Emergence and Composition of Trichoptera from Karst Habitats, Plitvice Lakes Region, Croatia

Abstract

Adult Trichoptera were observed at the Plitvice Lakes, Croatia during two years (2000 and 2001) using pyramid-type emergence traps. A total of 1350 individuals and 37 species were collected. Throughout the study, the emergence patterns showed only minor variations regarding differences in particular habitats. During 2000 most species emerged in June, and in 2001 in May. The complete emergence period is shown for all collected species and studied in detail for abundant species. Excluding Allogamus uncatus, all abundant species emerged in summer, with most exhibiting a long emergence period. Rhyacophila fasciata had the longest emergence period in both years of the study and also showed winter activity. Trichopteran diversity and equitability were calculated and trophic relationships of the collected species were identified for each sampling site in order to obtain better insight into trichopteran community structure. Results indicated that the trichopteran community could be grouped according to travertine barriers and stream habitat types. IntroductionTo date, there have been various studies focusing on trichopteran communities in karst habitats, but mostly based on larval stages (e.g. BONADA et al., 2005;HABDIJA, 1988; HAB-DIJA et al., 2002). Besides, data of adult Trichoptera ecology and faunistics are commonly obtained by sampling with light and Malaise traps (e.g. SMITH et al., 2002;SVENSSON, 1974;WARINGER, 1991;. Thus emergence patterns and the length of the emergence periods are still insufficiently investigated for many species inhabiting karst areas.The emergence method has been used for various studies all over the world. At first, the method was used for quantitative production studies (ILLIES, 1971;MALICKY, 1976), but more recently it is mostly used for faunistic, phenological and biodiversity studies of running waters (FREITAG, 2004;FÜREDER et al., 2005;PETERSEN et al., 1999;WARINGER, 1996) due to its advantages over some other methods, e.g. benthos sampling (MALICKY, 2002). Hence, the emergence method was applied to investigate trichopteran community composition and emergence patterns in different karstic habitats.The Balkan Peninsula is known to be an important evolutionary centre for a number of trichopteran genera (e.g. Drusus, Rhyacophila, Tinodes, Potamophylax) resulting in a high species endemism (KUMANSKI and MALICKY, 1999). The Plitvice Lakes National Park was chosen for this study because of the presence of different habitat types typical of the karst systems (springs, streams, lakes and travertine barriers). Moreover, some endemic species from the mentioned genera inhabit the Plitvice Lakes area (KUČINIĆ and MALICKY, 2002;MARINKOVIĆ-GOSPODNETIĆ, 1971) and were thus encompassed in the study. The objectives of the study were (1) to define emergence patterns of species inhabiting karst but also to compare these with data from different habitats and regions (2) to investigate the composition, diversity and similarity of trichopteran fauna at different karst habitats, (3) to determine ...

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