Biogeochemistry Commons^™

Assessment Of Soil Protein And Refractory Soil Organic Matter Across Two Chronosequences Of Newly Developing Marshes In Coastal Louisiana, Usa, Stuart Alexander Mcclellan

LSU Doctoral Dissertations

The impacts of sea-level rise and hydrologic manipulation are threatening the stability of coastal marshes throughout the world, thereby increasing the potential for re-mineralization of soil organic matter (SOM) in these systems. Such threats have prompted marsh restoration efforts, particularly in coastal Louisiana, yet it is unclear how the slowly decomposing (refractory) and quickly decomposing (labile) fractions of SOM may be differentially affected by different approaches to marsh restoration. Additionally, otherwise labile compounds may accumulate in the soil via a range of protective mechanisms, including rapid burial and association with organic compounds that are thought to enhance soil aggregation, such …

Microbial Degradability Of Terrigenous, Marsh-Exported, And Estuarine Colored Dissolved Organic Matter In Long Island Sound, John R. Supino

Dissertations and Theses

The Long Island Sound is one of the world's most urbanized estuaries, polluted from excess nutrients which impact the quality of water through increased biological productivity. Dissolved organic matter (DOM) is a sensitive indicator of anthropogenic pollution and nutrient enrichment in coastal waters as well as an important part of the carbon cycle and serves as a primary food source for aquatic food webs. Additionally, the colored portion of DOM (CDOM) impacts coastal optical properties, ocean color, and light attenuation. High levels of CDOM have been shown to inhibit the growth of phytoplankton and limit photosynthesis, damaging the food chain …

Reconstructing Energy Flow Through Modern And Historical Marine Communities: Insights From Amino Acid Isotope Analysis, Emma A. Elliott Smith

Biology ETDs

The fundamental currency of life is energy. Organisms need energy to grow, to survive and to reproduce. Understanding the acquisition of energy by consumers is thus a foundational aspect of biological research. This is especially important in the modern era, as impacts of ongoing anthropogenic effects will be mediated or amplified through food webs. Here, I explore how isotopic analysis of individual amino acids – a technique new to ecological studies – can be used to trace energy flow through animal communities in modern and ancient time periods. In particular, I focus on kelp forest food webs, which are nearshore …

Closing The Oxygen Mass Balance In Shallow Coastal Ecosystems, Matthew H. Long, Jennie E. Rheuban, Daniel C. Mccorkle, David J. Burdige, Richard C. Zimmerman

OES Faculty Publications

The oxygen concentration in marine ecosystems is influenced by production and consumption in the water column and fluxes across both the atmosphere-water and benthic-water boundaries. Each of these fluxes has the potential to be significant in shallow ecosystems due to high fluxes and low water volumes. This study evaluated the contributions of these three fluxes to the oxygen budget in two contrasting ecosystems, a Zostera marina (eelgrass) meadow in Virginia, U.S.A., and a coral reef in Bermuda. Benthic oxygen fluxes were evaluated by eddy covariance. Water column oxygen production and consumption were measured using an automated water incubation system. Atmosphere-water …

Hypoxia In Mangroves: Occurrence And Impact On Valuable Tropical Fish Habitat, Alexia Dubuc, Ronald Baker, Cyril Marchand, Nathan Waltham, Marcus Sheaves

School of Marine and Environmental Sciences Faculty and Staff Publications and Presentations

Intertidal mangrove forests are harsh environments that can naturally experience hypoxia in association with low tide. However, we know relatively little about dissolved oxygen (DO) fluctuations and DO-induced responses by fish, although DO is a fundamental water quality parameter. This study examines DO as a potential factor regulating the utilization of intertidal mangrove forests by fish and consequently their widely recognized feeding, refuge and nursery values. We deployed underwater video cameras, coupled with DO and depth loggers, in a mangrove forest to record changes in fish assemblages in response to tidal variations in DO and other associated environmental parameters. Our …

Biogeochemical Response To Vegetation And Hydrologic Change In An Alaskan Boreal Fen Ecosystem, Danielle L. Rupp

Dissertations, Master's Theses and Master's Reports

Boreal peatlands store approximately one third of the earth’s terrestrial carbon, locked away in currently waterlogged and frozen conditions. Peatlands of boreal and arctic ecosystems are affected increasingly by shifting hydrology caused by climate change. The consequences of these relatively rapid ecosystem changes on carbon cycling between the landscape and the atmosphere could provide an amplifying feedback to climate warming. Alternatively, the advancement of terrestrial vegetation into once waterlogged soils could uptake carbon as a sink. Previous work suggests that fens will become an increasingly dominant landscape feature in the boreal. However, studies investigating fens, their response to hydrologic and …

Colloidal And Truly Dissolved Metal(Loid)S In Wastewater Lagoons And Their Removal With Floating Treatment Wetlands, Lauren Sullivan

Graduate Student Theses, Dissertations, & Professional Papers

Climate change is predicted to cause continuing declines in late-season streamflow, thus increasing the relative contribution of wastewater effluent to surface water flows. Wastewater effluent represents a critical point source of metal and metalloid contamination to aquatic ecosystems and wastewater lagoons are the most common wastewater treatment system in the rural United States. Although the fraction of total wastewater metals and metalloids in "dissolved" forms (defined here asnm) likely drives the potential for negative effects on receiving waters, this broad operational definition lumps truly dissolved solutes (nm) with small colloids and nanomaterials (1-450 nm; hereafter colloids). This size distinction may …

Investigation Of Biogeochemical Mechanisms Of Greenhouse Gas Production In The Urban Hudson River Estuary, Brian Alan Brigham

Dissertations, Theses, and Capstone Projects

Coastal megacities deposit significant amounts of carbon (C), nitrogen (N) and other pollutants into surrounding waters. These inputs, including wastewater and surface water runoff, may affect estuarine and adjacent wetland biogeochemical cycles, microbial production and ultimately greenhouse gas (GHG) efflux. In many megacities pollutant loading is typically greatest after periods of precipitation when the volume of wastewater and storm water runoff exceeds local sanitation capacity, resulting in the discharge of raw sewage into adjacent waters. These combined sewage overflow (CSO) events have received considerable attention primarily due to their potential impact on human health and eutrophication. However, whether these events …

Radical Social Ecology As Deep Pragmatism: A Call To The Abolition Of Systemic Dissonance And The Minimization Of Entropic Chaos, Arielle Brender

Student Theses 2015-Present

This paper aims to shed light on the dissonance caused by the superimposition of Dominant Human Systems on Natural Systems. I highlight the synthetic nature of Dominant Human Systems as egoic and linguistic phenomenon manufactured by a mere portion of the human population, which renders them inherently oppressive unto peoples and landscapes whose wisdom were barred from the design process. In pursuing a radical pragmatic approach to mending the simultaneous oppression and destruction of the human being and the earth, I highlight the necessity of minimizing entropic chaos caused by excess energy expenditure, an essential feature of systems that aim …

Phosphorus Limitation Of Aboveground Production In Northern Hardwood Forests, Shinjini Goswami, Melany C. Fisk, Matthew A. Vadeboncoeur, Mariann Garrison-Johnston, Ruth D. Yanai, Timothy J. Fahey

All Materials

Forest productivity on glacially derived soils with weatherable phosphorus (P) is expected to be limited by nitrogen (N), according to theories of long-term ecosystem development. However, recent studies and model simulations based on resource optimization theory indicate that productivity can be co-limited by N and P. We conducted a full factorial N × P fertilization experiment in 13 northern hardwood forest stands of three age classes in central New Hampshire, USA, to test the hypothesis that forest productivity is co-limited by N and P. We also asked whether the response of productivity to N and P addition differs among species …

Carbon Fluxes And Interannual Drivers In A Temperate Forest Ecosystem Assessed Through Comparison Of Top-Down And Bottom-Up Approaches, Andrew P. Ouimette, Scott V. Ollinger, Andrew D. Richardson, David Y. Hollinger, Trevor F. Keenan, Lucie C. Lepine, Matthew A. Vadeboncoeur

All Materials

Despite decades of research, gaining a comprehensive understanding of carbon (C) cycling in forests remains a considerable challenge. Uncertainties stem from persistent methodological limitations and the difficulty of resolving top-down estimates of ecosystem C exchange with bottom-up measurements of individual pools and fluxes. To address this, we derived estimates and associated uncertainties of ecosystem C fluxes for a 100-125 year old mixed temperate forest stand at the Bartlett Experimental Forest, New Hampshire, USA, using three different approaches: (1) tower-based eddy covariance, (2) a biometric approach involving C flux measurements of individual ecosystem subcomponents, and (3) an inventory approach involving changes …

Biologically Available Phosphorus In Biocrust-Dominated Soils Of The Chihuahuan Desert, Grace Margaret Crain

Open Access Theses & Dissertations

In desert soils, phosphorus (P) is an important limiting nutrient and its cycling characteristics are less understood compared to nitrogen and carbon. Phosphorus cycling is controlled by both geochemical and biological factors. Traditionally, P availability has been characterized via sequential extraction analyses such as Hedley fractionation, but newly developed extraction methods allow for the examination of more biologically relevant P fractions, providing insight on mechanisms of P acquisition by plants and microbes. We examined these P cycling features in the context of biological soil crusts (biocrusts), which have been found to be important drivers of nutrient cycling and have the …

Effects Of Increasing Deciduous Shrub Litter On Ecosystem Functioning In Alpine Tundra, Alejandro Emmanuel Benhumea

Open Access Theses & Dissertations

Rising temperatures due to global warming have resulted in rapid environmental changes in northern environments, resulting in an increase in deciduous shrub growth which has the potential to alter soil ecosystem properties and processes. In order to address some potential mechanisms by which shrubs alter ecosystem properties and processes, we designed an experiment which separated the effects of physical shrub presence and the effects of litter quantity in a fully factorial experiment on a north facing alpine plateau in the southwest Yukon, Canada. Specifically, we asked the following questions: What are effects of shrub litter, independent of shrub presence, on …

Nitrogen And Carbon Isotopic Dynamics Of Subarctic Soils And Plants In Southern Yukon Territory And Its Implications For Paleoecological And Paleodietary Studies, Farnoush Tahmesabi, Fred J. Longstaffe, Grant Zazula, Bruce Bennett

Earth Sciences Publications

We examine here the carbon and nitrogen isotopic compositions of bulk soils (8 topsoil and 7 subsoils, including two soil profiles) and five different plant parts of 79 C₃ plants from two main functional groups: herbs and shrubs/subshrubs, from 18 different locations in grasslands of southern Yukon Territory, Canada (eastern shoreline of Kluane Lake and Whitehorse area). The Kluane Lake region in particular has been identified previously as an analogue for Late Pleistocene eastern Beringia. All topsoils have higher average total nitrogen δ¹⁵N and organic carbon δ¹³C than plants from the same sites with a …

The Effects Of Urbanization On Nitrogen Processing In Urban Streams, Peter Francissen, Dr. Kevin Geedey, Dr. Michael Reisner

Celebration of Learning

Urban stream syndrome is described as the deterioration of stream health in an urbanized watershed and is associated with the loss of ecosystem services, which in turn degrades downstream environments. One key symptom of the urban stream syndrome is reduced processing of inorganic nitrogen. Previous research suggests that as urbanization increases and water quality decreases, the uptake length (Sw) of inorganic N increases. This indicates that the stream is increasing the export of N downstream compared to in situ incorporation of N into the ecosystem. We measured uptake length (Sw) of NO3, using a pulse addition method, along 9 different …

Silica Uptake And Release In Live And Decaying Biomass In A Northern Hardwood Forest, Wim Clymans, Daniel J. Conley, John J. Battles, Patrick J. Frings, Mary Margaret Koppers, Gene E. Likens, Chris E. Johnson

Civil and Environmental Engineering - All Scholarship

In terrestrial ecosystems, a large portion (20–80%) of the dissolved Si (DSi) in soil solution has passed through vegetation. While the importance of this “terrestrial Si filter” is generally accepted, few data exist on the pools and fluxes of Si in forest vegetation and the rate of release of Si from decomposing plant tissues. We quantified the pools and fluxes of Si through vegetation and coarse woody debris (CWD) in a northern hardwood forest ecosystem (Watershed 6, W6) at the Hubbard Brook Experimental Forest (HBEF) in New Hampshire, USA. Previous work suggested that the decomposition of CWD may have significantly …

Dietary Effects On The Stoichiometry Of Growth, Regulation, And Wastes Of Ozark Stream Insect Detritivores, Halvor Matthew Halvorson

Graduate Theses and Dissertations

A widespread stressor, anthropogenic nitrogen (N) and phosphorus (P) pollution can increase resource nutrient content and alter animal community composition in freshwater ecosystems. In this dissertation, I used ecological stoichiometry theory to examine effects of diet nutrient content and leaf litter type on growth, regulation, and wastes of aquatic invertebrate detritivores. I tested effects of leaf litter diet carbon:phosphorus (C:P) on growth and stoichiometric regulation of the detritivorous caddisfly Pycnopsyche lepida and used results to determine a threshold elemental ratio of oak litter C:P=1620 that confers peak growth of this species. This empirical, growth-based approach provided a more accurate estimate …

Marine Ecoregion And Deepwater Horizon Oil Spill Affect Recruitment And Population Structure Of A Salt Marsh Snail, Steven C. Pennings, Scott Zengel, Jacob Oehrig, Merryl Alber, T. Dale Bishop, Donald R. Deis, Donna Devlin, A. Randall Hughes, John J. Hutchens, Jr., Whitney M. Kiehn, Caroline R. Mcfarlin, Clay L. Montague, Sean P. Powers, C. Edward Proffitt, Nicholle Rutherford, Camille L. Stagg, Keith Walters

University Faculty and Staff Publications

Marine species with planktonic larvae often have high spatial and temporal variation in recruitment that leads to subsequent variation in the ecology of benthic adults. Using a combination of published and unpublished data, we compared the population structure of the salt marsh snail, Littoraria irrorata, between the South Atlantic Bight and the Gulf Coast of the United States to infer geographic differences in recruitment and to test the hypothesis that the Deepwater Horizon oil spill led to widespread recruitment failure of L. irrorata in Louisiana in 2010. Size-frequency distributions in both ecoregions were bimodal, with troughs in the distributions consistent …

Juvenile Survival And Adult Return As A Function Of Freshwater Rearing Life History For Coho Salmon In The Klamath River Basin, Molly Gorman

Cal Poly Humboldt theses and projects

The Scott and Shasta rivers, Klamath River tributaries, experience spatial disparity in habitat quality in spring and summer as a result of historical and current land-use. Juvenile Coho Salmon (Oncorhynchus kisutch) born in the upper tributary reaches often rear in natal streams before migrating to sea. However, those born in the lower reaches often encounter unsuitable habitat and emigrate during their first spring to seek non-natal rearing habitats. It is assumed that these early outmigrants are population losses. This study evaluated first-summer survival, and contribution to the adult population, of non-natal rearing juveniles in the Klamath River Basin. …

Effects Of Epichloë Coenophiala−Tall Fescue Symbiosis On Plant-Microbe-Soil Interactions In A Temperate Pasture, Lindsey C. Slaughter

Theses and Dissertations--Plant and Soil Sciences

Plants interact in myriad ways with microorganisms to influence ecosystem processes such as nutrient cycling, which can regulate ecosystem response to global change. One important plant-microbe symbiosis occurs between cool-season grasses and asexual fungal Epichloë endophytes, such as tall fescue (Schedonorus arundinaceus) and Epichloë coenophiala. Because the common toxic strain of the endophyte (CTE) harms grazing livestock, non-livestock toxic endophyte (NTE) strains have been developed and are increasingly deployed in pastures. Little is known about how these symbioses impact other plant-microbe interactions and microbe-mediated soil processes in grassland ecosystems. I conducted three studies to determine how E. …

Synthesis Of Satellite Microwave Observations For Monitoring Global Land-Atmosphere Co2 Exchange, Lucas Alan Jones

Graduate Student Theses, Dissertations, & Professional Papers

This dissertation describes the estimation, error quantification, and incorporation of land surface information from microwave satellite remote sensing for modeling global ecosystem land-atmosphere net CO₂ exchange. Retrieval algorithms were developed for estimating soil moisture, surface water, surface temperature, and vegetation phenology from microwave imagery timeseries. Soil moisture retrievals were merged with model-based soil moisture estimates and incorporated into a light-use efficiency model for vegetation productivity coupled to a soil decomposition model. Results, including state and uncertainty estimates, were evaluated with a global eddy covariance flux tower network and other independent global model- and remote-sensing based products.

Convergence Of Microbial Assimilations Of Soil Carbon, Nitrogen, Phosphorus And Sulfur In Terrestrial Ecosystems, Xiaofeng Xu, Dafeng Hui, Anthony W. King, Xia Song, Peter E. Thornton, Lihua Zhang

Biology Faculty Research

How soil microbes assimilate carbon-C, nitrogen-N, phosphorus-P and sulfur-S is fundamental for understanding nutrient cycling in terrestrial ecosystems. We compiled a global database of C, N, P and S concentrations in soils and microbes and developed relationships between them by using a power function model. The C:N:P:S was estimated to be 287:17:1:0.8 for soils and 42:6:1:0.4 for microbes. We found a convergence of the relationships between elements in soils and in soil microbial biomass across C, N, P and S. The element concentrations in soil microbial biomass follow a homeostatic regulation curve with soil element concentrations across C, N, P …

The Functional And Distributional Ecology Of Mycetozoans Under Changing Edaphic And Climatic Dynamics, Geoffrey Lloyd Zahn

Graduate Theses and Dissertations

Investigations into the distribution and ecosystem functions of fruiting amoebae revealed that local-scale environmental conditions can largely explain broad biogeographical patterns in species assemblage, the way in which amoeboid predators shape bacterial communities and how this top-down influence may affect global biogeochemical processes in a changing climate. The distribution and assemblage of protosteloid amoebae on the islands of New Zealand and Hawaii did not yield any expected patterns of island biogeography, and conformed to other global regions studied. The strongest predictor of species richness in a given region was sampling effort and these species do not appear to have any …

Estimates Of Micro-, Nano-, And Picoplankton Contributions To Particle Export In The Northeast Pacific, B. L. Mackinson, S. B. Moran, M. W. Lomas, Gillian M. Stewart, R. P. Kelly

Publications and Research

The contributions of micro-, nano-, and picoplankton to particle export were estimated from measurements of size-fractionated particulate 234Th, organic carbon, and phytoplankton indicator pigments obtained during five cruises between 2010 and 2012 along Line P in the subarctic northeast Pacific Ocean. Sinking fluxes of particulate organic carbon (POC) and indicator pigments were calculated from 234Th;238U disequilibria and, during two cruises, measured by a sediment trap at Ocean Station Papa. POC fluxes at 100m ranged from 0.65 to 7.95 mmolm2 d1, similar in magnitude to previous results at Line P. Microplankton pigments dominate indicator pigment fluxes (averaging 6919% of total pigment …

Heterotrophic And Autotrophic Contribution To Dinitrogen Fixation In The Gulf Of Aqaba, Eyal Rahav, Barak Herut, Margaret R. Mulholland, Natalia Belkin, Hila Elifantz, Ilana Berman-Frank

OES Faculty Publications

We evaluated the seasonal contribution of heterotrophic and autotrophic diazotrophy to the total dinitrogen (N₂) fixation in the photic zone of a pelagic station in the northern Gulf of Aqaba, Red Sea. N₂ fixation rates were highest during a Trichodesmium bloom in winter (0.7 nmol N l^-1 d^-1), decreased 7-fold 1 wk later throughout the upper 200 m (~0.1 nmol N l^-1) d^-1), and were significantly coupled with both primary and bacterial productivity. N₂ fixation rates were generally higher in the upper 200 m (~0.4 nmol N l^{-1 …}

Chesapeake Bay Nitrogen Fluxes Derived From A Land-Estuarine Ocean Biogeochemical Modeling System: Model Description, Evaluation, And Nitrogen Bonds, Yang Feng, Marjorie A.M. Friedrichs, John Wilkin, Hanqin Tian, Qichun Yang, Eileen E. Hofmann

CCPO Publications

The Chesapeake Bay plays an important role in transforming riverine nutrients before they are exported to the adjacent continental shelf. Although the mean nitrogen budget of the Chesapeake Bay has been previously estimated from observations, uncertainties associated with interannually varying hydrological conditions remain. In this study, a land-estuarine-ocean biogeochemical modeling system is developed to quantify Chesapeake riverine nitrogen inputs, within-estuary nitrogen transformation processes and the ultimate export of nitrogen to the coastal ocean. Model skill was evaluated using extensive in situ and satellite-derived data, and a simulation using environmental conditions for 2001-2005 was conducted to quantify the Chesapeake Bay nitrogen …

Biogeochemical Cycling In Lake Superior Tributaries: Seasonality, Quantity And Quality Of Export, Ashley Anne Coble

Dissertations, Master's Theses and Master's Reports - Open

Seasonal and spatial variability in environmental factors may affect dissolved organic matter composition and nutrient transformation and retention in streams. The objective of this research was to quantify and describe seasonality, quantity, and quality of nutrient processing and export of ammonium (NH₄), soluble reactive phosphate (SRP), and dissolved organic carbon (DOC) into Lake Superior through intensive study in a small 1st order watershed coupled with snapshot measurements across 12 tributaries that varied in size, location, and wetland coverage. Our results suggest biodegradable C is exported from a small headwater stream year-round and that DOC mineralization rates can be …

Climate Anomalies And Primary Production In Lake Superior, Marcel L. Dijkstra

Dissertations, Master's Theses and Master's Reports - Open

This dissertation supports the modeling of primary production in Lake Superior by offering site specific kinetics and algorithms developed from lab experiments performed on the natural phytoplankton assemblage of Lake Superior. Functions, developed for temperature, light and nutrient conditions and the maximum specific rate of primary production, were incorporated in a 1D specific primary production model and confirmed to published in-situ measured rates of primary production.

An extensive data set (supporting model calibration and confirmation), with a fine spatiotemporal resolution, was developed from field measurements taken bi-weekly during the sampling seasons of 2011, 2012 and 2014; considered to be meteorologically …

Mass And Nutrient Loss In Decaying Hardwood Boles At Hubbard Brook, Chris E. Johnson

Civil and Environmental Engineering - All Scholarship

No abstract provided.

A Comprehensive Evaluation Of C25 Highly Branched Isoprenoid Alkenes Of Marine Diatoms As Proxies For Sea Ice Extent In The Arctic Ocean, Tetiana Muniak

OES Theses and Dissertations

Sea Ice extent is one of the major factors regulating carbon cycling and ecosystem function in the modern Arctic Ocean. It is an essential component of climate models and is crucial for the evaluation of various oceanographic processes that influence a particular region. Yet it is also one of the most difficult attributes of the ocean with respect to our ability for its accurate reconstruction from paleo records. The lack of the detailed records prior to satellite information has encouraged the development of new proxy records for the reconstruction of past

sea ice conditions. In recent years, a new monounsaturated …