Fauna of the Kemp Caldera and its upper bathyal hydrothermal vents (South Sandwich Arc, Antarctica)

Abstract

Faunal assemblages at hydrothermal vents associated with island-arc volcanism are less well known than those at vents on mid-ocean ridges and back-arc spreading centres. This study characterizes chemosynthetic biotopes at active hydrothermal vents discovered at the Kemp Caldera in the South Sandwich Arc. The caldera hosts sulfur and anhydrite vent chimneys in 1375–1487 m depth, which emit sulfide-rich fluids with temperatures up to 212°C, and the microbial community of water samples in the buoyant plume rising from the vents was dominated by sulfur-oxidizing Gammaproteobacteria. A total of 12 macro- and megafaunal taxa depending on hydrothermal activity were collected in these biotopes, of which seven species were known from the East Scotia Ridge (ESR) vents and three species from vents outside the Southern Ocean. Faunal assemblages were dominated by large vesicomyid clams, actinostolid anemones, Sericosura sea spiders and lepetodrilid and cocculinid limpets, but several taxa abundant at nearby ESR hydrothermal vents were rare such as the stalked barnacle Neolepas scotiaensis. Multivariate analysis of fauna at Kemp Caldera and vents in neighbouring areas indicated that the Kemp Caldera is most similar to vent fields in the previously established Southern Ocean vent biogeographic province, showing that the species composition at island-arc hydrothermal vents can be distinct from nearby seafloor-spreading systems. δ13C and δ15N isotope values of megafaunal species analysed from the Kemp Caldera were similar to those of the same or related species at other vent fields, but none of the fauna sampled at Kemp Caldera had δ13C values, indicating nutritional dependence on Epsilonproteobacteria, unlike fauna at other island-arc hydrothermal vents.

Volcanic activity and gas emissions along the South Sandwich Arc

“…Bathymetric surveys reveal numerous mass flow deposits associated with the submarine flanks of the SSI volcanoes (Leat et al 2010(Leat et al , 2013. Active seafloor hydrothermal venting, important for sustaining chemosynthetic communities, has been reported from Kemp and Adventure calderas in the southern section of the arc and from the Protector Seamount region in the north (Boschen et al 2013;Linse et al 2019). The SSI are located south of the Antarctic Circumpolar Current and the topographic profile of the arc strongly influences the path of oceanographic currents (Garabato et al 2002).…”

Ecophysiology and ecological limits of symbiotrophic vesicomyid bivalves (Pliocardiinae) in the Southern Ocean

“…In the Kemp Caldera A. s.l. puertodeseadoi was reported in several hard rock and soft sediment habitats (Linse et al 2019a) which dominant or visually distinct fauna comprised the seastar Paulasterias tyleri, the limpets Cocculina enigmadonta and Lepetodrilus concentricus, the pyconogonids Sericosura bamberi, S. curva, and S. dimorpha, and actinosolid anemones (Mah et al 2015;Linse et al 2019b;Chen and Linse 2020).…”

“…Hydrothermal activity was reported on the eastern side of the resurgent cone, originating from a white smoking vent field and with recognisable signatures in the water column (Cole et al 2014;Hawkes et al 2014). In the vicinity of the resurgent cone, nine different smallscale hydrothermally active sites are present and four were dominated by large pliocardiine clams, including the first live records of the group for the Antarctic region (Rogers 2010;Linse et al 2019a), and these sites are the focus of the present study.…”

“…Diverse geofluid-associated habitats have now been described from the Southern Ocean including active hydrothermal vents at the East Scotia Ridge (ESR), which represent a separate vent biogeographic province distinct from other known vents (Rogers et al 2012). Furthermore, the Kemp Caldera (59°42′S 28°20′W) located west of the Kemp Seamount on the South Sandwich Arc (Leat et al 2013(Leat et al , 2016 also hosts an additional hydrothermal vent fauna closely connected to the ESR vents (Roterman et al 2016;Linse et al 2019a). The sill depth is at 900 m, while the inner caldera floor depth is ~ 1600 m and has a resurgent cone in its centre.…”

Antarctic ecosystems in transition – life between stresses and opportunities

“…Hydrothermal and geothermal habitats are hotspots of unique biotas. Chemosynthetic marine assemblages living at hot hydrothermal vents on the East Scotia Ridge are dominated by the yeti crab (Kiwa tyleri), stalked barnacles, limpets, peltospiroid gastropods, anemones, and a sea star (Linse et al, 2019), and constitute a new vent-fauna province. Below the former Larsen B ice shelf, a low-activity seep (Niemann et al, 2009) with a seep-specific nematode fauna (Hauquier et al, 2011) was observed and analysed, while a small patch of bacteria occurred on the sediment at a different location (Gutt et al, 2011).…”