Life Sciences Commons^™

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- …