Meal size and sustenance time in the deep-sea amphipod Eurythenes gryllus collected from the Arctic Ocean

Abstract

Lysianassid amphipods (Eurythenes gryllus) were attracted to bottom-moored baited traps exposed for 6–8 h at 2075 m depth in the Canada Basin of the Arctic Ocean. Instars were separated by body length using a clustering algorithm, and meals sizes for instars were calculated from two allometric regressions of body length on wet weight for amphipods collected with and without protection for bait. No sex-related differences were observed in the length-weight relationships. Calculated values of meal size were not significantly different (P < 0.05) from the weight of dissected gut contents removed from amphipods trapped in bait containers. Meal sizes in the 1st to 5th instars amounted to <50% of empty-gut body weight, but values increased to >60%for mature males >8th instar and to > 75% for mature females > 14/1th instar. Proximate organic analyses of gut contents were used to estimate the calorific content of ingested material. Energy ingested plus that stored in body lipid would support respiration for 1–6 months in juveniles, for 9–14 months in mature males and for 14–22 months in mature females.