Identifying and counting zooplanktons and crustaceans in water of Karun River, Ahvaz city, Iran

Karun River has an important role in the lives of citizens in Ahvaz, especially those in the agricultural sector. Unfortunately, lack of any water management plans and the rather less attention paid to pollution have reduced water quality in this river. Given the importance of the ecological balance of the river, and considering the precise status of river water quality, the present study was aimed to identify and count the zooplanktons and crustaceans living in this river. In this study, sampling was done in two seasons (autumn and winter) at three stations. According to our findings, the most common types of zooplanktons were Monhystera simolis, Limnodrilus hoffmeister, Dero obtusa, and Rotaria rotatoria. The most common types of crustaceans were Daphnia magna, Monospilus dispar, and Alona costata. In addition, the measured BOD₅ was greater than the standard index for water quality in Iran’s aquatic ecosystems in all sites during winter and autumn. The temperature crossed the standard limitation in winter, but the measured pH was within the standard range (6–9). Results of this study showed sewage-induced pollution in Karun River. Consequently, there is an urgent need to control sewage discharge to the Karun River.