Benthic communities of the Filchner Region (Weddell Sea, Antarctica)

Abstract

Due to extreme pack ice, the Filchner Region in the southern Weddell Sea is one of the least studied regions on the planet. Here, we provide a detailed description of the benthic communities of this high-Antarctic ecosystem, and assess the relationship between environmental factors and benthic distribution patterns. Fieldwork was performed in the austral summers of 2013− 14 and 2015−16 during the R/V 'Polarstern' cruises PS82 and PS96. Using a combination of multibox corer (MBC) and seabed image data from 37 stations (water depths 243−1217 m), we differentiated 6 station groups. While 1 of these groups was comprised of a single station, the other 5 groups represented distinct benthic communities. Three of these correspond to the previously described Eastern Shelf, Southern Shelf, and Southern Trench communities. However, we found distribution shifts and MBC abundance and biomass reductions when comparing our results with earlier studies. The other 2 groups have novel characteristics and are presented here as an Ice/Ice Shelf Water-related community and a Continental slope community. Water depth in combination with 2 or 3 other environmental variables (out of 7 available) explained < 30% of the benthic distribution and composition. We found a tighter relationship between water mass circulation and spatial distribution of the communities; we suggest using water-mass-related characteristics (e.g. productivity regimes, water currents) to better explain benthic spatial distribution patterns.

A vast icefish breeding colony discovered in the Antarctic

“…Also conspicuous were large pycnogonids (>15-cm diameter), which were occasionally observed close to N. ionah eggs or egg husks observed outside of fish nests (Figure 1B), eggs potentially washed out by currents or fish movements, if not directly displaced by scavenging or predatory organisms. These community characteristics match the description of an undefined community for the Filchner region (group ''C'' sensu Pineda-Metz et al 22 ). Our observations, in combination with pending analysis of infauna, support the identification of the breeding colony area as a newly described benthic invertebrate community for the Weddell Sea, shaped by the presence of fish nests and the active guarding behavior of N. ionah adult inhabitants.…”

Ross Sea Benthic Ecosystems: Macro- and Mega-faunal Community Patterns From a Multi-environment Survey

“…The importance of sea ice conditions, their influence on productivity -and so on flux of organic material to the seafloor (Smith et al, 2006;Arrigo et al, 2015;Isla, 2016) as a driver of benthic community structure and function is well recognized (e.g., Cummings et al, 2018;Pineda-Metz et al, 2019), even at depths far below the surface (Gutt et al, 2019). Incorporating spatial and temporal variability in sea ice concentrations and conditions, rather than just an average concentration, is important in understanding different distribution patterns, particularly as the extent, timing and duration of sea ice break out will affect the magnitude and timing of primary production (e.g., Gutt et al, 2012;Ingels et al, 2012;Kim et al, 2018).…”

“…In fact, some of the same macro-infaunal species characterize both the Shelf and Abyssal sites (presence-absence ordination; Figure 5D). Several ecologically important variables, notably pressure, light, and the availability of food, co-vary with depth (Levin et al, 2001), and it is likely that these and other important environmental factors (e.g., hydrodynamic conditions) will be influential in determining distributions (e.g., Pineda-Metz et al, 2019). Past colonization history will also be key (e.g., Thatje, 2012).…”

Summertime productivity and carbon export potential in the Weddell Sea, with a focus on the waters adjacent to Larsen C Ice Shelf

“…Some portion of this CO 2 is effluxed to the atmosphere when WW upwells along the front of the ice shelf, while the remainder is mixed into MWDW and eventually transferred to the bottom waters where it will be stored for hundreds of years (Ito et al, 2010). Exported organic matter that escapes water-column and on-shelf remineralization settles on the seafloor where a small fraction is buried and thus removed from the ocean-atmosphere system while the bulk of the organic matter is consumed by the benthic community and ultimately converted back to CO 2 (Isla et al, 2006(Isla et al, , 2011Pineda-Metz et al, 2019). The CO 2 and nutrients recycled by the benthos may be resupplied to the surface during upwelling, whereupon remineralized CO 2 can escape to the atmosphere.…”

“…Inputs of dissolved iron from continental shelf sediments and coastal runoff further elevate the ambient iron concentrations, such that the CCSZ seldom experiences iron depletion (Klunder et al, 2014;Dinniman et al, 2020). As a result, the large phytoplankton blooms of the CCSZ can at times almost completely deplete the surface nitrate concentrations (Jennings et al, 1984;Hoppema et al, 2000;Henley et al, 2017), supporting high rates of carbon export that fuel the benthic community on the underlying continental shelf (Isla et al, 2006(Isla et al, , 2011Pineda-Metz et al, 2019) and/or eventually lead to long-term storage of atmospheric CO 2 in newly formed Antarctic Bottom Water (Arrigo et al, 2008). In contrast, the OOZ is far less productive due to persistent irondeplete conditions, along with incidences of light limitation associated with high sea-ice concentrations (particularly in the central WG) and/or deep mixed layers (Klunder et al, 2011;De Jong et al, 2012).…”