Comparative analysis of the metazoan parasite communities of leatherjackets, Oligoplites palometa, O. saurus, and O. saliens (Osteichthyes: carangidae) from Sepetiba Bay, Rio de Janeiro, Brazil

RESUMO

One hundred and fifty-seven specimens of leatherjackets, 84 specimens of Oligoplites palometa (Cuvier), 37 specimens of O. saurus (Bloch & Schneider), and 36 specimens of O. saliens (Bloch) captured at the Sepetiba Bay, State of Rio de Janeiro, between March of 1991 and November of 1992, were necropsied to study their communities of metazoan parasites. All fishes studied were parasitized by one or more metazoan species. Eighteen parasite species were found in O. palometa and 13 parasite species were found in O. saurus and O. saliens, respectively. The digeneans were the majority of the parasite specimens collected, with 90.3 per cent, 82.2 per cent, and 87.7 per cent in O. palometa, O. saurus, and O. saliens, respectively. The Simpson index was lower than 0.25 for the 3 host species, showing an absence of concentration for dominance. The similarity coefficients among the parasite communities of the 3 fish species was above 66 per cent. The parasites of the 3 host species showed typical overdispersed pattern of distribution. Four cases of positive correlation between host's total lenght and prevalence and parasite intensity were found. The majority of the species did not show influence of host sex. The 3 host species had similar parasite diversity, which was not correlated with the host's total body length and there was no significant difference between male and female hosts. Oligoplites palometa and O. saurus each had one pair of ectoparasite species sharing a positive association and with a positive correlation between their intensities. No pairs of associated species were found in O. saliens. Parasites were found along the entire extension of the gastrointestinal tract of the 3 host species. The parasite communities of O. palometa, O. saurus, and O. saliens are defined as isolationists because there are few evidences of interspecific association or covariation. The presence of larval stages of cestodes and nematodes suggests that the three species of Oligoplites are at an intermediate level in the marine trophic web.