No description available.

The objective of this project was to use ribosomal RNA genes, cloned from natural populations of Sargasso Sea bacterioplankton, as markers for picoplankton diversity. It is widely recognised that a majority of microorganisms have yet to be cultivated, and therefore much of extant microbial diversity remains unknown (50). The method described here for analyzing natural bacterial communities circumvents this problem by utilizing ribosomal RNA, found in all life forms, for defining and enumerating the components of natural populations. Two different clone libraries of eubacterial 16S rRNA genes amplified from a natural population of Sargasso Sea picoplankton by the polymerase chain reaction (11) have been phylogenetically analysed. The analyses indicate the presence of a wide variety of novel microorganisms, representing members of the α and γ proteobacteria and the oxyphototroph (13, 47) eubacterial phyla. One group of novel clones, represented by SAR 83, were found to be most closely related to Erythrobacter, a genus of aerobic bacteriochlorophyll~ containing organisms. The results imply that many closely related 16S rRNA lineages, or clusters of lineages, coexist within bacterioplankton communities. The significance of these clusters is uncertain. One interpretation, that they represent clonal structure within bacterial species, suggests that populations of marine bacteria are very ancient. / Graduation date: 1991

No description available.

No description available.

<p>The essay investigates hybridity in Jean Rhys's <em>Wide Sargasso Sea</em> with a focus on the main character Antoinette. Homi K Bhabha's theory of hybridity provides a way to analyze Antoinette's predicament as an outsider and threat to both the Caribbean society she is living in and her English husband. The aim of the essay is to examine the alienation and rejection of Antoinette in the light of her hybridity.</p>

The essay investigates hybridity in Jean Rhys's Wide Sargasso Sea with a focus on the main character Antoinette. Homi K Bhabha's theory of hybridity provides a way to analyze Antoinette's predicament as an outsider and threat to both the Caribbean society she is living in and her English husband. The aim of the essay is to examine the alienation and rejection of Antoinette in the light of her hybridity.

Thesis (Ph. D.)--Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1976.

The essay is about the unnamed husband in Jean Rhys's Wide Sargasso Sea. About how he is depicted as the European "Other" and made into a feminized and zombified weak character from a Caribbean/feminist perspective...

Sperm whales (Physeter macrocephalus) are widely distributed in all oceans, but principally found in areas of high primary productivity. Historically, they were whaled extensively in the Sargasso Sea and recent surveys have also found large numbers there. However, the Sargasso Sea is an oceanic gyre considered to be low in productivity. This dissertation explores the paradox of a high abundance of large top predators in a body of water once described as an “oceanic desert”. First, I compared the diet of sperm whales in the Sargasso Sea to those off Dominica, in the eastern Caribbean. Results suggested differences in trophic ecology between these two areas, with sperm whales in the Sargasso Sea feeding at a higher trophic level. Second, I examined the spatial and temporal distribution of sperm whales in the Sargasso Sea in relation to environmental variables using acoustic surveys and autonomous recording devices. Sperm whale prevalence around Kelvin seamount, part of the New England Seamount Chain, was higher in the spring compared to the winter. Habitat modeling results suggest that the mesoscale activity associated with the Gulf Stream plays an important role in sperm whale occurrence in this area, likely due to the enhancement of primary productivity in this region. Finally, I estimated the current density of sperm whales in the northwestern Sargasso Sea and compared their present distribution to their distribution during the open-boat whaling era (1775-1921). Sperm whale density in the northern Sargasso Sea is one of the highest found globally, showing that this region remains a hotspot for sperm whales. The area where sperm whale detections per unit effort is presently the highest showed little overlap with areas where whales were hunted historically. Whalers all but ignored this region except when transiting to other whaling grounds, perhaps a result of fixed whaling patterns due to the conservative use of knowledge at that time. My dissertation highlights patterns and processes that help to explain the presence and abundance of sperm whales in the Sargasso Sea and demonstrates the importance of western boundary currents, such as the Gulf Stream, to the distribution of marine top predators.

abstract: Phytoplankton comprise the base of the marine food web, and, along with heterotrophic protists, they are key players in the biological pump that transports carbon from the surface to the deep ocean. In the world's subtropical oligotrophic gyres, plankton communities exhibit strong seasonality. Winter storms vent deep water into the euphotic zone, triggering a surge in primary productivity in the form of a spring phytoplankton bloom. Although the hydrographic trends of this "boom and bust" cycle have been well studied for decades, community composition and its seasonal and annual variability remains an integral subject of research. It is hypothesized here that proportions of different phytoplankton and protistan taxa vary dramatically between seasons and years, and that picoplankton represent an important component of this community and contributor to carbon in the surface ocean. Monthly samples from the Bermuda Atlantic Time-series Study (BATS) site were analyzed by epifluorescence microscopy, which permits classification by morphology, size, and trophic type. Epifluorescence counts were supplemented with flow cytometric quantification of Synechococcus, Prochlorococcus, and autotrophic pico- and nanoeukaryotes. Results from this study indicate Synechococcus and Prochlorococcus, prymnesiophytes, and hetero- and mixotrophic nano- and dinoflagellates were the major players in the BATS region plankton community. Ciliates, cryptophytes, diatoms, unidentified phototrophs, and other taxa represented rarer groups. Both flow cytometry and epifluorescence microscopy revealed Synechococcus to be most prevalent during the spring bloom. Prymnesiophytes likewise displayed distinct seasonality, with the highest concentrations again being noted during the bloom. Heterotrophic nano- and dinoflagellates, however, were most common in fall and winter. Mixotrophic dinoflagellates, while less abundant than their heterotrophic counterparts, displayed similar seasonality. A key finding of this study was the interannual variability revealed between the two years. While most taxa were more abundant in the first year, prymnesiophytes experienced much greater abundance in the second year bloom. Analyses of integrated carbon revealed further stark contrasts between the two years, both in terms of total carbon and the contributions of different groups. Total integrated carbon varied widely in the first study year but displayed less fluctuation after June 2009, and values were noticeably reduced in the second year. / Dissertation/Thesis / M.S. Microbiology 2010