engleski

Succession of Ichthyocenosis in a Lateral Channel at Dubrava Dam in Croatia

Dubrava Dam is the largest hydroelectric dam on the Drava River in Croatia and its lateral channels are 11 km long. These channels contain seeping water from power plant reservoirs, therefore, the main aspects of such water are insufficient oxygen concentration, low temperature and high speed of running water. In this work, the results of nine years research are given. 268 specimens of 18 different fish species were caught on this location. The estimated species richness is 23.3; standard deviation of species richness 2.98 and the number of unique species is 6. The Shannon-Wiener index of species diversity is 3.148 of the possible maximum 4.170. Simpson's index of diversity is 0.853 of the possible maximum 0.948. Common fish species found on this location are burbot (26.49%), Alburnoides bipunctatus (19.03%), brown trout (12.69%), miller's-thumb (12.31%) and chub (7.09%). According to the these data this water could be classified as water similar to the upper reaches of a river. The diversity of zoobenthic fauna here is very low because of the uniformity of habitat, low temperature and insufficient oxygen concentration. Only 18 different zoobenthic species were found and their structure is similar to acalorheophilic fauna of the upper reaches of a river.

lateral channel; fish fauna; species diversity

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