Dr. Murai Éva - Gubányi András szerk.: Parasitologia Hungarica 28. (Budapest, 1995)

© Hungarian Natural History Museum Hungarian Society of Parasitologists Parasit. hung., 28: 109-112, 1995 Digenean parasite family Ardeidae assemblages in birds of the from a lake ecosystem in Bulgaria Nesho CHIPEV and Aneta KOSTADINOVA Institute of Ecology, Bulgarian Academy of Sciences, 2, Gagarin Street, Sofia 1113, Bulgaria Although the helminth fauna of ardeids is not well documented earlier work has indicated that digeneans are the most significant group of helminths in these birds (Leonov 1960, Feyzullaev 1962, Brglez and Gabrovsek 1988). However, no data are available on the organization of trematode communities in ardeids. The aim of the present paper is to identify patterns in trematode assemblages of ardeid birds which coinhabit a model ecosystem. The brackish lake Durankulak (approximately 5 km

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), situated in Northeastern Bulgaria at the Black Sea coast, was used as a model habitat. The lake is characterized by a moderate to high level of eutrophication and supports a diverse avian fauna. A total of 32 birds belonging to 5 ardeid species were collected from April to October. Birds were autopsied and the trematodes found were killed in hot water, preserved in 70 % alcohol, stained with iron acetocarmine, mounted in Canada balsam, identified and counted. The program BIODIV (Baev and Penev 1991) was used for group average clustering and calculation of similarity (Sorensen's) and diversity (Brillouin's evenness and diversity, and Simpson's dominance) indices. Detrended Correspondence Analysis (DCA) was performed following Ter Braak (1988) with CANOCO. A total of 18 digenean species were found in the birds studied (Table 1). Only one trematode species was established in the 6 Egretta garzetta examined. Ardeid specialists were the predominant group of digeneans in the studied hosts. Only 3 species (Cryptocotyle concavum, C. jejunum and Renicola sp.) could be considered generalists. These species also complete their lifecycles in the neighbouring marine environment. With a few exceptions (Codonocephalus urniger and Echinostoma sudanense) the trematodes found in ardeids were transmitted by fish as second intermediate hosts. Patterns of similarity among digenean assemblages in pooled monthly samples of the hosts were studied using cluster analysis on presence/absence data The clustering produced 2 main clusters (Fig. 1). The first cluster included the two Ardea species and the second cluster included A. ralloides and Botaurus stellaris. The only trematode species found in E garzetta was not present in the other hosts. At higher similarity levels the classification of trematode assemblages followed the host species studied. Further, spring and autumn samples of hosts seemed to differ in their trematode species composition. The pattern suggested by classification was further elaborated using detrended correspondence analysis (DCA) on abundance data. The first two axes of the specieshost biplot accounted for 34.5 and 20.3% of the variation and had eigenvalues 0.93 and 0.51, respectively. The first axis could be interpreted as a larger scale host-specificity gradient operating at the host generic level. Along this axis digenean assemblages of the two Ardea spp. were separated from those of Ardeola and Botaurus. The second axis was more complex in nature and could be interpreted, on the one hand, as a finer specificity gradient, MATERIALS AND METHODS RESULTS AND DISCUSSION