Marine Biology Commons^™

Fecal Pellet Production By North Atlantic Zooplankton, Michael Gibson

Undergraduate Honors Theses

Fecal pellet carbon (FPC) production by zooplankton is a significant component of the ocean’s biological carbon pump: the suite of biological processes that mediate export of carbon to the deep ocean, ultimately leading to the sequestration of atmospheric carbon dioxide in the ocean. In this study, mesozooplankton (zooplankton 0.2 mm to ~2 cm) were collected from the epipelagic zone in the temperate North Atlantic Ocean during day and night in May 2021. Zooplankton were live separated into five size fractions and incubated on board ship in natural surface seawater to measure fecal pellet production rate of the mixed mesozooplankton community. …

Carrying Capacity Of Cultured Bivalves In Cherrystone Inlet, Va, And The Implications Of Spatial Distribution And Environmental Change, Sophia Chirico

Undergraduate Honors Theses

Aquaculture is a growing industry internationally. In the United States, aquaculture of bivalves occurs throughout the Chesapeake Bay. Cherrystone Inlet, a tidal inlet on the Virginia Eastern Shore, is the location of intensive hard clam culture, and recently oyster aquaculture has become common there as well. Given the intensive culture in Cherrystone and similar systems in the Chesapeake, it is important to understand the carrying capacity of the respective bivalves and how they can be grown together. Carrying capacity is defined here as the largest population of individuals that can be supported that allows individuals to reach a harvestable size …

Juvenile Blue Crab (Callinectes Sapidus) Response To Altered Nursery Habitat, Megan Wood

Dissertations, Theses, and Masters Projects

Habitats of Chesapeake Bay have been altered due to anthropogenic impacts and climate change. Due to these human disturbances, seagrasses have been extirpated from many areas in lower Chesapeake Bay and persisting beds face future losses as water temperatures continue to rise. Further loss of seagrass habitat will negatively impact juvenile blue crabs (Callinectes sapidus) that use seagrass beds as nursery grounds. Habitat degradation allows for more successful introductions of exotic species, and the communities formed from the mixing of native and exotic species are known as emerging ecosystems. Gracilaria vermiculophylla, an exotic macroalga, may be an emerging nursery habitat …

Nitrogen Isotope Fractionation And Toxin Production During The Uptake Of Micromolar Concentrations Of Nitrate, Ammonium, And Urea By A Marine Dinoflagellate, Christen Taylor Armstrong

Dissertations, Theses, and Masters Projects

Despite an increased global interest in harmful algal bloom (HAB) species and eutrophication, the relationship between nutrient sources and changes in species composition or toxicity remains unclear. Stable isotopes are routinely used to identify and track nitrogen (N) sources to water bodies, as sources can be differentiated based on stable isotope values. While literature is available describing N fractionation by diatoms and coccolithophores, data are greatly lacking regarding isotope fractionation by dinoflagellates. Here we investigate the fractionation of nitrogen isotopes by saxitoxin-producing Alexandrium fundyense, to validate the use of the δ15N of particulate organic matter and identify the nitrogen source …

Spatiotemporal Abundance Patterns And Ecological Drivers Of A Nearshore U.S. Atlantic Fish And Invertebrate Assemblage, Mark A. Stratton

Dissertations, Theses, and Masters Projects

Taking an ecosystem approach to fisheries requires the consideration of relevant ecological processes within research and assessment frameworks. Processes affecting ecosystem productivity can be categorized as biophysical (climate variability, primary production), exploitative (fishing), or trophodynamic (food web interactions). This dissertation incorporates these three governing processes to characterize spatiotemporal diversity and population abundance trends for multiple demersal fish and invertebrate species that inhabit the nearshore zone (15-30 ft. depth) along portions of the U.S. Atlantic east coast.

Two large marine ecosystems (LMEs) encompass the U.S. East coast – the Southeast and Northeast U.S. Continental Shelf LMEs. The level of connectivity within …

Modeling Phytoplankton Community Response To Nutrient Loading And Climate Change In A Shallow Temperate Estuary, Sara Aimee Blachman

Dissertations, Theses, and Masters Projects

Phytoplankton account for at least half of all primary production in estuarine waters and are at the center of biogeochemical cycles and material budgets. Environmental managers use water column chlorophyll-a (chl-a) concentrations as a basic water quality indictor, as the problems of eutrophication and hypoxia are intrinsically linked to excessive phytoplankton growth. Evidence suggests that the distribution and frequency of harmful algal blooms may be increasing worldwide. For the most part, phytoplankton communities follow a standard seasonal pattern, with specific groups dominating the assemblage during the time of year when environmental conditions correspond to their requisites for growth. However, climate …

Assemblage Dynamics Of Larval Fishes In The York River Of Virginia And The Chesapeake Bay, Cindy Marlene Marin Martinez

Dissertations, Theses, and Masters Projects

This thesis developed from the VIMS Larval Fish Monitoring Program, which began in 2007 as part of a study comparing the larval fish assemblages of Chesapeake and Delaware Bays. Ribeiro et al. (2015) analyzed data from the first three years of this time series to describe the temporal variation in the larval fish assemblages. After this initial study was completed (three years in duration), the sampling continued at the fixed station near the mouth of the York River, which was used to represent the Chesapeake Bay. For this thesis, therefore, eight years of data (2007-2015) were available to investigate temporal …

Influence Of Structural Complexity And Location On The Habitat Value Of Restored Oyster Reefs, Melissa Ann Karp

Dissertations, Theses, and Masters Projects

In the Chesapeake Bay, < 1% of the historic oyster population remains, and efforts have been increasing to restore oysters and the services they provide. Building reefs that successfully provide ecosystem services–especially habitat and foraging grounds–may require different restoration techniques than those previously used, and success may depend on reef morphology (complexity), location, and environmental conditions. Salinity and habitat complexity are two important factors that may interact to effect benthic communities and predator-prey interactions on restored reefs. The goals of this project were: (1) Characterize the benthic communities on restored oyster reefs in lower Chesapeake Bay, and (2) examine the effects of structural complexity and salinity on benthic communities and predator-prey interactions. A two-year field survey of restored reefs was carried out in four rivers in lower Chesapeake Bay to characterize faunal communities on restored reefs and to quantify the effect of reef complexity on faunal communities. A laboratory mesocosm experiment was conducted to examine the effect of reef complexity on predator foraging. In total, 61 macrofaunal species were identified among all samples, and restored reefs supported on average, 6,169 org/m2 and 67.88 g-AFDW/m2. There were significant differences in the community composition and diversity among the rivers, and salinity was the environmental factor that best explained the observed differences in species composition across the rivers. Salinity and rugosity (i.e., structural complexity) both positively affected diversity, while salinity negatively affected macrofaunal abundance and biomass. Oyster density and rugosity positively affected macrofaunal biomass, and oyster density positively affected mud crab, polychaete, and mussel densities. In the mesocosm experiment, predator foraging, measured by proportion and number of prey consumed, was significantly reduced in the presence of oyster shell structure. However, predators were able to consume more prey when prey density was increased, even in the presence of oyster shell structure. These results combine to enhance our understanding of the benefits of increased habitat complexity for both prey and predators on restored oyster reefs. Increasing complexity worked to increase the abundance, biomass, and diversity of organisms inhabiting restored reefs, and even though predator consumption was reduced in the presence of structure compared to non-structured habitat, predators were able to consume more prey individuals when prey density was increased. Therefore, increasing the structure of oyster reef habitat may benefit prey species by providing refuge habitat, and benefit predators by providing an increased abundance of available prey items.

Modulation Of Watershed Nutrient Loads By Tidal Creek Ecosystems On The Virginia Eastern Shore, Britt Leighanne Dean

Dissertations, Theses, and Masters Projects

While deeper estuaries typically demonstrate predictable responses to increased nutrient loads, responses in shallow systems are more varied, due in part to the presence of multiple benthic autotrophs. Shallow systems are particularly vulnerable to increases in watershed nutrient loads due to their position at the interface between land and open water. The prevailing conceptual model of eutrophication for shallow systems currently describes a succession in the dominant autotroph from seagrass to macroalgae to phytoplankton, but this model does not include benthic microalgae, which can sequester nutrients in photic systems. The Virginia Eastern Shore is characterized by shallow lagoons connected to …

Finfish Communities Of Two Intertidal Marshes Of The Goodwin Islands, York River, Virginia, Lisa Ann Ayers

Dissertations, Theses, and Masters Projects

The finfish communities using the intertidal surfaces of a bay-exposed marsh and a sheltered, channel marsh of the Goodwin Islands, York River, Virginia were studied from May to November 1994. Samples were taken approximately twice monthly using a flume weir at three stations in each marsh. Species composition, abundance and biomass were estimated, and growth patterns and production rates were described for the dominant species. A total of 3001 fish were collected from 11 species and 8 families. Fundulus heteroclitus dominated both marshes and accounted for 83.07% of the total number of fish caught, and 84.83% of the total biomass …

Zooplankton Distribution, Biomass, Biochemical Composition And Seasonal Community Structure In Lower Chesapeake Bay, Fred Jacobs

Dissertations, Theses, and Masters Projects

Zooplankton composition, distribution, biomass and biochemical constituents were determined monthly in the lower Chesapeake Bay for two years beginning in August 1971. Settled volume, dry weight, and ash-free dry weight estimates of total biomass were generally consistent in showing summer and late winter peaks. A mean dry weight peak of 258 mg/m3 in August 1971 decreased precipitously to a December low of 9 mg/m3, then increased to a March 1972 peak of 199 mg/m3. The second year mirrored this pattern, except that the passage of Tropical Storm Agnes in June 1972 lowered the summer peak values for July and August …

The Effects Of Pollution On Benthic Communities Of The Tidal James River, Virginia, Robert J. Diaz

Dissertations, Theses, and Masters Projects

Benthic communities in the estuarine portion of the James River are controlled mainly by salinity. Pollution effects are localized and difficult to assess because of the rigorous physical environment. Mesohaline and oligohaline communities were very similar to those in other east coast estuaries. except for the dominance of Rangia cuneata in the oligohaline zone. Communities of the tidal freshwater zone are most affected by pollution. In the areas of Richmond and Hopewell, where the major portion of the pollution load enters the river, communities are most severely depressed. Separate multivariate analyses of species distributional patterns, and pollution and physical parameters …

Nitrogen Fixation In Virginia Salt Marshes And The Effects Of Chronic Oil Pollution On Nitrogen Fixation In The Mobjack Bay Marshes, Alyce Diane Thomson

Dissertations, Theses, and Masters Projects

N2 fixation rates for several Virginia salt marshes were determined using in situ acetylene-reduction assays. A control and a chronically polluted oil marsh of the mesohaline Mobjack Bay area were sampled over a 1975-76 annual cycle. N2 fixation occurred in all transects which extended from upper mudflat to the Spartina patens zone. An isolated blue-green algal mat exhibited some of the highest N2 fixation rates. Intertidal sediment N2 fixation was patchy, both spatially and seasonally. However average rates (91.45 μg N/m2/h) compared to the estimated N requirement of the graminoid vegetation indicated a significant contribution to the N budget. Vegetation …

Uptake, Metabolism, And Distribution Of Ddt In Organs Of The Blue Crab, Callinectes Sapidus, Peter F. Sheridan

Dissertations, Theses, and Masters Projects

Metabolites of DDT were detected in five out of six major organs of blue crabs, Callinectes sapidus, taken from estuarine populations. Residue concentrations were highest in the hepatopancreas and below the limit of detection in the heart. Concentrations in pooled gonad samples (ovaries + testes) depended on the stage of development of the ovaries. Residue levels were low in claw and backfin muscles. Adult blue crabs were exposed for 12 hours to 0.01, 0.1, and 1.0 ppm DDT in water. No significant mortality was recorded. DDT was absorbed through the gills and transported to the hepatopancreas via the hemolymph. Biotransformation …

Feasibility Of Artificial Propagation And Introduction Of Hybrids Of The Morone Complex Into Estuarine Environments, With A Meristic And Morphometric Description Of The Hybrids, Jerome Howard Kerby

Dissertations, Theses, and Masters Projects

Laboratory and environmental studies of striped bass (Morone saxatilis) X white perch (M. americana) and striped bass X white bass (M. chrysops) were used to-determine the feasibility of introducing these hybrids into an estuary as a supplement to natural populations of the parental species. Growth patterns, survival, and general hardiness of the hybrids were used as criteria. Growth of striped bass X white perch hybrids in the laboratory was apparently somewhat less than growth of natural populations of striped bass, but was much greater than growth of natural populations of white perch. Hybrid growth was slower than striped bass growth …