Diet of four species of deep-sea isopods (Crustacea: Malacostraca: Peracarida) in the South Atlantic and the Southern Ocean

Abstract

The food of four species of asellote isopods (Crustacea, Malacostraca), Haploniscusrostratus, Haploniscus unicornis, Acanthocope galatheae and Betamorpha fusiformis, was evaluated by analysis of their gut contents. The isopods were sampled at several stations on the abyssal plains of Guinea Basin, Angola Basin and Cape Basin (southeast Atlantic), the Weddell Sea abyssal plain and the Antarctic continental slope during the DIVA and ANDEEP expeditions in 2000, 2001 and 2005. While all species had mineral particles in their guts and mucus material was the most frequent food item, the remaining gut contents differed among species. Betamorpha fusiformis fed mostly on phytodetritus, especially in the Southern Ocean basins and ingested along with it whole calcareous foraminifers. Acanthocope galatheae showed some differences in gut contents between basins, but in the Guinea Basin, the contents were to a large extent stercomata, i.e., waste pellets of soft-walled foraminifers, i.e., the Komokiaceae. Indications were that the haploniscids were feeding on detritus and agglutinating foraminifers (stercomata). This indicates spatial differences in food availability for this diverse group of deep-sea isopods and the importance of poorly known foraminiferal groups, like the Komokiaceae, as a food source in the deep sea.