Environmental heterogeneity affecting spatial distribution of phytoplankton community structure and functional groups in a large eutrophic lake, Lake Chaohu, China

Abstract

Usually, physo-chemical parameters can affect the growth and development of phytoplankton, and even influence spatial distribution of phytoplankton community structure. However, whether environmental heterogeneity causing by several physo-chemical factors together can affect spatial distribution of phytoplankton is still unclear. In this study, seasonal variation and spatial distribution of phytoplankton community structure and its relationships with environmental factors in Lake Chaohu were investigated from August 2020 to July 2021. A total of 190 species from 8 phyla were recorded and these species were divided into 30 functional groups, including 13 dominating functional groups. Average annual phytoplankton density and biomass were (5.46 ± 7.17)×107cells/L and 4.80 ± 4.61 mg/L, respectively. Both density and biomass of phytoplankton were higher in summer ((14.64 ± 20.34)×107cells/L, 10.61 ± 13.16 mg/L) and autumn ((6.79 ± 3.97)×107cells/L, 5.57 ± 2.40mg/L), with the M and H2 of dominant functional groups. The dominant functional groups were N, C, D, J, MP, H2 and M in spring, whereas C, N, T and Y dominated in winter. The distribution of phytoplankton community structure and dominant functional groups in Lake Chaohu had significantly spatial heterogeneity, which was consistent with environmental heterogeneity of the lake and could be divided into four locations. Phytoplankton density and biomass in Location I was higher than those in the other three locations. Moreover, M, C and H2 of dominant function groups appeared in the whole lake, and all 13 dominant functional groups occurred in Location II. Our results suggested that environmental heterogeneity was one of key reasons affecting spatial distribution of phytoplankton community structure and functional groups in Lake Chaohu.