New data on the occurrence of Acanthocephala in some fish in Admiralty Bay (South Shetland Islands).

New data on the infection with Acanthocephala of 33 fish caught in Admiralty Bay in November 2007 to January 2008 are given. These fish belong to 5 species: Notothenia rossii (22 immature specimens), Lindbergichthys nudifrons (n = 7), Trematomus bernacchii (n = 1), T. newnesi (n = 1) and Harpagifer antarcticus (n = 2). Three species of Echinorhynchida: Aspersentis megarhynchus, Metacanthocephalus dalmori and M. johnstoni and four species of Polymorphida: Corynosoma arctocephali, C. bullosum, C. hamanni and C. pseudohamanni, were found. Prevalence of N. rossii and L. nudifrons was 100%. The mean abundance of infection of N. rossii (125.09) was larger than that of Notothenia coriiceps (82.93). Data of infection of N. rossii in 2007 was almost identical with that in 1979 (mean abundance 118.66). The most abundant in this host were A. megarhynchus, M. johnstoni, C. hamanni and C. pseudohamanni (mean abundances 36.36, 29.77, 13.86 and 44.73, respectively). In total Echinorhynchida were more abundant than Polymorphida in 2007/08 (66.18 versus 58.91). Reverse situation was in 1979 (mean abundance 47.36 for Echinorhynchida and 71.3 for Polymorphida. Only 7 L. nudifrons were examined in 2007/08 and Echinorhynchida were more numerous in this host (mean abundance 26.71) than Polymorphida (10.29). Single specimens of other fish were infected with a few Acanthocephala belonging to species recorded in the same hosts with those found in 1978/79.