First evaluation of three lakes’ (Çıldır, Aktaş and Aygır) macrozoobentic community structure in Aras River basin (North Eastern Türkiye)

In order to evaluate the macrozoobenthic fauna of Çıldır, Aktaş and Aygır lakes, 47 taxa were identified as a result of the samplings carried out in different periods in 2013, 2017 and 2019. 41 of 43 taxa identified at species level were new records for the study area. The dominant species of Lake Çıldır were Gyraulus (Armiger) crista (4.49%), Paratanytarsus lauterborni (3.90%) and Virgotanytarsus arduensis (3.80%). It was seen that the gammarid population was determined dominant among zoobenthos of Aktaş Lake. Gammarus pseudosyriacus was the dominant species with 15.24% dominance rate in Aktaş Lake, followed by Cricotopus (Isocladius) reversus with 7.53% and Gyraulus albus with 7.29%. Gammarid population was also high in Aygır Lake, but unlike Aktaş Lake, Gammarus balcanicus from this group with a dominance rate of 6.28%; it took the fourth place after Gyraulus albus (8%), Virgotanytarsus arduensis (6.92%) and Cricotopus (Isocladius) tricinctus (6.64%). In terms of macrozoobenthic fauna diversity, the highest Shannon and Margalef Index values were found in Lake Çıldır (Shannon Index H': between 1.73-2.23 (average 2.0), Margalef Index: between 1.89-2.06 (average 2.03)) while diversity indices were lower in Aktaş and Aygır lakes. The taxa detected in all three lakes are α and β mesotrophic species, and the high population density can be considered as a sign of the transition from the oligotrophic level to the mesotrophic level, especially for Lake Çıldır.