Variation in zoobenthic blue carbon in the Arctic's Barents Sea shelf sediments

Abstract

The flow of carbon from atmosphere to sediment fauna and sediments reduces atmospheric CO 2 , which in turn reduces warming. Here, during the Changing Arctic Ocean Seafloor programme, we use comparable methods to those used in the Antarctic (vertical, calibrated camera drops and trawl-collected specimens) to calculate the standing stock of zoobenthic carbon throughout the Barents Sea. The highest numbers of morphotypes, functional groups and individuals were found in the northernmost sites (80–81.3° N, 29–30° E). Ordination (non-metric multidimensional scaling) suggested a cline of faunal transition from south to north. The functional group dominance differed across all six sites, despite all being apparently similar muds. Of the environmental variables we measured, only water current speed could significantly explain any of our spatial carbon differences. We found no obvious relationship with sea ice loss and thus no evidence of Arctic blue carbon–climate feedback. Blue carbon in the Barents Sea can be comparable with the highest levels in Antarctic shelf sediments. This article is part of the theme issue ‘The changing Arctic Ocean: consequences for biological communities, biogeochemical processes and ecosystem functioning'.

Climate-driven benthic invertebrate activity and biogeochemical functioning across the Barents Sea polar front

“…To minimize the effect of non-climatic drivers of change, stations were selected with comparable water depths (200–400 m), sediment type and bottom fishing activity [69,70]. Bottom fishing activity was minimized by selecting locations that showed low levels of activity (based on VMS tracking data, visualized at: ) and we verified that there was no recent activity at the point of station occupancy using sediment surface imagery [71] and geochemical profiles [72,73].…”

The changing Arctic Ocean: consequences for biological communities, biogeochemical processes and ecosystem functioning

“…Climate change leading to ice loss could result in major gains in stored (probably sequestered) carbon at the shelf seafloor adjacent to parts of Antarctica [42]. Here, Souster et al [43] compare the stocks of zoobenthic blue carbon between the Barents Sea and shelf seas of the Western Antarctic Peninsula. They find that the blue carbon stock of the Barents Sea is twice that of the Antarctic soft sediment shelf and could have great potential for increased carbon drawdown.…”

“…Here, Souster et al . [43] compare the stocks of zoobenthic blue carbon between the Barents Sea and shelf seas of the Western Antarctic Peninsula. They find that the blue carbon stock of the Barents Sea is twice that of the Antarctic soft sediment shelf and could have great potential for increased carbon drawdown.…”

Societal importance of Antarctic negative feedbacks on climate change: blue carbon gains from sea ice, ice shelf and glacier losses

“…How sea ice indirectly drives zoobenthic carbon storage across different sea ice scenarios has been quantified in several different ways: (1) ocean scale; sample one taxon’s standing stock and annual increment across different years and seas and correlating with Earth Observation (remotely sensed) phytoplankton and sea ice conditions, then scale up from one to all taxa (Bryozoans in Barnes 2015 ). (2) Sea (intermediate) scale; sample standing stock of multiple taxa across multiple years in a sea with changing sea ice and phytoplankton performance (Pineda Metz et al 2020 , Souster et al 2020 ). (3) Small scale; directly observe local sea ice, ice scour and measure primary and secondary production with high detail across multiple years (Barnes 2017 ).…”

“…There is considerable literature on the nature and magnitude of zoobenthic biomass around Arctic and Antarctic shelf seabeds (e.g. Arntz et al 1994 ) and recently a subset of this has focused on quantifying the carbon storage and sequestration potential (Barnes et al 2018 ; Pineda Metz et al 2020 ; Souster et al 2020 ). The geographic and bathymetric location of this (zoobenthic) carbon storage makes it logistically difficult, time-consuming and expensive to sample; hence, data are sparser than those in other seas.…”