Distribution and Abundance of Chironomid Larvae in the Anzali Lagoon in 1993

Abstract

The Anzali Lagoon is situated in the south - west of the Caspian Sea (37, 28 N 43,25 E). Its surface area is 218 sq.krn. To study the distribution and abundance of Chironomid larvae a sampling was conducted biweekly in 25 stations in 1992. The Chironomid larvae had the maximum abundance compared to other benthic organisms during the study period. The maximum abundance of Chironomidae was seen in spring. The population of aquatic insects was diminished gradually in summer, and again increased from the middle of autumn to winter. Their monthly average in the lagoon was 125 ± 53 per sq.m. The number of larvae in the western basin (Abkenar), southern basin (Siyahkeshim) and eastern basin (Sheyjan) were 187 ± 62, 172 ± 136 and 137 ± 86 larvae per sq.m., respectively. In the main outlets of the lagoon, there were 9 ± 2 larvae per sq.m., monthly. On the other hand no Chironomidae larvae were observed in the Siyandarvishan River located within the limits of the sampling area except in spring and in the tide breaking region (harbour).