Diverse and self-sustaining benthos of an Arctic oil seep

Petroleum is well known to be highly prevalent in the Arctic, and arguably governs much of the commercial and political dynamics of the region. Though petroleum reserves tend to be located deep below the seafloor, recently the benthos in the Hopen Deep region south of Svalbard was observed to be saturated with petroleum, with oil even escaping into the water column and forming slicks on the sea surface. We used a highly interdisciplinary approach to characterize the ecology of the Hopen oil seep benthos and how the physical and chemical environment drives ecosystem function. Despite the presence of potentially toxic oil and gas, communities were diverse with high abundances of taxa. The local physico-chemical environment was measurably varied and heterogeneous, which drives site specific communities and species turnover, thereby increasing overall diversity. Chemosynthetically fixed carbon appears to be a major part of the food web, with contributions to higher level trophic levels surpassing what has been seen at Arctic gas seeps. The Hopen ecosystem appears thus to not be highly linked to photosynthesis which could suggest that oil seeps could affect pelagic benthic coupling (known to traditionally be tight on Arctic shelves). Since the Hopen seep itself covers a large area of the seafloor, and there is potential for similar such systems to exist across the Arctic, the presence of such ecosystems should be considered in key processes within the Arctic marine ecosystem.