Friday, 13 November 2009
While estuaries and marshland are known to be some of the most productive areas on the planet (DeWitt, 1989), these environments turn into sinks for contaminants and begin to pollute the ecosystems they have settled in (DeWitt, 1989; Morelli et al., 2009). There are countless contaminants that can occupy the estuarine environment. Many are produced by the production, usage, and destruction (or recycling) of man-made products. These contaminants are resistant to sources of degradation such as light, fire, water, acids, and bases thus making them persistent in ecosystems. The purpose of this study is to discover the acute lethal and chronic sub-lethal endpoints of L. plumulosus using two widely used anthropogenic contaminants: the brominated flame retardant, BDE-47 and the insecticide, Fipronil. The toxicity for both contaminants was accessed using a static sediment bioassay. A 28-day BDE-47 bioassay was used to observe survivorship, biomass and population growth rate. A 10-day Fipronil bioassay was used to observe survivorship. The BDE-47 bioassay showed a significant decrease in surviving amphipods in the 200µg/g dry weight concentration. The ratio of offspring per adult was highest in the solvent control and lowest in the 0.2µg/g dry weight concentration. Biomass was highest in the 20µg/g dry weight concentration and lowest in the solvent control. An increase in the amphipod population growth rate was observed in the control and solvent control and a decrease in the population growth rate was observed in the 200µg/g dry weight. The Fipronil bioassay showed survivorship only in the control, solvent control and 0.1µg/g dry weight concentrations. Future research for both chemicals would be determining concentrations in sediments in the southeastern US and to determine how these chemicals are being transferred trophically. Better understanding of these compounds will allow us to produce better substitutes which will be less harmful than their predecessors.
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