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Research Interests: Microbiology, Environmental Science, Petroleum, Microbial Ecology, Biology, and 13 moreEcology, Environmental Chemistry, Medicine, Biodegradation, Protein Structure and Function, Nitrogen, Sterilization, Environmental Impact, Diesel Fuel, Biostimulation, Particulate organic carbon, Coastal waters, and Bacterial Production
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CONTENTS Introduction 193 Bio-Optical Modeling 194 Plant Physiology 195 Methods 196 Calibrating a Bio-Optical Model 196 Light-Stress Experiments 197 Results 198 Water Quality Monitoring; North River, North Carolina 198 Light Stress... more
CONTENTS Introduction 193 Bio-Optical Modeling 194 Plant Physiology 195 Methods 196 Calibrating a Bio-Optical Model 196 Light-Stress Experiments 197 Results 198 Water Quality Monitoring; North River, North Carolina 198 Light Stress Experiment 200 Discussion 203 Water Quality Stress Indicators 203 Plant Physiology Indicators 204 Conclusions 205 Acknowledgments 206 References 207
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Research Interests: Marine Biology, Microbiology, Environmental Science, Environmental Chemistry, Medicine, and 15 moreBiodegradation, Phosphorus, Spartina alterniflora, Nitrogen, Poaceae, Nutrient, HYDROCARBONS, Diesel Fuel, Particulate organic carbon, Glass Fiber, Dissolved Organic Carbon, Coastal waters, Seasons, Gasoline, and Oceans and Seas
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Research Interests: Earth Sciences, Environmental Science, Phytoplankton, Biological Sciences, Environmental Sciences, and 14 moreNutrient Enrichment, North Carolina, Bioassay, Nitrogen, Community Structure, Nutrient Limitation, Nutrient, Estuary, NC, Human Activity, Plant Community, Community Composition, Tributary, and Nutrient Concentration
The purpose of this study was to assess the differences in the abundance and activity of the bacterioplankton at sites with varied boating activity, and to determine the response of the communities to additional petroleum pollution. Three... more
The purpose of this study was to assess the differences in the abundance and activity of the bacterioplankton at sites with varied boating activity, and to determine the response of the communities to additional petroleum pollution. Three sites, including two marinas and a site on Bogue Sound in coastal North Carolina, were selected for monthly experiments. Seasonal patterns of bacterioplanktonic abundance and diesel fuel biodegradation for each site were examined, and possible correlations with intensity of boating activities were explored. Bacterioplanktonic communities at the three sites in this study were more similar in their structure and biodegradation potential than would have been expected from previous studies. We found no differences in the abundance and biodegradation potential of theses communities at the three sites, and only a slightly elevated number of hydrocarbon degraders at one of the marinas. Patterns of biodegradation were more closely related to total bacterial abundance, rather than number of petroleum hydrocarbon degraders. There was a strong seasonal pattern in bacterial abundance and biodegradation at all three sites. The bacterioplanktonic Community at all sites responded similarly to additions of diesel fuel. Bacterial abundance and productivity were both elevated to some extent, and number of petroleum hydrocarbon degraders changed relatively little. These data indicate that marinas may not profoundly after the bacterioplankton and that coastal waters often have resident bacterial communities capable of degrading petroleum hydrocarbon pollution.
Research Interests: Environmental Science, Petroleum, Productivity, Marine And Environmental Pollution, International Marine Environmental Law, and 15 moreMedicine, Biological Sciences, Biodegradation, Environmental Sciences, North Carolina, Animals, Plankton, Bacteria, Seawater, CHEMICAL SCIENCES, Bacterioplankton, Diesel Fuel, Ships, Coastal waters, and Seasons
Publisher Summary Researchers have recognized growing imbalance between new nitrogen (N) inputs and N losses in the marine environment through human activities, especially in estuarine and coastal waters where N overenrichment has fueled... more
Publisher Summary Researchers have recognized growing imbalance between new nitrogen (N) inputs and N losses in the marine environment through human activities, especially in estuarine and coastal waters where N overenrichment has fueled accelerated primary production, or eutrophication, which is an increase in the rate of supply of organic matter to an ecosystem. This chapter focuses on this imbalance in organic matter specifically nitrogen and its effects on ecology. From a food web perspective, eutrophication is a condition where nutrient-enhanced primary production exceeds the ability of higher ranked consumers to utilize it. Characterized this condition as “too much of good thing,” or overfertilization of N-limited marine ecosystems with new N, the bulk of it being anthropogenic. Symptoms of N-driven eutrophication include: subtle increases in plant production, changes in primary producer community composition, rapidly accelerating algal growth, visible discoloration or blooms, losses in water clarity, and increased consumption of oxygen leading to ecosystem-scale oxygen depletion (hypoxia, anoxia), which is stressful to resident fauna and flora, and can lead to elimination of habitats. Lastly, excessive N enrichment, relative to other nutrient inputs, can alter nutrient input balances and cycling, including shifts to phosphorus and silicon limitation of primary production in receiving estuarine and coastal waters Anthropogenic or cultural eutrophication has been closely linked to population densities in coastal watersheds A significant, and in many instances increasing, proportion of new N input can also be attributed to remote sources delivered through airsheds and subsurface aquifers outside the immediate watershed.
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Research Interests: Environmental Science, Climate Change, Biomass, Environmental Management, Environmental Monitoring, and 15 moreClimate, Eutrophication, Medicine, Multidisciplinary, Disasters, Nutrient Management, Chlorophyll, Nutrient Enrichment, North Carolina, Nitrogen, Nutrient, Estuary, Nutrient Loading, Interaction effect, and Conservation of Natural Resources
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Research Interests: Earth Sciences, Environmental Science, Oceanography, Limnology, Phytoplankton, and 13 moreBiological Sciences, Seasonality, Environmental Sciences, North Carolina, Surface Water, Biological Oceanography and Limnology, High Performance Liquid Chromatography, Spatial Variability, Spatial Pattern, Estuary, Tropical Storm, Flow Rate, and Residence Time
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This study employed simulated spills of weathered diesel fuel and measured the initial effects on the intertidal sand flat microphytobenthic (MPB) communities. The goals were to examine the impacts of short-term (hours) and longer-term... more
This study employed simulated spills of weathered diesel fuel and measured the initial effects on the intertidal sand flat microphytobenthic (MPB) communities. The goals were to examine the impacts of short-term (hours) and longer-term (days) exposure to petroleum on the native sand flat MPB in coastal North Carolina and to assess recovery of the community following the exposure. We assessed
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Picophytoplankton (PicoP) are increasingly recognized as significant contributors to primary productivity and phytoplankton biomass in coastal and estuarine systems. Remarkably though, PicoP composition is unknown or not well-resolved in... more
Picophytoplankton (PicoP) are increasingly recognized as significant contributors to primary productivity and phytoplankton biomass in coastal and estuarine systems. Remarkably though, PicoP composition is unknown or not well-resolved in several large estuaries including the semi-lagoonal Neuse River Estuary (NRE), a tributary of the second largest estuary-system in the lower USA, the Pamlico-Albemarle Sound. The NRE is impacted by extreme weather events, including recent increases in precipitation and flooding associated with tropical cyclones. Here we examined the impacts of moderate to extreme (Hurricane Florence, September 2018) precipitation events on NRE PicoP abundances and composition using flow cytometry, over a 1.5 year period. Phycocyanin-rich Synechococcus-like cells were the most dominant PicoP, reaching ~ 106 cells mL−1, which highlights their importance as key primary producers in this relatively long residence-time estuary. Ephemeral “blooms” of picoeukaryotic phytop...
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Agricultural, urban and industrial activities have dramatically increased aquatic nitrogen and phosphorus pollution (eutrophication), threatening water quality and biotic integrity from headwater streams to coastal areas world‐wide.... more
Agricultural, urban and industrial activities have dramatically increased aquatic nitrogen and phosphorus pollution (eutrophication), threatening water quality and biotic integrity from headwater streams to coastal areas world‐wide. Eutrophication creates multiple problems, including hypoxic “dead zones” that reduce fish and shellfish production; harmful algal blooms that create taste and odor problems and threaten the safety of drinking water and aquatic food supplies; stimulation of greenhouse gas releases; and degradation of cultural and social values of these waters. Conservative estimates of annual costs of eutrophication have indicated $1 billion losses for European coastal waters and $2.4 billion for lakes and streams in the United States. Scientists have debated whether phosphorus, nitrogen, or both need to be reduced to control eutrophication along the freshwater to marine continuum, but many management agencies worldwide are increasingly opting for dual control. The unidir...
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A comprehensive carbon budget was constructed to quantify carbon flows through the freshwater‐marine continuum of a temperate, microtidal estuary. We performed coordinated measurements of dissolved inorganic carbon and total organic... more
A comprehensive carbon budget was constructed to quantify carbon flows through the freshwater‐marine continuum of a temperate, microtidal estuary. We performed coordinated measurements of dissolved inorganic carbon and total organic carbon fluxes to resolve spatial variability between and along the channel and shoals and diel variability across the entire estuary for 2 yr. Net ecosystem metabolism (NEM) was the most significant control on carbon flow within estuary regions. However, metabolic rates were spatially coupled such that counteracting fluxes across the channel‐shoal gradient or along the river‐ocean gradient resulted in system‐wide NEM that was closely in balance (–3.0 ± 3.3 to 1.1 ± 4.4 molC m−2 yr−1). Similarly, large diel and seasonal variability in air–water CO2 fluxes were observed during 72 spatial surveys, but these short‐term variations generally cancelled out when aggregated to annual budget terms. Although atmospheric exchanges were small (–0.2 ± 0.1 to 2.0 ± 0.4...
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Although much work has been undertaken to determine the toxicity of petroleum pollutants to phytoplankton, most studies have used pure cultures to monitor growth of selected phytoplankton species. Fewer have considered the net effect on... more
Although much work has been undertaken to determine the toxicity of petroleum pollutants to phytoplankton, most studies have used pure cultures to monitor growth of selected phytoplankton species. Fewer have considered the net effect on entire microalgal communities. Using high performance liquid chromatography (HPLC) to characterize diagnostic microalgal pigments, the authors were able to simultaneously assess sub-lethal pollutant effects on entire communities as well as on individual phytoplankton functional groups. Incubations of natural water samples with diesel fuel, an important contributor to coastal petroleum pollution, revealed significant changes in photopigments and relative abundance of taxonomic groups at sub-lethal concentrations. Differential rates of change of indicator pigment concentrations suggest a range of sensitivity among phytoplankton groups. In preliminary experiments, cyanobacteria exhibited the greatest overall tolerance to the diesel fuel concentrations tested, while cryptomonads displayed the most sensitivity. The authors are currently evaluating the responses of seasonal phytoplankton populations from 3 sites exposed to varied levels of petroleum pollution. HPLC will be used to characterize phytoplankton populations and to determine if the most abundant groups are also the most tolerant of diesel fuel. Preliminary experiments indicate that diesel fuel pollution may modify the structure and function of phytoplankton communities and subsequently altermore » the trophodynamics of impacted systems.« less
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Research Interests: Earth Sciences, Environmental Science, Agriculture, Environmental Monitoring, Eutrophication, and 14 moreMedicine, Biological Sciences, Environmental Sciences, North Carolina, Nitrogen deposition, Nitrogen, Rain, Watershed, Environmental quality, Estuary, Water Movements, Environment Quality, Emerging Pollutants In Water, and Air Pollutants
Research Interests: Environmental Science, Western Europe, Eutrophication, North Atlantic Ocean, Atmospheric deposition, and 11 moreNorth Carolina, Nitrogen deposition, Nitrogen, Industrial Revolution, North America, Algal Bloom, Coastal waters, Acid Deposition, Coastal Plain, Chemical Composition, and Developing Regions
Research Interests: Environmental Engineering, Environmental Science, Chemistry, Environmental Chemistry, Seasonality, and 15 moreAtmospheric sciences, Aerosol, North Carolina, Nitrate, Nitrogen, Sulfate, Ammonia, Ammonium, Particulate Matter, NITRIC ACID, Coastal Plain, Sulfur Dioxide, Nitrous acid, Atmospheric Environment, and ammonia emission
Research Interests: Earth Sciences, Environmental Science, Environmental Chemistry, Biological Sciences, Atmospheric deposition, and 15 moreEnvironmental Sciences, Food web, Estuaries, Fossil Fuels, Community Structure, Iron, Agricultural Production, Continental shelf, Gulf of Mexico, Algal Bloom, Estuary, Harmful Algal bloom, Coastal waters, Acid Deposition, and Current Account
Research Interests: Environmental Science, Oceanography, Environmental Monitoring, Nitrogen Cycle, Eutrophication, and 15 moreMedicine, Multidisciplinary, Seasonality, Atmospheric deposition, Estuaries, North Carolina, Nitrogen, Rain, Estuary, Harmful Algal bloom, Hypoxia and Anoxia, Community Composition, Environment, Air Pollutants, and Dry Deposition
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There is a need for a unified grazing method that can be used across the freshwater-to-marine continuum. To accomplish this, this research utilized dilution grazing assays across the freshwater-to-marine continuum and across the... more
There is a need for a unified grazing method that can be used across the freshwater-to-marine continuum. To accomplish this, this research utilized dilution grazing assays across the freshwater-to-marine continuum and across the oligotrophic-to-hypereutrophic gradient by measuring size fractions of dilution-based mortality. This was investigated by using 0.7 µm and 0.2 µm prefiltered water and major ion solutions (MIS) as diluent media for use in the Landry-Hassett grazing bioassays run in lake, river, estuarine (riverine and lagoonal), and oceanic shelf systems. Because MIS does not include vitamins that would be in prefiltered natural water, vitamin effects on grazing rate determination were also investigated for the MIS bioassays. Results show that the dilution grazing method can be broadly applied across the freshwater-to-marine continuum and across trophic gradients.
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Contemporaneous in situ acetylene-reduction, 15N2-fixation, and 3H2-exchange assays reveal parallel patterns of N2 fixation and H2 utilization in natural populations of the blue-green algae Anabaena and Aphanizomenon. As spring and summer... more
Contemporaneous in situ acetylene-reduction, 15N2-fixation, and 3H2-exchange assays reveal parallel patterns of N2 fixation and H2 utilization in natural populations of the blue-green algae Anabaena and Aphanizomenon. As spring and summer blooms progress, increasing ratios of acetylene reduction versus 15N2 fixation closely follow elevated rates of cellular H2 utilization. Both acetylene-reduction and H2-utilization rates were largely attributable to blue-green algae as opposed to associated bacteria and other phytoplankton. It is concluded that elevated H2 utilization reflects increased H2 production via nitrogenase. This can be substantiated by monitoring rising acetylene-reduction versus 15N2-fixation ratios during bloom development. Simultaneous deployment of the above techniques provides evidence for (a) in situ H2 production and (b) seasonal trends in rates of H2 production among natural blue-green algal populations.
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(N) limitation is a widespread feature of estuatine and oceanic waters (Dugdale 1967; Carpenter and Capone 1983). Despite this, benthic microbial mats frequently flourish in geographically-diverse intertidal and subtidal sand/mud flat,... more
(N) limitation is a widespread feature of estuatine and oceanic waters (Dugdale 1967; Carpenter and Capone 1983). Despite this, benthic microbial mats frequently flourish in geographically-diverse intertidal and subtidal sand/mud flat, lagoon, reef, marsh and mangrove habitats characterizing such waters (Cohen et al. 1984; Cohen and Rosenberg 1989). Mats are particularly prolific in oligotrophic tropical and subtropical waters, where an appreciable portion of the primary production can be attributed to benthic microalgae (Whitton and Potts 1982; Bauld 1984). The remarkable success of mats in these N-limited environments has been attributed to the ability of specific groups of mat microorganisms (cyanobacteria, photosynthetic-, heterotrophic- and lithotrophic bacteria) to “fix” (reduce) atmospheric N (N2), thereby providing biologically-available N (NH3) to mat flora and fauna (Wiebe et al. 1975; Potts and Whitton 1977; Carpenter et al. 1978; Paerl et al. 1981; Stal et al. 1984). Nitrogen fixation is often the sole biologically-derived source of “new” N supporting primary production in these waters. In the face of N loss (as N2) in mats (and other ecosystem components) via denitrification (Joye and Paerl 1993) and to a lesser extent ammonification, N2 fixation is also of importance in regulating flux and mass balance of this important nutrient.
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Under ongoing climate change and increasing anthropogenic activity, which continuously challenge ecosystem resilience, an in-depth understanding of ecological processes is urgently needed. Lakes, as providers of numerous ecosystem... more
Under ongoing climate change and increasing anthropogenic activity, which continuously challenge ecosystem resilience, an in-depth understanding of ecological processes is urgently needed. Lakes, as providers of numerous ecosystem services, face multiple stressors that threaten their functioning. Harmful cyanobacterial blooms are a persistent problem resulting from nutrient pollution and climate-change induced stressors, like poor transparency, increased water temperature and enhanced stratification. Consistency in data collection and analysis methods is necessary to achieve fully comparable datasets and for statistical validity, avoiding issues linked to disparate data sources. The European Multi Lake Survey (EMLS) in summer 2015 was an initiative among scientists from 27 countries to collect and analyse lake physical, chemical and biological variables in a fully standardized manner. This database includes in-situ lake variables along with nutrient, pigment and cyanotoxin data of 3...
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Abstract: Two remote-sensing optical algorithms for the retrieval of the water quality components (WQCs) in the Albemarle-Pamlico Estuarine System (APES) were developed and validated for chlorophyll a (Chl). Both algorithms were... more
Abstract: Two remote-sensing optical algorithms for the retrieval of the water quality components (WQCs) in the Albemarle-Pamlico Estuarine System (APES) were developed and validated for chlorophyll a (Chl). Both algorithms were semi-empirical because they incorporated some elements of optical processes in the atmosphere, water, and air/water interface. One incorporated a very simple atmospheric correction and modified quasi-single-scattering approximation (QSSA) for estimating the spectral Gordon’s parameter, and the second estimated WQCs directly from the top of atmosphere satellite radiance without atmospheric corrections. A modified version of the Global Meteorological Database for Solar Energy and Applied Meteorology (METEONORM) was used to estimate directional atmospheric transmittances. The study incorporated in situ Chl data from the Ferry-Based Monitoring (FerryMon) program collected in the Neuse River Estuary (n = 633) and Pamlico Sound (n = 362), along with Medium Resolut...
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Cyanobacterial harmful algal blooms (CyanoHABs) are a major threat to human and environmental health. As global proliferation of CyanoHABs continues to increase in prevalence, intensity, and toxicity, it is important to identify and... more
Cyanobacterial harmful algal blooms (CyanoHABs) are a major threat to human and environmental health. As global proliferation of CyanoHABs continues to increase in prevalence, intensity, and toxicity, it is important to identify and integrate the underlying causes and controls of blooms in order to develop effective short- and longterm mitigation strategies. Clearly, nutrient input reductions should receive high priority. Legacy effects of multi-decadal anthropogenic eutrophication have altered limnetic systems such that there has been a shift from exclusive phosphorus (P) limitation to nitrogen (N) limitation and N and P co-limitation. Additionally, climate change is driving CyanoHAB proliferation through increasing global temperatures and altered precipitation patterns, including more extreme rainfall events and protracted droughts. These scenarios have led to the “perfect storm scenario”; increases in pulsed nutrient loading events, followed by persistent low-flow, long water residence times, favoring bloom formation and proliferation. To meet the CyanoHAB mitigation challenge, we must: (1) Formulate watershed and airshed-specific N and P input reductions on a sliding scale to meet anthropogenic and climatic forcings. (2) Develop CyanoHAB management strategies that incorporate current and anticipated climatic changes and extremes. (3) Make nutrient management strategies compatible with other physical-chemical-biological mitigation approaches, such as altering freshwater flow and flushing, dredging, chemical applications, introduction of selective grazers, etc. (4) Target CyanoHAB toxin production and developing management approaches to reduce toxin production. (5) Develop broadly applicable long-term strategies that incorporate the above recommendations.