Phytoplankton community and ecological state of a high-mountain lake within an Important Natural Area (Eastern Black Sea, Turkey)

Abstract

Lake Aygir (Elmali) is located on the body of Mount Karagol on the Giresun Mountains in the Eastern Black Sea region of Turkey. It is a glacial lake at an altitude of 2900 m. In this study, the phytoplankton community and trophic state of Lake Aygir, which is subject to extreme conditions, were examined in the summer season when the lake is not covered with ice. A total of 48 taxa were identified belonging to Bacillariophyta (21), Chlorophyceae (10), Cyanobacteria (7), Ochrophyta (3), Euglenophyta (3), Charophyta (2), Cryptophyta (1) and Miozoa (1). Diatoms dominated both the species diversity and biomass, while among the small centric species, Lindavia (Cyclotella) comensis Grunow showed excessive reproduction. L. bodanica Eulenstein, Achnanthidium minutissimum Kutzing and Diatoma mesodon (Ehrenberg) Kutzing are the other subdominant taxa. The distribution of algae groups in phytoplankton concentration is as follows: Diatoms > Chlorophytes > Cyanophytes > Ochrophytes. Lake Aygir, which has circum-neutral characteristic, was, according to indicator taxa, diversity indices and trophic classification systems (OECD, TSI, TLI), found to be oligotrophic and clean (1st class).