Spatio-temporal structure of the communities of helminths in the digestive tract of Sciaena umbra L. 1758 (Teleostei).

The helminth community in the digestive tract of the sedentary predatory fish, Sciaena umbra, near the Scandola Nature Reserve, Corsica, consists of 5 species of digeneans. Anoiktostoma coronatum (in the rectum) and Metadena pauli (in the intestine) were found in almost all the fish, and in high numbers; they are considered core species. Distomum aloysiae, Pleorchis polyorchis (both in the intestine), and Stephanostomum bicoronatum (in the rectum) were relatively uncommon, usually found in small numbers, and are considered satellite species. The two core species were very abundant in June, when the size of their populations was strongly correlated with the size of the host fish. At this time, M. pauli was found mainly in the duodenum, but in high populations was spread throughout the intestine (s. strict.). Both species were much less abundant in October, their populations were less dependent on host size, and M. pauli was more limited to the anterior intestine. Pleorchis polyorchis and Distomum aloysiae were more frequent in October, were found predominantly in fish with few M. pauli, and were found posterior to M. pauli, suggesting some interactions between these species. Stephanostomum bicoronatum showed no seasonal patterns, and no apparent interactions with A. coronatum.