Dietary overlap in inshore notothenioid fish from the Danco Coast, western Antarctic Peninsula

CASAUX R.; BARRERA-ORO E.

POLAR RESEARCH

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2013 vol. 32 p. 1 - 8

0800-0395

We carried out a dietary overlap analysis between notothenioid species byexamining the stomach contents of more than 900 specimens collected in afish assemblage at the Danco Coast, western Antarctic Peninsula, in thesummer of 2000. Prey reoccurrences among fish species were 32.2%, with krillEuphausia superba, salps and the gammaridean Prostebeingia longicornis the mostreoccurring prey. The diet similarity between species pairs was lower than55%, in accordance with similar fish assemblages in the South Orkney Islands,the South Shetland Islands and the Antarctic Peninsula. Whereas at thoselocalities the higher prey overlap was between krill-feeding fish species, at theDanco Coast it was between Trematomus bernacchii and Lepidonotothen nudifrons,Notothenia coriiceps and Notothenia rossii, Notothenia coriiceps and Parachaenichthyischarcoti, and Trematomus newnesi and Notothenia rossii, which shared primarilygammaridean amphipods, algae, fish and krill, respectively. Krill is normallythe main prey of fish in summer in inshore waters of the western AntarcticPeninsula, but its density in January/February 2000 was notably lower thanin previous years. Therefore, at the Danco Coast, under conditions of krillshortage, most of the notothenioid species foraged more intensively on alternativeprey, such as gammarideans, fish and algae. The difference betweenareas in the pattern of dietary overlap might be related to differences in preyavailability between years and to the degree of competition for targeted prey.