Sipunculan fauna in the Pacific Arctic region: a significant component of benthic infaunal communities

Monika Kędra,Jacqueline M Grebmeier,Lee W Cooper

doi:10.1007/s00300-017-2179-z

Abstract

The Sipuncula show low species diversity in the Arctic Ocean, but they often occur in very high numbers and biomass, and can dominate shelf benthic communities. We describe here the patterns of sipunculan diversity, abundance, biomass, and species distribution in the Pacific Arctic, and the relation of those patterns to controlling environmental factors. Five species (including two subspecies) belonging to two families and three genera are known to be present in Pacific-influenced Arctic waters. Although sipunculans were found at only about 30% of sampled stations, they constituted, if present, up to about 10% of the total macrobenthic abundance, and over 80% of the total infaunal biomass, particularly in many locations in the Chukchi Sea. The mean sipunculan abundance was 24.5 ± 155.9 individuals m−2, with a maximum of 1745 individuals m−2. The mean sipunculan biomass was 14.0 ± 73.8 g wet weight m−2, with a maximum of 698.7 g wet weight m−2 in the northwest Chukchi Sea. The sipunculan abundances and biomass observed were related to latitude, depth, and sediment characteristics. The populations observed should be considered significant and characteristic components of the Pacific Arctic shallow shelf systems and food webs. This conclusion proves to be true also for other Arctic shelf seas like the Barents Sea, and deep Arctic ecosystems.

Highlights

The Sipuncula is a small and species-poor phylum of about 150 species widely distributed in the world’s oceans in all depths (Cutler 1994)
Sipunculans were found at 92 of 277 (33%) stations sampled in the northern Bering and Chukchi Seas, where 2215 sipunculan specimens were collected via quantitative sampling with van Veen grabs (Fig. 1; Table 1)
107 specimens were collected by qualitative sampling in the Beaufort Sea using trawls (Fig. 1; Table 1)

Summary

Introduction

The Sipuncula is a small and species-poor phylum of about 150 species widely distributed in the world’s oceans in all depths (Cutler 1994). Sipunculans are active burrowers and important bioturbators (Murina 1984). In the deep sea they are known as ‘ecosystem engineers’ and producers of deep burrows (genus Nephasoma; Romero-Wetzel 1987; Graf 1989). They are mainly deposit feeders, and usually transform particulate organic matter (microalgae, protista, meiofauna, detritus, fecal pellets) from the water column, sediment surface or sediment itself (Murina 1984), but some species may filter-feed (Gibbs 1977). Sipunculans are preyed upon by cephalopods, sea anemones, crabs (Fischer 1925; Divine et al 2017), gastropods and fish (Kohn 1975), and marine mammals, such as walruses (Sheffield et al 2001; Sheffield and Grebmeier 2009)

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