Small-scale spatial variation of soft-bottom polychaete biomass in an Antarctic glacial fjord (Ezcurra Inlet, South Shetlands): comparison of sites at different levels of disturbance

Abstract

There is still only a small number of studies dedicated to Southern Ocean benthic biomass, especially on species level. Here, we analyze polychaete biomass in two areas of the Antarctic fjord Ezcurra Inlet characterized by different levels of disturbance associated with activity of glaciers. Material was collected in March 2007 in the 90–130 m depth range. Twenty van Veen grab (0.1 m2) samples were collected in the inner area of the fjord and 20 in the fjord mouth. Cluster analysis clearly separated those two parts of the fjord. Mean total biomass was significantly higher in the outer region (14.4 ± 5.5 g/0.1 m2) compared with the inner part (3.6 ± 0.8 g/0.1 m2). The highest biomass in the outer, not disturbed area was noted for Amphitrite kerguelensis, Aphelochaeta/Chaetozone, Scalibregma inflatum, Euchone pallida and Maldane sarsi antarctica, while in the inner region, only Aphelochaeta/Chaetozone had high biomass values. Average individual biomass and biomass of majority of polychaete functional groups was also higher in the outer area. Comparison of species composition and abundance with data collected 30 years ago in the studied area revealed also important differences in community structure.