Studies on the deep-water pelagic community of Korsfjorden, western Norway

Abstract

The dry weight and biochemical composition (protein, lipid, carbohydrate, chitin, and ash) of adult female Chiridius armatus, and the biochemical composition of Boreomysis arctica and Eukrohnia hamata have been determined over a period of 13 months. The highest individual weight of C. armatus occurred in summer, the lowest in winter. Protein and lipid varied inversely, with the highest values of the latter in summer-autumn and the lowest in spring. The highest specific dry weight (dry weight per unit body length) of B. arctica occurred in autumn, the lowest in spring. Over the year the differences in biochemical composition between mature and spent females were small and females, males, and juveniles followed the same seasonal trend with maximum lipid in autumn — winter and minimum in late spring. The proportion of protein increased and the proportion of lipid and carbohydrate usually decreased with increasing individual weight. The highest lipid proportion and the lowest protein proportion of E. hamata occurred in winter, with the opposite situation in spring. The proportion of lipid increased and the proportion of protein usually decreased with increasing individual weight. Environmental and trophical factors probably govern the main seasonal trend in weight and lipid content of all three species, and differences in feeding preference and reproduction cycle add specific characteristics to the seasonal cycles. Since ash is a rather conservative component the ash content of a given species may be used as an index of size, unaffected by the physiological condition of the animal.