Megafaunal assemblages from two shelf stations west of Svalbard

Abstract

Megafauna plays an important role in benthic ecosystems and contributes significantly to benthic biomass in the Arctic. The distribution is mostly studied using towed cameras. Here, we compare the megafauna from two sites located at different distances from the Kongsfjord: one station at the entrance to the fjord, another on the outer shelf. Although they are only located 25 km apart and at comparable depth, there were significant differences in their species composition. While the inshore station was characterized by shrimps (2.57±2.18 ind. m⁻²) and brittlestars (3.21± 3.21 ind. m⁻²), the offshore site harboured even higher brittlestar densities (15.23±9.32 ind. m⁻²) and high numbers of the sea urchin Strongylocentrotus pallidus (1.23±1.09 ind. m⁻²). Phytodetrital concentrations of the upper sediment centimetres were significantly higher inshore compared with offshore. At a smaller scale, there were also differences in the composition of different transect sections. Several taxa were characterized by a patchy distribution along transects. We conclude that these differences were caused primarily by habitat characteristics. The seafloor inshore was characterized by glacial soft sediments, whereas the station offshore harboured large quantities of stones. Although the use of a new web-2.0-based tool, BIIGLE (http://www.BIIGLE.de), allowed us to analyse more images (∼90) than could have been achieved by hand, taxon area curves indicated that the number of images analysed was not sufficient to capture the species inventory fully. New automated image analysis tools would enable a rapid analysis of larger quantities of camera footage.

Keywords:

• Arctic
• image analysis
• megafauna
• seafloor photograph
• Svalbard

Published in collaboration with the University of Bergen and the Institute of Marine Research, Norway, and the Marine Biological Laboratory, University of Copenhagen, Denmark

Published in collaboration with the University of Bergen and the Institute of Marine Research, Norway, and the Marine Biological Laboratory, University of Copenhagen, Denmark

Acknowledgements

We thank the officers and crews of RV Polarstern for their professional help and assistance at sea. M. Ginzburg assisted with the phytodetrital analyses. D. Janussen (sponges, Forschungsinstitut und Naturmuseum Senckenberg), Á. Peña (hydroids, Universidad de Valencia), E. Rodriguez (anthozoa, American Museum of Natural History, New York), L. v. Ofwegen (soft coral, National Museum of Natural History, Leiden), S. Gromisz, M. Kedra J. Legezynska and P. Kuklinski (polychaetes, sipunculids, amphipods and bryozoa, Institute of Oceanology of the Polish Academy of Sciences), R. Bramber (pycnogonids, Natural History Museum, London), A. Warén (molluscs, Swedish Museum of Natural History), A. Dilman, A. Mironov and A. Rogacheva (asteroids, echinoids, holothuroids, P.P. Shirshov Institute of Oceanology), M. Damerau (ophiuroids, Institut für Polarökologie) and P.R. Møller (fishes, Zoological Museum Copenhagen) all kindly identified specimens from reference samples and/or images. This work was part of the StatoilHydro-funded projects CORAMM (Coral Risk Assessment, Monitoring and Modelling) and ‘KongHAU’ (The Kongsfjord-HAUSGARTEN transect case study: Impact of climate change on Arctic marine community structures and food webs). KongHAU is closely linked to the EU projects HERMES/HERMIONE. The suggestions of three anonymous referees improved an earlier version of the manuscript. This is publication no. awi-n18867 of the Alfred Wegener Institute for Polar and Marine Research.

Notes

Published in collaboration with the University of Bergen and the Institute of Marine Research, Norway, and the Marine Biological Laboratory, University of Copenhagen, Denmark