Morpho-functional classifications of phytoplankton assemblages of two deep karstic lakes

Morpho-functional classifications of phytoplankton are increasingly used in ecological studies of different aquatic ecosystems. The aim was to compare three different classifications: (a) functional groups (FG); (b) morpho-functional groups (MFG); and (c) morphologically based functional groups (MBFG), and to detect how well can the biomass of phytoplankton groups based on different classifications be explained by environmental conditions of two different karstic lakes in the National Park Plitvice Lakes. Phytoplankton biomass in Lake Kozjak was lower than in Lake ProA double dagger e (total avg. 1.13 and 2.59 mg l(-1), respectively). Several diatoms (Cyclotella spp., Discostella stelligera, Synedra sp., Ulnaria ulna var. acus) with Dinobryon divergens were dominant in Kozjak, while ProA double dagger e was characterized by Dinobryon sociale, D. divergens, Cryptomonas sp., Stephanodiscus sp. and Fragilaria crotonensis. The best results in describing the phytoplankton succession were obtained using MBFG approach although it is less sensitive in describing variability of individual descriptive algal groups in this environment than FG and MFG. Nonetheless, because of distinct differences among dominant phytoplankton groups in these systems, MBFG classification was shown to be applicable, as supported by statistical analyses. FG and MFG classifications showed a high level of similarity, thus proving to be applicable to deep karstic lakes.