Investigation of zooplankton fauna and seasonal change of some wetlands in the Bismil Plain

In this study, the water quality of Ambar, Kuruçay, Pamuk and Salat streams, which are the important tributaries of the Tigris River in the Bismil Plain (Diyarbakır, Türkiye) was evaluated using 18 physicochemical parameters. Kuruçay stream had significantly higher TOK, Na+, NO3-, NO2-, Cl- and SO42- levels and lower DO levels than other streams due to sewage water discharges, animal manure storage areas near the stream and irrigation return flows. According to Surface Water Quality Regulation of Türkiye, all streams had "very good" water quality (class I) in terms of the average pH, NH4+ and F- values. Based on the average DO levels, Kuruçay stream had "good" water quality (class II), while other streams had class I water quality. All streams had class II water quality according to the average EC values. The average NO3- levels showed that Ambar and Kuruçay streams had class II water quality, while Pamuk and Salat streams had class I water quality. In terms of average PO43- levels, Ambar and Kuruçay streams had class I water quality, while Pamuk and Salat streams had class II water quality. From August 2020 to July 2021, the temporal and spatial distributions of zooplankton taxa in some streams and lakes of the Bismil plain were investigated. A total of 188 zooplankton taxa were identified, including 157 from rotifers, 23 from cladocerans and 8 from copepods. Among the rotifers, Keratella procurva, Lecane dorysimilis and Lepadella koniari are new records for the zooplankton fauna of Türkiye. In species richness, the Rotifera group comprised approximately 84% of the total zooplankton, followed by the Cladocera group with 12% and the Copepoda group with 4%. Seventeen families were identified. Among 34 families; Brachionidae was recorded as the family with the richest species diversity with 23 taxa, followed by Notommatidae with 21 taxa, and Lecanidae families with 20 taxa. Also, the most diverse genus was Lecane with 20 species. The streams of the Bismil Plain contain more species than its lakes. Comparing three different ecosystems in the research area; 66 of the identified taxa were found only in rivers, 17 of them were found only in karst lakes and 1 of them was found only in dam lakes.