COMPARISON OF PARASITES OF MUMMICHOGS AND STICKLEBACKS FROM BRACKISH AND FRESH-WATER PONDS ON SABLE ISLAND, NOVA-SCOTIA

Mummichogs (Fundulus heteroclitus) and ninespine sticklebacks (Pungitius pungitius) were collected from brackish and freshwater ponds on Sable Island in 1991 and 1992 to examine and compare parasite faunas among habitats. Separate populations of mummichogs inhabiting a brackish (East Pond) and a freshwater pond (Main Pond) were infected with Cosmocephalus obvelalus, Paracuaria adunca, Contracaecum sp. and Neoechinorhychus cylindratus. Proteocephalus sp. was found only in mummichogs from the brackish pond. Ninespine sticklebacks from the brackish pond were infected with C. obvelatus, P. adunca, Contracaecum sp., Proteocephalus sp., Diphyllobothrium ditremum, Gyrodactylus spp. and Thersitina gasterostei. All parasites plus Schistocephalus pungitii were found in ninespine sticklebacks from the freshwater pond, and except for Proteocephalus sp. and T. gasterostei, from sticklebacks in a second freshwater habitat (Lily Pond). Abundances of most parasites varied among ponds. Abundances of several parasites, including C. obvelatus, D. ditremum, S. pungitii, Proteocephalus sp. and N. cylindratus, varied between years within ponds. Parasite species composition was similar between brackish and freshwater habitats, but habitat characteristics such as salinity, invertebrate species composition and ocean access contributed to differences in abundances of parasites among ponds, whereas temporal variations reflected the instability of the Sable Island environment.