Atypical biological features of a new cold seep site on the Lofoten-Vesterålen continental margin (northern Norway)

Abstract

A newly discovered cold seep from the Lofoten-Vesterålen margin (Norwegian Sea) is dominated by the chemosymbiotrophic siboglinid Oligobrachia haakonmosbiensis like other high latitude seeps, but additionally displays uncharacteristic features. Sulphidic bottom water likely prevents colonization by cnidarians and sponges, resulting in fewer taxa than deeper seeps in the region, representing a deviation from depth-related trends seen among seeps elsewhere. O. haakonmosbiensis was present among carbonate and barite crusts, constituting the first record of frenulates among hard substrates. The presence of both adults and egg cases indicate that Ambylraja hyperborea skates use the site as an egg case nursery ground. Due to sub-zero ambient temperatures (−0.7 °C), we hypothesize that small, seepage related heat anomalies aid egg incubation and prevent embryo mortality. We place our results within the context of high–latitude seeps and suggest they exert evolutionary pressure on benthic species, thereby selecting for elevated exploitation and occupancy of high-productivity habitats.

Discharge of Meteoric Water in the Eastern Norwegian Sea since the Last Glacial Period

“…The fine-grained interbed in this Tertiary bed potentially serves as the confined layer that maintains the overpressure condition and guides the groundwater flow. Indeed, the findings of interbedded Eocene sandstone/mudstone exposed on the flanks of the LV canyons ( Figure 1c) with methane seepage related microbial colonies associating with coarse-grained strata (Sen et al, 2019) support this conclusion. The fracture zone observed beneath the LV seep from the seismic profile ( Figure S1) also provides the pathway for fluid to migrate from the Paleocene-Miocene strata.…”

Development, Productivity, and Seasonality of Living Planktonic Foraminiferal Faunas and Limacina helicina in an Area of Intense Methane Seepage in the Barents Sea

“…It has also been hypothesized that CH 4 seepage can cause an increase in photosynthetic primary production (Pohlman et al, ), making CH 4 seepage areas CO 2 sinks. There have been several studies in the Arctic focusing on the effects of CH 4 seepage on the living benthic communities (Åström et al, , , ; Sen, Duperron, et al, , Sen et al, ), including living benthic foraminifera, although not exclusive to the Arctic region (Heinz et al, ; Herguera et al, ; Hill et al, ; Rathburn et al, ). However, no studies from the Arctic exist that examine the effects of CH 4 seepage on the pelagic ecosystem.…”

Frenulate siboglinids at high Arctic methane seeps and insight into high latitude frenulate distribution

“…However, O. haakonmosbiensis is conspicuously absent from two known and studied seep sites on the Arctic shelf and Barents Sea at about 350 m water depth: the Storfjordrenna “pingo” site and the Bjørnøyrenna “crater” site (Sen, Duperron, et al, ) (Figure ). So far, O. haakonmosbiensis has only been found in relatively deep water on the continental slope between 750 m and 1,250 m (Decker et al, ; Gebruk et al, ; Sen et al, ; Smirnov, ). Therefore, in addition to currents, water depth probably represents another factor determining the distribution of O. haakonmosbiensis .…”

“…The distribution of a few species over large geographic areas in the north could demonstrate how well bottom currents can help in the dispersal of these completely nonpelagic animals (although as mentioned with O. haakonmosbiensis , dispersal might be aided by other currents if larvae are capable of vertical movement in the water column). The low diversity could additionally be restricted by conditions in high latitude regions, such as subzero ambient water temperatures (Åström et al, ; Portnova, Mokievsky, Haflidason, & Todt, ; Sen et al, ), or the strong seasonality in surface primary production that affects organic matter flux to the seafloor (since frenulates are capable of supplementing their symbiont‐derived diet with organic matter uptake from the sediment) (Dando et al, ; Southward & Southward, ; Southward, Southward, Brattegard, & Bakke, ). The presence of extensive grounded ice sheets during past glaciations could have additionally limited or affected the dispersal capabilities of many species.…”