Epipelagic copepod assemblage in the Gerlache Strait (Antarctica) during the 2015 austral summer

Abstract

Oblique zooplankton tows were carried out in the Gerlache Strait from 17 to 22 January 2015 as part of the first Colombian oceanographic expedition to the Antarctic continent, to document the composition and structure of the epipelagic copepod assemblage, taking into account variations at a small spatial scale. The epipelagic environment of the Gerlache Strait was divided into two oceanographic regions during sampling: a stratified northern region and a homogeneous southern region. The epipelagic copepod assemblage comprised 17 species belonging to four orders and 13 families. Adult copepods as well as developmental stages ranging from copepodite II (C2) to copepodite V (C5) from eight different species were recorded in the study area. The dominant species by number was Oithona similis, followed by O. frigida, Ctenocalanus citer, Drescheriella glacialis, and Calanoides acutus. There were significant differences between the epipelagic copepod assemblages present in the northern and southern regions of the Gerlache Strait (Anosim, p = 0.01), with a dissimilarity percentage of 52%. Moreover, Aetideus armatus is reported for the first time in the western sector of the Antarctic Peninsula. The oceanographic conditions and the geomorphological characteristics of the study area modulated the surface circulation pattern, as well as the structure and composition of the primary producers during the study period, determining the spatial variation of the abundance and composition of the epipelagic copepod assemblage in the Gerlache Strait during the 2015 Austral summer.