Physical Sciences and Mathematics Commons^™

Drivers And Dynamics Of Phytoplankton Communities And Harmful Algal Blooms In Mountain Lakes, Lara Stephanie Jansen

Dissertations and Theses

Harmful cyanobacterial blooms (cyanoHABs) are a complex and widespread disturbance in freshwater water bodies, impacting water quality for wildlife and human populations. While cyanobacteria often bloom in warm lakes impacted by human development like agriculture, blooms are increasingly reported in cooler waters with limited development in the surrounding watershed. As much of cyanoHAB research has focused on lakes in highly developed watersheds, the understanding of factors leading to cyanobacteria dominance and blooms in the absence of major development remains limited. Mountain lakes can serve as ideal systems to study bloom-forming cyanobacteria in watersheds with minimal development. In addition, mountain lakes …

Diatom Blooms In Harpswell Sound: Seasonality, Succession, And Origin, Charlie Francis O'Brien

Honors Projects

Harpswell Sound (HS) is an inlet in northeastern Casco Bay that exerts control on Gulf of Maine ecosystem health, yet its complex phytoplankton community dynamics have not been characterized with sufficiently detailed analyses. In this research, high-resolution automated microscopy and current velocity observations were used to test the seasonality, ecological succession, bloom origin location, and potential toxicity of populations in HS between 2020 and 2022. Winter months could exhibit slow accumulation of diatom biovolume. Cold, salty surface water has net outflow in winter as nutrients from depth are replenished during net upwelling conditions, and populations could be exported from the …

Developing A Method To Track Marine Snow Aggregation Through Individual Collisions Using Stereoscopic Imaging, Riley Henning

Theses

The aggregation of individual phytoplankton into marine snow allows particles to sink more quickly, thus resulting in the transport of particulate organic carbon from surface waters to the deep ocean. Aggregate formation has previously been measured in experiments indirectly by quantifying how particle size or particle concentration changes over time. Here, I present my thesis in which I applied high-resolution imaging to quantify aggregate formation using two different methodologies.

We conducted experiments to investigate aggregate formation using stereoscopic imaging, tracking individual particles directly in a 3D volume. Phytoplankton cultures were rolled in cylindrical tanks and imaged by two cameras illuminated …

Assessing Chemical And Biological Recovery From Acid Rain Deposition In Montane Vermont Lakes, Sydney Diamond

Graduate College Dissertations and Theses

Vermont’s inland lakes are changing rapidly in response to anthropogenic disturbance pressures. While changes in water chemistry are well documented across the state, the biological response of primary producer communities to these shifts remains poorly understood. This project investigated the response of phytoplankton communities to the interacting effects of recovery from acidification and climate change in high-altitude lakes. We analyzed long-term monitoring and meteorological data in four of Vermont’s acid-impaired lakes and found that as pH and acid-neutralizing capacity has increased, so have concentrations of dissolved organic carbon (DOC) in most lakes. To assess the biological response to these processes, …

Role Of Coastal Environmental Conditions During Austral Winter On Plankton Community Dynamics And The Occurrence Of Pseudo-Nitzschia Spp. And Domoic Acid In Inhambane Province, Mozambique, Holly Kelchner

LSU Master's Theses

Harmful algal blooms (HABs) are increasing globally in frequency, persistence, and geographic extent. HABs pose a threat to economic stability, and ecosystem and human health. To date no incidences of marine toxins produced by phytoplankton have been recorded in Mozambique, which may be due to the absence of a monitoring program and general awareness of the potential threat. This study is the first documentation of the occurrence of a neurotoxin, domoic acid (DA), produced by the diatom genus Pseudo-nitzschia spp. along the east coast of Africa. The coast of Inhambane Province is a biodiversity hotspot where year-round Rhincodon typus (whale …

The Stability Of Temperate Lakes Under The Changing Climate, Aleksey Paltsev

Electronic Thesis and Dissertation Repository

There is a collective prediction among ecologists that climate change will enhance phytoplankton biomass in temperate lakes. Yet there is noteworthy variation in the structure and regulating functions of lakes to make this statement challengeable and, perhaps, inaccurate. To generate a common understanding on the trophic transition of lakes, I examined the interactive effects of climate change and landscape properties on phytoplankton biomass in 12,644 lakes located in relatively intact forested landscapes. Chlorophyll-a (Chl-a) concentration was used as a proxy for phytoplankton biomass. Chl-a concentration was obtained via analyzing Landsat satellite imagery data over a 28-year period (1984-2011) and using …

The Influence Of Juncus-Rhizosphere Dissolved Organic Matter On Coastal Plankton Communities, Brittany Zepernick, Robert Michael Mckay, George S. Bullerjahn, Jeffrey W. Krause, Behzad Mortazavi

Honors Projects

Many aquatic plants produce copious amounts of dissolved organic matter (DOM) which enters surrounding waters and potentially stimulates planktonic activity. In the northern Gulf of Mexico, Juncus roemarianus (i.e. black needlerush) is a dominant marsh grass species residing in coastal zones and barrier islands. The below-ground biomass i.e. rhizosphere, can be consistently submerged, serving as a potential source of DOM to the surrounding waters. The lability and possible stimulatory effect of J. roemarianus DOM was examined for three plankton communities collected within the discharge region of Mobile Bay and adjacent waters of Gulf Shores, Alabama (less affected by Mobile Bay). …

Impacts To Phytoplankton After The Establishment Of Quagga Mussels In Lake Mead, Nevada, Warren Bruce Turkett

UNLV Theses, Dissertations, Professional Papers, and Capstones

Quagga mussels (Dreissena rostriformis bugensis) are an invasive species that were discovered in Lake Mead in January of 2007, and rapidly spread throughout the lake. Quagga mussels are about the size of a fingernail, but are known to clog pipes, damage infrastructure and alter ecosystems. In large numbers, mussels can have a dramatic impact on an ecosystem by reducing the phytoplankton and potentially increasing toxin producing cyanobacteria. This research analyzed data collected from three separate basins in Lake Mead to determine if water quality characteristics that are commonly impacted by invasive mussels have changed. Transparency, chlorophyll-a, phytoplankton and zooplankton samples …

Assessing Biogeochemical Impacts And Environmental Conditions Associated With Cross-Shelf High Chlorophyll Plumes In The Northern Gulf Of Mexico, Erin Brooke Jones

Dissertations

The northern Gulf of Mexico is a complex marine system subject to episodic physical phenomena such as loop current eddies. Flow fields generated by these eddies can result in cross-shelf exchanges between riverine influenced shelf waters and the offshore water column. This study considers the impacts of high chlorophyll plumes (HCPs) resulting from cross-shelf exchanges to the bio-optical properties of affected waters and how these plumes are influenced by their environment. The seasonal, interannual and decadal chlorophyll cycles of the Gulf of Mexico and the northern Gulf of Mexico are described to provide context for evaluating the ecological effects of …

Exploration Of Spatial And Temporal Changes In Trophic Status Of Lakes In The Northern Temporal Forest Biome Using Remote Sensing, Aleksey Paltsev

Electronic Thesis and Dissertation Repository

There is a critical need for detailed surveys of lakes covering large spatial (>100 km²) and temporal scales (decades) to determine if there is an increase in the magnitude and frequency of phytoplankton blooms. Remote sensing was used to: (1) develop a regression model that relates chlorophyll a (chl-a) as a proxy of lake phytoplankton biomass to Landsat TM and ETM+ optical reflectance (r²=0.85, p

Mathematical Modeling Of Competition For Light And Nutrients Between Phytoplankton Species In A Poorly Mixed Water Column, Thomas George Stojsavljevic

Theses and Dissertations

Phytoplankton live in a complex environment with two essential resources forming various gradients. Light supplied from above is never homogeneously distributed in a body of water due to refraction and absorption from biomass present in the ecosystem and from other sources. Nutrients in turn are typically supplied from below. In poorly mixed water columns phytoplankton can be heterogeneously distributed forming various layering patterns. The relationship between the location and the thickness of the layers is an open problem of interest. Here we present three models which study how competition for light and resources can form common layering patterns seen in …

Benthic And Planktonic Microalgal Community Structure And Primary Productivity In Lower Chesapeake Bay, Matthew Reginald Semcheski

Biological Sciences Theses & Dissertations

Microalgal populations are trophically important to a variety of micro- and macroheterotrophs in marine and estuarine systems. In Chesapeake Bay, microalgae facilitate the survival and development of ecologically and economically relevant fauna, including shellfish and finfish populations. While regarded as significant components of coastal environments, microphytobenthic communities are historically understudied. In Chesapeake Bay, the importance of phytoplankton to the ecosystem is understood, but the contribution of microphytobenthos remains unclear. This project surveys intertidal microphytobenthic communities, in relation to phytoplankton communities, around lower Chesapeake Bay describing the taxonomic makeup of these populations, coupled with quantification of cell abundance, biomass, and primary …

Phytoplankton Life History Events: Resting Stages And Physiological Cell Death, Christine R. Kozik

Theses and Dissertations

Understanding and predicting changes in phytoplankton populations requires knowledge of key life history processes such as recruitment from benthic resting stages and losses due to sedimentation and cell death. Currently, these processes are poorly understood in freshwater systems. Phytoplankton resting stage and cell death life history events were separately examined in two freshwater systems in Wisconsin, four northern lakes and an urban pond. In the norther lakes, sedimentation and benthic recruitment were examined using sediment and recruitment traps that were sampled weekly over two summers. Sedimentation and benthic recruitment contributed little to changes in standing crop chl a, but rather …

Investigations Of Phytoplankton Diversity In Chesapeake Bay, Todd Arthur Egerton

Biological Sciences Theses & Dissertations

Characterizing the diversity of a community in relation to environmental conditions and ecosystem functions are core concepts in ecology. While decades of research have led to a growing comprehension of diversity in many ecosystems, our understanding in aquatic habitats and microbial organisms remains relatively limited. Phytoplankton represent a diverse and important group that contribute approximately half of global primary productivity and are intrinsically connected to changing environmental conditions, especially in systems as dynamic as estuaries. To better understand the ecological processes governing phytoplankton composition and diversity, spatial and temporal patterns of environmental parameters and their relation to the algal community …

Freshwater Phytoplankton Populations Detected Using High Pressure Liquid Chromatography (Hplc) Of Taxon-Specific Pigments, Lauren Jeanne Simmons

Theses and Dissertations

Phytoplankton are key primary producers in aquatic ecosystems, and the principle food source for primary consumers. Individual phytoplankton species respond to different physical, chemical and biological parameters, so monitoring taxonomic composition of the phytoplankton community is a means to monitor changes in environmental conditions. Phytoplankton community changes have frequently been monitored by estimating biomass (using chlorophyll a, measured fluorometrically), and taxonomic data obtained from cell counts. While such methods are useful, they are time-consuming. I hypothesized that high pressure liquid chromatography (HPLC) methods, which have been frequently used in marine systems, would allow separation and identification of key pigments. …

Analysis Of Optical Spikes Reveals Dynamics Of Aggregates In The Twilight Zone, Nathan Briggs

Electronic Theses and Dissertations

The "biological pump," whereby phytoplankton grow in the surface ocean, aggregate, and sink, is a critical process contributing to global atmospheric CO2 drawdown and provides the vast majority of food for deep ocean and benthic ecosystems. The strength of this pump hinges on the amount of material that stick together to form larger aggregates, the sinking rates of these aggregates, and the rate at which they are consumed as they sink. However, marine aggregates, also called "marine snow," are often fragile and notoriously difficult to sample, their sinking rates are highly variable and difficult to quantify, and their concentrations can …

Interactions Between Phytoplankton And Bacteria In The Uptake Of Organic Compounds, Andrea Michel Rocha

OES Theses and Dissertations

The most common methods for estimating bacterial productivity are [³H]-leucine and [³H]-thymidine incorporation. Uptake of these compounds has been attributed primarily to bacteria; however, because dissolved organic nitrogen may be an important N source for some phytoplankton, the use of these compounds to estimate bacterial productivity needs to be reexamined. In order to ascertain whether phytoplankton could compete with bacteria on relevant timescales and thereby bias bacterial productivity estimates in estuaries, I examined the ability of cultured phytoplankton and size-fractionated natural populations to take up leucine and thymidine in systems seasonally dominated by phytoplankton mixotrophs. In …

A Comparison Of Phytoplankton Communities In Lake Prince And The Western Branch Reservoir, Suffolk, Virginia, Cara Marie Muscio

Biological Sciences Theses & Dissertations

Lake Prince and the Western Branch Reservoir are two eutrophic bodies of water located in Suffolk, Virginia. Lake Prince and its two small tributaries join the Western branch via a constructed spillway. This lake system is a source of water for the surrounding municipalities, and a recreational area for community citizens. In the past, these bodies of water had repeated incidents of low oxygen and nuisance algal blooms, particularly cyanobacteria species. As a result aerators have been installed in the main body of both Lake Prince and the Western Branch Reservoir. In addition, a pipeline has been installed from North …

The Impacts Of External Nutrient Sources On Marine Phytoplankton In An Eastern Shore Sea-Side Estuary, Claudette Lajoie Jenkins

OES Theses and Dissertations

The Eastern Shore of Virginia (Greens Creek) as well as a large portion of the North Atlantic coastline is characterized by estuarine systems not dominated by large river systems. Instead, small freshwater creeks influence many coastal systems yet little information has been documented on their ecological significance. The focus of this research is to identify the biogeochemical and physical interactions within an estuarine water-column and understand the importance of freshwater sources in governing phytoplankton production. The hypothesis of this research is that increases in external nutrient loading into Greens Creek will not result in an increase in primary production. The …

Modeling Nutrient And Plankton Processes In The California Coastal Transition Zone, John Roland Moisan

OES Theses and Dissertations

Two time- and space-dependent, physical-bio-optical models have been developed for the California Coastal Transition Zone (CTZ) region with the overall objective of understanding and quantifying the processes th at contribute to the spatial and temporal development of nutrient and plankton distributions in the CTZ. The first of these models considers only time- and vertical processes at specific locations in the CTZ. The model food web components include: silicate, nitrate, ammonium, two phytoplankton size fractions, copepods, doliolids, euphausiids and a detritus pool. The wavelength dependent attenuation of the subsurface irradiance field, due to sea water, phytoplankton pigment concentrations and dissolved organic …

Factors Affecting The Kinetics Of Light Intensity Adaptation In Marine Phytoplankton, Chunzhi Guo

OES Theses and Dissertations

It has been suggested that the recent light history of phytoplankton and the kinetics of photoadaptation can be used to provide information about the vertical mixing processes in the upper mixed layer. To be useful as a parameter in a model of photoadaptation and vertical mixing, the response of a photoadaptive variable to changes in growth irradiance must be monotonic, significant, and comparable in time rate scale to mixing processes. Previous studies of photoadaptation kinetics have focused on the response of phytoplankton to changes in light intensity under continuous illumination. This dissertation attempts to elucidate the effects of light:dark cycle, …

Phytoplankton In Lake Drummond And Two Drainage Ditches In The Great Dismal Swamp, Virginia, Christine Gregory Phillips

Biological Sciences Theses & Dissertations

A twelve month study was conducted on the phytoplankton of Lake Drummond and Washington and Jericho Ditches from December 1988 to November 1989. Surface water samples were collected for nutrient and chlorophyll analysis from June 1989 to November 1989. The dominant phytoplankton component was the pico-nanoplankton (< 3 micron) category. A total of 57 species were identified from Lake Drummond, 51 species from Washington Ditch, and 31 species from the Jericho Ditch. Three major phytoplankton groups were identified at these sites: bacillariophyceans, cyanophyceans and cryptophyceans. The dominant species was the diatom Asterionella formosa. Nutrient and chlorophyll concentrations increased from summer to fall. Based on nutrient and chlorophyll g concentrations and species diversity indices, Lake Drummond is classified as eutrophic.

Picoplankton/Phytoplankton Dynamics In Hampton Roads, Virginia, Leslie E. Dorworth

OES Theses and Dissertations

The biomass distribution of the three main size components of the phytoplankton (net, nano, and picoplankton) was examined in the lower Chesapeake Bay. Work was done at two stations during the spring and neap tidal cycles when freshwater flow into the bay was at its seasonal minimum and maximum. Emphasis was placed on how the picoplankton ( < 2.0 μm, > 0.2 μm) reacted during the sampling period.

Picoplankton made up approximately 13% of the total biomass, during the observed time period, at the more oceanic station. The picoplankton fraction contributed up to 16% of the total biomass at the estuarine station. From this …

Phytoplankton Dynamics In The Very Low Salinity Region Of The James River Estuary, Virginia, U.S.A., Changho Moon

OES Theses and Dissertations

During summer and autumn discharge from the James River estuary, Virginia, was less than 120 _m³sec^-1. There was a peak phytoplankton biomass in the very low salinity region (defined as the location where surface salinity measured less than 0.5$ 0/00) and this peak represented five to ten times greater biomass than adjacent waters. The peak biomass occurred independent of the tidal state and the location of nutrient inputs. It disappeared during winter and spring, and nutrient limitation was not responsible for the low phytoplankton biomass, indicating there were physical, not chemical controlling factors.

The peak biomass …

Phytoplankton Ecology And Dynamics In The James River Estuary Virginia, U. S. A., Margaret J. Filardo

OES Theses and Dissertations

Autotrophic biomass and productivity as well as nutrient distributions and phytoplankton cell populations in the James River estuary, Virginia, from Newport News Shipyard to the 0 o/oo isohaline, were sampled on a monthly basis from August of 1981 to December of 1982. Particular emphasis was placed on the very low salinity region (defined as the location where surface salinity measured between 0.0 and 0.75 o/oo based on conductivity) in order to determine the fate of fresh water phytoplankters upon being advected into the estuary because of their suspected role in the biogeochemical cycling that occurs there.

Both chlorophyll a and …

The Distribution Of Phytoplankton In Frontal Regions Of The Lower Chesapeake Bay, Richard V. Lacouture

OES Theses and Dissertations

The spatial and temporal distribution of phytoplankton was measured in relation to frontal areas located in the entrance to the Chesapeake Bay. Phytoplankton biomass, taxonomy, and several physical parameters were measured on fifteen sampling cruises between September,1981 and February, 1983.

Several statistical tests revealed that phytoplankton biomass did not accumulate at the fronts and that generally the distribution of phytoplankton biomass was homogenous across the frontal region. The cell count data indicated that the community structure of the phytoplankton assemblage was usually very similar on both sides of the front. The data which was concerned with temporal variations in the …

Factors Effecting Phytoplankton Assemblages In The Lafayette River Estuary, Laurie Ann Kalenak

OES Theses and Dissertations

Chemical and physical parameters were measured with phytoplankton species composition and abundance in the Lafayette River from August to October 1981. Stations located in four distinct areas of the river were statistically analyzed to determine data relationships. Environmental factors considered as potentially influencing the presence and numbers of phytoplankton were salinity, temperature, Secchi depth, tidal phase, orthophosphate, combined nitrates and nitrites, ammonia, and reactive silicates.

The River mouth had higher salinity and nutrient values, with lower temperatures than the other river sections. Diatoms were the dominant cells in this section of the River. At mid-river, salinity and nutrient concentrations decreased, …

Algal Dynamics In A Cypress Stand In The Seasonally Flooded Great Dismal Swamp, Joseph A. Atchue Iii

Biological Sciences Theses & Dissertations

The dynamics of epiphytic algae and phytoplankton were studied at a cypress stand in the Great Dismal Swamp, Virginia. Mean epiphytic algal biomass was 19.9 g m^-2 and mean planktonic biomass was 3.4 g m^-2.Nutrient concentrations in the epiphytic algae and the litter were determined. The algae had mean concentrations of 1.67% and 0.18%. They were found to immobilize as much as 0.5 g N m^-2 and 0.06 g P m^-2. This suggests that the algae are important as nutrient conservers. The phytoplankton were composed primarily of Bacillariophyceae. They exhibited a more or less …

A Seasonal Study Of Phytoplankton Composition Abundance And Productivity In Back Bay, Virginia, Robert Ringgold Comegys

Biological Sciences Theses & Dissertations

Phytoplankton samples were collected monthly (August 1974-June 1975) at two stations in the Back Bay system of southeastern Virginia. Measurements of phytoplankton productivity and potentially influencing environmental parameters (water and air temperature, turbidity, depth, pH, salinity, dissolved oxygen) accompanied sample collections. A total of 106 phytoplankton species, representing six algal divisions and 54 genera were identified. Cyanophyta species were dominant at both stations in the warmer months of August, September, October, and June, and in April at one station only. In all remaining months, Chlorophyta species were dominant, indicating a seasonal shift in phytoplankton composition during winter and spring. The …

Microbenthic Algal Production Of An Intertidal Sandflat In Little Creek Harbor, Virginia Beach, Virginia, Clayton Barry Shedrow

OES Theses and Dissertations

Estimated annual net microbenthic algal production of an intertidal sandflat on Little Creek Inlet, Virginia Beach, Virginia, was 105 g C/m². Seasonally, primary production was greatest during the summer and fall periods (38 and 49 g C/m², respectively). Productivity was found to vary directly with water temperature and standing crop of benthic diatoms, and inversely with incident solar radiation and standing crops of sedimentary chlorophyll 'a' and 'c'. Orthophosphate and nitrate-N appeared to be limiting factors, nitrate-N more so than orthophosphate. Mean annual net photosynthetic efficiency (based upon total light) for the microphytobenthic community was 0.09%. …