L. Forró szerk.: Miscellanea Zoologica Hungarica 9. 1994 (Budapest, 1994)

Andrikovics, S.; Hadnagy, T.: Ecological evaluation of aquatic invertebrates distribution of Apátkút Creek (Visegrádi Mountain, Hungary) in winter

MISCELLANEA Tomus 9. ZOOLOGICA 1994 HUNGARICA p. 89-103 Ecological evaluation of aquatic invertebrates distribution of Apátkút Creek (Visegrád Mountain, Hungary) in winter by S. Andrikovics and T. Hadnagy (Received April 15, 1994) Abstract: Aquatic insects and amphipods were collected between December 1984 and March 1985. The number of species and individuals is high in the creek even in winter. The mean water current is about 1 m/sec. Distribution of larvae primarily depends on the mean velocity of the water. All of the other ecological factors are closely related with the water current. The anthropogenic effects are also discussed. Key words: aquatic invertebrates, water current, dissolved O2, stone size. Introduction Ecological studies of small creeks in Hungary were carried out mainly from spring to autumn (Dvihally & Ponyi 1956, Entz 1958, Papp 1966, Oláh 1967, 1972, Kiss 1977, 1978, 1979, 1981). Our aim was the investigation of Apátkút Creek during winter. Tourism is much smaller in winter, while we can explore the original and natural situation more precisely. Some researches (Bengtsson 1981, Macan 1980, Flannagan 1983, Singh et al. 1984) pointed out that the invertebrate macrofauna in winter is not necessarily poorer than in summer, although the temperature is lower but the pollution is not so high. Others have opposite opinion (Bagge 1965, Bradt & Wieland 1981, Harper & Harper 1982). The question is whether the number of species and individuals of invertebrates in Apátkút Creek is rich or poor in winter. The subject of our work was the macro- and micro-distribution of macroinvertebrates in the creek and the evaluation of the ecological factors influencing them, with special regard to water current. The distribution of running-water organisms is determined first of all by water current (Lepnyeva 1949, Oláh 1967, 1972, Kiss 1978, 1981, Fuller & Mackay 1980, Madsen & Warnocke 1983, etc). Our aim was to measure the mean velocity of the creek water and to relate it to the distribution of aquatic insect larvae. Considering the complex effect of different ecological factors on the distribution, our task was to examine other ecological circumstances, too. We wanted to know what is the effect of water temperature, dissolved oxygen content, water-depth, and substrate-type on the distribution of invertebrate rhithron organisms.