from the equation as samples were combusted below the range where carbonates are generally lost. Other than samples from the mangrove reference site where roots were too prolific, roots from the SL 15 mangrove sites were analyzed for %C and %N analysis and added back into sample values afterward to get final numbers. These values are used in the result section as an estimate of TOC. Total Nitrogen (% Weight and I sotopic N 15) Total nitrogen values were derived from the first attempt to acquire total organic carbon data. Subsamples were taken and sieved through 1 mm sieve to remove root, wood, rock, and shell materials. These samples were acidified and filtered to remove carbonates, and then dried in a drying oven at 105 C for at least two days. Once dry, each subsamples was placed into a scintillation vile and milled in a ball mill for 5 minutes or until the sediment sample was a fine powder. Subsamples were then weighed out at varying weights between 20 mg and 400 mg to account for l arge variability between SL 15 mangrove, seagrass, and reference sediments into 5 mm x9
35 mm tin capsules (CE Elantech, Lakewood, NJ). These were then run on an elemental analyzer (ECS 4010, Costech Analytical Technologies, Valencia, CA) linked through a Th ermofinnigan EA3 to a mass spectrometer (Thermofinnigan Delta Plus XL, Waltham, MA) to get total nitrogen % weight and N 15 isotopic values. Some samples showed nitrogen values that were below detection limit and had to be rerun or could not be detected a t all. Statistical Analyses Repeated t tests assuming unequal variance (Welch t test) in Microsoft Excel were performed to compare parameters between SL 15 plots in 2006, 2015 , and the reference plots from 2015. The individual plots at SL 15 were used as subjects and the year was used as the repeated measure. The 0 5 cm depth and 5 10 cm depth were separated and run in two different sets of tests for each parameter. In 2006, three cores were taken at each plot (and composited for analysis of %TOC and %TN) , whereas 4 cores were taken at each plot in 2015 (and all analyz ed individually) . To account for this discre pancy, cores for t tests were used that assumed unequal variance with an alpha value of 0.05 for a 95% confidence interval (p values shown in table 3 2) . The data was assumed to be approximately normal, although n was small enough for some data sets that it was difficult to determine normality/ non normality. In 2006, results were analyzed using repeated measures of One Way Hoc analyses for 2005, 2006, and reference site data in SAS. Methodologies were altered currently, due to differences in number of samples and variances across treatments. Results Results are divided into data from mangrove sediments and seagrass sediments in the pages below. Values from 2005 and 2006 were collected and analyzed by Caitlin
36 Hicks (year 1) are used for comparisons in the figures below, as 2005 is time point zero of restoration where nutrient accretion was negligible from the raw spoil present. Mangrove Planter Nutrient analyses on SL 15 were compared between 2006, 2015, and the natural reference site. Bulk density, % organic matter, extractable organic carbon, microbial biomass carbon, and % total organic carbon were the parameters used for comparison. Averages of bulk density and % total organic matter (figure 2 3A and 2 3B) at 0 5 cm and 5 10 cm depths between 2006 and 2015 were shown to no t be significantly different, whereas the reference site shows a significant decrease of greater than 50% in bulk density from the SL 15 values. Total % organic matter shows a significant decrease as well between 2015 and reference site values (total % or ganic matter was not measured in 2006). Percentages for 0 5 cm and 5 10 cm depths for 2015 values are 2.93% and 1.73%, much less than the reference values of 12.00% and 9.73%. Extractable organic carbon (ExOC) shows a steady drop with aging (figure 2 3C ). Values in the 0 5 cm layer decrease from 3.80 gm 2 in 2006 to 2.36 gm 2 in 2015 to only 0.50 gm 2 in the reference site. Values for the 5 10 cm layer show a similar trend decreasing from 2.80 gm 2 in 2006 to 1.73 gm 2 in 2015 to 0.41 gm 2 in the refer ence site. Statistical analysis showed there to be a significant differen ce between 2006 and 2015 values on SL 15, as well as significant differences between SL 15 at both time points and the reference site. Percent total nitrogen on SL 15 is much lower t han that of a natural mangrove site (figure 2 3D). The top 5 cm layer including values at 0.018%, 0.023%, and 0.237% for 2006, 2015, and the reference site, and the bottom 5 cm layer displaying values at
37 0.01 0%, 0.002%, and 0.339% . I t was determined that there is no significant difference between 2006 and 2015 in the 0 to 5 cm depth , but there is a significant difference between 2006 and 2015 at the 5 10 cm depth . These values are approximately .25 .4% lower than those shown in the natural reference sit e, which is an order of magnitude lower and very significantly different. MBC is shown to decrease 30% from 60.00 gm 2 to 39.12 gm 2 in the 0 5 cm depth in sediment between 2006 and 2015, and decrease 15% from 51.00 gm 2 to 37.01 gm 2 in the 5 10 cm dep th (figure 2 4). Reference values are shown at 18.54 gm 2 and 12.63 gm 2 for 0 5 cm and 5 10 cm depths. All differences were shown to be signifi cant or highly significant . A 10 year trajectory for percent total organic carbon (%TOC) shows a slight incr ease in %TOC over the ten year period (figure 2 5). The 0 5 cm depth indicate an approximate 4.3% increase in % total organic carbon (TOC) in the top 5 cm of the sediment of the mangrove planter on SL 15, and the 5 10 depth shows an approximate 3.8% incre ase in %TOC over the same 10 year period. The reference site values are shown to be 3 4% above the %TOC values at SL 15. Current % TOC in the sediment of the mangrove planter at SL 15 is still significantly lower than %TOC in the reference site. By assum ing this trend continues in a linear trajectory, the trajectory lines were extrapolated to determine when the 0 5 cm and 5 10 cm depths in the sediment would reach the reference values. The following equations, as given by the trajectory lines, were used t o determine an approximate time (in years) until the 0 5 cm and 5 10 cm depths wi ll reach the percentage of TOC seen in the reference site:
38 0 5 cm: Y= 0.1416X 283.88 5 10 cm Y= 0.088X 173.36 Reference values were input for Y (representing % TOC) to determine X (time in years). From these equations it was determined that it would ta ke approximately 34 years for the 0 5 cm and 44.3 for the 5 10 cm depths to reach reference site values at corresponding depths. All averaged values shown above were show n to be significantly different through statistical analysis . Percent TOC was converted to gm 2 which showed average values of 886 in the 0 5 cm layer and 546 in the 5 10 cm layer at SL 15. The reference site show ed average values of 1804 in the 0 5 cm layer and 1286 in the 5 10 cm layer. Molar ratios for C:N ratios were also calculated and were widely variable, ranging from 14 to 20 for reference samples and 16 to 250 in SL 15 samples in the 0 5 cm layer with mea n values of 18 and 104. In the 5 10 cm layer values ranged from 6 to 22 in the reference site and 140 to 1683 at SL 15 with means of 13 and 447. Seagrass Bed Seagrasses within the SL 15 seagrass beds are sparse in numbers or absent. Biogeochemical data i s not purely from seagrass biomass, as algal mats, mixing within the estuary, and the 2011 Super bloom in the Indian River Lagoon are confounding factors that have affected biogeochemical processes within the SL 15 seagrass embayment er Management District 2012). Measured values are shown, but not necessarily indicative of what would be seen if seagrasses had established and recovered within the embayment.
39 Nutrient analyses on SL 15 were compared between 2006, 2015, and the natural re ference site. Bulk density, % organic matter, extractable organic carbon, microbial biomass carbon, and % total organic carbon were the parameters used for comparison. Bulk density and perc ent total organic matter have values of 1.51 gcm 3 , 1.53 gcm 3 , and 1.44 gcm 3 for 2006, 2015, and the reference site at 0 5 cm depth (figure 2 6A and B). For 5 10 cm depth, values are shown to be 1.48 gcm 3 , 1.46 gcm 3 , and 1.16 gcm 3 . There is no significant difference in bulk density bet ween 2006 and 2015 sediment on SL 15 or between SL 15 and reference site sediment at both 0 5 cm and 5 10 cm layers. Percent total orga nic matter shows values at 1.57% and 1.55 % for 2015 and reference site v alues at 0 5 cm depth, and 1.57% and 1.41 % at the 5 10 cm depth. There is no significant difference between percent organic matter at SL 15 and the seagrass reference site at either the 0 5 cm or 5 10 cm depths. Between 2006 and 2015 the extractable organic carbon fraction has increased (figure 2 6C). Values are 2.20 gm 2 , 2. 46 gm 2 , and 1.50 gm 2 for 2006, 2015, and the reference site at the 0 5 cm depth, and 1.80 gm 2 , 2.21 gm 2 , and 1.03 gm 2 at the 5 10 depth. Although organic matter percentage was similar in the reference site and SL 15, extractable O.C. is much lower in the reference system. Val ues for 2006 and 2015 are not significantly different, but the reference site values are shown to be significantly different from both time points on SL 15 at both depths . Percent total nitrogen displays values of 0. 0 25 %, 0.04 %, and 0.06 % for 2006, 2015, and the reference site data for the 0 5 cm layer and 0. 041 %, 0.032 %, and 0.053 % for the 5 10 cm layer (figure 2 6D). Thes e values are all extremely low and statistical analysis showed significant differences between SL 15 in 2006 and 2015 and 2006 and
40 the reference site in the 0 5 cm layer. Values from 2015 and the reference site in the 5 1 0 cm layer were also shown to be significantly different. A 10 year trajectory for microbial biomass carbon indicates values for the 0 5 cm depth are 64.00 gm 2 , 34.12 gm 2 , and 32.39 gm 2 for 2006, 2015, and the reference site, and 59.00 gm 2 , 28.67 gm 2 , and 24.98 gm 2 for 5 10 cm depth (figure 2 7). Microbial biomass carbon has decreased by approximately 30% over the past ten years at both 0 5 cm and 5 10 cm depths. MBC numbers between 2006 and 2015 are significantly different. 2015 values are shown to be not significantly different from reference site values, but reference values are very significantly different from 2006 values at both depths. A 10 year trajectory for percent total organic carbon (%TOC) in SL 15 seagrass beds shows a significan t increase in %TOC (figure 2 8). The 0 5 cm d epth indicates an approximate 0.4 % increase in % total organic carbon (TOC) in the top 5 cm of the sediment of the seagrass beds on SL 15, and the 5 10 depth shows an approximate 0.2 % dec rease in %TOC over the same 10 year period. The 0 5 cm layer and 5 10 cm layer have similar levels of accretion that are not significantly different. The trajectory line indicates that the SL 15 seagrass beds have equaled or surpassed the reference site in %TOC (although this ma y be due to confounding see discussion). The following equations, as given by the trajectory lines, were used to determine an exact time (in years) when the 0 5 cm and 5 10 cm depths reached the levels of accretion seen in the reference site: 0 5 cm: Y= 0. 0297X +59.122 5 10 cm Y= 0.049X 98.014
41 Reference values were input for Y (representing % TOC) to determine X (time in years). From these equations it wa s determined that i t took approximately 7.9 yea rs for the 0 5 cm depth and 5.1 years for the 5 10 cm depth to reach reference site values at corresponding depths. Statistical analysis showed values from 2006 and 2015 to b e significant ly different at 0 5 cm depth but not the 5 10 cm depth. Values from 2006 and the reference site we re shown to be significantly different at the 0 5 cm depth, but no ot her compa risons between SL 15 and reference site values were shown to be significantly different. Percent TOC was converted to gm 2 which showed average values of 263 in the 0 5 cm layer and 242 in the 5 10 cm layer at SL 15. The reference site showed average values of 203 in the 0 5 cm layer and 218 in the 5 10 cm layer. Molar ratios for C:N ratios were also calculated and were widely variable, ranging from 2 to 6 for reference samples and 3 to 23 in SL 15 samples in the 0 5 cm layer with mean values of 4 and 10. In the 5 10 cm layer values ranged from 2 to 12 in the reference site and 3 to 33 at SL 15 with means of 7 and 14. Discussion Spoil islands in estuarine systems tend to be pri marily composed of carbonate based shell fragments that overwhelm organic carbon fractions with inorganic carbon in the base material until an organic layer has accreted. This can create difficulties in measuring the miniscule organic fractions, making d etermining true values difficult. However, by using a variety of techniques to try to separate the organic fragments into pieces, this study has managed to get good estimates of the various organic carbon and nitrogen fractions studied at SL 15 and show t he associated trends. Mangrove and seagrass systems are discussed separately as mangrove and seagrass habitats show
42 very different patterns of functional recovery. Other studies on organic carbon and nitrogen fractions are sparse, and therefore SL 15 dat a is not compared to those of other spoil islands specifically. Mangroves Mangroves at the reference site have expansive root systems and biomasses that are magnitudes greater than those seen at SL 15. Mangrove root growth creates pore space and decreases sediment density over time , causing the large drop in bulk density that is shown between SL 15 and the reference site (figure 2 3A). Over time bulk density decreases as mangrove roots expand and create organic matter (Alongi 2011), assuming that young man grove forests have much less organic matter than mature systems (figure 2 3B). However, organic matter % is also seen to be very low, indicating that root systems have not expanded enough to create enough pore space to decrease density. Several studies a lso show bulk densities to be much greater in constructed systems in comparison to natural systems (Craft et al. 1999; McKee and Faulkner 2000; Craft et al. 2002). Percent total organic carbon was seen to be extremely low on SL 15 in the 2006 study (and n egligible in 2005 results not shown in this paper) and increase significantly between then and 2015 (figure 2 5). However, the sign ificant increase shows only approximately 1 % TOC in the entire first 10 cm within the mangrove planter and is still 3 4 % l ower than wh at is seen in the reference site. If the planter continues along this linear trajectory, SL 1 5 should take approximately 34 years in the 0 5 cm and 44.3 years in 5 10 cm layers to reach natural values. Mangrove systems range from 2.3% to 37% TOC (McKee and Faulkner 2000; Alongi et al. 2001; Jennerjohn and Ittekkot 2002; Alongi et al. 2004; Bouillon et al. 2004; Otero et al. 2006). Even the reference site for
43 this study in the IRL had values on the lower end of that spectrum, which were alread y significantly higher than those values seen at SL 15. It is also possible that area of the study site is not able to accrete carbon at levels that are as high as other systems. However, within the estuary it may be difficult to determine a single cause or combination thereof. The two fractions of OC that were studied, ExOC and MBC, are extremely active pools of OC that develop quickly in sediments with short turnover times (Buyanovsky et al 1994; Rochette and Gregorich 1998). As estuarine systems are h ighly dynamic, environmental conditions can change quickly and alter concentrations in these pools. As has been well documented (Dierberg et al. 1991; Lapointe 2015; Kamerosky 2015), the Indian River Lagoon has had a variety of water quality and clarity i ssues over the past few decades (especially after the super bloom in 2011) that has potentially aided in decreasing microbial and extractable OC fractions at SL 15 (figure 2 3C and figure 2 4). Microbial biomass carbon shows a decreasing trajec tory over t he ten year period in both 0 5 cm and 5 10 cm depths (figure 2 4). In addition, a previous study on SL 15 noted biofilms and algal mat presence on the island within the first two years of its creation (Hicks 2006). Overtim e, this layer may have been los t from out shading of sediment by vegetation, lowering photosynthetic microbial populations, as well as loss of those present in the biofilms (Demmig Adams et al. 2014). The pollution in the Indian River Lagoon has shown to have high dissolved and parti culate loads (Lapointe et al. 2015) that increase binding surfaces that cause decreases in extractable fractions of OC (Modin et al. 2015). SL 15 showed an overall decrease in extractable organic carbon over time and depth (figure 2 3C). This trend
44 may be associated with microbial mineralization of the extractable portion of organic carbon over time, assuming mature systems would show lower extractable fractions than younger systems. In addition to high surface binding, this process could further decreas e numbers. Total nitrogen values are much lower than those in reference site (figure 2 3D). This is most likely due to greater root growth in the natural reference site that controls accumulation of organic matter and nutrients in mangrove systems (Alongi et al. 200 3). Most nitrogen may be assimilated into plant and microbial biomass and free porti ons may be consistently reuptaken for growth, leaving very little left in the sediment. In addition, roots are still too small to play a large presence in sediment organic matter and increase TN values. Seagrasses Bulk density is similar at both SL 15 (where seagrasses are primarily abse nt) and the reference site (where some seagrasses are present), and it shows a slight but not significant increase from 2006 to 2015 (figure 2 6A). As seagrass did not establish at SL 15, there are few root systems to create pore space in the sediment. I n addition, a previous study (Fischler 2006) showed the center of the seagrass area to be a low flow environment, allowing particles to settle and adding to the high levels of compaction created by site construction. Bulk densities have been shown to be m uch greater in constructed systems in comparison to natural reference systems (Craft et al. 1999; McKee and Faulkner 2000; Craft et al. 2002). However, the bulk densities seen in the reference site (lowest being 1.16 gcm 3 at 5 10 cm depth at the referenc e site) as well as the constructed seagrass site p otentially indicate similarity that area of the IRL.
45 According to the results (figure 2 6B), seagrass beds at SL 15 have organic matter percentages close to those of the reference site values. There is no significant difference between these values, making it appear as though the SL 15 seagrass beds have been successfully restored. However, as noted previously, seagrasses have not established within the seagrass bed section and biogeochemical values are confounded by other factors, such as settling of drift algae and particle trapping, caused by site design. Quality of organic matter was not directly determined, but is thought to be highly labile as indicated by algal specimens from the embayment (Stevens on et al. 1996). Percent organic carbon (figure 2 8) in SL 15 seagrass beds has become equivalent or surpassed levels seen in the reference site. Based on the trajectory, it appears as though the 0 5 cm layer recovered after 7.9 years and the 5 10 cm layer after 5.1 years. However, drift algae and particle entrapment have likely added to the %TOC as opposed to seagrass biomass itself. Therefore, quality of OC present may be poor, as is common in algal dominated communities (Stevenson et al. 1996). Another indicator of algal establishment and poor quality organic matter is shown by extractable organic carbon (figure 2 6C). Between 2006 and 2015 the extractable fraction has increased slightly (though not significantly) , indicating more easily extractable OC . Although organic matter percentage was similar in the reference site and at SL 15, extractable O.C. is much lower in the reference system. Values for 2006, 2015, and the reference site are all significantly different, indicating change over time. Howe ver, the extractable fraction at SL 15 has increased slightly , which could be caused by the sedimentation processes occurring within this system.
46 Microbial biomass carbon showed a significant decrease as well from 2006 values to 2015. However, these value s are not significantly different from the reference site values. Algal mats and biofilms that were originally seen on th e island (Hicks 2006 ) were probably the cause of the higher MB C values directly after reclamat ion. These are no longer present on the sediment surface (although there are still some drift algae and algal films on reference site leaf blades). These layers may be shaded out from increased turbidity due to water quality problems from the 2011 super bloom (Kamerosky et al. 2015). Total ni trogen values in the SL 15 seagrass embayment were shown to increase over time in the 0 5 cm layer and are not significantly different from reference site values, indicating that some nitrogen has accreted in this layer most likely due to sedimentation pro cesses. However , e ven these values are almost negligible at less than 0.06% across the embayment and reference plots. These low levels could potentially be due to rapid cycling of nitrogen by algae or a known gradient in the Indian River Lagoon that decr eases in TN from north to south (Phlips 2010 ; Stevenson et al. 1996) . Synthesis The definition of reclam ation success can be interpreted in a variety of different ways, including successful return of vegetation, successful return of biogeochemical function, or successful return of ecosystem services. Ideally, structural and functional factors should both be ev aluated when determining reclama tion success. Both factors play a role in habitat health and provision of ecosystem services. In coastal F lorida, mangrove and seagrass ecosystems are regularly reclaim ed, but functionality is rarely assessed. As seen in this study, after ten years, vegetative structure has returned to at
47 least the mangrove system, but functionality may still be many decades away from returning to natural system levels (as seen in the mangrove system). However, vegetative structure may have failed to return altogether, but functionally may falsely appear to have recovered completely (as seen in the seagras s system). Time is probably a main factor affe cting the outcome of enhancement/ reclamation/ restoration projects , as well as environmental conditions . More holistic ap proaches for these projects that monitor water quality, sediment, and other such environmental variables o ver more realistic timescales for recovery can a id in establishing better reclam ation practices and protocols.
48 Table 3 1. Equations used to estimate % organic carbon in mangroves and seagrasses at SL 15. These equations were found in Blue Carbon: meth ods for assessing carbon stocks in mangroves, tidal salt marshes, and seagrass meadows by the Blue Carbon Initiative. Ecosystem Relationship Strength (r 2 ) Relationship Between %LOI and %Corg Location (source) Mangroves 0.59 %Corg = 0.415* %LOI Palau (Kauffman et al. 2011) Seagrasses (% LOI > 0.2) 0.96 %Corg = 0.43 * %LOI Global Data Set (Fourqurean et al. 2012)
49 Table 3 2. P values generated from Microsoft Excel using t tests assuming unequal variances for comparisons among years and chemical parameters on SL 15 and reference sites. Year/location/depth BD ExOC MBC TOC TN LOI Mangrove 0 5 cm 2006/2015 0.056711 0.005414 1.46E 06 2.19E 03 0.968545 N o data 2006/Ref 6.91E 08 2.28E 05 5.17E 05 8.05E 04 0.001334 N o data 2015/Ref 1.75E 08 4.21E 07 0.014715 6.21E 04 0.000372 0.001815 Mangrove 5 10 cm 2006/2015 0.998169 0.069608 6.26E 09 9.15E 04 0.002655 N o data 2006/Ref 4.62E 05 2.13E 07 6.86E 08 1.30E 03 0.046468 N o data 2015/Ref 1.89E 05 0.000206 9.29E 05 2.62E 03 0.042782 0.002293 Seagrass 0 5 cm 2006/2015 0.592253 0.493331 7.24E 09 1.09E 03 0.029536 N o data 2006/Ref 0.706963 2.44E 05 0.000771 3.17E 03 0.014216 N o data 2015/Ref 0.415749 0.001964 0.764934 9.26E 01 0.168886 0.926409 Seagrass 5 10 cm 2006/2015 0.966613 0.084507 6.71E 11 7.89E 02 0.513787 No data 2006/Ref 0.054832 9.07E 07 3.91E 09 9.53E 02 0.428884 No data 2015/Ref 0.054286 2.74E 05 0.333646 9.26E 01 0.015238 0.195307
50 Figure 3 1. Location of SL 15 site north of Ft. Pierce Inlet (inset B) within the Indian River Lagoon (Inset A) on the central east coast of Florida.
51 A. B. Figure 3 2 A . SL 15 and its proximity to reference sites are shown above. Red boxes mark the reference sites, the one marked as reference indicating the location of the mangrove reference site and the red box marked seagrass reference marks the seagrass reference site . B . Plots created on SL 15 in 2005. Green dots indicate were sediment cores were taken in 2005 2006 and 2015.
52 Figure 3 3. A. Mangrove sediment bulk densities were averaged for comparison across depths 0 5 cm and 5 1 0 cm and time 2006 and 2015. B. Organic matter (%) in mangrove sediment cores was averaged among plots at 0 5 cm and 5 10 cm. C. Extractable organic carbon values are compared above between 0 5 cm and 5 10 cm depths and between 2006 and 2015. D. Percent total Nitrogen in sediment cores on the mangrove planter at SL 15 are shown above for 0 5 cm and 5 10 cm depths for 2006 and 2015 as well as a comparison from the reference site. 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 0-5 cm 5-10 cm Bulk Density (gcm 3 ) 2006 2015 Reference a b a a b A 0 2 4 6 8 10 12 14 16 0-5 cm 5-10 cm % Organic Matter 2015 Referernce b a b B 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 0-5 cm 5-10 cm Ex O.C. (gm 2 ) 2006 2015 Reference c a a b 0 0.1 0.2 0.3 0.4 0.5 0.6 0-5 cm 5-10 cm % TN 2006 2015 Reference a b a b c D a a b a a C
53 Figure 3 4. Microbial biomass carbon trajectories in the mangrove planter over a ten year period (2006 2015) are shown above for averaged MBC values measured in gm 2 . * indicates significantly different values between 2006 and 2015 and between SL 15 and reference site values. 0 10 20 30 40 50 60 70 2004 2006 2008 2010 2012 2014 2016 MBC ( gm 2 ) Year 0 5 cm 5 10 cm Ref 0 5 Ref 5 10 Linear (0 5 cm) Linear (5 10 cm) * * * *
54 Figure 3 5 . The above figure shows the 10 year trajectory on SL 15 for organic carbon accretion in the mangrove planter . * represents significant differences between 2006 and 2015 values and between SL 15 and reference site values. 0.00 1.00 2.00 3.00 4.00 5.00 6.00 7.00 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 % TOC Year 0-5 cm 5-10 cm Reference 0-5 cm Reference 5-10 cm Linear (0-5 cm) Linear (5-10 cm) * * * *
55 Figure 3 6. A. Average bulk density is compared above in the seagrass beds at SL 15 for 2006, 2015, and the reference site at 0 5 cm and 5 10 cm depths. B. Average percent total organic matter in SL 15 seagrass beds are compared to the natural reference s ystem over 0 5 cm and 5 10 cm depths. This data was not collected in 2006, so there is no comparison to previous values. C. Extractable organic carbon in seagrass sediments is compared above at SL 15 for 2006, 2015, and the reference site. D. Average tot al % nitrogen in 2006, 2015, and reference site is compare at 0 5 and 5 10 cm depths. 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 0-5 cm 5-10 cm Bulk Density (gcm 3 ) 2006 2015 Reference a a a a a A 0 0.5 1 1.5 2 2.5 0-5 cm 5-10 cm % Organic Matter 0-5 cm 5-10 cm a a a 0 0.5 1 1.5 2 2.5 3 3.5 4 0-5 cm 5-10 cm Ex O.C. (gm 2 ) 2006 2015 Reference a b a a b a C 0 0.02 0.04 0.06 0.08 0.1 0.12 0-5 cm 5-10 cm % TN 2006 2015 Reference b b ab a b a a D B a
56 Figure 3 7. The figure above shows the decreasing trend in microbial biomass carbon over the past ten years at 0 5 cm and 5 10 cm depths in the seagrass e mbayment .* represent significantly different values between 2006 and 2015 and SL 15 and the reference site at corresponding depths. *06 represents only significantly different values between SL 15 2006 numbers and those of the reference site at correspond ing depths. 0 10 20 30 40 50 60 70 2004 2006 2008 2010 2012 2014 2016 MBC ( gm 2 ) Year 0 5 cm 5 10 cm Ref 0 5 Ref 5 10 Linear (0 5 cm) Linear (5 10 cm) * * 06 * *06
57 Figure 3 8. The above figure shows the 10 year trajectory on SL 15 for organic carbon accretion in the seagrass embayment . * Represents significant difference between 2006 and 2015 values for the 0 5 cm layer. *06 represents sign ificant difference between 2006 values at SL 15 and the reference site in the 0 5 cm layer. 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 % TOC Year 0-5 cm Ref 0-5 cm 5-10 cm Ref 5-10 cm Linear (0-5 cm) Linear (5-10 cm) * *06
58 CHAPTER 4 BLUE CARBON ACCRETION IN MANGROVE AND SEAGRASS VEGETATION OVER A TEN YEAR PERIOD ON A CONSTRUCTED SPOIL ISLAND Introduction Carbon sequestration reduces greenhouse gas release to the atmosphere by trapping carbon within coastal sediments and vegetation. Mangroves and seagrass ecosystems account for a major part of global carbon pools with mangroves storing an approximate mean of 1500 Mg C and seagrass sto ring an average of 600 Mg C (Fourqurean et al. 2012; Pendelton et al. 2012). These values dwarf values seen in boral and tropical forests that average only about 200 Mg C (Pan et al. 2011). Mangroves are lost at a rate of 0.7 to 3% annually across the glo be (Valiela et al. 2001; Alongi 2002; FAO 2007; Spalding et al. 2010), and seagrass is lost at a rate of approximately 7% (Constanza et al. 1997; Duarte et al. 2005; Waycott et al. 2009). These losses are part of the larger blue carbon discussion that eva luates carbon storage in these ecosystems. Blue carbon describes carbon stocks stored in biomass and sediments of seagrass beds, tidal marshes, mangrove and similarly vegetated ecosystems. These carbon pools are being lost or degraded by anthropogenic sou rces, releasing an estimated 0.15 to 1.02 Pg (billion tons) of CO 2 into the atmosphere each year (Pendelton 2012). There is wide variability in carbon sequestration potential between mangrove and seagrass ecosystems, but studies agree that overall these p ools play a globally significant role in carbon storage (Ross 2001 ; Mcleod 2011; Pendelton 2012; Lavery 2013 ; Kauffman 2014 ). As these habitats are lost, carbon storage decreases, calling for implementation of ecosystem restoration to regain both vegetati on and biogeochemical function.
59 As wetlands and coastline are destroyed for development, agriculture, and mining purposes, more ecological restor ation and reclam ation efforts are being enacted to recover vital habitat that has been lost (Shackelford 201 3). Although monitorin g is an essential part of reclam ation, the time required for recovery varies widely. Many species, including mangroves (although difficult to age) take decades to reach their full growth potential, depending on environmental conditi ons (Saenger 2002). Site monitoring lasting three to five years may not be enough to asse ss the outcome of a reclamation site. Other species, including seagrasses are annual, fast growing species that may appear to recover quickly after restoration, but their overall health and stability at the site may not be apparent immediately (Hemminga 2000). Returning to sites ten, twenty, thirty, or even more years af ter restoration may be required to fully assess vegetative recovery and carbon storage capacity in these vegetative systems. Coastal Florida contains three native species of mangroves and seven native species of seagrasses that sequester carbon as they grow (Kauffman and Donato 2011; Rey et al. 2015). Rhizophera mangle (red mangrove), Avicennia ger minans (black mangrove), and Laguncularia racemosa (white mangrove) the species of mangroves seen in Florida (Kauffman and Donato 2011). The seven species of seagrass known to survive in waterways, wetlands, springs, and coastal shorelines throughout the state are Thalassia testudinum , Halodule wrightii , Syringodium filiforme , Ruppia maritima , Halophila engelmanii , Halophila decipiens , and Halophila johnsonii (Rey et al. 2015). This study attempts to asses s success of vegetative reclamation in mangrov e an d seagrass habitats at one enhanc ed spoil island containing all three species of mangrove and potential for five of the seven species of seagrasses seen in Florida ten years post -
60 reclam ation. Assessment is made by using allometric equations to calculate current carbon storage in vegetation on the island. By comparing these values to others within Florida and across the globe, it is possible to see how SL 15 is recovering and the time it will require for SL 15 to reach maturity and full carbon sequestrati on capacity. Methods Site D escription SL 15 is an reclaim ed spoil island located in the Indian River Lagoon (IRL) across from the IRL boat ramp off of US Route 1 that was restored as a mitigation site in 2005 by the Florida Department of Transportation (FD OT) (figure 3 1). The island was originally created in the 1950s from dredging the Atlantic Intracoastal Waterway (ICW) in St. Lu cie County. Before the reclamat ion, the island was primarily vegetated by exotics with only a small native mangrove fringe. Reconstruction of the island involved removing excess fill, eradicating exotic vegetation, and reforming the island to create an area for seagrass bed development (though no seagrass was planted) . Seven tidal channels were cut around the edge of the wetla nd area to allow tidal flushing and natural recruitment of local seagrass species. Vegetation Assessment Since its reclam ation in 2005, 16 plots have been established in the mangrove planter and ten within the seagrass bed (Figure 3 2 A). Each plot consi sts of a 2m x 2m area, in which the vegetation was surveyed (or subsampled) based on density . Diameter at breast height (Dbh), total tree height, and canopy volume (length of crown (cm) x depth of crown (cm) x width of crown (cm)) measurements were taken of mangroves within the area measured. All these measurements were not required for biometrics calculated later but were measured as an extra precaution. Three mangrove
61 plots randomly selected were measured within the mangrove reference site as well (fig ure 3 2B). The mangrove reference site was dominated by Rhizophera mangle and standardized to SL 15 by species composition. Mangroves were measured at each of the 16 plots on SL 15 and at three reference plots on the ref erence site . There were three s pecies present on the island, Rhizophera mangle, Avicennia germinans, and Laguncularia racemosa . Rhizophera mangle was the dominant species present. Numbers of mangroves measured per plot was based on mangrove density and dependent on statistical relevance . Several measurements were taken of each mangrove, including diameter at breast height or the equivalent depending on mangrove species and size (table 3 1 ). Total height, height of prop roots (for Rhizophera mangle only), canopy width, and ca nopy height measurements were also taken. These me asurements were plugged into allometric equations (table 3 1) to calc ulate above ground biometrics, divided up by dwarf and tall mangroves . The summation of gm 2 C per plot was calculated and then extrap olated to get the estimated values for each individual plot and the entire mangrove planter. Seedling allometrics require separate equations and are calculated separately. Seagrass plots at SL 15 were mostly absent of seagrass vegetation, so few measurem ents were taken. Shoot counts, percent cover, and species present were assessed in the reference plot approximately 200 m from SL 15 (figure 3 2B). Mangrove above ground allometric e quations Equations were used for all above ground allometric calculation s depending on mangrove height (table 3 1). Dwarf mangroves were assumed to be under 1.3 m tall due to the distribution of data collected.
62 Mangrove b iometric e quation for s eedlings The below equation from Simpson, L.T . (2011) was used to calculate above ground biomass of all seedlings. Ln (AB) = 1.6367*ln (Db) + 1.3045*ln (H) 2.8853 Ab = above ground biomass; Db= basal diameter; H = height Mangrove b elow gr ound allometric e quations Equations below were used for all below ground allometric calculations regardless of mangrove height (table 3 2) . The DBH measurements taken from the mangroves used to calculate the above ground allometrics above were also used for below .ground calculations. Mangrove area calculations for t otal g carbon For cal culation of biomass across the entire island, polygons were drawn on a georeferenced map of SL 15 to divide the mangrove planter into 16 sections (figure 3 3). Each section encompasses a plot where biomass data was measur ed and calculated and was then ex trapolated over the entire area of the polygon . To account for the diverse spatial patterning in mangrove growth patterns and associated biomasses, the sixteen polygons were used to extrapolate more accurate values of total biomass for each area, as the s ixteen plots do not have equal biomass value s. The calculated areas were then multiplied by the determined gm 2 C to determine g C across each area of the island and the total for the SL 15 mangrove planter. Seagrass biomass m easurements Numbers of plant s and stem length per plant would have been measured and calculated if seagrass had been present at SL 15. However, most plots showed 0 less than 1% seagrass presence within the plots seen at several trips to SL 15 between
63 March and December 2015. Resul ts are assumed to be negligible and show extremely poor recruitment. Shoot counts and % cover were measured at the reference seagrass site in August and % cover was estimated again in December. Results Mangrove Planter Allometric measurements were used to calculate carbon storage in the individual mangrove plots in gm 2 C for both above ground and below ground biomass (table 3 3). Above ground biomasses at reference plots are significantly greater than those on SL 15, the a verage across SL 15 being 10,445. 65 gm 2 C in comparrison to an average of 129,801.80 gm 2 C across the reference site. Below ground biomassses show a similar trend as av erage for SL 15 values are 5,997.23 gm 2 C, which is much less than 183,736.22 gm 2 C that is seen at the refere nce site. Overall, the reference site stores a much greater amount of carbon, and stores are slightly greater in below ground than above ground biomass (figure 3 3 and 3 4). Values from calculated above and below ground biom a ss were used to extrapolate values of vegetative C storage across the entire island by assuming each plot was representative of the larger are a of the polygons (figure 3 5) . Distinctive spatial patterns based on above ground mangrove biomass can be observed across the island. Plots SLM 2A, SLM 2B, SLM 3A, SLM 3B, SLM 4A, and SLM 4B showed higher populations of dwarf mangroves than other plots. The calculated total above ground and below ground biomass of SL 15 is 204,935,896 grams and 1 19,289,236 grams (Table 3 4). Seagrass Beds The re are very few results to show for seagrass bed vegetation surveys. Zero to less than 1% seagrass coverage was seen in the seagrass bed area at SL 15 between
64 March and December 2015. Visibility was low, especially between September December, and seagr ass was either absent o r obscured by drift algae. There are a few results (table 3 4) for the one reference plot within 100 meters of the island (figure 3 2B). Shoot number and percent cover is seen to be very poor in the reference site (% cover being <10 %) in addition to what is seen at SL 15. Several issues with water quality and seagrass loss in the Indian River Lag oon may be at fault and are discussed mor e in depth in the next section. Discussion Mangroves Healthy mangroves take many years to reach full carbon sequestration potential , depending on location, temperature, water quality, flow, and a variety of other factors . As mangroves grow and accumulate above ground biomass as shoots and leaves and below ground biomass as roots, they uptake and seq uester CO 2 . Mangroves have the highest below ground to above ground biomass ratio, especially during early development (Saenger 1982; Snedaker 1995). The mangroves at SL 15 are still very young, ten years being the maximum age. Assuming they continue to grow without disturbance, it will still take them many more year s to reach the biomasses seen at the reference site or other areas across the globe (table 3 6). Comparisons of forests dominated by Rhizophera spp. (assuming these are the most comparable t o SL 15) show above ground and below ground biomass values to vary greatly across the globe and maturity levels. Assuming the Florida sites are the best comparison for the future of the SL 15 mangrove island, eventually SL 15 will have biomasses two to fi ve times greater t han what is currently there.
65 Spatially, SL 15 may become less patchy over time as the mangroves grow and mature. However, mangrove dwarfism observed near the back of the island may b e indicative of water pooling on the island due to a bsence of drainage channels to aid in flow movement. Mangroves uptake only fresh water and can osmocompensate to avoid up taking salt (Raines and Epstein 1967; Scholander 1968; Werner and Stelzer 1990; Popp et al. 1993), but regular flushing is still vita l to avoid salt build up and accumulation around roots (Passioura et al. 1992; Hollins et al. 2000). Nutrient limitations near the back of the planter may be another potential reason for the height differences in mangroves across the planter (Feller et al . 2002) . Dwarf mangroves sequester less carbon than tall mangroves, decreasing some of the biomass numbers seen at SL 15 currently and possibly in the future. Seagrasses Results from seagrass surveys indicate that the seagrass beds at SL 15 have not reco vered since reclam ation. Lack of any seagrass in most plots between March and December 2015 suggest that whether or not seagrass had reestablished at some other time, it is currently not suitable for seagrass propagation. Factors, such as the super bloom in 2011, have affected seagrass populations throughout the IRL. There are five species of seagrass known to grow in this area: Halodule wrightii, Syringodium filiforme, Thalassia testudinum, Ruppia martimia, Halophila englemanii, and Halophila johnsonii (Dawes et al. 1995). Over the past 80 years, seagrass populations of all species within the IRL have risen and fallen, but ultimately with a downward trend. One study showed populations dropping from 33,700 ha in 1984 1986 to 28,400 ha in 1992 (Fletcher and Fletcher 1995). Although some seagrass species seen within the lagoon have higher
66 light requirements than others, it is believed that the fall in population is mostly due to light limitations (Steward 2005). Conversion of land surrounding the IRL fro m suburban to agricultural uses have caused increases in algal abundance and light limitation within the lagoon. Large loadings of nitrogen, phosphorus, and DOC have caused eutrophication of the estuary from both agricultural runoff and wastewater treatme nt discharge (Dierberg 1991). In altering biogeochemical cycling and submerged aquatic vegetative (SAV) growth (St. s time, the seagrass bed at SL 15 would ideally have been recruiting new seagrass and recovering. However, this was difficult due to the major alterations in biogeochemical cycles, light availability, and nearby seagrass abundance caused by the super bloo m event. Other factors, such as site construction issues, could also affect seagrass recruitment and recovery. Ultimate causation of the lack of seagrass vegetation in the seagrass beds is difficult to determine due to a wide variety of possible causes o f a combination thereof. Without seagrass present to make an assessment of carbon sequestration potential in SL 15 seagrass beds, it is difficult to determine possible carbon storage. However, to attempt to estimate th is potential, values were collect ed from the literature (table 3 7) specifically focusing on Syringodium filiforme and Thalassia testudinum (as these were the two species seen in the reference site near SL 15). Drying and weighing in the laboratory is necessary for seagrass biomass calculations (Duarte 1990). Seagrass specimens were not taken f rom the field, so there are no biomass values f rom the reference site to use as comparisons.
67 Although these values vary and are not indicative of the precise conditions at SL 15, and the maximum values are not likely to be achieved within the IRL Estuary due to water quality issues and seagrass loss, t hey can be used to form an idea of the potential for blue carbon storage if environmental and construction factors had been amenable to seagrass establishment and growth at SL 15. Synthesis Mangrove and seagrass habitats are ecologically important habi tats in coastal ecosystems for blue carbon sequestration and storage. These ecosystems accrete large amounts of carbon in above ground and below ground biomass, even in early stages of growth. Mangroves on SL 15 are recovering and gaining carbon seques tration potential over time, adding significantly to blue carbon pools. However, seagrasses were less successful vegetatively and are not present to sequester substa ntial amounts of carbon. Reclaim ing degraded mangrove and seagrass ecosystems is vital to improving ecosystem health and improving blue carbon storage capability. Unfortunately, site construction and environmental factors do not always allow for restoration success, or sites are not monitored long enough to make informed decisions about site quality. Therefore, making scientific observations and studies on restored sites over long time periods can help to assess temporal trajectories for recover y and determine long term reclam ation success.
68 Table 4 1. Allometric equations used to calculate the g/kg C for each measured mangrove according to species and height. The references for each equation are shown on the right. Species Biomass Allometric Equations Reference R. mangle (dwarf) Ln B (g) = 2.528+(1.1 29 (Ln D 5 2 (cm))+(0.156* Ln Crown Volume (cm 3 )) Ross et al. (2001) R. mangle (tall) B (Kg) = 0.722*D 1.731 Kauffman and Donato (2011) A. germinans (dwarf) Log 10 B(g) = 2.19Log 10 (DBH) 3.39 Simpson, L.T. (2011) A. germinans (tall) B (Kg) = 0.403*D 1.934 Kauffman and Donato (2011) L. racesmosa (dwarf)** Log 10 B(g) = 2.19Log 10 (DBH) 3.39 Simpson, L.T. (2011) L. racesmosa (tall) B(Kg) = 0.362*D 1. 930 K auffman and Donato (2011) B = biomass; D R = diameter above highest prop root; DBH = diameter at breast height; D 5 = diameter at 5 cm fro m the biggest branching stem. ** No equations currently exist for dwarf L. racesmosa , so the equation for dwarf A. germinans was used as its structure is most similar.
69 Table 4 2. Allometric equations used to calculate kg C for below ground biomass of mangroves at SL 15 and the reference site. Species Allometric Equation Reference R. mangle B (kg) = 0.196*(1.05 0.899 )* (D R 2 ) 1.11 Komiyama et al. (2005) A. germinans B (kg) = 0.196*(0.90 0.899 )* (DBH 2 ) 1.11 Komiyama et al. (2005) L. racesmosa B (kg) = 0.196*(1.05 0.899 )* (DBH 2 ) 1.11 Komiyama et al. (2005) B = biomass (kg), D R = diameter above highest prop root; DBH = diameter at breast height
70 Table 4 3. Above and below ground biomass (gm 2 C) per plot on the SL 15 mangrove planter as calculated by allometric equations. Site Above ground biomass ( gm 2 C) Below ground Biomass ( gm 2 C ) SLM 1D 1849 4630 SLM 1C 3168 1516 SLM 1B 2576 1867 SLM 1A 6841 4825 SLM 2D 11589 4989 SLM 2C 1511 1459 SLM 2B 7309 6878 SLM 2A 7279 10694 SLM 3D 7936 4359 SLM 3C 6309 3956 SLM 3B 14539 4356 SLM 3A 5535 6710 SLM 4D 65664 28887 SLM 4C 13355 7415 SLM 4B 0.00 0.00 SLM 4A 11830 3415 Ref 1 223392 353949 Ref 2 80643 98731 Ref 3 85370 98529
71 Table 4 4. Area cal culations for total grams of C per polygon for both above ground biomass and below ground biomass. Site Area (m2) Above ground biomass (g/polygon ) Below ground biomass (g/polygon ) SLM 1D 1752 3239637 8110814 SLM 1C 1190 3768669 1802879 SLM 1B 1140 2938115 2129127 SLM 1A 1468 10041417 7082052 SLM 2D 2064 23924231 10298889 SLM 2C 1540 2326127 2247010 SLM 2B 1063 7766700 7308781 SLM 2A 1182 8602143 12637464 SLM 3D 1312 10408693 5717188 SLM 3C 1562 9855893 6179966 SLM 3B 1615 23482064 7035846 SLM 3A 1178 6517993 7900849 SLM 4D 932 61201818 26923831 SLM 4C 1406 18774850 10424900 *SLM 4B 1021 0 0 SLM 4A 1022 12087546 3489638 Total: 21445 204935896 119289236 *SLM 4B is located along a tidal creek that has representative of the entire polygon area. However, due to inaccuracies in geospatial monitoring and other tidal creeks and areas with low mangrove density not represented elsewhere, values are assumed to be representative of total g C on SL 15 as a whole .
72 Table 4 5. Results of reference plot approximately 100 m outside of SL 15. Date Species # of shoots % cover 8/10/2015 Syringodium filiforme 99 5 8/10/2015 Thalassia testudinum 68 5 10/19/2015 Syringodium filiforme N/A < 10
73 Table 4 6. Values for above ground and below ground biomass across the globe divided by location and forest type and age are shown above. References are shown on the right. All values, except for those starred are compiled in Allometry, biomass, and productivity i n mangrove forests by Akira Komiyama, Jin Eong Ong, and Sasitorn Poungparn, 2008. Location Forest Type/ Age Above ground biomass (tons/ha) Below Ground biomass (tons/ha) Reference Thailand Primary forest 298.5 272.9 Komiyama et al. (1987) Thailand Primary forest 281.2 11.76 Tamai et al. (1986) Sri Lanka Fringe 240 Amarasighe and Balasubramaniam (1992) India Primary forest 214 Mall et al. (1991) Sri Lanka Island 71.0 Amarasughe and Balasubramaniam (1992) French Guiana Mature coastal 315.0 Fromard et al. (1998) Panama Primary forest 279.2 306.2 Golley et al. (1975) Dominican Republic 50 years 233.0 Sherman et al. (2003) French Guiana Matured Coastal 180.0 Fromard et al. (1998) French Guiana Senescent Forest 143.3 Fromard et al. (1998) Puerto rico 62.9 64.4 Golley et al. (1962) USA (Florida) 56.0 Coronado Molina et al. (2004) USA (Florida) 7.9 Lugo and Snedaker (1974) USA (Florida)* Fringe 56.02 Ross et al. (2001) USA (Florida)* dwarf 22.28 Ross et al. (2001) Dominican Republic* Low forest 11.9 14.6 Kauffman et al. (2014) Dominican Republic* Medium forest 60.5 107.2 Kauffman et al. (2014) Dominican Republic* Tall forest 275.0 90.6 Kauffman et al. (2014) USA (Florida) SL 15 Young island forest 9.55 5.56 This study
74 Table 4 7. A few above and below ground biomass values of seagrasses in other systems are shown above in grams dry weight mass/ m 2 . *An estimate of the maximum average biomass values in grams dry weight/m 2 are also shown. ** Total biomass (above+ below ground) Location Seagrass Species Above ground biomass (gm 2 ) Below ground biomass (gm 2 ) Reference Mexican Caribbean Syringodium filiforme 3.05 Duarte et al. 1998 Mexican Caribbean Thalassia testudinum 97.3 Duarte et al. 1998 Philippines Syringodium isoetifolium 1.2 Duarte et al. 1998 Philippines Thalassia hemprichii 79.3 Duarte et al. 1998 *Average maximum worldwide Syringodium filiforme 368.2 (6) 450.8 (4) Duarte et al. 1999 *Average maximum worldwide Thalassia testudinum 519.0 (62) 582.5 (22) Duarte et al. 1999 Texas, USA (shallow water) Thalassia testudinum 800 1400** Kaldy and Dunton 2000 Texas, USA (deep water) Thalassia tesstudinum 250 700** Kaldy and Duntan 2000 Philippines Thalassia hemprichii 14.6 93.9 _ Terrados et al. 1998 Thailand Thalassia hemprichi 3.4 10.3 _ Terrados et al. 1998
75 Figure 4 1. Location of SL 15, off of Fort Pierce, FL near the inlet of the Indian River Lagoon.
76 A. B. Figure 4 2. A . Reference plots in proximity to SL 15 as established in 2015. B . Plots established on SL 15 in 2005.
77 Figure 4 3. A bove ground biomass (grams m 2 C) across SL 15 and reference site plots . -50000 0 50000 100000 150000 200000 250000 gm 2 Carbon
78 Figure 4 4. B elow ground biomass (grams m 2 C) across SL 15 and reference site plots . 0.00 50000.00 100000.00 150000.00 200000.00 250000.00 300000.00 350000.00 400000.00 gm 2 Carbon
79 Figure 4 5. Map of SL 15 divided into polygons representing 16 sections used for area calculations in ArcGIS.
80 CHA PTER 5 TOWARDS A MORE ACCURATE INTERPRETATION OF COASTAL MANGROVE AND SEAGRASS RE CLAMA TION Mangrove and seagrass ecosystems provide a variety of ecosystem services, perhaps most notably OC sequestration and greenhouse gas reduction. These habitats store large amounts of carbon in both above and below ground b iomass that eventually becomes part of the sedim ent pools. Approximately 1 mangrove area is estimated to be lost every year (Valiela 2001), and approximately 7% of seagrass area (Waycott 2009). When these systems are degraded (i.e. vegetative structure is lost), the ecologica l functions it provides are also lost. Through ecological reclama tion of these systems, carbon sequestration and other ecosystem services can be regained. Although SL 15 is only a small spoil island within the Indian River Lagoon, it has the potential to sequester more than 300 metric tons of carbon. Determining the full potential of SL 15 t o recover and the overall reclam ation the following objectives: (1) assessing organic carbon in the mangrove habitat, (2) assessing organic carbon in the seagrass habitat, (3) assessing vegetative recovery, and (4) evaluating trajectories of recovery in mangrove and seagrass habitats. Objective 1: As sessing Organic Carbon in Mangrove S ediments B y taking measurements of %TOC and %TN, as well as MBC, ExOC, bulk density, and total organic matter, changes in organic carbon and its constituent parts were evaluated in SL 15 mangrove sediments. For the carbon fractions, % TOC was 3.8 4.3%, MBC was 37 to 39 gm 2 , and ExOC was 2.36 gm 2 and 1.73 gm 2 for the 0 5 and 5 10 cm depths. Total organic matter values were 2.93% and 1.73% for the 0 5 cm and 5 10 cm depths. %TN value s were 0.237% for the top 5 cm layer and 0.002% for
81 the bottom 5 cm layer. B ulk density values were both approximately 1.5 gm 3 for the 0 5 and 5 10 cm fractions. These values describe the current biogeochemical state of the SL 15 mangrove planter for 2015 and suggest that the sediment is gradually accreting organic carbon and ot her nutrients. The spoil on the island itself most likely slows the process further, as there was very little particulate matter to begin with to aid in trapping allochthanous organic matter and nutrients. Objective 2: Assessing Organic Carbon Accretion i n the Seagrass H abitat Similar soil charac teristics indicative of blue carbon accretion were also assessed for the seagrass sediments. Percent TOC was approximately 0.33 and 0.34 % in the 0 5 cm and 5 10 cm depths. MBC was 34.12 gm 2 in the top 5 cm l ayer and 28.67 gm 2 in the bottom 5 cm layer, and ExOC values were 2.46 gm 2 and 2.21gm 2 at 0 5 cm and 5 10 cm depths. Percent organic matter was between 1.55% and 1.58 % in the 0 5 cm and 5 10 cm layers. Percent TN numbers were 0.04% for the top 5 cm and 0.032% for the bottom 5 cm. Lastly, bulk density values were 1.53 gm 3 and 1.46 gm 3 for 0 5 cm and 5 10 cm depths. These values describe the current biogeochemical state of the SL 15 seagrass beds for 2015, which have accreted enough organic carbon to match or surpass reference site values and recover functionality. However, these values may be misleading in an overall determination of restoration success, since seagrass vegetation never established at SL 15 in the long term. Objective 3: Evaluatin g Vegetative Community E volution Mangrove and seagrass vegetation on SL 15 suggested two very different stories. Mangrove vegetation on SL 15 has begun to recover, sequestering 204,893,969 g C in above ground biomass and 118,857,691 g C in below ground b iomass. The mean value of carbon in above ground biomass was 10, 680 gm 2 C,
82 which is still much less than the reference site that averaged 104,593 gm 2 C. Below ground biomass was also greater at the reference site with an average of 183,736.22 gm 2 C f or the reference site in comparison to 5,979 gm 2 C at SL 15. Since mangroves are slow growing, it may still take decades for them to reach maturity and fully recover both ecologically and biogeochemically. However, seagrass was almost entirely absent w ithin the SL 15 seagrass bed plots. Many factors, including water quality and construction issues may be causing the problems with seagrass recruitment. Seagrasses may have previously begun to establish and grow within the seagrass bed, but there are cur rently no signs of establishment or recovery. Objective 4: Evaluating Trajectories of Recovery in Mangrove and Seagrass H abitats Over the past ten years, approximately 4% TOC has been accreted in the mangrove sediments. It is estimated to take about 16.7 years to reach the OC % of the reference site in surface soils up to 10 cm, which is much quicker than many temporal estimations for similar systems (McKee and Faulkner 2000 ; Ballantine 2009 ). Deeper soils were not sampled in this study, but they may take many more years to accumulate significant blue carbon pools. With continued observation, it will be possible to see this system grow and continue to accrete carbon and other nutrients overtime as productivity increases and mangrove vegetation reaches mat urity. In the past ten years, the sediment in the SL 15 seagrass beds has increased %TOC by less than 1 % or decreased and functional recovery was estima t ed to have returned between 8.3 and 16.0 years. However, confounding factors, such as algal establishm ent and construction issues were most likely the reason these numbers were not significantly different from reference site values . Further studies should be
83 conducted at SL 15 to determine the causes of seagrass failure and measure factors such as elevati on, flow velocities, and photosynthetically active radiation (PAR) that may affect the seagrass growth and health. Conclusions Before beginning the studies on SL 15, three hypotheses were identifi ed. These hypotheses are discussed below: Carbon accretion in sediments will increase measurably after ten years . o Carbon accretion increased by around 4% in mangrove s ediment s, which is measurable. o Carbon increased by around 0.1% in the seagrass beds at the 0 5 cm depth and decreased by 0.06% in the 5 10 cm dept h Vegetation growth on SL 15 occurs along a different and more rapid temporal trajectory than functional recovery. o Vegetative recovery occurred in the mangrove planter more rapidly than accretion of organic matter and nutrients. o Seagrass vegetation did not establish and recover within the seagrass beds, but functionality (% TOC) is equivalent to or above the levels in the reference site o The trajectories for vegetative and functional recovery are temporally different, but vegetation might not necessarily rec over more quickly than functionality depending on location and associated environmental factors Functionality of carbon dynamics is still impaired after ten years and has not met background conditions
84 o Accretion of carbon and nutrients and therefore biogeoc hemical functionality has improved over the ten year study period o Mangrove vegetation has regrown, but seagrass vegetation has not o Even though mangrove vegetation has started to regrow and some nutrients have accreted in both the mangrove planter and seagr ass embayment, most comparisons have shown SL 15 to not yet meet background conditions Overall, the SL 15 reclam ation was a success in some aspects and a failure in others. The mangrove planter is still not fully functionally recovered; however, vegetativ e growth appears to be on a developmental trajectory that will reach function equivalence (of a natural site) over time. Unfortunately, the seagrass beds at SL 15 did not become vegetatively established and do not show signs of recovery in the near future . There are many aspects to consider in ecosystem reclam ation that make it d ifficult to fully assess reclama tion success. However, further r esearch and monitoring of reclaim ed sites over an extended period of time can help to establish temporal trajector ies for return of structural and functional characteristics to better aid in establishment of improved reclam ation practices.
85 LIST OF REFERENCES Conserv. 29: 331 349 Alon gi DM (2011) Carbon sequestration in mangrove forests. Carbon Management 3: 313 322 Alongi DM, Clough BF, Dixon P (2003) Nutrient partitioning and storage in arid zone forests of the mangroves Rhizophera stylosa and Avicennia marina . Trees 17: 51 60 Along i DM, Sasekumar A, Chong VC, Pfitzner J, Trott LA, Tirendi F (2004) Sediment accumulation and organic material flux in a managed mangrove ecosystem: estimates of land ocean atmosphere exchange in peninsular Malaysia. Mar. Geol. 208: 383 402 Alongi DM, Watt ayakorn G, Pfitzner J, Tirendi F, Zagorskis I, Brunskill GJ, Davidson A, Clough BF (2001) Organic carbon accumulation and metabolic pathways in sediments of mangrove forests in southern Thailand. Mar. Geol. 179: 85 103 Amarasinghe MD, Balasubramaniam S (1992) Net Primary Productivity of two mangrove forest stands on the northwest coast of Sri Lanka. Hydrobiologia 247: 37 47 Balesdent J , Wagner GH , Mariotti A (1988) Soil organic matter turnover in long term field experiments as revealed by Carbon 13 natu ral abundance. Soil Sci Soc Am J 52 :118 124 Ballantine K, Schneider R, Groffman P, Lehmann J (2012) Soil Properties and Vegetative Development in Four Restored Freshwater Depressional Wetlands. Soil Science Society of America Journal 76: 1482 1495 Bauer JE, Bianchi TS (2011) Dissolved Organic Carbon Cycling and Transfromation In: Wolanski, E. and D.S. McLusky (eds.) Treastise on Estuarine and Coastal Science 5: 7 67. Waltham: Academic Press, Cambridge, MA, USA Bianchi TS (2007) Biogeochemistry of Estuarie s. Oxford University P ress, Inc. New York, New York Bianchi TS, Lambert C, Biggs D ( 1995) Distribution of chlorophyll a and phaeopigments in the northwestern Gulf of Mexico: a comparison between fluorimetric and high performance liquid chromatography measurements. Bulletin of Marine Science 56: 25 32 Bianchi TS, Wysocki LA, Stewart M, Filley TR, McKee BA (2007) Temporal
86 variability in terrestrially derived sources of particulate organic carbon in the lower Mississippi River. Geochimica et Cosmochimica Acta 71: 4425 4437 Bouillon SF, Moens T, Overmeer I, Koedam N, Dehairs F (2004) Resource utilization patterns of epifauna from mangrove forests with contrasting inputs of local versus imported organic matter. Mar. Ecol. Prog. Ser. 278 : 77 88 Breithaupt JL, Smoak JM, Smith III TJ, Sanders CJ (2014) Temporal variability of carbon and nutrient burial, sediment accretion, and mass accumulation over the past century in a carbonate platform mangrove forest of the Florida Everglades. Journal of Geophysical Resear ch: Biogeosciences 119: 2032 2048 Buyanonovsky GA, Aslam M, Wagner GH (1994) Carbon turnover in soil physical fractions. Soil Sci. Soc. Am. J. 58: 1167 1173 Cammen LM (1975) Accumulation rate and turnover time of organic carbon in a salt marsh sediment. Li mnol. Oceanogr. 20: 1012 1014 Chapin FS, Matson PA, Mooney HA (2002) Principles of Terrestrial Ecosystem Ecology. Springer Science. Stanford, California. lo J, Raskin RG, Sutton P, van den Belt M (1997 ) 253 260` Coronado Molina C, Day JW, Reyes E, Prez BC (2004) Standing crop and aboveground partitioning of a dwarf mangrove fores t in Taylor River Slough, Florida. Wetlands Ecol. Manage. 12: 157 164 Craft C, Broome S, Campbell C (2002) Fifteen years of vegetation and soil development after brackish water marsh creation. Restor. Ecol. 10: 248 258 Craft C, Reader J, Sacco JN, Broome SW (1999) Twenty five years of ecosystem development of constructed Spartina alterniflora (Loisel) marshes. Ecol. Appl. 9 : 1405 1419 Dagg M, Benner R, Lohrenz S, Lawrence D (2004) Transformation of dissolved and particulate materials on continental shelves influenced by large rivers: Plume Processes. Cont. Shelf. Res. 24: 833 858 Dawes CJ, Hanisak D, Kenworthy WJ (1995) Seagrass biodiversity in the Indian River Lagoon. Bulletin of Marine Science 57(1): 59 66 Demmig Adams B, Stewart JJ, Burch TA, Adams WW ( 2014) Insights from placing photosynthetic light harvesting into context. The Journal of Physical Chemisty Letters 5: 2880 2889
87 Dierberg, FE (1991) Non point source loadings of nutrients and dissolved organic carbon from an agricultural suburban watershed in East Central Florida. Wat. Res. 25(4 ) : 363 374 Dittmar T, Hertkorn N, Kattner G, and RubÃ©n JL (2006) Mangroves, a major source of dissolved organic carbon to the oceans. Global Biogeochemical Cycles 20: GB1012 Dittmar T, Lara RJ (2001) Do mangroves rat her than rivers provide nutrients to coastal environments south of the Amazon River? Evidence from long term flux measurements. Marine Ecology Progress Series 213: 67 77 Duarte CM (1990) Seagrass nutrient content. Marine ecology progress series. Olendorf 6: 201 207 Duarte CM, Chiscano CL (1999) Seagrass biomass and production: a reassessment. Aquat. Bot. 65: 159 174 Duarte CM, Martin M, Agawin NSR, Uri J, Fortes MD, Gallegos ME, MarbÃ N, Hemminga MA (1998) Root production and belowground seagrass biomass. Mar. Ecol. Prog. Ser. 171: 97 108 Duarte CM, Middelburg J, Caraco N (2005) Major role of marine vegetation on the oceanic carbon cycle. Biogeosciences 2: 1 8 across a n ecotonal gradient in a mangrove forest. Biogeosciences 62: 145 175 Fischler KC (2006) Observations and Characterizations of Subaqueous Soils and Seagrasses in a Recently Constructed Habitat in the Indian River Lagoon, Florida. University of Florida Fletcher SW, Fletcher WW (1995) Factors affecting changes in seagrass distribution and diversity patterns in the Indian River Lagoon complex between 1940 and 1992. Bulletin of Marine Science 57(1): 49 58 s mangroves 1980 2005. Rome, Italy Fourqurean JW, Duarte CM, Kennedy H, MarbÃ N, Holmer M, Mateo MA et al. (2012) Seagrass ecosystems as a globally significant carbon stock. Nature Geoscience 5: 505 509 Fromard F, Puig H, Mougin E, Marty G, Betoulle JL, C adamuro L (1998) Structure above ground biomass and dynamics of mangrove ecosystems: new data from French Guiana. Oecologia 115: 39 53
88 Garland, Ed (2014) "The Indian River Lagoon: An Estuary in Distress." News Releases . St. Johns River Water Management D istrict, 4 Oct. 2014, http://floridaswater.com/itsyourlagoon/ (acc essed Apr 27 2015) Golley FB, Mcginnis JT, Clements RG, Child GI, Duever MJ (1975) Mineral Cycling in a Tropical Moist Forest Ecosyste m. Georgia Univ. Press, Athens, GA, USA Golley F, Odum HT, Wilson R (1962) The structure and metabolism of a Puerto Rican red mangrove forest in May. Ecology 43: 9 19 Greiner JT, McGlathery, KJ, Gunnell J, McKee BA (2013) Seagrass Restoration los One 8(8): e72469 Harris D, Horwath WR, Van Kessel C (2001) Acid fumigation of soils to remove carbonates prior to total organic carbon or carbon 13 isotopic analysis. Soil Soc. Am. J. 65: 1853 1856 He B, Dai M, Zhai W, Wang L, Wang K, Chen J, Lin J, Han A, Xu Y (20 10) Distribution, degradation and dynamics of dissolved organic carbon and its major compound classes in the Pearl River Estuary, China. Marine Chemistry 119: 52 64 Hedges JI, Hatcher PH, Ertel JR, Meyers Schulte KJ (1992) A comparison of dissolved humic substances from seawater with Amazon River counterparts by 13C NMR spectroscopy. Geochimica et Cosmochimica Acta 56: 1753 1757 Hedges JI, Stern JH (1984) Carbon and nitrogen determinations of ca rbonate containing solids. Limnol. Oceanogr. 29 : 657 663 Hemminga A, Duarte CM (2000) Seagrass Ecology. Cambridge University Press. Cambridge, UK Hicks C (2007) Sediment organic carbon pools and sources in a recently constructed mangrove and seagrass ecosystem. University of Florida Hollins SE, Ridd PV, Read WW (2000) Measurement of the diffusion coefficient for salt in salt flat and mangrove soils. Wetlands Ecology and Management 8: 257 262 Howard ., Hoyt S, Isensee K, Pidgeon E, Telszewski M (eds.) (2014). Coastal Blue Carbon: Methods for assessing carbon stocks and emissions factors in mangroves, tidal salt marshes, and seagrass meadows. Conservation International, Intergovernmental Ocea nographic Commission of UNESCO, International Union for Conser vation of Nature. Arlington, Virginia, USA Jennerjahn TC, Ittekkot V (2002) Relevance of mangroves for the production and deposition of organic matter along tropical continental margins. Naturwissenschaften 89: 23 30
89 Jespersen J, Osher LJ (2007) Carbon Sto rage in the Soils of a Mesotidal Gulf of Maine Estuary. Soil Sci. Soc. Am. 71: 372 379 Jia G, Peng P (2003 ) Temporal and spatial variations in signatures of sedimented organic matter in Lingding Bay (Pearl estuary), Southern China. Marine Chemistry 82: 47 54 Joergensen RG, Mueller T (1995) Estimation of the microbial biomass in tidal flat sediment by fumigation extraction. Helgolander Meeresuntersuchungen 49: 213 221 Kaldy JE, Dunton KH (2000) Above and below ground production, biomass and reproductive ecology of Thalassia testudinum (turtle grass) in a subtropical coastal lagoon. Marine Ecology P rogress Series 193: 271 283 Kamerosky A, Cho HJ, Morris L (2015) Monito ring of the 211 Super Algal Bloom in Indian River Lagoon, FL, USA, Using MERIS. 0emote Sens. 7: 1441 1460 Kauffman JB, Donato D (2011) Protocols for the measurement, monitoring and reporting of structure, biomass and carbon stocks in mangrove forests. Bog or, Indonesia: Center for International Forestry Research (CIFOR) Kauffman JB, Heider C, Norfolk J, Payton F (2014) Carbon stocks of intact mangroves and carbon emissions arising from their conversion in the Dominican Republic. Ecological App0lications 24 : 518 527 Kennedy H, Beggins J, Duarte CM., Fourqurean JW, Holmer M, Marba N, Middelburg ( 2010) Seagrass sediments as a global carbon sink: Isotopic constraints. Global Biogeochemical Cycles 24: GB4026 Keuskamp JA, Feller IC, Laanbroek HJ, Verhoeven JTA, H eftig MM (2015) Short and long term effects of nutrient enrichment on microbial exoenzyme activity in mangrove peat. Soil Biology and Biochemistry 81: 38 47 Kim Y, Engle BA., Lim K, Lim KJ, Larson V, Duncan B (2002) Runoff Impacts of Land Use Change in In dian River Lagoon Watershed. J. Hydrol. Eng 10: 245 251 Komiyama A, Ogino K, Aksornkoae S, Sabhasri S (1987) Root biomass of a mangrove forest in southern Thailand. 1. Estimation by the trench method and the zonal structure of root biomass, J. Trop. Ecol. 3: 97 108 Komiyama A, Ong JE, Poungparn S (2008) Allometry, biomass, and productivity of mangrove forests: A review. Aquatic botany 89: 128 137 Komiyama A, Poungparn S, Kato S (2005) Common allometric equations for estimating the tree weight of mangroves. Journal of Tropical Ecology 21: 471 477
90 Lapointe BE, Herren LW, Debortoli DD, Vogel MA (2015) Evidence of sewage driven Harmful Algae 43: 82 102 Lavery PS, Mateo MA, Ser rano O, Rozaimi M (2013) Variability in the Carbon Storage of Seagrass Habitats and Its Implications for Global Estimates of Blue Carbon Ecosystem Service. Plos One 8(9): e73748 Lewis DB, Brown JA, Jimenez KL (2014) Effects of flooding and warming on soil organic matter mineralization in Avicennia germinans mangrove forests and Juncus roemerianus salt marshes. Estuarine, Coastal, and Shelf Science 139: 11 19 Li T,Yi Y (2014) Dynamics of decomposition and nutrient release of leaf litter in Kandelia obovate mangrove forests with different ages in Jiulongjiang Estuary, China. Ecolog. Engineer. 73: 454 460 Lugo AE, Snedaker SC (1974) The ecology of mangroves. Ann Rev. Ecol. Syst. 5: 39 64 Mall LP, Garge A (1991) Study of biomass, litter fall, litter decomposit ion and soil respiration in monogeneric mangrove and mixed mangrove forests of Andaman Islands. Trop. Ecol. 32: 144 152 Martin JB, Cable JE, Hartl K, Smith CG (2006) Thermal and Chemical Evidence for Rapid Water Exchange across the Sediment Water Interfac e by Bioirrigation in the Indian River Lagoon, Florida. Limnology and Oceanography 51: 1332 1341 Maybeck M (1993) C, N, P, and S in rivers: from sources to global inputs. Pages 163 191 In: interactions of C, N, P, and S Biogeochemical cycles and global ch ange (Wollast, R., Mackenzie, F.T. and Chou, L., eds). NATO ASI Series, 14. Springer Verlag, Berlin, Germany Mckee KL, Faulkner PL (2000) Restoration of biogeochemical function in mangrove forests. Restor. Ecol. 8: 247 259 Mcleod E, Chmura GL, Bouillon S, Salm R, Bjork M, Duarte CM, Lovelock CE, Schlesinger WH, Silliman BR (2011) A blueprint for blue carbon: toward an improved understanding of the role of vegetated coastal habitats in sequestering CO 2 . Ecol. Soc. Of Amer. 9(10):552 560 Meade RH (1996) Rive r sediment inputs to major deltas, in Sea Level Rise and Coastal Subsidence: Causes, Consequences and Strategies, edited by J. D. Milliman and B. U. Haq, pp. 63 85, Kluwer Acad., Dordrecht, Netherlands Meentemeyer V (1978) Macroclimate and Lignin Control o f Litter Decomposition Rates. Ecological Society of America 59(3): 465 472
91 Melillo JM , Aber JD, Muratore JF (1982) Nitrogen and Lignin Control of Hardwood Leaf Litter Decomposition Dynamics. Ecology 63 :621 626 Meyers PA (1997) Organic geochemical proxies of paleoceanographic, paleolimnologic, and paleoclimatic processes. Organic Geochemistry 27: 213 250 Milliman JD, Meade RH (1983) World wide delivery of sediment to the ocean. J. Geol. 91: 1 21. Milliman JD, Syvitski JPM (1992) Geomorphic tectonic control of sediment discharge to the ocean The importance of small mountainous rivers. J. Geol. 100: 525 544 Modin O, Alam SS, P ersson F, Wilen BM (2015) Sorption and Release of Organics by Primary, Anaerobic, and Aerobic Activated Sludge Mixed with Raw Municipa l Wastewater. Plos One 10(3): e0119371 Moreira Turcq P, Seyler P, Guyot J L, Etcheber H (2003) Exportation of organic carbon from the Amazon River and its main tributaries. Hydrological Processes 17: 1329 1344 Merriam Webster (2015) Dictionary, http://www.merriam webster.com/dictionary/seston (accessed Dec 22 2015) Morgan PA, Short FT (2002) Using functional trajectories to track constructed salt marsh development in the Great Bay Estuary, Ma ine/New Hampshire, USA. Restor. Ecol. 10: 461 473 Osborne TZ, DeLaune RD (2013) Soil and Sediment Sampling of Inundated Environments. Pages 21 40 In: Methods in Wetland Science : DeLaune RD, Reddy KR, Richardson CJ, Megonigal JP (eds) Soil Science Society of America, Madison WI, USA Osland MJ, Spivak AC, Nesterlode JA, Lessmann JM, Almario AE, Heitmuller PT, Russell MJ, Krauss KW, Alvarez F, Dantin DD, Havey JE, From AS, Cormier N, Stagg CL (2012) Ecosystem Development After Mangrove Wetland Creation: Plant Soil Change Across a 20 Year Chronosequence. Ecosystems 15: 848 866 Otero X L, Ferreira TO, Vidal Torrado P, Macias F (2006) Spatial variation in pore water geochemistry in a mangrove system (Pai Matos island, Cananeia Brazil). Applied Geochemistry 21 : 2171 2186 Pan Y, Birdsey RA, Fang J, Houghton R, Kauppi PE, Kurz WA, et al. (2011) A Large 993 Passioura JB, Ball MC, Knight JH (1992) Mangroves may salinize the soil and in so din limi t their transpiration rate. Functional Ecology 6: 476 481
92 Pendelton L, Donato DC, Murray BC, Crooks S, Jenkins WA, Sifleet S, Craft C, Fourqurean JW, Kauffman JB, MarbÃ N, Megonigal P , Pidgeon E, Herr D, Conversion and Degradation of Vegetated Coastal Ecosystems. P los One 7(9): e43542 Phlips EJ, Badylak S, Christman MC, Lasi MA (2010) Climatic Trends and Temporal Patterns of Phytoplankton Composition, Abundance, and Succession in the Indian River Lagoon, Florida, USA. Estuaries and Coasts 33(2): 498 512 Popp M, Polania J, Weiper M (1993) Physiological adaptations to different salinity levels in mangrove. Pages 217 224 In: H. Lieth and A. Al Masoom (Eds.) Towards the rational use of high salinity tolerant plants. Vol. 1. Kluwer Academic Publishers, Utrecht, Netherlands Porcal P, Koprivnjak J, Molot LA., Dillon PJ (2009) Humis substances part 7: the biogeochemistry of dissolved organic carbon and its interactions with climate change. Environ. Sci. Pollut. Res. 16: 714 726 Rains DW, Epstein E (1967) Preferential absorption of p0otassium by leaf tissue of the mangrove Avicennia marina : an aspect of halophytic competence in coping with salt. Aust. J. Biol. Sci. 20: 847 857 Reddy R, Dela une R (2008) Biogeochemistry of Wetlands: science and applications, 1 st ed.CRC Press. Boca Raton, FL Rey JR, Rutledge CR (2015) Seagrass Beds of the Indian River Lagoon https://edis.ifas.ufl.edu/in189 ( access ed Feb 13 2016) Rice T, Baker F (2015) Indian River Lagoon U.S. EPA. Web.
93 Saenger P (1982) Morphological, anatomical and reproductive adaptations of Australian mangroves. Pages 153 191 In: Clough, B.F. (Ed.) Mangrove ecosystems in Australia. Australian National University Press, Canberra, Australia Saenger, P (2002) Mangrove Ecology, Silviculture and Conservation. Klu wer Academic Publishers. Lisomore, Australia Savoye N, David V, Morisseau F , Etcheber H, Abril G, Billy I (2012 ) Origin and composition of particulate organic matter in a macrotidal turbid estuary: The Gironde Estuary, France. Estuarine, Coastal, and Shel f Science 108: 16 28 Scholander, PF (1968) How mangrove desalinate seawater. Physiol. Plant. 21: 251 261 Shackelford N, Hobbs RJ, Burgar JM, Erickson TE, Fontaine JB, LalibertÃ© E, Ramalho CE, Perrig MP, Standish RJ (2013) Primed for change: developing ecol ogical restoration for the 21 st century. Restoration Ecology 21(3): 297 304 Sherman RE, Fahey TJ, Martinez P (2003) Spatial patterns of biomass and aboveground net primary productivity in a mangrove ecosystem in the Dominican Republic Ecosystems 6: 384 39 8 Simpson LT (2011) Global change and community competition alter Avicennia germinans growth in the salt marsh mangrove ecotone. Masters Thesis, Villanova University, Villanova, P ennsylvania Smith CG, Osterman LE (2014) An Evaluation of Temporal Changes in Sediment Accumulation and Impacts on Carbon Burial in Mobile Bay, Alabama, USA. Estuaries and Coasts 37: 1092 1106 Smith TJ, Whelan KRT (2006) Development of allometric relations for three mangrove species in South Florida for use in the Greater Evergla des Ecosystem restoration. Wetlands Ecology and Management 14:409 419 Smoak JM, Breithaup JL, Smith III TJ, Sanders CJ (2013) Sediment accretion and organic carbon burial relative to sea level rise and storm events in two mangrove forests in Everglades Na tional Park. Catena 104: 58 66 Smithsonian Marine Station (2014) Indian River Lagoon Species Inventory Homepage http://www.sms.si.edu/IRLspec/ (accessed 30 Apr. 30 2015) Snedaker SC (1995) Mangroves and climate change in Florida and Caribbean region: Scen arios and hypotheses. Hydrobiologia 298: 43 49 Sparks DL (1996) Methods of Soil Analysis part 3 chemical methods. Soil Science Society of America, Madison, Wisconsin Spalding MD, Kainuma M, Collins L (2010) World Atlas of mangroves. Earthscarn, London, U nited Kingdom
94 Spitzy A, Ittekkot V (1991) Dissolved and particulate organic matter in rivers. Pages 5 17 In:Ocean Margin in Global Change, Mantoura RFC, Martin JM, Wollast R (eds). John Wiley & Sons, New York, USA Steinberg CEW, Meinelt T, Timofeyev MA, Bi ttner M, Menzel R (2008) Humic Substances (review series): Part 2: interactions with organisms. Environ Sci Pollut Res 15(2):128 135 St. Johns county water management district (2012) Indian River Lagoon 2011 Superbloom Plan of Investigation, http://floridaswater.com/indianriverlagoon/ technicaldocumentation /pdfs/2011superbloom_investigationplan_June_2012.pd f (acc essed Jan 2 2015) Stevenson RJ, Bothwell ML, Lowe RL (1996) Algal Ecology: Freshwater Benthic Ecosystems. Academic P ress, San Diego, California Steward JS, Virnstein RW, Morris LJ, Lowe EF (2005) Setting seagrass depth, coverage, and light targets fo r the Indian River Lagoon system, Florida. Estuaries 28: 923 935 Tamai S, Nakasuga T, Tabuchi R, Ogino K (1986) Standing biomass of mangrove forests in sourthern Thailand. J. Jpn. Forest Soc. 68: 384 388 Terrados J, Duarte CM, Fortes MD, Agawin NSR, Bach S, Thampanya U, Kamp Nielsen L, Kenworthy WJ, Geertz Hansen O, Vermaat J (1998) Changes in Community Structure and Biomass of Seagrass Communities along Gradients of Siltation in SE Asia. Estuarine, Coastal, and Shelf Science 46(5): 757 768 Trumbore SE (1997) P otential responses of soil organic carbon to global environmental change. Proc. Natl. Acad. Sci. 94: 8284 8291 Twilley RR, Chen RH, Hargis T (1992) Carbon sinks in mangroves and their implications to carbon budget of tropical coastal ecosystems. Water, Air, and Soil Pollution 64: 265 288 Major Tropical Environments. Bioscience 51(10): 807 815 Vance ED, Brookes PC, Jenkinson DS (1987) An extraction method for mea suring soil microbial biomass C. Soil Biology & Biochemistry 19: 703 707 Wang W, Tarr MA, Bianchi TS, Engelhaup E (2000) Ammonium photoproduction from aquatic humic and colloidal matter. Aquat Geochem 6:275 292 Wang X, Ma H, Li R, Song Z, Wu J (2012) Seas onal fluxes and source variation of organic carbon transported by two major Chinese Rivers: The Yellow River and Changjiang (Yangtze) River. Global Biogeochemical Cycles 26: GB2025
95 Waycott M, Duarte CM, Carruthers TJB, Orth RJ, Dennison WC, Olyamik S, Call adine A, Fourqurean JW, Heck, KL, Hughes AR, Kendrick GA, Kenworthy WJ, Short FT, Williams SL (2009) Accelerating loss of seagrass across the globe threatens coastal ecosystems. PNAS 106(30): 12377 12381 Werner A, Stelzer R (1990) Physiological resp0onss of the mangrove Rhizophera mangle grown in the absence and presence of NaCl. Plant, Cell and Environ. 13: 243 255 Wetzel RG (1995) Death, detritus, and energy flow in aquatic ecosystems. Freshwater Biology 33: 83 89 Winter PED, Schlacher TA, Baird D (19 96) Carbon flux between an estuary and the ocean: a case for outwelling. Hydrobiologic 337: 123 132 Wu J, Joergensen RG, Pommeremomg B, Chaussod R, Brookes PC (1990) Measurement of soil microbial biomass c by fumigation extraction an automated procedure . Soil Biology & Biochemistry 22 : 1167 1169 Xue B, Yan C, Lu H, Yang B (2009) Mangrove derived organic carbon in sediment from Zhangjiang estuary (China) mangrove wetland. Journal of Coastal Research 25(4): 949 956 Yan CX, Yang Y, Zhou JL , Liu M, Nie M, S hi H, Gu L ( 2013) Antibiotics in the surface water of the Yangtze Estuary: occurrence,distribution,and risk assessment. Environ. Pollut. 175: 22 29 Yan C, Yang Y, Zhou J, Nie M, Liu M, Hochella MF (2015 ) Selected emerging organic contaminants in the Yangtz e Estuary, China: A comprehensive treatment of their association with aquatic colloids. Journal of Hazardous Materials 283: 14 23 Young RG, Matthaei CD, Townsend CR (2008) Organic matter breakdown and ecosystem metabolism: functional indicators for assessi ng river ecosystem health. Journal of North American Benthological Society 27: 605 625 Zedler JB (2000) P rogress in wetland restoration ecology. Tree 15(10): 402 407 Zedler JB, Callaway JC (1999) Tracking wetland restoration: Do mitigation sites follow d esired trajectories? Restoration ecology 7(1): 69 73 Zhang L, Yin K, Wang L, Chen F, Zhang D, Yang Y (2009) The sources and accumulation rate of sedimentary organic matter in the Pearl River Estu ary and adjacent coastal areas, Southern China. Estuarine, C oastal and Shelf Science 85: 190 196 Zhu J, Olsen CR (2014) Sedimentation and Organic Carbon Burial in the Yangtze River and Hudson River Estuaries: Implications for the Global Carbon Budget. Aquat. Geochem. 20: 325 342
96 BIOGRAPHICAL SKETCH Tracey Schafer is originally from Champaign, Illinois where she learned about the importance of nature and protecting the environment from her parents. She attended the University of Illinois at Urbana Champaign, where she received her bachelors degree in Natural Resource and Environmental Science with a concentration in resource ecology in December 2010. During her senior year of college, she worked for a weed ecology lab, studying the invasive potential of Miscanthus bignoniaceae . F rom there, the realization that she wanted to pursue a career in environmental research was born. In August 2011, Tracey left the United States to become an agro forestry Peace Corps volunteer in Senegal, West Africa. She lived in a small rural village there without many resources for two years, missing the mental challenge and ability to study science. Therefore, when she returned to the states and had the opportunity to work as a laboratory technician for Todd Osborne and learn about coastal biogeoch emistry, she jumped at the opportunity. In A ugust 2014, she began her master and Water Science D epartment at the University of Florida. At the end of her master degree, she is even more determined to pursue a career in environmental research and is hoping to pursue a doctoral degree as the next step.