The Gelatinous Zooplankton communities of Godthåbsfjorden, West Greenland

1. The Gelatinous Zooplankton communities of Godthåbsfjorden, West Greenland Russell R. Hopcroft1,3, Cornelia Jaspers2, Torkel G. Nielsen2,3 hopcroft@ims.uaf.edu 1Institute of Marine Science, University of Alaska Fairbanksm, USA National Institute of Aquatic Resources, Technical University of Denmark, Copenhagen Greenland Climate Research Centre, Greenland Institute of Natural Resources, Nuuk, Greenland   Introduction: The zooplankton communities of high latitude fjords remains poorly know. This is particularly true for those that are seasonally ice-covered and/or containing tide-water glaciers such as most fjords in Greenland and other polar archipelagos. Their gelatinous fauna remains virtually ignored. We conducted a survey of the composition, abundance, and distribution of non-copepod groups along a transect leading from the furthest inland extend of Godthåbsfjorden into the offshore waters of Fyllas Bank, West Greenland. Preliminary Results: In total we collected 17 species of hydromedusae, 3 species of siphonophores, 3 species of scyphomedusae, 3 species chaetognaths, 5 species of ctenophore, 3 species of pteropods, 1 species of pelagic polychaete, and 3 species of larvaceans (=appendicularians), for a total of 38 species. Ctenophores were unexpectedly abundant during the cruise with Fyllas Bank communities dominated by the ctenophore Mertensia ovum, with lesser contributions by Bolinopsis infundibulum. Inside the fjord, Mertensia abundance declined precipitously with the community becoming dominated by at least 2 species of Beroe. Table 1. Average abundance (numbers m-2) of gelatinous species Methods: Zooplankton collections were taken vertically with a 0.25 m2 Multinet MIDI equipped with 505 µm nets from near bottom to surface, as well as a 2 m diameter MIK net of 1300 µm mesh hauled obliquely to 100m depth. Gelatinous zooplankton were identified and measured soon after collection on unpreserved material with the aid of a light table. The only non-crustaceans that were left for processing after preservation were chaetognaths and larvaceans. For all other taxa considered, samples were processed in their entirety. Fig.1. Abundance per square meter of the most dominant gelatinous zooplankton in Godthåbsfjorden, West Greenland Thoughts: Although the numbers of many taxa appear low, this is compensated for by the generally large size of most species, particularly so for the ctenophores. The grazing impact of these communities must be substantial. Acknowledgements: This contributes to the Greenland Climate Research Centre project 6505, and the Arctic Ocean Diversity (ArcOD) project of the Census of Marine Life . Fig.2. Cluster analysis and Multidimensional Scaling of Bray-Curtis similarity coefficients showing clear zonationof gelatinous zooplankton communities in Godthåbsfjorden