Driving factors affecting the phytoplankton functional groups in a deep alkaline lake

Abstract

This study evaluated the phytoplankton communities based on functional groups to obtain information about the water quality of Lake İznik, Turkey. The phytoplankton consisted of 103 taxa, classified in 12 phytoplankton functional groups (PFGs), with dominancy of 5 species, Chrysosporum ovalisporum, Dolichospermum mendotae, Planktothrix rubescens, Fragilaria capucina, and Mougeotia sp. The Shannon–Wiener diversity index (H’) was calculated and results ranged between 0.41 and 2.47. The redundancy analysis (RDA) and Spearman’s correlation analysis were used to assess the relationships between the PFGs and environmental variables. According to the multiple comparisons of the data, the main efficient factors that determined the seasonal distribution of the PFGs were TP, DO, SiO2 , SD, and pH. The ecological requirements of the dominant PFGs (C, D, F, J, H1 , Lo, SN, N, P, R, T, and X2 ) indicated mainly meso-eutrophic waters. Similarly, Carlson’s trophic state index (TSI) stated mesotrophy conditions. As a result, the approach of PFGs can be successfully applied in a deep, alkaline lake to understand the water quality and trophic status.