Biology session

Investigation of the interaction between natural and artificial water habitats is important for economical reasons and also for the conservation of the natural environment. In our study, we seek to find out whether artificial water habitats have an effect on the parasite infection of fish fauna in a natural habitat. We compared the parasite infection of the fish fauna in two areas of the stream Benta near Százhalombatta. The first study area was situated few kilometers away from the town, near Mainroad 6. The second study area was located in the town, near the vent drains of the Tempered Water Fish Hatchery and Benta Anglers Park. The sampling went on through five months, once a month by angling, with a few days lag between the two study areas. In the course of fieldwork, we sampled the water three times for inorganic chemical tests and microbiological studies. Fishes were subjected to complete parasitological dissection. The obtained parasites were identified and ranged in larger taxonomical groups (phylum or class) for the induction. Data were statistically analyzed.

In the aspect of seasonality, the results showed that in spring, the prevalence of flukes (Trematoda) in the fish from the second study area was twice as high as that in the fish from the first study area having no connection to artificial water area. The effect of the fish farm may be presumed from the result that the prevalence of myxozoans (Myxozoa) increased in spring and early summer compared to the fish of the first study area. We analyzed the distribution of parasites by their location in organs and organ-groups. The results showed that the intestine and inner organs were more heavily infected in the fish from the first study area than in the ones from the second area. However, in fish from the second area, we found myxozoans in the muscle tissue, in contrast to the fish of the first area. In the parasite infection of male and female fish, we did not detect remarkable difference. Evaluating the prevalence data by parasite groups, we surprisingly found that the rate of protozoans (Protozoa) was higher in the first area. In this area, the nematode infection of male fish was also higher. The prevalence of tapeworms (Cestoda) and acanthocephales (Acanthocephala) were similarly low in both areas. The rate of other parasite groups (Myxozoa, Monogenea, Trematoda) were higher in the study area near the fish farm, as expected.

Our results showed that the artificial water habitats near the study area had an effect, although in low rate, to the fish fauna of stream Benta. Further investigations would be required to get a more complete image on the nature and measure of the effect.