Survey on Macro-Zoobenthic resource in Seyahdarvishan and Passikhan Rivers, Potamon Zone (Quantitative)

The Rivers Seyahdarvishan and Passikhan are the main two rivers which evacuate water to Anzali coastal lagoon. The two rivers has sustain flow in potamon zone with only variations in rate during spring and autumn season. The existence of bivalve Corbicula and the aquatic insect Ephemeroptera in benthic composition indicate good environmental condition being prevailed during one year research programme conducted in 1993. Furthermore, finding of fishes Alburnoides bipunctatus and Caspiomyzom wagneri showed the Rivers had sound water quality. The average standing stock of macrozoobenthic in the study area, the potamon zone estimated 961±450(9.5g) and 546±254(5.4g) per sq.m. respectively, Therefore, the fish-yield in the study area in relationship with benthic biomass represent low natural productivity. These benthic trophy level probably could support 30-40 kg and 20-30 kg per hectare of fishes in Seyahdarvishan and Passikhan potamon zone respectively. Low bottom dwelling fishes is an ev.....