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

Abstract

Abstract. Despite their high abundance and diversity, microfossil taxa adapted to a particular chemosynthetic environment 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, Fram Strait. The new species shows a distinct morphology, different from other eucytherurine ostracod genera. It has a marked similarity to Xylocythere, an ostracod genus known from chemosynthetic environments of wood falls and hydrothermal vents. Rosaliella svalbardensis is probably an endemic species or genus linked to methane seeps. We speculate that the surface ornamentation of pore clusters, secondary reticulation, and pit clusters may be related to ectosymbiosis with chemoautotrophic bacteria. This new discovery of specialized microfossil taxa is important because they can be used as an indicator species for past and present seep environments (http: //zoobank.org/urn:lsid:zoobank.org:pub:6075FF30-29D5-4DAB-9141-AE722CD3A69B).

Hydrothermal vent chimney-base sediments as unique habitat for meiobenthos and nanobenthos: Observations on millimeter-scale distributions

“…Ostracods have been associated with active hydrothermal vents (e.g., Maddocks, 2005;Yasuhara et al, 2018) with some noted to be endemic (Karanovic and Brandão, 2015;Tanaka and Yasuhara, 2016). Our observations suggest that ostracods can inhabit hydrothermal vent chimney-base sediments.…”

Are CO2‐rich seafloor pockmarks a suitable environment for ostracod assemblages? The example of the Zannone Giant Pockmark (central‐eastern Tyrrhenian)

“…can give rise to wider species definitions, thus artificially widespread geographical and stratigraphical distributions, than those based both on soft parts and valve morphology (Jellinek et al, 2006). It is interesting to note that recent abundant and well-preserved ostracod assemblages have been recovered from methane seepage areas in the western Svalbard margin (Yasuhara et al, 2018) and hydrocarbon seeps (Degen et al, 2012), implying that they can survive in peculiar geochemical conditions.…”

“…A study about the biodiversity associated with seafloor pockmarks in the Gulf of Lion, western Mediterranean Sea, highlighted the fact that Ostracoda account to <1% of total meiofaunal abundance around inactive pockmarks and are completely absent inside and around active pockmarks (Zeppilli et al, 2012). In cold methane seepage, it seems that although the overall assemblage does not differ much from the typical soft bottom assemblage, indicator species, defined as endemic species or genus linked to methane seeps, could be used to identify depositional paleoenvironments under the influence of such emissions (Ambrose et al, 2015; Yasuhara et al, 2018).…”

Late Triassic ostracods from the Lycian Nappes, southwestern Turkey: implications on taxonomy and palaeobiogeographical distribution

“…Ostracods are millimetre-size crustaceans that today live in various aquatic environments, from temporary freshwater ponds to hydrothermal sources or cold methane seep sites (e.g. Horne et al, 2002;Maddocks, 2005;Karanovic, 2012;Yasuhara et al, 2018). The deepest known living species has been reported from 9307 m water depth (Brandão et al, 2019).…”