Population structure of Gammarus izmirensis (Amphipoda) inhabiting Yi？itler Brook (Nif Stream, ？zmir)

Yi？itler Brook, one of the branches of Nif Stream, has a regular flow regime throughout the year. The brook is one of the important aquatic habitats in terms of biological diversity by having relatively unpolluted water. The main objective of the present study is to get information about the population structure of Gammarus izmirensis ？zbek, 2007 whose type locality is Yi？itler Brook. There is no information about the species in literature except its original description paper. Gammarus specimens were sampled in monthly intervals between October 2015 and November 2016. Samplings were performed at one locality. During the study, a total of 1938 G. izmirensis specimens were investigated. Of them; 850 were females, 586 were males and 502 were juveniles. The maximum body length was 14.5 mm in males and 14.0 mm in females. The number of juveniles is higher in March and August. The species has a multivoltine life cycle with two generations (spring and summer) throughout the year