Distribution and diversity of sipunculan fauna in high Arctic fjords (west Svalbard)

Abstract

Sipuncula is a relatively species poor and generally rarely investigated phylum; nonetheless, it may play a considerable role in the ecosystem. During this study sipunculan species distribution patterns in four fjords of west Spitsbergen (Kongsfjorden, Hornsund, Isfjorden and van Mijenfjorden) were examined. Material was collected during ten cruises undertaken from 1997 to 2006. A total of 381 samples were taken at 132 stations located in the four fjords and, a total number of 920 sipunculans specimens were found in 114 of those samples. The highest sipunculan species richness was observed in Hornsund (six species), followed by Kongsfjorden and Isfjorden (Wve species in each fjord). Sipunculan fauna in all fjords was strongly dominated by GolWngia vulgaris (80% of all sipunculan individuals in Kongsfjorden), and GolWngia margaritacea (84% in van Mijenfjorden and 40% in Hornsund) or Nepha- soma diaphanes (54% in Isfjorden). Locally, sipunculans were found in high densities (max. 62 ind. 0.1 m i2 and up to 11% of macrobenthic densities) and biomass (max. 110.87 g 0.1 m i2 and up to 80% of total fauna biomass). At such sites, sipunculans may play an important role in bioturbation of sediments and as a food source for higher trophic levels. Sipunculans did not occur within close proximity of the gla- cier where they might be eliminated due to high sedimenta- tion rate and low amounts of organic matter. Because of their importance in benthic systems, a need to include sipunculans in routine macrobenthic surveys is emphasized.