Life Sciences 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 …

The Effects Of Variations In Light And Nutrient Availability On Phytoplankton And Zooplankton, Jake Anthony Swanson

Theses and Dissertations

Aquatic ecosystems experience a wide range of variation in resource availability; two of the resources that are most essential to phytoplankton and zooplankton are light and nutrients. Light can vary in both its color and intensity; these variations can directly impact phytoplankton by altering the amount and color of light available for photosynthesis. Nutrient variability, particularly increases in nutrient levels, also alter phytoplankton communities by favoring the growth of certain taxa such as cyanobacteria.

To understand whether phytoplankton respond differently to changes in light availability I investigated whether the diversification of cryptophytes, phytoplankton with diverse light-capturing pigments, showed evidence of …

Exploring The Relationship Between Dreissenids And The Deep Chlorophyll Layer In The Laurentian Great Lakes, Lara E. Hargrave

Great Lakes Center Masters Theses

In the Laurentian Great Lakes, two invasive bivalves Dreissena polymorpha and Dreissena rostriformis bugensis have induced a number of changes, including increased water transparency, alterations in nutrient cycling, decreased chlorophyll concentrations, and changes in phytoplankton community composition and structure. These changes are likely to have implications for the deep chlorophyll layer (DCL), a feature characterized by phototrophic organisms reaching abundance at light levels far below ideal for photosynthesis. Though the impacts of D. polymorpha and D. r. bugensis in the Great Lakes have been studied for at least the last three decades, little is known about how these ecosystem engineers …

Analysis Of Microbial Abundance On Marine Snow In The Deep Ocean, Matthew Qilan Thompson

Undergraduate University Honors Capstones

The ocean plays a critical role in the carbon cycle, with phytoplankton serving as a source of energy and nutrients (such as nitrogen and phosphorus) to larger organisms in upper trophic levels. Additionally, marine snow, a cluster of components including dead zooplankton, organic carbon debris, and polymers as carbohydrates, proteins, and DNA, transport these nutrients and associated microorganisms to the deeper parts of the ocean. However, the relationship between microbial abundance and particle sizes of marine snow across the water column is not well understood. Previous studies suggest that microbial abundance is lower in the bathypelagic zone (1,000m - 4,000m) …

Controls Of Physical Drivers On The Formation And Toxicity Of Harmful Cyanobacteria Blooms (Cyanohabs), Courtney N. Hammond

LSU Master's Theses

Estuaries within the Gulf of Mexico are exhibiting profound alterations due to climatic changes and the implementation of coastal restoration activities. These changes are attributed to the increasing frequency of harmful cyanobacteria blooms (cyanoHABs) within Lake Pontchartrain, an estuary located in southeastern Louisiana, USA. There is a better understanding into how the opening of the Bonnet Carré Spillway (BCS) impacts cyanoHAB formations compared to the effect of other physical drivers when the spillway doesn’t dominate the system. The goal of this study is to provide a greater understanding of the baseline conditions when the BCS is closed and determine what …

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 …

The Impact Of Nutrient Depletion On The Effect Of Hhq On Emiliania Huxleyi, Marley Gonsalves

Honors Theses and Capstones

Emiliania huxleyi is a ecologically important, bloom-forming coccolithophore. HHQ is a bacteria compound that causes cell stasis in E. huxleyi that can lead to bloom termination. This study analyzed the role that nutrient depletion plays in this relationship. Results show that nitrogen depletion protects cells from the effects of HHQ, affecting bloom dynamics.

The Toxicity Of Dopamine On Salish Sea Phytoplankton, Allyson Lombardo

WWU Graduate School Collection

In the Salish Sea, blooms of the intertidal macroalgae, Ulvaria obscura, are common and can achieve extraordinarily high biomass. Upon desiccation and subsequent rehydration from incoming tides, U. obscura releases dopamine. Previous studies showed that dopamine negatively affects other macroalgal species and can deter grazers. However, the effects of dopamine on co-occurring phytoplankton remains unknown. This study explored the toxicity of dopamine on four phytoplankton known to inhabit the Salish Sea: the haptophyte, Isochrysis galbana; the chlorophyte, Dunaliella tertiolecta; the dinoflagellate, Heterocapsa triquetra; and the diatom, Thalassiosira sp. Over the course of 8 days, phytoplankton growth …

Interactions Between Juvenile Estuary-Dependent Fishes And Microalgal Dynamics, Ian C. Williams

USF Tampa Graduate Theses and Dissertations

The ontogenetic movement of juvenile estuary-dependent fishes upstream in estuarine settings is a phenomenon observed around the world. These movements usually coincide with a shift in diet from smaller prey, such as calanoid copepods, to larger prey, such as mysids. However, the mechanism that drives this pattern has yet to be conclusively described. Prior to the current study, zooplankton/hyperbenthos (“zooplankton”), primary production, and water quality data were collected from the Caloosahatchee River estuary in two concurrent and coordinated studies over a two-year period. One of the products of these sampling efforts was a classification of primary-producer types at the sediment-water …

Phytoplankton Community Response To Changing Environmental Conditions Across Two Central California Sites, Nicholas Soares

Biological Sciences

Understanding the role that changing environmental conditions play in altering phytoplankton abundance and community composition, and in turn ecosystem structure and function, will be increasingly important for the sustainable use and management of ocean resources in a changing climate. Characterizing change in nearshore ecosystems requires long-term studies with a broad spatial extent, with most studies sacrificing spatial extent for temporal duration. However, phytoplankton and ecosystem response can vary substantially over small spatial scales due to local oceanographic forcing and anthropogenic influence, making the application of long-term data from one site to another in the same geographic vicinity potentially challenging. In …

Construction Of Dichotomous Taxonomic Keys For San Francisco Bay Planktonic Diatoms, Ria Angelica Laxa

Undergraduate Honors Theses

Planktonic diatoms exhibit high biodiversity in marine systems and make a significant contribution to water column primary productivity. This makes research on planktonic diatoms particularly important in measuring the health of coastal marine ecosystems. At the University of San Francisco (USF), undergraduate research has been conducted since September 2015 to study planktonic diatoms in San Francisco Bay. A previous study by Keith (2018), Planktonic Diatom Species Succession in San Francisco Bay, documented changes in species diversity over time, observing seasonal patterns in species richness as well as the effect of environmental factors such as salinity, temperature, and rainfall on species …

Fortnightly Effects Of Urea Additions On Cyanobacteria In A Stormwater Detention Pond, Halley Carruthers

Theses and Dissertations

Increased urban and suburban population growth along the South Carolina (SC) coast has led to a rise in impervious surfaces, altering the course of stormwater runoff events. The construction of stormwater detention ponds (SDPs) is one of the many ways to best mitigate the flow of this water. In their function as natural pollutant traps, SDPs often contain increased levels of nutrients (nitrogen, N and phosphorus, P), which can lead to eutrophication. Under these high eutrophic conditions, primary production is overstimulated, and the formation of phytoplankton blooms, including harmful algal blooms (HABs) can occur. In recent decades, the forms of …

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 …

Effects Of Changing Winter Severity On Plankton Ecology In Temperate Lakes, Allison Rose Hrycik

Graduate College Dissertations and Theses

Climate change has rapidly altered winter conditions in temperate regions of the globe. Over the last several decades, snowpack has decreased, spring snowmelt is earlier, and ice cover has declined. Associated changes in lake mixing, inflow, nutrient cycling, and light transmission during winter can affect lake biota both under ice and into the open-water season. Unfortunately, under-ice lake research is limited compared to open-water research. Recent winter limnology research, however, suggests that ecosystem processes do not stop under ice, and many questions remain about the drivers of phytoplankton and zooplankton dynamics in winter. My research aimed to uncover mechanisms by …

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, …

Contrasting Patterns Of Nutrient Limitation In The Littoral And Pelagic Zones Of Mesotrophic Maine Lakes, Grace C. Neumiller

Honors Theses

Intense nutrient loading of nitrogen (N) and phosphorus (P) causes sudden regime shifts in freshwater ecosystems from clearwater to turbid conditions with frequent cyanobacterial blooms. Characterization of nutrient limitation patterns of primary productivity in these ecosystems is necessary for effective management of algal blooms. However, much of this research has focused on pelagic habitats. The influence of lake habitat (i.e. benthic littoral versus pelagic zones) on nutrient limitation of primary production in mesotrophic lakes is largely unknown, particularly in contrast to research on pelagic nutrient limitation in eutrophic systems. Using paired nutrient diffusing substrata and mesocosm experiments, we measured chlorophyll- …

Surface Levels, Keisha Brathwaite

Electronic Theses and Dissertations

Surface Levels are depictions of unobserved and imperceptible realities of many phytoplankton exteriors. The exhibition explores various structures, textures, and repetitious forms from microscopic surfaces of objects that cannot be seen with unaided eyes. Electron microscopy is used to perceive and analyze these otherwise unseeable surfaces in depth. Magnifications provide a reference in creating three- and two-dimensional works that are minimalistic and abstract at a visible level. This abstract 3D/2D image collection is translated into material expressions using acrylic sheets, acrylic ink, and wood as the main media for construction of individual works. Collectively, they serve to make the invisible …

Bloom Or Bust: Search For Phytoplankton Community Drivers Using Long-Term Time-Series Observations And Field Measurements In A Model Great Lakes Estuary, Jasmine Mancuso

Masters Theses

As sentinels of climate change and other anthropogenic effects, freshwater lakes are experiencing ecosystem disruptions at every level of the food web, beginning with the phytoplankton. One of the major threats to waterbodies around the world are cyanobacterial harmful algal blooms (HABs) resulting from anthropogenic eutrophication and exacerbated by climate change. Muskegon Lake, a drowned river mouth Great Lakes estuary on the east coast of Lake Michigan, is no exception and was declared an Area of Concern by the EPA in 1987 with nuisance algal blooms cited as a beneficial use impairment. Using long-term data and additional 2019 sampling, we …

Plankton Dynamics In An Urban, Subtropical Lake Prior To Lake Restoration, Jennifer C. Pulsifer

LSU Master's Theses

This research assessed plankton dynamics in two urban, subtropical lakes (University Lake and City Park Lake) shortly before a proposed and approved lake restoration project. Plankton dynamics were determined in University Lake by the dilution method to attempt to quantify growth rates of phytoplankton and grazing rates of zooplankton. Landry and Hassett’s (1982) dilution method has been widely used in marine systems to estimate rates of growth and grazing. In many marine systems, nutrients must be added to prevent nutrient limitation. However, it is assumed, due to the hypereutrophic conditions, that nutrients would not be a limitation in University Lake. …

Spatiotemporal Dynamics Of Benthic Microalgae In South Carolina Shelf Sediments, Sarah N. Zaunbrecher

Theses and Dissertations

Benthic microalgae (BMA) play essential roles in food webs and regulating nutrient exchange at the sediment-water interface in continental shelf ecosystems. However, shelf BMA are not widely studied due to the difficulties sampling the upper few millimeters of shelf sediments. A few published studies have highlighted the high spatiotemporal distribution of BMA, but detailed explanations for this known variability are limited. The objectives of this study were to quantify BMA biomass variability on scales of cm to km and relate these measurements to in situ nutrient concentrations, sediment grain size, in situ irradiance, depth, and other environmental factors. Water and …

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 …

Diatom Community Responses To Development And Climate Change In Lake George, An Oligotrophic Lake In The Adirondack Mountains, Adam T. Ruka

Masters Theses

Lake George is a highly monitored, oligotrophic lake that experiences widespread tourism in the summer months. The southern basin is more developed than the northern basin, suggesting a north-south gradient of anthropogenic impairment. This study aimed to assess differences in nearshore diatom communities regarding gradients of water chemistry and watershed development throughout the lake. Using Redundancy analyses, water chemistry was found to explain more variation within diatom assemblages than watershed variables. Weighted averaging optima and tolerances specified taxa of concern, F. gracilis and A. formosa, that indicate increased phosphorus (μg/L) and conductivity (μS/cm), respectively. Two hypotheses related to the effect …

Surfacant Contamination Alters Freshwater Phytoplankton Community Composition, William H. Hodge

Electronic Theses and Dissertations

Pollution from cleaning and personal care products enter freshwater systems and have the potential to alter phytoplankton abundance and diversity. Alkyl polyglucoside (APG), a widely used foaming agent in detergents, decreases phytoplankton abundance, but whether sensitivity to APG is affected by taxonomic identity and/or the presence of competitors is unclear. Establishing taxon-specific responses to APG is important, because taxa differ in nutritional quality and palatability for zooplankton grazers.

Chapter one describes comparisons between how individual phytoplankton communities respond to the same range of APG concentrations to test hypotheses that: 1) chemical concentration determines how individual taxa respond to APG; 2) …

Assessing The Competitive Advantage Of Carbonic Anhydrase In Estuarine Microalgae Through Removed Enzymatic Activity, Eilea R. Knotts

Theses and Dissertations

Carbon concentrating mechanisms (CCMs) are used by photoautotrophs to overcome possible limitations in carbon acquisition but the competitive strategies and efficiencies of these mechanisms among photosynthesizers can be variable. The diversity in carbon acquisition abilities establishes the potential for alterations in community structure with shifting carbon concentrations. Given the role of phytoplankton and benthic microalgae (BMA) in the trophodynamics of estuaries, understanding the mechanisms of carbon acquisition in these systems is important in predicting how primary productivity and nutrient cycling might change in response to increasing concentrations of atmospheric CO2. Our approach to investigate whether induced carbon limitation would show …

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 Microcystis Microbiome: Interactions With Heterotrophic Bacteria In The Microcystis Phycosphere, Alexa Hoke

Masters Theses, 2010-2019

Harmful algal blooms are a growing problem globally in both freshwater and marine systems. Cyanobacterial harmful algal blooms (cHABs) can have numerous environmental and economic impacts. cHABs can reduce oxygen levels in the water column, ultimately leading to the death of larger organisms, and reduce light penetration, impacting aquatic vegetation. cHABs can also release toxins into the water and efforts to prevent toxins from entering drinking water can cost cities millions of dollars in added filtration. Microcystis is a freshwater cyanobacterium that is globally distributed. While many of the abiotic factors that can impact bloom formation are known, biotic factors, …

Effects Of Invasive Watermilfoil And Seasonal Dynamics On Primary Production In Littoral Zones Of North-Temperate Lakes, Ryan R. Van Goethem

Dissertations, Master's Theses and Master's Reports

Climate change and species invasion are two agents of global change altering aquatic ecosystems worldwide. Submerged aquatic macrophytes control lake ecosystem processes through their direct and indirect interactions with other primary producers, but how their interactions may be altered by species invasions or how they function over full seasonal cycles in temperate lakes is poorly understood. We first addressed whether the presence of invasive watermilfoil (IWM) altered standing crops and gross primary pro-duction (GPP) of other littoral primary producers (macrophytes, phytoplankton, attached algae or periphyton) in littoral zones of 6 Michigan lakes. We found no differences in primary producer standing …

A Comparison Of Phytoplankton Nutrient Limitation Between The Marsh And Beach Environments Of Waties Island, Sc, Raymond Sgambati, George Boneillo

Honors Theses

The aim of this study was to investigate the differences in nutrient limitation within the beach and marsh environments at Waties Island, SC. Conducting the experiment on Waties Island allowed most physical factors to be held as constant, meaning the marsh and beach environments would serve as the only variables. Experiments were performed in the winter, spring, summer and fall of 2018 to determine temporal changes in limitation to phytoplankton and cyanobacteria growth. Nutrient additions included dissolved inorganic nitrogen (nitrate, nitrite, and ammonium), dissolved organic nitrogen (urea), and phosphate. To test for co-limitation, a nitrate & phosphate treatment was also …

Planktonic Diatom Species Succession In San Francisco Bay (September 2015 - December 2017), Theresa Keith

Undergraduate Honors Theses

Since Hutchinson first described the “Paradox of the Plankton” in 1961, research has been done to determine how and why the coexistence of so many different species of phytoplankton is possible. A critical part of this question is species succession, or how the assemblage of phytoplankton in a region changes over time. This study examines the succession of planktonic diatoms in San Francisco Bay, CA (USA) from September 2015 through December 2017 using phytoplankton samples and environmental data. Periodic sampling was conducted at a site in the Golden Gate Strait and taxa were identified using light microscopy and scanning electron …

Nutrient Limitation Of Algal Growth In Fishery Lakes, Madeline Ludwig

Biological and Agricultural Engineering Undergraduate Honors Theses

This study investigated the effect of nutrient addition on algal growth in three United States Forest Service lakes for fishery management in Arkansas. In fishery managed lakes, fertilization works by manipulating algae growth, a basal food resource in lakes, to promote the growth of the fish population. For the nutrient addition experiments, water was collected from each lake in cubitainers and spiked with nutrients; the treatments included the control, nitrogen (+N), phosphorus (+P), and nitrogen and phosphorus (+N +P). When algal growth was visually observed, a water sample was collected from each cubitainer and analyzed for chlorophyll-α. The results showed …