A comparative study on the parasite fauna of perch, Perca fluviatilis L., collected from a freshwater coastal lake, brackish-water Baltic Sea, and the interconnecting canal.
BACKGROUND
Parasitological surveys of freshwater fishes rarely include comparisons between two ecologically different bodies of water. Such studies might help to understand processes of establishment of parasite faunas in estuary areas. The results obtained could also provide useful tools for discriminating various fish populations based on the composition of their parasite faunas. The present authors attempted to study such data from Resko Lake-a freshwater coastal lagoon (6 km2 surface area), and the adjacent areas of the Baltic Sea. Resko Lake, located 12 km west of the city of Kołobrzeg, is shallow (1.5 m) and is connected to the sea through a small canal (1.3 km long, 30 m wide).


METHODS
The material was collected from April 1969 and July 1970. A total of 159 perch were collected, in this number 104 fish from the lake, 43 from the sea, and 12 from the canal.


RESULTS
A total of 32 parasite species were recovered from the fish necropsied. The parasites represented 7 higher taxa: Protozoa (3 species), Cestoda (4), Digenea (13), Nematoda (5), Acanthocephala (3), Mollusca (1), and Crustacea (3). The parasite fauna of perch from the sea was definitely more abundant (31 species) compared to that of the lake (21), and the canal (12 species). Infection parameters of 13 parasite species demonstrated significant differences between the locations studied. The infection level of 6 parasite species was significantly higher in perch from the sea: Bothriocephalus scorpii, Ligula sp., Brachyphallus crenatus, Camallanus truncatus, Hysterothylacium aduncum, and Echinorhynchus gadi. On the other hand, infection levels of 7 other species were higher at the lake: Triaenophorus nodulosus, Bucephalus polymorphus, Azygia lucii, Tylodelphys clavata, Camallanus lacustris, Acanthocephalus lucii, and Achtheres percarum. The infection parameters of the fish from canal were similar to those from the lake. Interesting observations were made on the seasonality of certain parasites of both lake- and Baltic perch. The presently observed differences between parasite faunas of the fish from ecologically different adjacent estuarine locations are certainly caused by diversified environmental conditions that affected the processes of formation of the parasite communities there. Among important factors that could affect compositions of the parasite faunas could have been: availability of the intermediate hosts, exchange of waters (Baltic water influxes to the lake), fish migrations (spawning), and finally the separate identity of the two fish stocks studied.
Wierzbicka
Jadwiga
J
Division of Fish Diseases, Agricultural University of Szczecin, ul. Kazimierza Królewicza 4, 71-550 Szczecin, Poland.
Wierzbicki
Krystyn
K
Piasecki
Wojciech
W
Smietana
Przemysław
P
D000818:Animals; D005393:Fish Diseases / Q000453:epidemiology / Q000469:parasitology*; D005398:Fisheries; D005618:Fresh Water / Q000469:parasitology*; D006790:Host-Parasite Interactions; D010271:Parasites / Q000145:classification / Q000502:physiology*; D010471:Perches / Q000469:parasitology*; D011044:Poland / Q000453:epidemiology; D015995:Prevalence; D012189:Retrospective Studies; D012621:Seasons; D012623:Seawater / Q000469:parasitology*