Parasite communities and feeding ecology of the European sprat (Sprattus sprattus L.) over its range of distribution.

The metazoan parasite fauna and feeding ecology of 165 Sprattus sprattus (L., 1758) was studied from different geographic regions (Baltic Sea, North Sea, English Channel, Bay of Biscay, Mediterranean Sea). A total of 13 metazoan parasite species were identified including six Digenea, one Monogenea, two Cestoda, two Nematoda and two Crustacea. Didymozoidae indet., Lecithocladium excisum and Bomolochidae indet. represent new host records. The parasite species richness differed according to regions and ranged between 3 and 10. The most species-rich parasite fauna was recorded for sprats from the Bay of Biscay (North Atlantic), and the fishes from the Baltic Sea contained the lowest number of parasite species. More closely connected geographical regions, the North Sea, English Channel and Bay of Biscay, showed more similar parasite component communities compared with more distant regions. From the examined stomachs of S. sprattus, a total of 11 different prey items were identified, including Mollusca, Annelida, Crustacea and Tunicata. The highest number of prey organisms belonged to the crustaceans. The variety of prey items in the stomach was reflected by the parasite community differences and parasite species richness from the different regions. The feeding ecology of the fish at the sampled localities was responsible for the observed parasite composition and, secondarily, the zoogeographical distribution of the parasites, questioning the use of the recorded sprat parasites as biological indicators for environmental conditions and change.