Parasite transmission in sympatric cetaceans of the Patagonian ecosystem.

BERÓN-VERA, B., E.A. CRESPO, M. FERNÁNDEZ, & J.A. RAGA

San Sebastián

Congreso; 21 ANNUAL CONFERENCE OF THE EUROPEAN CETACEAN SOCIETY; 2007

EUROPEAN CETACEAN SOCIETY

Marine mammal endoparasites are transmitted through prey, therefore, feeding habits should always be considered. We provide information on prey consumption in relation to parasite transmission. Latitudinal gradients in larval parasites of preys are reflected in marine mammals. Over the continental shelf, C. cetaceum is characteristic in northern dolphins (common dolphins, franciscanas). In accordance to this, it was also present in one dusky dolphin from sympatric areas, contrary to others from higher latitudes. Cynoscion guatucupa harbors juveniles so we assume that they become infested consuming this prey.  Larval A. simplex are present in northern Patagonia and infestations are not as high as expected (common dolphins, Burmeister´s porpoise). The opposite is seen in duskies from central Patagonia. This is related to a latitudinal rather than to a longitudinal gradient as previously suggested. Common dolphins feed on Argentine anchovy where Anisakis is less frequent, so its recruitment to final hosts turns low. At higher latitudes, this fish is an important prey of duskies, showing higher infestations and is, then, the major intermediate host in its transmission to duskies. Commerson´s dolphins, however, they feed on small fish (juvenile Argentine hake, Fuegian sprat) and are lightly infested with larval Anisakis. So, to the north, C. cetaceum is characteristic of franciscana, common and dusky dolphins. To the south A. simplex, B. cordiformis and P. gastrophilus parasitise dusky, common and Commerson?s dolphins. Besides, A. simplex and O. rochebruni are common to hourglass dolphins. Not enough data is available to account for latitudinal gradients outside the continental shelf but, as a common pattern, cestodes appear in the blubber. Narrow diets reflect low species richness. In general, these marine mammals concentrate only on a few most abundant prey species out of their whole diet; while other species rarely appear what may directly reflect parasite aggregation in the preys consumed.