scispace - formally typeset
Search or ask a question
Journal Article

The role of standing dead Spartina alterniflora and benthic microalgae in salt marsh food webs: considerations based on multiple stable isotope analysis

TL;DR: In this article, the stable isotope compositions (C, N, and S) of hve, senescent, and standing dead Spartina alterniflora were compared in order to determine the effects of aerial decomposition on the isotopic signature of aboveground S. alternjflora entering the food chain, which indicated that N2fixing microorganisms associdated with microalgal communities were an important source of N to salt marsh consumers.
Abstract: The stable isotope compositions (C, N, and S) of hve, senescent, and standing dead Spartina alterniflora were compared in order to determine the effects of aerial decomposition on the isotopic signature of aboveground S. dlterniflora tissue entering the food chain. Aerial decomposition of aboveground S. alterniflora resulted in a 6 to 18% increase in P S , and a 2 to 3 % decrease in 615N values; 613c values were unchanged. We describe mechanisms whereby the activity of fungi and epiphytic microorganisms may contribute to the observed shlfts in and 6I5N, respectively. The 613c value of salt marsh benthic and eplphytic microalgae ranged from -13.0% in summer to -17.6%0 in early spring. Average 6'\" values of microalgae and standing dead S. altemiflora were -0 3 and l.?%, respectively, reflecting the activity of NZ-fixing microorganisms. The 615N values for omnivorous and herbivorous salt marsh macrofauna ranged between 7.5 and 2.2% and for predatory Fundulus spp. averaged 9.2%. Given a presumptive + 3 % trophic shift in N assimilation, these results suggest that N2-fixing microorganisms associdted with microalgal communities were an important source of N to salt marsh consumers. The 6% 6'\"N, and 6\"'s values of primary producers were compared to the values of the following consumers: Fundulus spp., Uca spp., Ilyanassa obsoleta, and Littoraria irrorata. 6I3C VS 6 1 5 ~ and 613C vs 63JS dual isotope plots demonstrated that microalgae and standing dead S. alternjflora are important food resources in the North Carolina (USA) marshes we sampled. In addition, a compilation of literature values suggests that this is true in salt marshes throughout the East and Gulf coasts of North America. Future isotope studies of marsh food webs should include detrital Spartina spp. material in analyses of trophic structure.
Citations
More filters
01 Jan 1980
TL;DR: In this article, the influence of diet on the distribution of nitrogen isotopes in animals was investigated by analyzing animals grown in the laboratory on diets of constant nitrogen isotopic composition and found that the variability of the relationship between the δ^(15)N values of animals and their diets is greater for different individuals raised on the same diet than for the same species raised on different diets.
Abstract: The influence of diet on the distribution of nitrogen isotopes in animals was investigated by analyzing animals grown in the laboratory on diets of constant nitrogen isotopic composition. The isotopic composition of the nitrogen in an animal reflects the nitrogen isotopic composition of its diet. The δ^(15)N values of the whole bodies of animals are usually more positive than those of their diets. Different individuals of a species raised on the same diet can have significantly different δ^(15)N values. The variability of the relationship between the δ^(15)N values of animals and their diets is greater for different species raised on the same diet than for the same species raised on different diets. Different tissues of mice are also enriched in ^(15)N relative to the diet, with the difference between the δ^(15)N values of a tissue and the diet depending on both the kind of tissue and the diet involved. The δ^(15)N values of collagen and chitin, biochemical components that are often preserved in fossil animal remains, are also related to the δ^(15)N value of the diet. The dependence of the δ^(15)N values of whole animals and their tissues and biochemical components on the δ^(15)N value of diet indicates that the isotopic composition of animal nitrogen can be used to obtain information about an animal's diet if its potential food sources had different δ^(15)N values. The nitrogen isotopic method of dietary analysis probably can be used to estimate the relative use of legumes vs non-legumes or of aquatic vs terrestrial organisms as food sources for extant and fossil animals. However, the method probably will not be applicable in those modern ecosystems in which the use of chemical fertilizers has influenced the distribution of nitrogen isotopes in food sources. The isotopic method of dietary analysis was used to reconstruct changes in the diet of the human population that occupied the Tehuacan Valley of Mexico over a 7000 yr span. Variations in the δ^(15)C and δ^(15)N values of bone collagen suggest that C_4 and/or CAM plants (presumably mostly corn) and legumes (presumably mostly beans) were introduced into the diet much earlier than suggested by conventional archaeological analysis.

5,548 citations

Dissertation
16 Mar 2018
TL;DR: In this paper, a Mesocosm and Microcosm Experiments on the Feeding of Temperate Salt Marsh Foraminifera are described, and a taxonomic resolution and Tidal Gradients in Food Webs for Two Temperate salt Marshes: How Much Detail is Enough?
Abstract: ............................................................................................................................xv List of Abbreviations and Symbols Used .....................................................................xvi Acknowledgements................................................................................xvii Chapter 1: Introduction...........................................................................1 1.1 General Introduction .....................................................................................................1 1.2 Study Location and Evolution of Thesis........................................................................8 1.3 Chapter Outlines and Objectives.................................................................................11 1.3.1 Chapter 2: Development of a Salt Marsh Mesocosm to Study Spatio-Temporal Dynamics of Benthic Foraminifera............................................11 1.3.2 Chapter 3: Taxonomic Resolution and Tidal Gradients in Food Webs for Two Temperate Salt Marshes: How Much Detail is Enough?...............13 1.3.3 Chapter 4: Use of δ 13 C and δ 15 N Stable Isotopes Within and Between Two Temperate Salt Marshes in Atlantic Canada to Examine Patterns of Food Web Structure and Function......................................................14 1.3.4 Chapter 5: Mesocosm and Microcosm Experiments on the Feeding of Temperate Salt Marsh Foraminifera...................................................16 1.3.5 Chapter 6: Conclusions.................................................................................17 1.4 Overview ..........................................................................................17 Chapter 2: Development of a Salt Marsh Mesocosm to Study SpatioTemporal Dynamics of Benthic Foraminifera ..............................................19 2.0 Abstract ..........................................................................................19 2.

5 citations

Dissertation
01 Apr 2004
TL;DR: Swartwood et al. as mentioned in this paper investigated whether the age structure, population density, and distribution of Littoraria angulifera in the Smithsonian Institution's Florida Everglades mesocosm in Washington, DC is analogous to that of wild populations.
Abstract: Title of thesis: ASSESSMENT OF MANGROVE AND SALT MARSH MESOCOSM FUNCTIONAL VALUE USING PERIWINKLE SNAILS, LITTORARIA ANGULIFERA AND LITTORARIA IRRORATA, AS AN INDICATOR Stacy Lyn Swartwood, Master of Science, 2004 Thesis directed by: Associate Professor Patrick Kangas Marine, Estuarine, and Environmental Science Program Although much research has been conducted on restoration techniques, questions about the functional value of restored and constructed ecosystems remain. Gastropods are a particularly useful indicator organism because they play a vital role at the detrital interface. This study addresses the question of whether the age structure, population density, and distribution of Littoraria angulifera in the Smithsonian Institution's Florida Everglades mesocosm in Washington, DC is analogous to that of wild populations. The second phase investigates these same factors, in populations of Littoraria irrorata at a reference site on Slaughter Creek and six mesocosm replicates at Horn Point Laboratory in Cambridge, Maryland. Neither the mangrove nor the salt marsh mesocosms were able to support healthy, reproducing populations of periwinkle snails. Salinity, humidity, territory requirements, habitat complexity, precipitation, photoperiod, and tidal variation were identified as potential causal factors for mortality and the absence of evidence of juvenile recruitment to mesocosm populations. ASSESSMENT OF MANGROVE AND SALT MARSH MESOCOSM FUNCTIONAL VALUE USING PERIWINKLE SNAILS, LITTORARIA ANGULIFERA AND LITTORARIA IRRORATA, AS AN INDICATOR by Stacy Lyn Swartwood Thesis submitted to the Faculty of the Graduate School of the University of Maryland, College Park in partial fulfillment of the requirements for the degree of Master of Science 2004 Advisory Committee: Associate Professor Patrick Kangas, Chair Associate Professor William Lamp Professor Court Stevenson

4 citations

Dissertation
01 Jan 2012
TL;DR: Oduro et al. as mentioned in this paper reported one of the first sulfur isotope constraints on the factors that control the expression on the S-isotope effects of VOSCs and their natural precursors.
Abstract: Title of Document: ISOTOPE GEOCHEMISTRY OF ORGANIC SULFUR COMPOUNDS WITH LINKS TO BIOGEOCHEMICAL SULFUR CYCLING AND RADICAL CHEMISTRY Harry D. Oduro, Ph.D. 2012 Directed By: Professor James Farquhar, Department of Geology and Earth System Science Interdisciplinary Center (ESSIC) Research on volatile organic sulfur compounds (VOSCs) such as dimethylsulfide (DMS), methanethiol (MT), carbonylsulfide (OCS), dimethyl disulfide (DMDS), and carbon disulfide (CS2) from aquatic environments has focused on the production and flux of DMS from the oceans into the atmosphere. In contrast, the biogeochemical connections between the atmosphere and the major reservoirs of VOSC species in freshwater, estuarine, wetlands and coastal marine environments are poorly understood. This thesis reports one of the first sulfur isotope constraints on the factors that control the expression on the S-isotope effects of VOSCs and their natural precursors. It describes ties to their formation, connections with inorganic and microbial processes, and chemical reactions that link the various productions of VOSCs in natural environments. Results from the four field sites studied in this research – Two Pacific Northwest Islands in the Washington State, the York River Estuary in Virginia, Fayetteville Green Lake in New York, and the Delaware Great Marsh – have demonstrated several strikingly different pathways for VOSCs production. In the Pacific Northwest Islands and York River Estuary, DMSP produced by marine algae and phytoplankton have δS values of +18.5 ‰ to +19.2 ‰, and ΔS and ΔS nearly similar to seawater sulfate. These values are slightly S-depleted relative to seawater sulfate. This observation is consistent with the origin of sulfur in DMSP being related to assimilatory pathways of sulfate. Analyses of VOSCs from Fayetteville Green Lake, a stratified freshwater system and the Delaware Great Marsh yield different δS, ΔS, and ΔS values of total VOSCs (consisting of MT, DMS, CS2, and DMDS) that are similar to but slightly Senriched relative to the compositions of coexisting sulfide produced via bacterial sulfate reduction (negative δS and ΔS, and positive ΔS) and reflect organic matter sulfurization pathways in addition to assimilatory sulfate pathways. Extension of chemical protocols to thermochemical sulfate reduction (TSR) process using a simple amino yielded sulfur radical adducts with uncompensated electron spins and S isotope enrichment of up to 13‰. These enrichments are hypothesized to originate from reactions involving sulfur radicals generated by thiyl-mediated thermolysis reaction via sulfur ion-radical pair mechanisms leading to the manifestation of magnetic isotope effect (MIE). ISOTOPE GEOCHEMISTRY OF ORGANIC SULFUR COMPOUNDS WITH LINKS TO BIOGEOCHEMICAL SULFUR CYCLING AND RADICAL CHEMISTRY

4 citations

DissertationDOI
05 Apr 2019
TL;DR: This thesis investigates the pathways of dissolved inorganic carbon production in anoxic permeable sediments and the challenge of replicating flow conditions under anoxic conditions using FTRs and experimental design.
Abstract: This research focused on investigating the large quantity of dissolved inorganic carbon production observed in anoxic permeable sediments, that could not be attributed to known heterotrophic processes. Through the use of flow through reactor experiments, metabolomic and porewater analyses were used to identify the process responsible. Large quantities of dissolved hydrogen and extensive lipid accumulation indicated fermentation was a major process under such conditions. Antibiotic flow through reactor treatments were used to confirm the minimal contribution by bacteria, indicating eukaryotic microalgae are likely employing dark fermentation to survive dark anoxic sediments.

3 citations

References
More filters
01 Jan 1980
TL;DR: In this article, the influence of diet on the distribution of nitrogen isotopes in animals was investigated by analyzing animals grown in the laboratory on diets of constant nitrogen isotopic composition and found that the variability of the relationship between the δ^(15)N values of animals and their diets is greater for different individuals raised on the same diet than for the same species raised on different diets.
Abstract: The influence of diet on the distribution of nitrogen isotopes in animals was investigated by analyzing animals grown in the laboratory on diets of constant nitrogen isotopic composition. The isotopic composition of the nitrogen in an animal reflects the nitrogen isotopic composition of its diet. The δ^(15)N values of the whole bodies of animals are usually more positive than those of their diets. Different individuals of a species raised on the same diet can have significantly different δ^(15)N values. The variability of the relationship between the δ^(15)N values of animals and their diets is greater for different species raised on the same diet than for the same species raised on different diets. Different tissues of mice are also enriched in ^(15)N relative to the diet, with the difference between the δ^(15)N values of a tissue and the diet depending on both the kind of tissue and the diet involved. The δ^(15)N values of collagen and chitin, biochemical components that are often preserved in fossil animal remains, are also related to the δ^(15)N value of the diet. The dependence of the δ^(15)N values of whole animals and their tissues and biochemical components on the δ^(15)N value of diet indicates that the isotopic composition of animal nitrogen can be used to obtain information about an animal's diet if its potential food sources had different δ^(15)N values. The nitrogen isotopic method of dietary analysis probably can be used to estimate the relative use of legumes vs non-legumes or of aquatic vs terrestrial organisms as food sources for extant and fossil animals. However, the method probably will not be applicable in those modern ecosystems in which the use of chemical fertilizers has influenced the distribution of nitrogen isotopes in food sources. The isotopic method of dietary analysis was used to reconstruct changes in the diet of the human population that occupied the Tehuacan Valley of Mexico over a 7000 yr span. Variations in the δ^(15)C and δ^(15)N values of bone collagen suggest that C_4 and/or CAM plants (presumably mostly corn) and legumes (presumably mostly beans) were introduced into the diet much earlier than suggested by conventional archaeological analysis.

5,548 citations

Book ChapterDOI
01 Jan 1989
TL;DR: Stable isotope ratios provide clues about the origins and transformations of organic matter and have been used as a tool for understanding complex ecological processes as mentioned in this paper, which has prompted increasing use of stable isotope analyses as a method to understand complex biological processes.
Abstract: Stable isotope ratios provide clues about the origins and transformations of organic matter. A few key reactions control the isotopic composition of most organic matter. Isotopic variations introduced by these reactions are often passed on with little change so that isotopic measurements can indicate natural pathways and flows “downstream” from these key reactions. When chemical and metabolic processes scramble the information content of molecules, isotopic compositions are often preserved. This realization has prompted increasing use of stable isotope analyses as a tool for understanding complex ecological processes.

1,936 citations

Journal ArticleDOI
TL;DR: A comprehensive review of stable isotope analysis techniques, and a set of suggestions that transcend individual analytical approaches, are provided to help identify the most useful approaches to apply to a given data set.
Abstract: Stable isotope analysis has emerged as one of the primary means for examining the structure and dynamics of food webs, and numerous analytical approaches are now commonly used in the field. Techniques range from simple, qualitative inferences based on the isotopic niche, to Bayesian mixing models that can be used to characterize food-web structure at multiple hierarchical levels. We provide a comprehensive review of these techniques, and thus a single reference source to help identify the most useful approaches to apply to a given data set. We structure the review around four general questions: (1) what is the trophic position of an organism in a food web?; (2) which resource pools support consumers?; (3) what additional information does relative position of consumers in isotopic space reveal about food-web structure?; and (4) what is the degree of trophic variability at the intrapopulation level? For each general question, we detail different approaches that have been applied, discussing the strengths and weaknesses of each. We conclude with a set of suggestions that transcend individual analytical approaches, and provide guidance for future applications in the field.

1,035 citations

Journal ArticleDOI
01 Oct 1987-Nature
TL;DR: In this article, the carbon isotope compositions of the polysaccharide and lignin components of a variety of vascular plants, including the salt-marsh grass Spartina alterniflora, were investigated.
Abstract: Stable carbon isotope compositions of organic matter are now widely used to trace carbon flow in ecosystems, and have been instrumental in shaping current perceptions of the importance of terrestrial vegetation to estuarine and coastal marine environments. A general assumption in these and other studies relying on carbon isotope compositions for source identification of organic matter has been that the major biochemical components of plant tissues are isotopically invariant. We report here large differences between the carbon isotope compositions of the polysaccharide and lignin components of a variety of vascular plants, including the salt-marsh grass Spartina alterniflora, and demonstrate that the carbon isotope composition of Spartina detritus gradually changes during biogeochemical processing as polysaccharides are preferentially removed, leaving a material that is relatively enriched in lignin-derived carbon and depleted in 13C.

985 citations

Journal ArticleDOI
15 Mar 1985-Science
TL;DR: The use of a combination of the stable isotopes of sulfur, carbon, and nitrogen allows the flow of organic matter and trophic relations in salt marshes and estuaries to be traced while eliminating many ambiguities that accompany the use of single isotopic tracer.
Abstract: The use of a combination of the stable isotopes of sulfur, carbon, and nitrogen allows the flow of organic matter and trophic relations in salt marshes and estuaries to be traced while eliminating many ambiguities that accompany the use of a single isotopic tracer. Salt-marsh grasses take up the isotopically light sulfides formed during sulfate reduction, and the transfer of this light sulfur through the marsh food web is illustrated with data on the ribbed mussel (Geukensia demissa) from various locations in a New England marsh. The multiple isotope approach shows that this filter feeder consumes both marsh grass ( Spartina) detritus and plankton, with the relative proportions of each determined by the location of the mussels in the marsh.

633 citations