Spatial and temporal variability of microphytobenthos in a marine hypersaline lake (Crimea): Are there some general patterns?

Abstract

The microphytobenthos is one of the key elements in the marine hypersaline water bodies. To find the general regularities of microphytobenthos distribution patterns in marine hypersaline lakes and lagoons, the accumulation of data on various cases is needed. Studies on species composition and abundance of microphytobenthos were conducted in a Crimean closed hypersaline lagoon at three stations from April to September 2018. Floating mats of the filamentous green algae Cladophora and the benthic community were investigated. Salinity varied from 23 to 170 g L−1. In total, 25 microalgal species were recorded in the mats and on the bottom, including Bacillariophyta – 19 species, Haptophyta – 2 species, Miozoa – 2 species, and Cyanobacteria – 2 species. 17 Bacillariophyta species were recorded in the mats, and 5 species at the bottom. In the mats, Bacillariophyta species contributed from 50 to 100% of the total species richness. The total microalgal abundance in the mats varied from 2.5 × 106 cells m−2 to 3.8 × 108 cells m−2 (on Cladophora filament area). In 43% of all bottom samples, there was no microphytobenthos at all or there were only single cells, due to hypoxic or even anoxic conditions under the floating mats. The average microalgal abundance in the soft-bottom community was very low, on average 4.1 × 108 cells m−2 of the bottom area. Data on fluctuations of the total microalgae abundance in mats showed that temporal variability is higher than spatial. The factor of chance is important in the determination of microphytobenthos structure variability.