Phytoplankton functional groups provide a quality assessment method by the Q assemblage index in Lake Mogan (Turkey)

The aim of this research is to test the Q phytoplankton assemblage index based on phytoplankton functional groups in Lake Mogan and to provide a quality state estimation by data from 2006. Phytoplankton was sampled at 2 stations of the lake, paralleled with physical (water temperature, Secchi depth, pH, conductivity) and chemical (DO, chlorophyll-a, alkalinity, total hardness, soluble reactive phosphorus, total phosphorus, NO2-N, NO3-N, NH3-N) analyses. The Q index was able to follow the main seasonal changes of the physical and chemical parameters and indicated a moderate ecological status for Lake Mogan. Phytoplankton biomass varied between 0.75 and 10.12 mg/L in the research period, and provided a similar ecological state by Q index, chlorophyll-a, total phosphorus, and Secchi depth. A total of 76 phytoplankton species were identified in the study period, belonging to 12 functional groups. The seasonal succession of dominant functional groups followed this sequence of coda: X2 (Chlamydomonas), Lo (Merismopedia, Peridinium, Chroococcus), F (Botryococcus, Sphaerocystis, Oocystis, Planktosphaeria), S1 (Phormidium, Planktothrix), M (Microcystis), and F (Botryococcus, Oocystis).