Infection patterns of Corynosoma spp. (Acanthocephala: Polymorphidae) in paratenic fish hosts from Patagonia (Argentina).

HERNÁNDEZ-ORTS, J.S., E.A. CRESPO, N.A. GARCÍA, F.E. MONTERO, J.A. RAGA & F.J. AZNAR

Melbourne, Australia,

Congreso; THE XIITH INTERNATIONAL CONGRESS OF PARASITOLOGY (ICOPA); 2010

Cystacanth larvae of most species of Corynosoma are found in a number of fish species, many of which act as paratenic hosts filling the trophic gap between intermediate hosts (small crustaceans) and definitive hosts (DH) (marine mammals). However, other fish species potentially act as an ecological sink’ for the parasite, either if they are never consumed by the DH, or if they do not survive predation by fish that are consumed by the DH. In this study, we explore the role of 20 fish species for the transmission of Corynosoma spp. in the neritic zone of the North Patagonia sea. A total of 544 individual fish were examined. Three species of Corynosoma were found: C. australe (total n= 1050), C. cetaceum (n= 22) and C. bullosum (n= 1). The rarity of C. bullosum could be related to the fact that elephant seals (their DH) forage at deeper waters. Infection levels of C. australe and C. cetaceum were smaller than those reported in fish from northern Argentina, supporting the hypothesis that there is a latitudinal trend of abundance regardless of the population size of their DHs (otariids and small cetaceans, respectively). In agreement with previous data from other localities, C. australe occurred in pelagic, demersal and benthic fishes, whereas C. cetaceum was restricted to demersal/benthic fishes. The reasons for this ecological difference are unknown. Interestingly, C. australe was hardly found in the most important prey (the common hake, Merluccius hubbsi) for South American sea lion, its main DH in the study area. Apparently, the ubiquity of C. australe in the trophic web would increase the likelihood of infection through alternative prey.