Cold seeps are areas of high biomass in the deep-sea, the impacts of these food-rich environments upon the sediment community is unknown in the Gulf of Mexico. The structure and function of benthic communities was investigated at food-rich and food-limited sites on the northern Gulf of Mexico continental slope. Cold seeps were richer in macrofauna densities and total sediment respiration, but were poorer in biomass and taxa diversity than normal slope communities. Decreased diversity is seen at most chemosynthetic communities and suggests a competition for resources. The spatial extent of these results at seeps is unknown and may be a localized, bioenhancement effect caused by seeping fluids.

published_or_final_version / Ecology and Biodiversity / Master / Master of Philosophy

The Little Lagoon is a shallow sandflat habitat situated in Durban Bay, which has been earmarked for removal, as part of the port expansion. In order to prevent the possible loss of such a significant habitat, it was proposed that this habitat be re-created elsewhere in the Bay. The aims of this project were therefore to provide a detailed assessment of the macrobenthic habitat of the Little Lagoon, and to identify the major determinants of the community structure. The ultimate goal was to provide essential background information to assess the success of the recreation of the Little Lagoon. Apart from seasonal changes in water temperature, no ecologically significant temporal fluctuations in the physical environment of the Little Lagoon were detected. This was directly translated into an extremely stable macrobenthic community, in which negligible seasonal changes to its composition were recorded. The polychaetes Prionospio sexoculata, Glycera sp, the isopod Leptanthura laevigata and cumaceans dominated the community during every sampling season. From a spatial perspective, particle sizes and organic contents of surficial sediments were the major determinants of macrobenthic community structure. Densities of macrofauna were three to five times higher in organically rich sediments, and were dominated by surface and sub-surface deposit feeders such as the tanaid Apseudes digitalis and cirratulid polychaetes. In organically poor sediments, burrowing infauna such as Prionospio sexoculata and Glycera sp. dominated. Significantly though, biological interactions, specifically bioturbation by the sandprawn Callianassa kraussi, was an important determinant of community structure in the Little Lagoon. Two zones of high and low abundance of C. kraussi were recorded in the Little Lagoon. Abundance, species richness and diversity of macrofauna were significantly lower in the zone of high C. kraussi abundance. These parameters were significantly and negatively influenced by the abundance of C. kraussi, indicating that C. kraussi may act as a disturbance organism. Surface dwelling macrofauna were recorded in the zone of low C. kraussi abundance, but not in the zone of high C. kraussi abundance. It appeared that the bioturbative activity of C. kraussi of expelling sediment from burrows to the sediment surface resulted in the exclusion surface dwelling fauna, and played a major role in structuring the Little Lagoon macrobenthic community. / Thesis (M.Sc.)-University of Natal, Durban, 2002.

This research examined the toxicity of complex industrial effluents as measured by chemical analyses, whole effluent toxicity (WET) tests and surveys of the receiving water biota. Toxicity of final effluents from 45 diverse facilities was examined to determine whether inferred toxicity based on presence and concentration of priority substances could predict WET, calculated from a battery of bioassays on bacteria, cladocerans and algae. Following corrections of inferred toxicity for particle-bound contaminants and adjustment for free ion activity, correlation between inferred and whole effluent toxicity was highly significant. Effluents with elevated metal concentrations exhibited lower WET than predicted, likely due to negative interactions among trace metals; kraft mill effluents exhibited higher WET than predicted which is consistent with findings in the literature. / The ability of laboratory WET tests to predict thresholds of invertebrate community response to a complex industrial effluent was examined. Patterns in invertebrate community structure were detrended for environmental factors and compared to measured instream effluent concentrations. Laboratory effect thresholds, reported as Maximum Allowable Toxicant Concentrations (MATC), were calculated from a battery of toxicity tests on bacteria, algae, cladocerans and fish. Declines in taxonomic richness corresponded to calculated lab thresholds, while changes in abundance of total taxa and sensitive taxa, (Ephemeroptera, Plecoptera, Trichoptera) occurred at lower concentrations than predicted from MATCs. The tendency for invertebrate abundance to decline at lower instream effluent concentrations than richness supports findings in the literature. Lack of correspondence between lab and field thresholds may be ameliorated by the addition of behavior endpoints, (e.g. avoidance) to toxicity tests.

Thesis (M.S.)--University of Hawaii at Manoa, 2007. / Includes bibliographical references (leaves 94-96). / ix, 96 leaves, bound col. ill., col. maps 29 cm

Thesis (Ph. D.)--West Virginia University, 2007. / Title from document title page. Document formatted into pages; contains xi, 170 p. : ill. (some col.), maps. Vita. Includes abstract. Includes bibliographical references.

Univ., Diss.--Bremen, 1998. / Literaturverz. S. 116 - 140.

Thesis (Ph. D.)--University of Sydney, 1999. / Title from title screen (viewed Apr. 21, 2008). Submitted in fulfilment of the requirements for the degree of Doctor of Philosophy to the Dept. of Chemical Engineering, Graduate School of Engineering. Includes bibliography. Also available in print form.

Thesis (Ph.D.)--Murdoch University, 2007. / Thesis submitted to the Faculty of Sustainability, Environmental and Life Sciences. Includes bibliographical references (leaves 249-274)

Thesis (Ph. D.)--Rutgers University, 2008. / "Graduate Program in Ecology and Evolution." Includes bibliographical references (p. 186-199).