Reproductive trade-off in male Antarctic krill, Euphausia superba

• Published in: Marine Biology
• Main Authors: Virtue, P, Nichols, P, Nicol, S, Hosie, G
• Format: Article in Journal/Newspaper
• Language: English
• Published: Springer-Verlag 1996
• Subjects: Biological Sciences; Ecology; Marine and Estuarine Ecology (incl. Marine Ichthyology); Antarctic; Prydz Bay; Antarc*; Antarctic Krill; Euphausia superba
• Online Access: https://doi.org/10.1007/BF00354634; http://ecite.utas.edu.au/90432

Freshly caught male and female Euphausiasuperba from the same swarm exhibited different ratesof mortality subsequent to capture. Mortality was significantlyhigher for reproductive males (100%, n = 68)than for females (3%, n = 186) within the first 3 d ofcapture. Total lipid and triacylglycerol levels in male,female and juvenile Euphausia superba were analysedand compared. All reproductive male krill analysedfrom this swarm had low lipid levels (1 to 3% dryweight) with negligible triacylglycerol stores (0 to 2% oftotal lipid). Somatic lipid stores in female and juvenilekrill ranged from 8 to 30%, of which up to 40% wastriacylglycerol. The levels of algal sterols in the digestivegland of males, females and juveniles indicate thatall krill had been feeding recently. An analysis of the sexratio of krill catches derived from data collected overseven summers from the Prydz Bay region showeda decrease in the proportion of males with increasingsize. There was a sharp decline in numbers of male krillonce they attained a length of 51 to 55 ram. Low lipidlevels in redroductive male krill may be due to reproductivecosts. The resulting low storage-lipid levels areaccompanied by high mortality in male krill.