Free-living nematode assemblages in various environmentally impacted marine sites

Lawlor, Jennifer Jean (2001) Free-living nematode assemblages in various environmentally impacted marine sites. Masters thesis, Memorial University of Newfoundland.

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Abstract

This study considers the composition of nematode assemblages in marine sites receiving discharges from an oil refinery in Come-By-Chance, ones supporting aquaculture and ones that are affected by other forms of human activity in Bay d'Espoir. Changes in nematode population were recorded with respect to season, and in the case of the aquaculture sites comparisons were drawn with non-aquaculture locations. The Maturity Index was calculated together with the Shannon-Weaver, Simpson, Evenness and Species Richness Indices. A suite of environmental conditions (sediment size, temperature, depth, pH and redox potential) in the aquaculture sites was compared to that in non-aquaculture ones. -- The importance of integrating absolute numbers and genera collected, feeding type analysis, diversity indices, Evenness, Species Richness, Maturity Index (MI) and c-p analysis was indicated at both study locations. The utility of smaller samples or sub- samples of larger samples was demonstrated (Chapter 2), as was the importance of having a complete data set (Chapter 3). -- The identity of nematode communities have been established for these areas for the first time. Both sampled sites near the Come-By-Chance Oil Refinery had relatively high numbers of nematodes and many of the species have been previously associated with oil spills (Chapter 2). In comparison, the samples from Bay d'Espoir had relatively fewer nematodes and in general the aquaculture sites had even fewer nematodes per sample than the non-aquaculture sites in the same region. No nematodes were isolated from forty per cent of the aquaculture samples (Chapter 3). -- For the MI calculation fewer nematodes were required which need only be identified to family. That is, an entire sample need not be examined to yield statistically similar MI values. This gets results faster, leaving more time for a more comprehensive analysis. The advantages and disadvantages of all above mentioned indices are discussed (Chapter 4). -- In addition, there was one nematode that occurred several times in Bay d'Espoir samples that could not be identified to genus. The nematode belongs to the family Comesomatidae.

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