Ecology of Pseudoterranova decipiens (Krabbe, 1878) (Nematoda : Anisakidae) from Antarctic waters

The present study provides further data on the occurrence of Pseudoterranov a decipiens in fish from two different sampling sites in the Antarctic. A t otal of 690 fish belonging to 33 species from the eastern Weddell Sea and 3 22 fish belonging to 12 species from the South Shetland Islands were examin ed. Altogether, 23 fish species were found to be infested and 11 new host r ecords could be established. P. decipiens occurred at a water depth of betw een 80 and 820 m. Chaenocephalus aceratus and Notothenia coriiceps from the South Shetland Islands were the species with the highest prevalence (95%) and intensity (2-194 and 1-121, respectively) of infestation. Both are tran sport hosts, which mainly feed on benthic nototheniid fish species and accu mulate the nematodes. Bathypelagic, pelagic, or mainly euphausid feeding fi sh species were only lightly infested, if at all. This demonstrates the ben thic life cycle of P. decipiens in the Antarctic. The preferred site of inf estation was the body cavity and the liver; no specimen could be isolated f rom the fish musculature. This might bit explained by the low water tempera tures. The infestation of fish from the Weddell Sea was distinctly lower th an that of fish around the South Shetland Islands. Besides possible differe nces in final host populations at the two localities studied, the loss of e ggs and larvae under the eastern Weddell Sea shelf ice and over the contine ntal slope and differences in the availability of the first intermediate an d macroinvertebrate hosts led to a lower level of infestation. Another role , although nondecisive, may be played by the reduced time of development an d infectivity of eggs and larvae, respectively, in the extremely cold water s of the Weddell Sea. P. decipiens is not a rare but, rather a well-establi shed parasite of the Antarctic fauna, which demonstrates the ability of thi s cosmopolitan species to complete its life cycle even under conditions of subzero temperatures.