Distribution of epipelic algae and related environmental nutrients in Taihu Lake, revealed by HPLC analysis

Abstract

Epipelic algal biomass and composition (determined by HPLC pigment analysis) and related environmental nutrients were investigated in a phytoplankton-dominated area (Meiliang Bay), a macrophyte-dominated area (East Taihu Lake) and a transition zones (Gonghu Bay) in a shallow eutrophic freshwater lake (Taihu Lake, eastern China). Surface sediment samples were collected at 11 sampling sites in April and August 2016. Average epipelic algal biomass for Meiliang Bay, Gonghu Bay and East Taihu Lake was 6.5, 4.9 and 4.6μg chlorophyll (Chl)-ag–1 sediment respectively in April, and 3.8, 7.4 and 2.7μg Chl-ag–1 sediment respectively in August. The maximum biomass of epipelic algae appeared at the G1 sampling site (9.6μg Chl-ag–1 sediment) in August, whereas the minimum biomass of epipelic algae appeared at the E4 sampling site (1.7μg Chl-ag–1 sediment). Pigment (fucoxanthin, zeaxanthin and Chl-b) to Chl-a ratios indicated that epipelic algae were primarily diatoms, secondarily cyanobacteria and lastly green algae in Taihu Lake. Epipelic algae were significantly correlated with total nitrogen in the water and total phosphorus in the sediment (P<0.05), except for green algae. In general, using pigment as an indicator revealed that the epiphytic algal community varied over time and space. The distribution of variations in epipelic algae was related to the heterogeneity of environmental factors.