The phytoplankton functional group concept provides a reliable basis for ecological status estimation in the Caygoren Reservoir (Turkey)

Abstract

The phytoplankton functional group (FG) concept has been successfully used to determine water quality states in both lake and river systems, but is not yet stressed in regular studies in reservoir environments. The purpose of our study was to estimate the ecological status of the temperate Caygoren Reservoir (2007-2009) using the Q((r)) FG composition metric, and to test whether it is able to follow the main structuring of the physical and chemical parameters studied. The main occurring coda were codon C (Cyclotella meneghiniana Kutzing, Stephanodiscus neoastraea Hakansson and Hickel), codon T (Gloeotila subconstricta (G.S. West) Printz, Mougeotia sp.), codon X2 (Cryptomonas pyrenoidifera Geitler, Plagioselmis nannoplanctica (H.Skuja) G.Novarino, I.A.N.Lucas and S.Morrall), codon K (Aphanocapsa holsatica (Lemmermann) G.Cronberg and J.Komarek, Aphanothece clathrata West and G.S. West), and codon S1 (Planktothrix sp.). The seasonal succession of phytoplankton displayed the lake-like coda series of Y (winter) -> C (spring) -> K/S1 (summer) -> T (fall) in each year, which demonstrated well the transitional behavior of reservoirs between lake and river ecosystems. The FG compositions showed high relationships with water temperature, ammonia, phosphate, and light availability in this temperate reservoir, where the Q((r)) index estimated reliable water quality states between hypertrophic and oligotrophic conditions.