SPATIOTEMPORAL 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 predato ry fish, Sciaena umbra, near the Scandola Nature Reserve, Corsica, con sists of 5 species of digeneans. Anoiktostoma coronatum (in the rectum ) and Metadena pauli (in the intestine) were found in almost all the f ish, and in high numbers; they are considered core species. Distomum a loysiae, Pleorchis polyorchis (both in the intestine), and Stephanosto mum bicoronatum (in the rectum) were relatively uncommon, usually foun d in small numbers, and are considered satellite species. The two core species were very abundant in June, when the size of their population s 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 w as spread throughout the intestine (s. strict.). Both species were muc h less abundant in October, their populations were less dependent on h ost size, and M. pauli was more limited to the anterior intestine. Ple orchis polyorchis and Distomum aloysiae were more frequent in October, were found predominately in fish with few M. pauli, and were found po sterior to M. pauli, suggesting some interactions between these specie s. Stephanostomum bicoronatum showed no seasonal patterns, and no appa rent interactions with A. coronatum.