232 specimens of Notothenia coriiceps neglecta and 578 specimens of Notothenia rossi marmorata were collected in the region of Admiralty Bay during the period from March to December 1977. The age of the fish was determined from scales. Length — weight relationship was calculated for both species. The parameters of the von Bertalanffy equation were calculated for Notothenia coriiceps neglecta, whereas mean lengths for Notothenia rossi marmorata were given according to the particular age groups.

Total toxicity of two types of mineral oil (from Zakum and Kuwait) was determined with respect to hydrobionts of the Antarctic ecosystem. Crustacean — Euphausia superba proved to be sensitive to hydrocarbon pollution of the sea environment (LC50 x 48 h-1 = 7.62 ppm). Fish — Notothenia rossi marmorata showed much lower sensitivity.

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 three months in 1978/79, based on the examination of twenty fish collected in each month. Digenea found in 1978/1979 season were more numerous, and more diverse. Only five digenean species, Macvicaria georgiana , Neolebouria antarctica , Lepidapedon garrardi , Genolinea bowersi and Lecithaster macrocotyle , were recorded 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 therefore 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. g arrardi 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.