BG Biogeosciences BG Biogeosciences 1726-4189 Copernicus Publications Göttingen, Germany 10.5194/bg-10-3479-2013 Interannual variation in the epibenthic megafauna at the shallowest station of the HAUSGARTEN observatory (79° N, 6° E) Meyer K. S. 1 Bergmann M. 2 Soltwedel T. 2 Oregon Institute of Marine Biology, 63466 Boat Basin Road, Charleston, Oregon 97420, USA HGF-MPG Group for Deep-Sea Ecology and Technology, Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Am Handelshafen 12, 27570 Bremerhaven, Germany 03 06 2013 10 6 3479 3492 Copyright: © 2013 K. S. Meyer et al. 2013 This work is licensed under the Creative Commons Attribution 3.0 Unported License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/3.0/ This article is available from https://bg.copernicus.org/articles/10/3479/2013/bg-10-3479-2013.html The full text article is available as a PDF file from https://bg.copernicus.org/articles/10/3479/2013/bg-10-3479-2013.pdf

Epibenthic megafauna play an important role in the deep-sea environment and contribute significantly to benthic biomass, but their population dynamics are still understudied. We used a towed deep-sea camera system to assess the population densities of epibenthic megafauna in 2002, 2007, and 2012 at the shallowest station (HG I, ∼1300 m) of the deep-sea observatory HAUSGARTEN, in the eastern Fram Strait. Our results indicate that the overall density of megafauna was significantly lower in 2007 than in 2002, but was significantly higher in 2012, resulting in overall greater megafaunal density in 2012. Different species showed different patterns in population density, but the relative proportions of predator/scavengers and suspension-feeding individuals were both higher in 2012. Variations in megafaunal densities and proportions are likely due to variation in food input to the sea floor, which decreased slightly in the years preceding 2007 and was greatly elevated in the years preceding 2012. Both average evenness and diversity increased over the time period studied, which indicates that HG I may be food-limited and subject to bottom-up control. The community of HG I may be unique in its response to elevated food input, which resulted in higher evenness and diversity in 2012.

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