The Impact of Nutrient Loading on Nitrogen Removal and Carbon Dynamics in a Juncus Roemerianus and Spartina Alterniflora Dominated Salt Marsh in the Northern Gulf of Mexico PDF Download
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Author: Taylor Ledford
Publisher:
ISBN:
Category : Electronic dissertations
Languages : en
Pages : 49
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Book Description
Increased anthropogenic nutrient loading of nitrogen (N) and phosphorus (P) to estuaries and bays can lead to eutrophication, anoxia or hypoxia, and/or loss of native or other important species. Coastal salt marshes help to counteract eutrophication by removing excess N through microbially-mediated denitrification. One important factor that regulates salt marsh N removal is vegetation type, which affects sediment N-removal capacity by modifying redox potential and altering the microbial community structure within sediments. Additionally, plant community structure can alter carbon (C) uptake via photosynthesis and C release via sediment oxidation and organic matter degradation. A 1-year field study was conducted in a salt marsh located on Dauphin Island, AL, where we increased N and P inputs by 20 g N m-2 yr-1/ 1.25 g P m-2 yr-1 (low fertilization) and 40 g N m-2 yr-1/2.5 g P m-2 yr-1 (high fertilization) in plots dominated by either Juncus roemerianus (black needlerush) or Spartina alterniflora (smooth cordgrass). Denitrification was 5X higher in unamended J. roemerianus plots versus S. alterniflora, but denitrification in S. alterniflora was more responsive to fertilization, increasing ten-fold while denitrification in J. roemerianus plots did not respond to fertilization. Gross primary productivity (GPP) was marginally higher (~5%) in control plots of J. roemerianus than in control S. alterniflora plots. High fertilization increased GPP by 27% in S. alterniflora plots, however, GPP did not respond to fertilization in J. roemerianus plots. Additionally, ERCO2 was similar across vegetation types in control plots, and did not respond to fertilization in either vegetation type. Net ecosystem exchange was similar in J. roemerianus and S. alterniflora control plots and did not change in response to N and P additions for either vegetation type. Our results illustrate that while both J. roemerianus and S. alterniflora marshes have the capacity to withstand nutrient loading in the Gulf of Mexico via N removal, S. alterniflora dominated marshes may have a greater capacity to mitigate N inputs. Additionally, in a world with higher nutrient inputs and despite higher GPP in S. alterniflora, both vegetation types will continue to sequester C at similar rates.
Author: Taylor Ledford
Publisher:
ISBN:
Category : Electronic dissertations
Languages : en
Pages : 49
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Book Description
Increased anthropogenic nutrient loading of nitrogen (N) and phosphorus (P) to estuaries and bays can lead to eutrophication, anoxia or hypoxia, and/or loss of native or other important species. Coastal salt marshes help to counteract eutrophication by removing excess N through microbially-mediated denitrification. One important factor that regulates salt marsh N removal is vegetation type, which affects sediment N-removal capacity by modifying redox potential and altering the microbial community structure within sediments. Additionally, plant community structure can alter carbon (C) uptake via photosynthesis and C release via sediment oxidation and organic matter degradation. A 1-year field study was conducted in a salt marsh located on Dauphin Island, AL, where we increased N and P inputs by 20 g N m-2 yr-1/ 1.25 g P m-2 yr-1 (low fertilization) and 40 g N m-2 yr-1/2.5 g P m-2 yr-1 (high fertilization) in plots dominated by either Juncus roemerianus (black needlerush) or Spartina alterniflora (smooth cordgrass). Denitrification was 5X higher in unamended J. roemerianus plots versus S. alterniflora, but denitrification in S. alterniflora was more responsive to fertilization, increasing ten-fold while denitrification in J. roemerianus plots did not respond to fertilization. Gross primary productivity (GPP) was marginally higher (~5%) in control plots of J. roemerianus than in control S. alterniflora plots. High fertilization increased GPP by 27% in S. alterniflora plots, however, GPP did not respond to fertilization in J. roemerianus plots. Additionally, ERCO2 was similar across vegetation types in control plots, and did not respond to fertilization in either vegetation type. Net ecosystem exchange was similar in J. roemerianus and S. alterniflora control plots and did not change in response to N and P additions for either vegetation type. Our results illustrate that while both J. roemerianus and S. alterniflora marshes have the capacity to withstand nutrient loading in the Gulf of Mexico via N removal, S. alterniflora dominated marshes may have a greater capacity to mitigate N inputs. Additionally, in a world with higher nutrient inputs and despite higher GPP in S. alterniflora, both vegetation types will continue to sequester C at similar rates.
Author: Thomas Bianchi
Publisher: Cambridge University Press
ISBN: 1107022576
Category : Science
Languages : en
Pages : 673
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Book Description
A comprehensive, state-of-the-art synthesis of biogeochemical dynamics and the impact of human alterations at major river-coastal interfaces for advanced students and researchers.
Author: M.P. Weinstein
Publisher: Springer Science & Business Media
ISBN: 0792360192
Category : Nature
Languages : en
Pages : 862
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Book Description
Tidal salt marshes are viewed as critical habitats for the production of fish and shellfish. As a result, considerable legislation has been promulgated to conserve and protect these habitats, and much of it is in effect today. The relatively young science of ecological engineering has also emerged, and there are now attempts to reverse centuries-old losses by encouraging sound wetland restoration practices. Today, tens of thousands of hectares of degraded or isolated coastal wetlands are being restored worldwide. Whether restored wetlands reach functional equivalency to `natural' systems is a subject of heated debate. Equally debatable is the paradigm that depicts tidal salt marshes as the `great engine' that drives much of the secondary production in coastal waters. This view was questioned in the early 1980s by investigators who noted that total carbon export, on the order of 100 to 200 g m-2 y-1 was of much lower magnitude than originally thought. These authors also recognized that some marshes were either net importers of carbon, or showed no net exchange. Thus, the notion of `outwelling' has become but a single element in an evolving view of marsh function and the link between primary and secondary production. The `revisionist' movement was launched in 1979 when stable isotopic ratios of macrophytes and animal tissues were found to be `mismatched'. Some eighteen years later, the view of marsh function is still undergoing additional modification, and we are slowly unraveling the complexities of biogeochemical cycles, nutrient exchange, and the links between primary producers and the marsh/estuary fauna. Yet, since Teal's seminal paper nearly forty years ago, we are not much closer to understanding how marshes work. If anything, we have learned that the story is far more complicated than originally thought. Despite more than four decades of intense research, we do not yet know how salt marshes function as essential habitat, nor do we know the relative contributions to secondary production, both in situ or in the open waters of the estuary. The theme of this Symposium was to review the status of salt marsh research and revisit the existing paradigm(s) for salt marsh function. Challenge questions were designed to meet the controversy head on: Do marshes support the production of marine transient species? If so, how? Are any of these species marsh obligates? How much of the production takes place in situ versus in open waters of the estuary/coastal zone? Sessions were devoted to reviews of landmark studies, or current findings that advance our knowledge of salt marsh function. A day was also devoted to ecological engineering and wetland restoration papers addressing state-of-the-art methodology and specific case histories. Several challenge papers arguing for and against our ability to restore functional salt marshes led off each session. This volume is intended to serve as a synthesis of our current understanding of the ecological role of salt marshes, and will, it is hoped, pave the way for a new generation of research.
Author: R. Knapp
Publisher: Springer Science & Business Media
ISBN: 9401023441
Category : Science
Languages : en
Pages : 333
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Book Description
During the International Botanical Congress in Edinburgh, 1964, Mrs. 1. M. WEISBACH-J UNK of The Hague discussed a plan for preparation by her publishing company (Dr. W. Junk b.v.) of an international Handbook of Vegetation Science. She proposed a series that should give a comprehensive survey of the varied directions within this science, and their achievements to date as well as their objectives for the future. The challenge of such an enterprise, and its evident value for the further development of vegetation research, induced the undersigned after some consideration to accept the offer of the honorable but also burdensome task of General Editor. The decision was encouraged by a well formulated and detailed outline for the Handbook worked out by the Dutch phytosociolo gists J. J. BARKMAN and V. WESTHOFF. A circle of scholars from numerous countries was invited by the Dr. Junk Publishing Com pany to The Hague in January 1966 to draw up a list of editors and contributors for the parts of the Handbook. The outline and list have served since for the organization of the Handbook, with no need for major change. The different burdens of editors and authors have compelled quite different timings for completion of the individual sections.
Author: Thomas S. Bianchi
Publisher: John Wiley & Sons
ISBN: 9780471161745
Category : Science
Languages : en
Pages : 454
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Book Description
The definitive ecological guide to the Gulf of MexicoEstuaries Today the ecological health of the Gulf of Mexico--long the base ofvast commercial fisheries--is at risk from a potent array ofthreats, from increased nutrient inputs to the loss of coastalwetlands that impact water quality. Never before has knowledge of the biogeochemical processes of theGulf's estuaries and wetlands been so critical to its preservation,and yet until now research on this vital area has beenfragmented. Biogeochemistry of Gulf of Mexico Estuaries offers a comprehensive,integrated examination of these vital natural resources and theirecology. Featuring contributions from a diverse group of expertscientists from all regions of the Gulf Coast, thisinterdisciplinary reference provides extensive coverage of what isknown about biogeochemical processes--and the factors that regulatethem--in warm temperate and subtropical systems. Organized around aframework that integrates geomorphology, sedimentary processes,nutrient cycling, and trace metals chemistry, it not onlydemonstrates how the Gulf's estuarine systems work, but alsoestablishes a basis for how they compare with other, better-studiedtemperate estuaries. In addition, the book features afascinating--and timely--examination of the effects ofbiogeochemical processes on estuarine management. Biogeochemistry of Gulf of Mexico Estuaries will be welcomed byecologists, marine scientists, environmental activists, and anyoneinvolved with managing these precious natural resources.
Author: L. R. Pomeroy
Publisher: Springer Science & Business Media
ISBN: 1461258936
Category : Science
Languages : en
Pages : 277
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Book Description
Ecologists have two long-standing ways to study large ecosystems such as lakes, forests, and salt-marsh estuaries. In the first, which G. E. Hutchinson has called the holological approach, the whole ecosystem is first studied as a "black box," and its components are investigated as needed. In the second, which Hutchinson has called the merological approach, the parts of the system are studied first, and an attempt is then made to build up the whole from them. For long-term studies, the holological approach has special advantages, since the general patterns and tentative hypotheses that are first worked out help direct attention to the components of the system which need to be studied in greater detail. In this approach, teams of investigators focus on major func tions and hypotheses and thereby coordinate their independent study efforts. Thus, although there have been waves, as it were, of investigators and graduate students working on different aspects of the Georgia salt-marsh estuaries (personnel at the Marine Institute on Sapelo Island changes every few years), the emphasis on the holo logical approach has resulted in a highly differentiated and well-coordinated long-term study. Very briefly, the history of the salt-marsh studies can be outlined as follows. First, the general patterns of food chains and other energy flows in the marshes and creeks were worked out, and the nature of imports and exports to and from the system and its subsystems were delimited.
Author: National Research Council
Publisher: National Academies Press
ISBN: 0309288487
Category : Nature
Languages : en
Pages : 247
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Book Description
As the Gulf of Mexico recovers from the Deepwater Horizon oil spill, natural resource managers face the challenge of understanding the impacts of the spill and setting priorities for restoration work. The full value of losses resulting from the spill cannot be captured, however, without consideration of changes in ecosystem services-the benefits delivered to society through natural processes. An Ecosystem Services Approach to Assessing the Impacts of the Deepwater Horizon Oil Spill in the Gulf of Mexico discusses the benefits and challenges associated with using an ecosystem services approach to damage assessment, describing potential impacts of response technologies, exploring the role of resilience, and offering suggestions for areas of future research. This report illustrates how this approach might be applied to coastal wetlands, fisheries, marine mammals, and the deep sea-each of which provide key ecosystem services in the Gulf-and identifies substantial differences among these case studies. The report also discusses the suite of technologies used in the spill response, including burning, skimming, and chemical dispersants, and their possible long-term impacts on ecosystem services.
Author: juanyong li
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
Although salt marshes cover only a small area of the Earth, their contribution to long term carbon (C) burial is comparable to C sinks in many more dominant terrestrial ecosystem types. Continuous nitrogen (N) loading alters plant growth and subsequently has the potential to impact soil organic carbon (SOC) accumulation in salt marshes. However, there is presently little information concerning the input and allocation of photosynthesized C in plant-soil-microbial systems. This knowledge gap hampers the quantification of C fluxes and the clarification of the mechanisms controlling the C budget under N loading in salt marsh ecosystems. To address this, we conducted an N fertilization field observation combined with a five hour 13C-pulse labeling experiment in a salt marsh dominated by Suaeda. salsa (S. salsa) in the Yellow River Delta, China. N fertilization increased net 13C assimilation of S. Salsa by 177.37%, which was primarily allocated to aboveground biomass and SOC. However, N fertilization had little effect on 13C allocation to belowground biomass. Correlation analysis showed that 13C incorporation in soil was significantly and linearly correlated with 13C incorporation in shoots rather than in roots both in a 0N (0 g N m-2 yr-1) and +N (20 g N m-2 yr-1) group. The results suggest that SOC increase under N fertilization was mainly due to an increased C assimilation rate and more efficient downward transfer of photosynthesized C instead of root lysate and detritus. In addition, N fertilization strongly improved the 13C amounts in the chloroform-labile SOC component by 315%. However, the absolute increment of newly fix 13C mainly existed in the form of residual SOC, which had more tendency for burial in the soil. Thus, N fertilization enhanced SOC accumulation although C loss increased via belowground respiration. These results have important implications for predicting the carbon budget under further human-induced N loading.
Author: U.S. Fish and Wildlife Service
Publisher:
ISBN:
Category : Aquatic ecology
Languages : en
Pages : 110
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Book Description
Author: Paul Adam
Publisher: Cambridge University Press
ISBN: 9780521448239
Category : Nature
Languages : en
Pages : 480
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Book Description
A broad introduction to the ecology of the unique environment of the saltmarsh.
