Spatial and Temporal Variation in Fish and Crustacean Communities in Lemon Shark (Negaprion brevirostris) Nursery Areas Around Bimini, Bahamas.
Kelsie Jackson, Bryan Franks & Dr. Samuel H. Gruber
The crew hauling in the seine.
Previously, the main of the areas used by juvenile lemon sharks around Bimini as nursery grounds have been studied to look at the species present within different habitat types. Studies have also been conducted to discover whether juvenile lemon sharks actively select prey and which species they favour. This study looks at two lemon shark nursery areas that were previously unstudied in this way prior to 2004. During the wet season, a team of volunteers and I will be pulling a total of 110 seines nets around the Duckpond and Backbeach nursery areas on South Bimini.
These nets are pulled both at night and during the day, and both close to and far from the shore or fringing mangroves. After each net is pulled the catch is examined, which includes identifying all fish and crustaceans to species, as well as measuring, weighing and counting all individuals. This project was also completed earlier in 2004 during the dry season so seasonal variation could be discerned. Using the data collected we are able to look at variation amongst the fish and crustacean assemblages. During this analysis I will be looking for variation (or similarity) with habitat (especially between the two sites, which are both markedly different), variation with distance form the shore or mangrove fringe, diel variation, and seasonal variation. Preliminary results indicate that species richness and diversity differs between sites and seasons, and that many species are more readily caught at night than during the day. Further analysis using multivariate statistical techniques will be able to highlight any patterns within the data. As well as simply analysing the data for variation, species that are known to be important prey items for juvenile lemon sharks will be mapped for their density across the two sites, to attempt to look at both nursery sites in terms of their importance as a food resource for juvenile lemons.
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