Dense ampeliscid bed on the Canadian Beaufort Shelf: an explanation for species patterns

Abstract

The first known ampeliscid (Amphipoda: Ampeliscidae) bed for the Canadian Arctic was reported in 2013 from the Canadian Beaufort Shelf (CBS), but species patterns were not examined. This study examines their distributions relative to differences in life strategies and environmental variables. The intent is to build a better understanding of this highly productive system in comparison with ampeliscid beds in the neighboring Bering and Chukchi Seas which are important resources for higher trophic level consumers. Data from 412 samples collected to 1000 m depth over 2002–2009 indicate that there are at least eight ampeliscid species on the CBS. Five occur elsewhere in polar and temperate latitudes and three may be new to science or are species complexes. All are limited to bottom temperatures < 0.41 °C. Congeners do not distribute coherently (Similarity Profiles analysis, p < 0.05). Resource-demanding Ampelisca macrocephala (max. 8467 ind. m−2) dominates Byblis spp. and Haploops laevis on the shelf enriched by wind-driven upwelling but dominance switches with depth to Haploops tubicola, Haploops sibirica and Haploops sp. Obligate suspension feeding with adaptations for fine particle capture enables deep living while abundance dominants supplement their diets with deposit feeding and predation. The ampeliscids may facilitate other amphipods by providing attachment sites on their tubes. Polychaetes may facilitate the ampeliscids by bringing buried resources to the surface. Given that the CBS is undergoing substantial environmental change, we recommend the CBS ampeliscids for monitoring its environmental regime to complement ongoing monitoring in other polar and temperate ampeliscid beds.