The effects of environmental variables on hotspots of Antarctic krill (Euphausia superba) in the Bransfield Strait during autumn

Abstract

Antarctic krill (Euphausia superba), a typical aggregation species, is the keystone species in the Antarctic ecosystem and supports an important fishery in the Southern Ocean. The unique topographic conditions of this region provide an important habitat for krill, and it has therefore become a critical krill fishing ground. To investigate the factors affecting krill hotspot patterns in the central basin of the Bransfield Strait in autumn 2021, an area with a high level of krill biomass and a persistent fishing ground, we used Getis-Ord Gi* approach to perform a hotspot analysis of the spatial and temporal variability of krill distribution. From this analysis we examined the relationship between krill distribution in hotspot and coldspot areas and environment variables such as geospatial features and eddy kinetic energy. We found that environmental variables generally showed opposing trends for krill distribution at hot- and coldspot areas. Moreover, geospatial features, including the distance to 200m and 1000m isobaths and depth, may be the dominant factor determining krill habitat characteristics, and moderate levels of eddy kinetic energy were conducive to krill aggregation.