Fauna parasitária de peixes Sciaenidae (Teleostei, Perciformes) da região de Valença, Bahia

Abstract

Sciaenidae fishes live in coastal environments, and some species are found in estuaries and others only in freshwater. They are important fishing resource, due to the meat ́s quality. Wakefish are included in the family, and are important commercial species. Nevertheless, studies on its parasitic fauna are concentrated in Brazilian southeastern region. Thus, the work aim to study the ectoparasite and endoparasite fauna of the Sciaenidae Cynoscion leiarchus, Cynoscion jamaicensis, Cynoscion microlepidotus, Cynoscion sp., Macrodon ancylodon and Isopisthus parvipinnis from Valença - BA, and to observe the similarity between the hosts. The fish were caught from August 2009 to May 2010, August 2015 and February 2016, and were sent to the Laboratório de Estudos da Ictiofauna at UFRB for biometry, necropsy and parasites collection, quantifing and identification, following specific techniques. With the obtained data, the parasitisms levels (prevalence, mean intensity and average abundance) and the community and infracommunity descriptors (richness and diversity) were calculated. One hundred and eighty four (184) specimens of wakefish were analyzed: 34 C. leiarchus, 21 C. jamaicensis, 19 C. microlepidotus, 6 Cynoscion sp., 94 M. ancylodon, and 10 I. parvipinnis. A total of 1,197 parasites, 223 ectoparasites and 975 adult endoparasites or larvae, were collected, distributed in 31 taxa identified. The most representative taxonomic groups in abundance and species richness were Trematoda (33.3%), followed by Nematoda (19.35%). All the found species had a relatively low prevalence, not exceeding 60%. Lernanthropus cynoscicola, D. monticelli and P. americanus had the highest prevalence in at least one of the species studied. Significant differences were observed in the means of richness and Shannon and Brillouin diversity indexes among the six host species indicating that, despite the degree of taxonomic proximity between hosts, other factors influence the composition and structure of parasitic communities. The qualitative similarity among the host species was low, with a higher value slightly above 38%. This low qualitative similarity is due to the presence of only a few parasitic species characteristic of sciaenids and many generalist species. The most similar hosts are C. leiarchus, M. acncylodon and I. parvipinnis and the most distinctive was Cynoscion sp.. It is concluded that the parasite fauna of the six host species differs in composition and descriptors of ecological communities. Ecological factors, probably, to play a more relevant role in arrangement these communities than phylogenetic factors. The low similarity between the hosts indicates great parasitic diversity within the family in the region.