Life Sciences Commons^™

Phytoplankton Growth Rates In The Ross Sea, Antarctica, Anna Ford Mosby

Dissertations, Theses, and Masters Projects

The Ross Sea is a highly productive region of the Southern Ocean characterized by spatially variable distribution of phytoplankton, primarily Phaeocystis antarctica, but phytoplankton growth rates in the region have not been thoroughly investigated. Variability in growth rates was investigated from January to February 2012 on a cruise to the Ross Sea using two methods: 14C-isotopic tracer incubations and dilution experiments. Because all methods of measuring growth rates may not be appropriate in all systems due to errors inherent to each method, I assessed and compared the two methods for possible sources of error by examining the effect of extended …

Effects Of Episodic Turbulence On Diatoms: With Comments On The Use Of Evans Blue Stain For Live-Dead Determinations, Haley S. Garrison

Dissertations, Theses, and Masters Projects

Episodic turbulence is a short-lived, high-intensity phenomenon in marine environments produced by both anthropogenic and natural causes, such as boat propellers, strong winds, and breaking waves. Episodic turbulence has been shown to cause mortality in zooplankton, but its effects on marine phytoplankton have rarely been investigated. This study focused on two diatoms: Thalassiosira weissflogii and Skeletonema costatum. I found that exposure for 45 s to turbulence intensities above 2.5 cm2 s-3 caused 24-32% reduction in diatom abundance and increased the amount of intact dead cells to 22%. Turbulence also caused extracellular release of optically reactive DOM. At a turbulence level …

Seasonal Nitrogen Uptake And Regeneration In The Water Column And Sea-Ice Of The Western Coastal Arctic, Steven E. Baer

Dissertations, Theses, and Masters Projects

The logistical difficulties of research in extremely low temperatures and lack of access to the Arctic have meant that there is a historic dearth of knowledge of coastal Arctic biogeochemistry, especially during winter when sea ice is present. Recent observations, however, indicate that the Arctic is changing rapidly. Changes include increased temperatures, decreased extent and volume of sea ice, and increased freshwater inputs. How these changes influence biogeochemical cycles is an open question, especially in the highly productive coastal regions of the Chukchi Sea. Here I present nitrogen (N) uptake and regeneration rates for phytoplankton and bacteria measured in the …

Improvements In Triploid Crassostrea Virginica Production: Characterizing The Diploid Parent, Brian R. Callam

Dissertations, Theses, and Masters Projects

The effect of triploidy to effect faster growth and increased survival compared to diploid oysters is called the ‘triploid advantage’ and this advantage in the Chesapeake Bay for Crassostrea virginica is the principal reason for the value of triploid C. virginica in the Chesapeake Bay, USA. The triploid advantage is hypothesized to be the result of genetic effects, physiological changes, or a combination of both. The causative genetic mechanisms at play may include additive genetic effects and heterosis while the physiological changes obtain from triploid sterility. The triploid advantage was examined by comparing 13 diploid and 13 triploid crosses across …

Modeling The Formation Of Periodic Hypoxia In Partially Mixed Estuaries And Its Response To Oligotrophication And Climate Change, Samuel J. Lake

Dissertations, Theses, and Masters Projects

The development of hypoxia represents one of the most common and ecologically detrimental effects of anthropogenic nutrient enrichment in coastal marine ecosystems. Due to the physiological importance of oxygen as a key component of metabolic processes, the development and persistence of hypoxia can reduce the distribution of important species, modify food webs, decrease diversity and richness, and sub-lethally affect growth and reproductive rates. While many recent studies have focused on the global increase in hypoxia and highlighted the need for nutrient reduction strategies, some key processes associated with hypoxia remain understudied. of particular importance is the resolution of the major …

Investigations Of The Life Cycle Of The Peritrich Ciliate Zoothamnium Intermedium In Chesapeake Bay, Sikai Peng

Dissertations, Theses, and Masters Projects

Epibiosis is a common phenomenon in aquatic environments. The chitinous exoskeletons of crustaceans provide stable surfaces for attachment and growth of epibiotic microorganisms. Epibiont ciliate colonization on copepods is commonly recorded but has rarely been studied in Chesapeake Bay; also, little is known about the life cycles of epibiont ciliates in the bay.

The present work focuses on the life cycle of Zoothamnium intermedium in Chesapeake Bay. A peritrich ciliate belonging to the genus Zoothamnium was found as an epibiont on the calanoid copepods Acartia tonsa and Pseudodiaptomus pelagicus during the summer in the York River, a tributary of the …

Distribution And Impacts Of Invasive Bivalve Corbicula Fluminea In Tidal Freshwater York River Tributaries, Matthew Ryan Freedman

Dissertations, Theses, and Masters Projects

The Asian clam, Corbicula fluminea, is one of the most invasive bivalves in the world but there is limited research on its presence in tidal freshwater systems. Despite its introduction into Chesapeake Bay tributaries in the 1970s, the initial colonization and subsequent development of populations of C. fluminea in the Mattaponi and Pamunkey sub-tributaries of the York River, Virginia, is mostly undocumented. This study assessed the spatial distribution and population structure of C. fluminea in tidal freshwater sections of these rivers (~45km) with benthic surveys during summer 2011 – 2012. Benthic grabs (2.4L, 0.023m2) taken at 40 sites in each …

Foraging Ecology And Habitat Use Of The Northern Diamondback Terrapin (Malaclemys Terrapin Terrapin) In Southern Chesapeake Bay, Diane C. Tulipani

Dissertations, Theses, and Masters Projects

The northern diamondback terrapin (Malaclemys terrapin ) is the only estuarine turtle residing along western Atlantic and Gulf of Mexico coasts of North America. Through predation, terrapins may be a key species in coastal marine habitats by exerting top-down control on marsh invertebrates, and thereby help to maintain healthy marshes. Despite the terrapin's ecological importance, there has not been a thorough study of terrapin foraging ecology and movements in lower Chesapeake Bay. In this dissertation, the research focused on the foraging habits of diamondback terrapins and their effects within salt marsh and seagrass habitats of lower Chesapeake Bay. I provided …