Zoobenthic invertebrate of Anzali Lagoon and their relation with organic matter of the bottom

Abstract

The study was conducted in Anzali Lagoon (37 ̊ 28 N , 45 ̊ 25 E) in 38 stations during April 1994 to March 1996. In this study 13 biogroups were separated and counted. The abundance of most biogroups was very low, while that of the groups Chironomidae and Tubificidae were high and the abundance of the biogroup Amphipoda, Culicidae and Ephemeroptera was lower than the mentioned groups. Tubificidae was seen in all stations and all months of the year and its maximum density was 3740 organisms in each square meter. After Tubificidae the Chironomidae family had the second level of density. The total percentage of the organic substances of the bottom had not considerable changes in different month and its mean amount differed from 2.57% in the site of breakwater and the sea to 27.1% (maximum) in central portion of the lagoon. No considerable relation was observed between the amount of organic matter and the abundance of benthos in the region. According to the obtained results, Tubificidae and Chironomidae families showed little correlation with the bottom organic substances. The correlation of biogroup Ephemeroptera with the organic substances was greater than that of the 2 mentioned groups. Using the cluster type analysis and dendrograms made clear that the relation of biogroups Culicidae, Ephemeroptera and Tubificidae with the bottom organic substances was more than that of Chironomidae. Culicidae and Chironomidae showed close correlation with silt and clay of the bottom, but Tubificidae was more adaptable with the bottom fine particles.