L. Forró szerk.: Miscellanea Zoologica Hungarica 7. 1992 (Budapest, 1992)

Andrikovics, S., Bankovics, A. , Csörgő, T. , Gere, G. , Sass, M.; Török, J.: Hydrozoological characters of a reconstructed wetland

field, or harvest area into open water, into the lower section of running water, or into the ecological environment of a littoral region. After we contemplated these facts, our research was focused on two main areas: 1. Studying the development of the fauna in and around the newly established reservoir and comparing it with the relatively undisturbed fauna of the protection area. 2. Studying the feeding of animals and evaluating the consequences of their metabolism on water quality. In the present paper our investigations concerning point 1. will be presented, whereas the questions concerning point 2. only those will be discussed which deal with the feeding of frogs. All other questions concerning different aspects of our investigations will be discussed elsewhere. Methods Certain groups of animals characteristic of the given biotope were studied, in spite of the fact that in the traditional biological monitoring system these groups are rarely taken into consideration. We investigated the mayflies (Ephemeroptera), the dragonflies (Odonata), and the caddisflies (Trichoptera) out of insects, and the amphibians and the birds out of the group of vertebrates. Larvae and imagos of the water insects were sampled by the traditional water and aerial nets, but imagos were also collected with the help of light traps. Amphibian populations were studied by walking through the area as well as by trappings. The changes occurring in the bird populations were followed also by walking through the studied area. In 1987 for differentiation of the species of the Rana esculenta complex, gelelectrophoretic investigations of blood serum proteins were carried out (Vogel & Chen 1976,1977, Uzell 1978). Altogether 26 blood samples (it lessonae 8, R esculenta 5, R ridibunda 13) were analyzed using lactate dehydrogenase (LDH) and albumin for separation of species (see for methods Low et al 1989). Results and conclusions In our surveys carried out in 1984 in the territory of the natural protection area, we found insect species in the water in very great numbers (e.g. Platycnemis pennipes, Agrion splendens, Gomphus vulgatissimus). Having compared our results with those of former investigations (Újhelyi 1955a, b) there were no significant differences. However, in 1988 the species mentioned above were pushed into the background whereas in the newly established reservoir common mayflies appeared (Cloeon dipterum, Caenis horaria, C. robusta). In contrast to these species, Potamantus luteus, which is characteristic of the lower part of rivers seems to be proceeding towards extinction. This species can not tolerate water pollution. At the same time, dragonflies appeared (Coenagrion puella, C. pulchellum, Ischnura elegáns, Sympetrum vulgatum, Anasciaeschna isocèles). The most characteristic rare dragonflies in the territory are (Aeshna viridis, Brachytron pratense, Leucorrhinia caudalis, L. pectoralis). Trichoptera of the studied area represent about 25% of all the species known to live in Hungary. The caddisfly fauna is relatively poorer than the dragonfly fauna (representing 50% of the Hungarian species, and this fact seems to be correlated with the high degree of water pollution). It is worth mentioning that stoneflies were not found in the investigated area because these species inhabit only clean waters.