Abstract
Frenulate siboglinids are a characteristic component of communities living in various reducing environments, including sites with hydrocarbon seeps. High concentrations of hydrocarbons in the sediments of the Arctic basin seas, including the Barents Sea, suggest the presence of a rich siboglinid fauna there. This reflects the fact that microbiological oxidation of methane occurs under reducing conditions, generating high concentrations of hydrogen sulfide in the sediment. This hydrogen sulfide acts as an energy source for the sulfide-oxidizing symbionts of siboglinids. Here we report on the findings of the frenulate siboglinid species Nereilinum murmanicum made between 1993 and 2020 in the Barents Sea. These data significantly expand the range of this species and yield new information on its habitat distribution. The depth range of N. murmanicum was 75–375 m. The species was most abundant from 200 to 350 m and was associated with temperatures below 3 °C and salinities from 34.42 to 35.07. Most of the findings (43 locations or 74%) fall on areas highly promising for oil and gas production. Twenty-eight locations (48%) are associated with areas of known oil deposits, 22 locations (37%) with explored areas of gas hydrate deposits. N. murmanicum was also found near the largest gas fields in the Barents Sea, namely Shtokman, Ludlovskoye and Ledovoye.
Highlights
The Siboglinidae are a family of sedentary marine annelids whose representatives all lack a digestive tract
310 juveniles and adult individuals, 128 embryos, and 177 larvae of a frenulate Nereilinum murmanicum were discovered at 46 stations in different parts of the Barents Sea
Larval stages were found in tubes of 22 adults of N. murmanicum sampled from June to November
Summary
The Siboglinidae are a family of sedentary marine annelids whose representatives all lack a digestive tract. Modern taxonomy distinguishes four siboglinid groups: Vestimentifera, Monilifera (genus Sclerolinum Southward, 1961), Frenulata, and Osedacinae (genus Osedax Rouse, Goffredi & Vrijenhoek, 2004) [4,5,6,7,8]. Representatives of the Osedacinae live on the sunken skeletons of whales and other large vertebrates and have heterotrophic symbionts [9,10,11]. The trophosome in representatives of Vestimentifera, Monilifera and Frenulata is populated by chemoautotrophic bacteria. The possible presence of both sulfide and methane-oxidizing bacteria has currently been shown for representatives of the latter two groups [12,13,14,15,16]
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