Cold-seep ostracods from the western Svalbard margin: direct palaeo-indicator for methane seepage?

Abstract

Despite their high abundance and diversity, microfossil taxa adapted to a particular chemosyntheticenvironment have rarely been studied and are therefore poorly known. Here we report on an ostracod species, Rosaliella svalbardensis gen. et sp. nov., from a cold methane seep site at the western Svalbard margin, FramStrait. The new species shows a distinct morphology, different from other eucytherurine ostracod genera. It hasa marked similarity to Xylocythere, an ostracod genus known from chemosynthetic environments of wood fallsand hydrothermal vents. Rosaliella svalbardensis is probably an endemic species or genus linked to methaneseeps. We speculate that the surface ornamentation of pore clusters, secondary reticulation, and pit clusters maybe related to ectosymbiosis with chemoautotrophic bacteria. This new discovery of specialized microfossil taxais important because they can be used as an indicator species for past and present seep environments.