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As a prime source of revenue for the tourist industry in San Diego, Mission Bay is a crucial part of the city?s economy. Therefore, it is important to understand how certain factors, both natural and anthropogenic, could alter the ecological health of the bay for both marine organisms and humans. As an extension of an ongoing project studying the benthic composition of Mission Bay, my project focused on how benthic meiofaunal communities vary in abundance and diversity spatially throughout the bay in response to abiotic factors such as organic matter and grain size. Using sediment samples dyed with Rose Bengal, I quantified and identified taxa of meiofauna from 14 sites. I used the Shannon-Weiner and Simpson?s indices to quantify species richness and evenness for each site. Results indicate that grain size is a greater driving force than organic matter for species richness. Sites composed of 75% or more sand showed richness values less than 0.3, while sites composed of 30% or less sand had values greater than 0.9. Furthermore, any change in abiotic factors affecting grain size, like water flow and dredging, changes the patterns of distribution and abundance. Therefore, contrary to the broader scientific perspective, geography of Mission Bay does not seem to be the driving factor of the benthic composition. Instead, grain size seems to have the greatest effect on the diversity of these estuarine communities, although further analysis is necessary to fully understand the natural and anthropogenic factors that contribute to varying grain size across Mission Bay.

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Sediment Grain Size and Organic Matter as Indicators for Benthic Meiofauna Community Composition and Distribution in Mission Bay, San Diego

As a prime source of revenue for the tourist industry in San Diego, Mission Bay is a crucial part of the city?s economy. Therefore, it is important to understand how certain factors, both natural and anthropogenic, could alter the ecological health of the bay for both marine organisms and humans. As an extension of an ongoing project studying the benthic composition of Mission Bay, my project focused on how benthic meiofaunal communities vary in abundance and diversity spatially throughout the bay in response to abiotic factors such as organic matter and grain size. Using sediment samples dyed with Rose Bengal, I quantified and identified taxa of meiofauna from 14 sites. I used the Shannon-Weiner and Simpson?s indices to quantify species richness and evenness for each site. Results indicate that grain size is a greater driving force than organic matter for species richness. Sites composed of 75% or more sand showed richness values less than 0.3, while sites composed of 30% or less sand had values greater than 0.9. Furthermore, any change in abiotic factors affecting grain size, like water flow and dredging, changes the patterns of distribution and abundance. Therefore, contrary to the broader scientific perspective, geography of Mission Bay does not seem to be the driving factor of the benthic composition. Instead, grain size seems to have the greatest effect on the diversity of these estuarine communities, although further analysis is necessary to fully understand the natural and anthropogenic factors that contribute to varying grain size across Mission Bay.

 

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