Aerosol production from surface waters results in the transfer of aquatic materials (including nutrients and bacteria) to air. These materials can then be transported by onshore winds to land, representing a biogeochemical connection between aquatic and terrestrial systems not normally considered. In urban waterfront environments, this transfer could result in emissions of pathogenic bacteria from contaminated waters. Despite the potential importance of this link, sources, near-shore deposition, identity and viability of microbial aerosols are largely uncharacterized. This dissertation focuses on the environmental and biological mechanisms that define this water-air connection, as a means to build our understanding of the biogeochemical, biogeographical, and public health implications of the transfer of surface water materials to the near-shore environment in both urban and non-urban environments. The effects of tidal height, wind speed and fog on coastal aerosols and microbial content were first quantified on a non-urban coast of Maine, USA. Culture-based, culture-independent, and molecular methods were used to simultaneously sample microbial aerosols while monitoring meteorological parameters. Aerosols at this site displayed clear marine influence and high concentrations of ecologically-relevant nutrients. Coarse aerosol concentrations significantly increased with tidal height, onshore wind speed, and fog presence. Tidal height and fog presence did not significantly influence total microbial aerosol concentrations, but did have a significant effect on culturable microbial aerosol fallout. Molecular analyses of the microbes settling out of near-shore aerosols provided further evidence of local ocean to terrestrial transport of microbes. Aerosol and surface ocean bacterial communities shared species and in general were dominated by organisms previously sampled in marine environments. Fog presence strengthened the microbial connection between water and land through air by increasing microbial aerosol settling rates and enhancing viability of aerosolized marine microbes. Using methods developed for the non-urban site, the role of local environment and winds in mediating water-air connections was further investigated in the urban environment. The local environment, including water surfaces, was an important source of microbial aerosols at urban sites. Large portions of the urban waterfront microbial aerosol communities were aquatic and, at a highly polluted Superfund waterfront, were closely related to bacteria previously described in environments contaminated with hydrocarbons, heavy metals, sewage and other industrial waste. Culturable urban aerosols and surface waters contained bacterial genera known to include human pathogens and asthma agents. High onshore winds strengthened this water-air connection by playing both a transport and production role. The microbial connection between water and air quality outlined by this dissertation highlights the need for information on the mechanisms that deliver surface water materials to terrestrial systems on a much larger scale. Moving from point measurements to landscape-level analyses will allow for the quantitative assessment of implications for this microbial water-air-land transfer in both urban and non-urban arenas.

<p>Rates of habitat alteration and degradation are increasing worldwide due to anthropogenic influence. On coral reefs, the loss of live coral reduces structural complexity while facilitating algal increase. In many coastal lagoons seagrass and corals are cleared to make room for cultivated macroalgae. This thesis deals with reef and lagoon habitat structure and how fish assemblage patterns may be related to physical and biological features of the habitat. It further examines assemblage change following habitat disturbance. Four studies on East African coral reefs concluded that both the abundance and species richness of recruit and adult coral reef fish were largely predicted by the presence of live coral cover and structural complexity (Papers I-III, VI). Typically, recruits were more selective than adults, as manifested by limited distributions to degraded sites. Paper VI compared short- and long-term responses of fish assemblages to the 1997-1998 bleaching event. The short-term response to coral mortality included the loss of coral dwelling species in favour of species which feed on algae or associated detrital resources. Counterintuitively, fish abundance and taxonomic richness increased significantly at one of two sites shortly after the bleaching. However, the initial increase was later reversed and six years after the death of the coral, only a limited number of fish remained. The influence of fleshy algae on fish assemblages was studied in algal farms (Paper IV), and examined experimentally (Paper V). The effects of algal farming in Zanzibar were significant. Meanwhile, manually clearing algal-dominated patch reefs in Belize from macroalgae resulted in short-term increases of abundance, biomass and activity of a few species, including major herbivores. The findings of this thesis demonstrate the significance of habitat as a structuring factor for tropical fish assemblages and predicts that coral death, subsequent erosion and algal overgrowth may have substantial deleterious impacts on fish assemblage composition, abundance and taxonomic richness, with recovery being slow and related to the recovery of the reef framework.</p>

<p><strong>Abstract</strong></p><p>The European eel (<em>Anguilla anguilla</em>) migrates to the Sargasso Sea to spawn. Even though the biology of <em>A. anguilla </em>leptocephali in the Sargasso Sea has been studied for several decades, information regarding their diet has remained unknown until now. Previous dietary studies concerning other species of leptocephali in the Pacific Ocean have been limited to the recognition of identifiable prey remains amongst gut contents. Hence, in this study a molecular approach relying on the detection of prey DNA amongst gut contents was used to study dietary profiles of <em>A. anguilla</em> leptocephali in the Sargasso Sea.</p><p> </p><p>Leptocephali were collected during the circumglobal Galathea 3 expedition in spring 2007 to the Sargasso Sea. DNA extracted from gut contents were PCR amplified using universal primers targeting the nuclear 18S rRNA gene. In order to separate eel amplicons from prey amplicons, PCR products were analyzed by denaturing gradient gel electrophoresis (DGGE). Furthermore, clone libraries were constructed using universal primers targeting a portion of the 18S rRNA and mitochondrial COI gene, respectively. In total, the gut contents of 78 leptocephali were screened by DGGE.</p><p> </p><p>A diverse array of eukaryotic taxa was identified, hence demonstrating the applicability of a universal PCR- DGGE approach to study gut contents of leptocephali. The results presented here show, for the first time, that young stages of <em>A. anguilla</em> leptocephali feed on a large variety of zooplankton of which many were gelatinous (e.g. Hydrozoa, Thaliacea and Ctenophora). Several of the identified taxa also constitute important parts of the Sargasso Sea zooplankton community and are of size ranges (adult or larval stages) that made them reasonable as leptocephali prey.</p>

Observations were made of salinity, temperature, nitrate + nitrite, phosphate, silicate, total available nitrogen, and chlorophyll a in nine areas of the Alaskan Inside Passage during April of 1971. In general all properties indicated the water to be well mixed throughout this area. The conservative properties were particularly uniform. The greatest range in temperature from the surface to 200 m was only 1.1°C. The largest salinity range over the same depth was 2.0 ₀/₀₀ Spring phytoplankton blooms were just beginning to appear. Clarence Strait, in the southern part, presented the most evidence of biological activity. Values of chlorophyll a in this area were the highest observed (7.25 mg chl a/m³) outside of Auke Bay. This area also had the most density structure, probably due to stabilization brought on by warming. N:Si:P ratios for Clarence Strait indicate that silicate could become limiting in this area. The only other area, outside of Auke Bay, that had evidence (high chlorophyll a) of biological activity was Taku Inlet. The N:Si:P ratios for this area indicate that nitrate will probably be the limiting nutrient. Low oxygen values (2 ml/l) from the bottom of several deep basins indicate the possibility of anaerobic conditions developing as the water column stabilizes. Flow within the Inside Passage seems to be controlled by freshwater and saltwater inputs. Several major sources of both types of water are found. Tides and winds contribute to the circulation of the area but the mixing of saltwater and freshwater seems to be the predominant force. Local effects such as land runoff, glacial melt, input from hot springs and bottom topography are important in determining water conditions. Total available nitrogen may be a better indicator of photosynthesis than nitrate. TAN:P ratios tend to remain higher during photosynthesis than nitrate:P ratios. / Graduation date: 1972

Graduation date: 2005

Thesis (M.S.)--Oregon State University, 1984. / Typescript (photocopy). Includes bibliographical references (leaves 37-41). Also available on the World Wide Web.

Abstract The European eel (Anguilla anguilla) migrates to the Sargasso Sea to spawn. Even though the biology of A. anguilla leptocephali in the Sargasso Sea has been studied for several decades, information regarding their diet has remained unknown until now. Previous dietary studies concerning other species of leptocephali in the Pacific Ocean have been limited to the recognition of identifiable prey remains amongst gut contents. Hence, in this study a molecular approach relying on the detection of prey DNA amongst gut contents was used to study dietary profiles of A. anguilla leptocephali in the Sargasso Sea.   Leptocephali were collected during the circumglobal Galathea 3 expedition in spring 2007 to the Sargasso Sea. DNA extracted from gut contents were PCR amplified using universal primers targeting the nuclear 18S rRNA gene. In order to separate eel amplicons from prey amplicons, PCR products were analyzed by denaturing gradient gel electrophoresis (DGGE). Furthermore, clone libraries were constructed using universal primers targeting a portion of the 18S rRNA and mitochondrial COI gene, respectively. In total, the gut contents of 78 leptocephali were screened by DGGE.   A diverse array of eukaryotic taxa was identified, hence demonstrating the applicability of a universal PCR- DGGE approach to study gut contents of leptocephali. The results presented here show, for the first time, that young stages of A. anguilla leptocephali feed on a large variety of zooplankton of which many were gelatinous (e.g. Hydrozoa, Thaliacea and Ctenophora). Several of the identified taxa also constitute important parts of the Sargasso Sea zooplankton community and are of size ranges (adult or larval stages) that made them reasonable as leptocephali prey.

Thesis (M.S.) in Marine Policy--University of Maine, 2001. / Includes vita. Includes bibliographical references (leaves 68-72).

No description available.

Graduation date: 1965