Differences in oil biodegradation and associated bacterial communities during summer and winter in Svalbard
Hydrophobic Fluortex adsorbents were coated with a thin oil film, placed in field systems and deployed in a marine coastal area near Longyearbyen on Svalbard. Two field experiments were carried out during the study, one during summer and the other one during winter. Field systems were deployed in an uncovered (open, only during summer) and a covered (closed, during both seasons) version to allow/avoid light exposure and allow estimations of potential influences of photooxidation on oil depletion. Samples for the summer experiment consisted of adsorbents coated with two crude (Statfjord and Grane) and one fuel (ULSFO) oil, respectively, and uncoated adsorbents as controls. The systems (uncovered and covered for each of the oils and controls) were deployed for a total of 57 days during the summer. Before deployment. samples were rinsed with seawater from the sampling site after which initial samples were taken (T0) followed by samplings after 8, 14, 29, 41 and 57 days (T1-T5) after deployment. Samples of the winter experiment consisted of adsorbents coated with Statfjord and Grane, respectively, and uncoated adsorbents as controls. The systems of the winter experiment were deployed for a total of 120 days. Samples were taken before deployment (T0) and after 62, 99 and 120 days (T1-T5). DNA was extracted from the oil-coated and uncoated adsorbents, the v3+v4 regions of the 16S rRNA gene amplified by PCR and PCR products sequenced on HiSeq and MiSeq.