Cladophora mats in a Crimean hypersaline lake: structure, dynamics, and inhabiting animals

Filamentous green algae play an important functional role in element cycling and productivity in the different water bodies. In hypersaline lakes and lagoons of the Crimea, filamentous green algae are present and form bottom and floating mats that occupy large areas with high biomass, up to 4–5 kg (wet biomass)/m 2 . Cladophora spp. dominated in those mats. Five species of filamentous green algae (Chlorophyta) in Lake Chersonesskoye: Cladophora vadorum (Aresch.) Kütz., C. siwaschensis C. Meyer, C. echinus (Biasol.) Kütz., Ulothrix implexa (Kütz.) Kütz., Rhizoclonium tortuosum (Dillw.) Kütz., and seagrass (Angiospermae) Ruppia cirrhosa (Petagna) Grande were found. Cladophora spp. and R. cirrhosa were found in the lake throughout the year, other types of algae were encountered episodically. In most cases the biomass of bottom mat exceeded that of the floating mat. In general, the total biomass of the bottom and floating mats in the lake areas at depths up to 30 cm was in a stable range of values from 100 to 290 mg (dry weight)/cm 2 . Animal and infusorian average abundance in mats reach high values: infusorians—up to 15 000 000 ind./m 2 , Cletocamptus retrogressus (Copepoda, Harpacticoida)—up to 730 000 ind./m 2 , Eucypris mareotica (Ostracoda)—up to 91 000 ind./m 2 and Chironomidae larvae (Insecta, Diptera)—up to 140 ind./m 2 . Those values were much higher than in the plankton.