Changes in digenean infection of the Antarctic fish Notothenia coriiceps in Admiralty Bay,King George Island, over three decades

Abstract

Abstract: The infection of black rockcod, Notothenia coriiceps, with digeneans in Admiralty Bay (South Shetland Islands) within three months, from November 2007 to January 2008, is compared with the infection in the same threemonths in 1978/79, based on the examination of twenty fish collected in each month. Digenea found in 1978/1979 season were more numer− ous, and more diverse. Only five digenean species, Macvicaria georgiana, Neolebouria antarctica, Lepidapedon garrardi, Genolinea bowersi and Lecithaster macrocotyle, were re− corded during both investigations,whereas three species, Neolepidapedon trematomi, Elytro− phalloides oatesi and Gonocerca phycidis, only in 1978/79. M. georgiana was the dominant species in 1978/79 and sub−dominant in 2007/08. Other digeneans were found in N. coriiceps in 2007/08 invariably together with M. georgiana. G. bowersi was the sub−dominant species in 1978/79 and the most common species in 2007/2008. Infections with Digenea belonging to other species were much less intense. Of the three rare or common species in 1978/79, the two, L. garrardi and L. macrocotyle, occurred in both seasons, whereas E. oatesi occurred only in 1978/79. Three remaining species were sporadic or absent. The overall results there− fore demonstrated that infections with almost all digenean species were less strong in 2007/08 than three decades earlier, in 1978/79. Only data on M. georgiana, G. bowersi and L. garrardi were statistically significant (p <0.05). Data on the occurrence of 14 species of Digenea in N. coriiceps from South Shetland Islands, South Orkney Islands, South Georgia, Argentine Is− lands, Melchior Islands, Adelie Land and Heard Island are given.