Phytoplankton characteristics in Lake Matano, Indonesia

Abstract

Lake Matano is one of the oligotrophic lake in Indonesia that has unique phytoplankton characteristic. This study was aimed to find out the composition and abundance of phytoplankton at Lake Matano. Observations were conducted in 2015 (April and August) and 2016 (May and August). A total 10-20 L of water samples were collected from eight locations in the Lake Matano. Temperature, pH, dissolved oxygen, conductivity and turbidity were measured to determine the water quality. Phytoplankton abundance was calculated using the Sedgewick Rafter method. Phytoplankton community structure was analysed by Diversity Index (H'), Evenness Index (E) and Simpson Dominance Index (D). A total five phyla and 80 species of phytoplankton were found in Lake Matano, comprised of Chlorophyta (26 species), Dinophyta (2 species), Bacillariophyta (43 species), Chrysophyta (1 species) and Cyanophyta (8 species). The abundance of phytoplankton ranged between 0.36 × 102 - 1.281 × 104 individual/L. Peridinium inconspicuum and P.cinctum (Dinophyta) was found highest in abundance in April and August 2015 (96.38% of the abundance). Low to moderate community (H'=0.122 to 3.454) and low uniformity (E = 0.065 to 0.556) among species in phytoplankton community was found in Lake Matano. Dominance species (D = 0.216 to 0.967) occurred in several locations at Lake Matano. CCA ordination shows that the presence of all phytoplankton groups is strongly influenced by turbidity of which the lower turbidity value causes the higher phytoplankton abundance.