Spatial Structure of Deep-Sea Pelagian Ichthiocenes in the Northern Weddell Sea (Powell Basin) and Brunsfield Strait in the Summer 2020 and 2022

Abstract

A review of the composition and structure of deep-sea pelagic ichthyocenes in the Bransfield Strait and the northern part of the Weddell Sea (Powell Basin) in the Atlantic sector of the Southern Ocean is presented. The material was received in the summer of 2020 and 2022 at 26 stations at the layers from 120–0 to 2200–0 m. 901 specimens of juveniles and adult fishes belonging to 19 species from 10 families were collected. Statistical analysis made it possible to identify 4 significantly different regions, in which the dominant ichthyocenes were located in waters of different origin. These ichthyocenes are poor in the number of identified species, but often quite numerous. Relatively shallow-water representatives of the families Bathydraconidae, Channichthyidae, Liparidae, Nototheniidae, endemic to the shelf and slope of Antarctica, dominated in the area of the Antarctic Strait and on the shelf of the Antarctic Peninsula, while in the Bransfield Strait, the abyssal basin of the Powell Basin, as well as in the pelagic zone above deep-sea ridges and trenches, bordering it from the north are meso- and bathypelagic fish from the families Mycthophidae, Bathylagidae, Gonostomatidae, Paralepididae and Scopelarchidae. Near the northern boundary of the Powell Basin, the number of caught mesobatypelagic species and their average abundance were higher than in its central part (11 vs. 7 species and 63.5 vs. 84.1 ind./100 m2). In the central part of the basin, Bathylagus antarcticus dominated, with an average share of 40% in catches and 28.8 ind./100 m2, while in its northern part Electrona antarctica dominated, with an average share of 33% in – 27.4 ind./100 m2.