Thesis (M.S.) in Marine Biology--University of Maine, 2009. / Includes vita. Includes bibliographical references (leaves 62-72).

No description available.

Benthic uptake of mercury (Hg) governs bioavailability to fish yet there are still large gaps in our knowledge of what mediates this process. Without this information it is difficult to ascertain where Hg accumulation in the foodweb will be greatest. In the St. Lawrence River Area of Concern (AOC) at Cornwall, one contaminated zone (Zone 1) shows elevated Hg in yellow perch (Perca flavescens) and their prey items compared to those from other zones in the AOC. Greater availability of Hg to benthos due to unique physical features (large deposition of woodfibre deposits) of Zone 1 is hypothesized to account for this observation. In this study, amphipods (Gammarus fasciatus) and (Echinogammarus ischnus) were collected in Zone 1 using artificial substrates between June-September 2007, and Hg concentrations compared to those obtained in sediments and porewaters of surficial sediments, as well as methane gas evasion rates. Methylmercury (MeHg) concentrations in amphipods were significantly related to porewater total Hg (THg) and MeHg concentrations. No parallel relationship was found for sediment Hg concentrations or methane bubbling rates from sediments. Spatial and temporal trends in Hg bioavailability were evident from significant relationships with water column depth and temperature. Water column depth was associated with higher MeHg concentrations in amphipods and porewaters. Concentrations of porewater MeHg were above the detection limit in all of the June samples, the month which also coincided with highest amphipod MeHg concentrations. Finally, sediment organic matter may be influencing patterns of MeHg availability in Zone 1, and displayed a negative relationship to amphipod MeHg. Although bubbling from contaminated sediments did not directly correlate with amphipod Hg uptake, future studies should look at the influence of bubbling on the redistribution of contaminated sediment particles within the zone. / Thesis (Master, Biology) -- Queen's University, 2008-12-30 23:34:20.287

No description available.

No description available.

Although the deep seafloor represents the largest biome on the planet, its benthos has remained understudied because of logistical difficulties and the cost of access. Long-term, time-series information is needed to understand the small-scale and inter-annual variations required to build predictive models of ecological processes. In this thesis, we employed three newly developed observatory systems, which coupled in situ imagery with environmental data to examine ecological processes in three deep-sea benthic habitats: 1) Megabenthic surface bioturbation on the upper continental slope (400m depth) near Barkley Canyon, off Vancouver Island, 2) Thermal response in polynoid taxa at Main Endeavour Hydrothermal Vent Field (2,100m depth) on the Juan de Fuca Ridge and 3) Behavioural rhythms and bacterial mat growth in Saanich Inlet (100m), a fjord in southern Vancouver Island. To ensure that the imagery collected was useful for quantitative hypothesis testing by a single observer, we employed a step-wise methodological approach, taking advantage of previously acquired knowledge and, in two cases, the interactive nature of cabled observatories, to tailor the sampling frequency to the variables of interest. The application of a diverse array of image analysis techniques and statistical models, easily extendable to other systems, was also demonstrated. The results obtained while conducting the protocol optimization phase described organism and community level responses to environmental variations. Using a remotely operated camera connected to the NEPTUNE Canada cabled observatory, we estimated that total surface sediment turnover by sea urchins and flatfish, the two most important megafaunal contributors, within the field of view required 93 to 125 days in the absence of phytodetrital accumulations. When employing a camera-temperature array system, the most frequently observed mobile megafaunal species, two polynoid taxa, were not found to exploit the recorded temperature gradients suggesting that they employed a thermoconforming strategy to cope with thermal variability. In the aphotic, mostly hypoxic benthos of Saanich Inlet, strong behavioural entrainment, neither diel nor tidal, was not observed. However, significant changes in species composition and bacterial mat substratum coverage were observed following intrusion of oxygenated waters, a yearly event resulting from specific bathymetric features and oceanographic dynamics of this fjord. A Bayesian approach to data modeling was found to be particularly well suited to protocol optimization purposes as complex models could be more easily and intuitively implemented. The further application of our multi-disciplinary step-wise approach will reduce the time required to approach new ecological questions and improve integration of studies carried in different locations. By carefully choosing ecosystem functions which can be used as indicators of change, the current baseline state of the system can be described. Informed long-term monitoring initiatives can then be implemented in order to quantify global ocean responses to anthropogenic factors such as climate change, resource extraction or eutrophication. / Graduate

Graduation date: 1984

Zugl.: Stuttgart, Univ., Diss., 2008.

Thesis (M. Sc.)--University of Canterbury, 2008. / Typescript (photocopy). "June 2008." Includes bibliographical references (leaves 74-84). Also available via the World Wide Web.

Thesis (Ph.D.)--Memorial University of Newfoundland, 1999. / Restricted until June 2000. Includes bibliographical references.