Microcosms containing beach sediment, seawater and bioturbators (the ghost shrimp Lepidophthalmus louisianensis or the razor clams Tagelus plebeius) and dosed with surrogate oil were used for this study. The concentration and distribution of fifteen polycyclic aromatic hydrocarbons (PAHs) were studied in surface water, and sediment (surface and subsurface). The influence of sediment bioturbators on biodegradation and distribution of petroleum hydrocarbons in sediments of coastal ecosystems was tested over a period of 33 days. Sediment bioturbators often function as ecosystem engineers, moving large amounts of sediment and changing sediment characteristics. During the biological transport of sediment, oil present on the sediment will be moved as well. Liquid-liquid extraction was used for water samples, while PAHs in sediments were extracted using Microwave Extraction and analyzed using gas chromatography with flame ionization detector (GC-FID). Preliminary results indicate that the concentration of TPAHs was found in surface sediment 7,750 � 70 �g/kg. The concentrations dropped to about half that concentration after a week in presence of ghost shrimp. Ongoing research is assessing whether the presence of the bioturbators resulted in an increased burial of the PAHs, an increased release of PAHs to the water column, or an increase in microbial degradation. Preliminary results indicate also that bioturbation by ghost shrimp is affecting sediment characteristics that in turn affect both the oil distribution and the hydrocarbon-degradation potential of the microbial community in the sediment.

Effect of bioturbators on the degradation and distribution of polycyclic aromatic hydrocarbons in sediment

248th National Meeting (2014)

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