Limno-ecological assessment of lentic ecosystems in the western Mediterranean basin (Turkey) using phytoplankton indices

Great attention has been given to freshwater ecosystems worldwide due to the increased exploitation of water resources and the degradation of water quality. This study was aimed to demonstrate the phytoplankton-stressor interactions using multivariate approaches and assess the ecological conditions of 28 sampling stations of 12 lentic ecosystems (five lakes and seven reservoirs) in the western Mediterranean basin using phytoplankton indices in dry and rainy seasons 2018. Freshwater and brackish water systems were separately ordinated by canonical correspondence analysis. The brackish ecosystems were under pressures of Ar (arsenic), N-NO2-(nitrite), Ca (calcium), EC (electrical conductivity), Cl (chloride), B (boron), etc., whereas shallow freshwater ecosystems were associated with total organic carbon. These factors had significant effects on phytoplankton distribution among lentic ecosystems on the basin. Ecological associations of phytoplankton assemblages varied in the western Mediterranean basin during the study.Pseudanabaena catenataandPalatinus apiculatus, considered tolerant taxa, are associated with higher Ar, EC, and V (vanadium) whileDesmodesmus abundansandMicrocystis flos-aquaeare related to total organic carbon. The modified PTI (phytoplankton trophic index) had the highest correlation coefficient value. Scores of the PTI varied from 2.02 in cavdir Reservoir to 2.59 in Lake Kocagol. Results of phytoplankton indices indicated that two (Golhisar and Yazir) lakes and two (Yaprakli and cavdir) reservoirs were classified as Good, and three lakes and five reservoirs were classified as Moderate condition. Other predicted classifications (high, poor, and bad) by phytoplankton metrics were not represented. The modified PTI could be a suitable phytoplankton metric for assessing the ecological status of lentic ecosystems in the Mediterranean system according to its highest correlation coefficient value. Overall, the results of this limno-ecological study demonstrated that responses of phytoplankton taxa to explanatory factors provide crucial ecological information about their ecology and to estimate the ecological status of lentic ecosystems.

Automated summary

This study assessed the ecological conditions of lentic ecosystems in the western Mediterranean basin, demonstrating significant effects of different stressors on phytoplankton distribution. The Phytoplankton Trophic Index (PTI) was found to be a useful metric for evaluating the ecological status of these ecosystems, with some lakes and reservoirs classified as Good or Moderate conditions based on phytoplankton metrics.