As oil exploration and shipping routes expand in Arctic regions, the potential for oil to enter these cold water environments increases. Therefore it becomes important to understand how the indigenous Arctic microbial community will respond to oil. Arctic seawater was incubated with Alaska North Slope (ANS) crude oil to detect the presence of known petroleum degrading microorganisms and to assess how the baseline microbial community changes with inputs of ANS and ANS dispersed with Corexit 9500. Surface seawater was collected from the Chukchi Sea in near shore (Barrow, AK) and offshore (Hanna Shoal Study Area) environments to provide an indigenous consortium of microorganisms. Incubations were conducted at the temperature of the ocean at the time of collection (-1°C and 4°C), with minimal nutrient addition and sampled at 5, 10 and 28 days. To determine the baseline microbial community, seawater was collected from varying water depths within the Hanna Shoal Study Area. All seawater samples were filtered (0.2 μm) and frozen (–80°C) for DNA extraction. Pyrosequencing of 16S rRNA genes provided taxonomic information to identify microbes that are present in near shore and offshore marine environments and microbes that grow in response to oil or chemically dispersed oil. The indigenous Arctic marine microbial community was found to shift in response to the presence of oil and dispersant, providing an indication of the identity of oil degraders.

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