The link between meiofauna and surface productivity in the Southern Ocean

Particulate organic carbon (POC) export fluxes generally reflect patterns of primary production in the upper ocean, sinking to the seabed and acting as a food source for benthic organisms. Data on meiobenthic communities from two SYSTem COupling cruises (SYSTCO) in the deep Southern Ocean (RV Polarstern ANT-XXIV/2, north–south transect along the prime meridian, and ANT-XXVIII/3, east–west transect along the Polar Front) were combined with surface and benthic environmental parameters, as well as POC flux estimates based on satellite measurements. It was tested to what extent meiofaunal communities were determined by prevailing conditions of an east–west increase in net primary productivity (NPP) and bottom Chlorophyll a (Chla) concentration, and a westwards, divergently decreasing estimated POC flux. Nematodes dominated the meiofauna (84.4–92.4%) and occurred with a westward increase in relative abundance and density for the ANT-XXVIII/3 stations, associated with a parallel increase in NPP and Chla. Nematode biomass was negatively correlated to the estimated POC flux. Along the north–south transect no significant correlation was found but higher estimated POC fluxes at stations south of the Polar Front were associated with higher meiofauna diversity and density at higher taxon level, while stations located at the Polar Front, which were associated with lower POC fluxes, contained communities with lower diversity and density.