CEPAVE   05420
CENTRO DE ESTUDIOS PARASITOLOGICOS Y DE VECTORES
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Recruitment and ecological parameters of three Anisakid larvae (Nematoda: Anisakidae) parasites of Engraulis anchoita (Pisces: Engraulidae) from South West Atlantic Ocean
Autor/es:
GARBIN, L.; JULIA I. DIAZ; CECILIA CARBALLO; FLORENCIA CREMONTE; GRACIELA T. NAVONE
Lugar:
Viterbo, Lazio, Italia
Reunión:
Simposio; 7th International Symposium on Fish Parasites; 2007
Institución organizadora:
Società Italiana di Parassitologia, Università di Roma "La Sapienza"
Resumen:
Anisakid nematodes have a worldwide distribution and are associated with fish, birds, and marine mammals. Transmission of species usually involves aquatic invertebrates. and fish as intermediate or paratenic hosts (Anderson, 2000, Cabi Publishing, New York, 650 p.). Species of Contracaecum Railliet and Henry, 1912, (Anisakinae) use piscivorous birds and pinnipeds associated with freshwater, brackish, and marine systems as definitive hosts. Recent studies on anisakids from Península Valdés, Chubut, Argentina, have demonstrated the presence of Contracaecum pelagicum parasitizing Spheniscus magellanicus (Spheniscidae) (Garbin L et al., 2007, J Parasitol 90: 103-114). Objectives of this work were: to demonstrate that Engraulis anchoita (Engraulidae), predilect item prey of the penguin, could represent an intermediate/paratenic host of Contracaecum spp.; and to evaluate the anisakid recruitment and infection caused by a regular anchovy food ingest on Magellanic penguins. A total of 202 anchovies were obtained from fishing ships at the Rawson's Port, Chubut province, Argentina. Fish were analysed for nematodes and 40 of them were weigthed and measured. Prevalence (P), mean intensity (MI), and abundance (MA) were calculated for the three Anisakid genera found. Results were respectively the following: P=52.5%, MI=2.81, and MA=1.47 for Contracaecum spp.; P=90%, MI=6.97, and MA=6.27 for Hysterothylacium spp.; and P=25%, MI=1.40, and MA=0.35 for Anisakis spp. Mean anchovy weigth was 19.08g (12.89-29.45g). Penguin mean mass of stomach content is 430g with a range between 80 to 1183g (Scolaro et al., 1999, Waterbirds 22: 104-110). Therefore, a penguin might ingest an average of 22.5 anchovies with a minimum of 4.9 and a maximum of 62 individuals daily. In this way, nematode recruitment could be 63.22 (13.77-174.22) individuals in each ingest for Contracaecum spp. third-stage larvae, 156.82 (34.15-432.14) third-stage larvae for Hysterothylacium spp., and 31.50 (6.86-86.80) third-stage larvae for Anisakis spp. This last anisakid is not able to mature in the digestive tract of S. magellanicus; their definitive hosts are marine mammals. Hysterothylacium spp. will develop to adult since teleost fish are their definitive hosts. Despite prevalence value of infection by Contracaecum spp. larvae observed in the anchovies is low we might infer that they could act as paratenic hosts of C. pelagicum due to the prevalence found in S. magellanicus (40%). Moreover, E. anchoita is the main food resource of penguins which showed a mean intensity of 149 C. pelagicum adult individuals in stomach (Garbin et al., 2007, J Parasitol 90: 103-114). This mean intensity of Contracaecum sp. on penguins could be explained as a result of several anchovy ingests that penguins do during their development from nestling to adults. On the other hand, the adult penguin habit of feeding nestlings would contribute to reduce the larval nematode recruitment. In addition, not all Contracaecum larvae infecting anchovies are capables to mature in the stomach of the penguin since we could observe third-stage larvae in bird intestine. Probably, this finding show that these larvae compete for space and food resources, or they represent to other species which are not able to parasitize S. magellanicus.