Dr. Éva Murai szerk.: Miscellanea Zoologica Hungarica 3. 1985 (Budapest, 1985)

Ponyi, E. J.; Bankós, L.: The effect of different pesticides on the amphipod Gammarus roeseli Gervais

2, 4-D. The pH of the lake water and that of the Aszófö stream was nearly equal. The test animals were collected in different months, but their sensitivity did not show any significant changes. Adaptability of the "Gammarus-test" for characterization of the "toxicity" of inflowing waters Following the local fishkill in 1975, complex investigations were carried out in 13 inflows of Lake Balaton with the aim of predicting any massive fish mortality. These studies were initiated by István LÁNG, Deputy Secretary General of the Hungarian Academy of Sciences, and organized by VITUKI (Research Centre for Water Resources, Budapest). The participating institutions determined different water quality indicating components. We were responsible for the so-called "Gammarus-tests". Our investigations proved two inflows to be highly toxic out of the 13 checked (Fig. 5), while in the others about 20-40% mortality was observed. Water samples from the two most toxic inflows were diluted to different concentrations and even at 50% dilution complete mortality (100%) occurred (Table 5). The toxicity of the waters has not been determined, because no additional data were placed at our disposal (i. e. results of gas-chromatographic analyses). We have to point out that Gammarus roeseli inhabits or inhabited those inflowing waters and lake water of Lake Balaton which do not or did not contain any polluting agents (PONYI 1956, 1957). Figure 5. Map of 13 investigated inflows of Lake Balaton with indication of the three most polluted streams according to the Gammarus roeseli tests (the areas of black circular segments are proportional to the mortality of the test animals) B9