Life Sciences Commons^™

Effect Of Temperature On Growth And Gene Expression In The Marine Diatom, Thalassiosira Pseudonana, John M. Foster

USF Tampa Graduate Theses and Dissertations

Diatoms are unicellular, eukaryotic, photosynthetic algae responsible for the production of 20% of our atmospheric oxygen. Diatoms contribute to several important biogeochemical functions. Diatoms contribute to the carbon cycle, sequestering carbon and forming oxygen as a product of photosynthesis. Moreover, by converting abiotic forms of energy such as sunlight into organic compounds (i.e., sugars, starches and lipids), primary producers including diatoms, plants, and phytoplankton feed organisms at higher trophic levels. Consequently, changes in temperature, light intensity, nutrients, salinity and other stress factors that affect primary producers can generate a potentially catastrophic ripple effect at higher trophic levels In this study …

Microbial Community Structures In Three Bahamian Blue Holes, Meghan J. Gordon

USF Tampa Graduate Theses and Dissertations

This study used 16S rDNA metagenomics and water chemistry to conduct an examination of microbial community dynamics and biogeochemistry in three physically adjacent, sunlit blue holes with variable hydrologic regimes on San Salvador Island, Bahamas. Church and Watling’s Blue Holes are holomictic with relatively clear waters, while Inkwell Blue Hole hosts density stratification and waters stained brown with tannins. Based on water color and clarity and physicochemical profiles, I hypothesized Church and Watling’s Blue Holes would be dominated by oxigenic photoautotrophs, and that the bottom layer of Inkwell would be characterized by euxinic (anoxic and sulfidic) conditions and host primarily …

The Growth Response Of Two Diatom Species To Atmospheric Dust From The Last Glacial Maximum, Tim M. Conway, Linn J. Hoffmann, Eike Breitbarth, Robert F. Strzepek, Eric W. Wolff

Marine Science Faculty Publications

Relief of iron (Fe) limitation in the surface Southern Ocean has been suggested as one driver of the regular glacial-interglacial cycles in atmospheric carbon dioxide (CO2). The proposed cause is enhanced deposition of Fe-bearing atmospheric dust to the oceans during glacial intervals, with consequent effects on export production and the carbon cycle. However, understanding the role of enhanced atmospheric Fe supply in biogeochemical cycles is limited by knowledge of the fluxes and 'bioavailability' of atmospheric Fe during glacial intervals. Here, we assess the effect of Fe fertilization by dust, dry-extracted from the Last Glacial Maximum portion of the EPICA Dome …

Nitrogen Inputs And Losses In Response To Chronic Co2 Exposure In A Subtropical Oak Woodland, B. A. Hungate, B. D. Duval, P. Dijkstra, D. W. Johnson, M. E. Ketterer, Peter Stiling, W. Cheng, J. Millman, A. Hartley, D. B. Stover

Integrative Biology Faculty and Staff Publications

Rising atmospheric CO₂ concentrations may alter the nitrogen (N) content of ecosystems by changing N inputs and N losses, but responses vary in field experiments, possibly because multiple mechanisms are at play. We measured N fixation and N losses in a subtropical oak woodland exposed to 11 years of elevated atmospheric CO₂ concentrations. We also explored the role of herbivory, carbon limitation, and competition for light or nutrients in shaping the response of N fixation to elevated CO₂. Elevated CO₂ did not significantly alter gaseous N losses, but lower recovery and deeper distribution in the …

Chlorophyll Fluorescence And Thermal Stress In Archaias Angulatus (Class Foraminifera), Heidi M. Toomey

USF Tampa Graduate Theses and Dissertations

ABSTRACT

Benthic foraminifers that host algal symbionts are similar to corals in that they rely on their algal endosymbionts for their energy needs, calcify prolifically, and are sensitive to changes in environmental conditions. They are abundant in the benthos of coastal coral-reef areas and are found throughout the tropical and subtropical regions. Pulse Amplitude Modulated (PAM) chlorophyll fluorometry and chlorophyll a extraction techniques were used to quantify and compare the photosynthetic responses of the benthic foraminiferal, Archaias angulatus and their isolated endosymbionts, Chlamydomonas hedleyi, to short-term changes in temperature. Maximum quantum efficiency (F_v/F_m) and rapid …

Consequences Of Kleptoplasty On The Distribution, Ecology, And Behavior Of The Sacoglossan Sea Slug, Elysia Clarki, Michael Louis Middlebrooks

USF Tampa Graduate Theses and Dissertations

The sacoglossan sea slug Elysia clarki is able to photosynthesize for three to four months using chloroplasts sequestered from its algal food sources. Furthermore, the slug is able to store multiple chloroplasts from different algal species within the same cell. This research, consisting of several related studies, explores the role that provision of organic nutrients via photosynthesis plays in the biology of the slug. The first chapter demonstrates that, under conditions of starvation, photosynthetic activity in E. clarki remains fully functional for one month after which it then declines. During the first month of starvation the slug exhibits similar feeding …