Macrozoobenthos Community and Ecological Status in Prespa Lake (oteshevo, Stenje and Ezerani) in Spring 2022

This study represents the results for the invertebrate fauna carried out in the spring of 2022 at Prespa Lake (Republic of North Macedonia). The survey has covered three distinctive localities: Oteshevo, Stenje and Ezerani. Twelve species from six systematic groups have been registered from the above mentioned localities in Lake: Oligochaeta, Hirudinea, Gastropoda, Bivalvia, Amphipoda and Insecta. The results of the survey clearly showed that the structure of the invertebrate community along the littoral zone of the Lake varies from one locality to another. Thus, more than half of the total diversity was registered in the locality of Ezerani, while the community of invertebrates is almost half poorer in Stenje and Oteshevo, with 5 species on each locality. As for the density, similarly to biodiversity, the highest number of individuals per square meter was registered in the Ezerani locality - a total of 10,750 ind/m². The second-highest density was recorded in the locality of Stenje with 4,225, while the lowest density was recorded in the locality of Oteshevo with 1,200 ind/m². The highest population density of Dreissena carinata was recorded - 3,250 ind/m² in the Stenje locality at a depth of 5 m in the shell zone. The results of the research indicate that the biodiversity of the invertebrate fauna decreases with increasing depth, which is closely related to the increase in the uniformity of the sediments and the stability of the environmental factors along its depth. In contrast, there is no density dependence with depth.