Composition and indication of plankton fatty acids under the influence of environmental factors in the Hongfeng Reservoir, Southwest China

To clarify the indication of plankton fatty acids (FAs) under the influence of the natural environmental factors that affect FA composition and transmission, the Hongfeng Reservoir was investigated including plankton community structure and FA composition as well as the physical and chemical indicators of water quality. Thereafter, redundancy analysis (RDA) was performed to analysis the pattern of plankton FA composition during August 2018 to July 2019. The results showed that water quality indicators, including total phosphorus (TP), total nitrogen (TN), chlorophyll a (Chl a ), pH, and DO, exerted significant influence on plankton FA composition. It was also observed that Cyanophyta ( Pseudanabaena limnetica , Merismopedia and Cylindrospermopsis raciborskii ) and copepod ( Mongolodiaptomus birulai ) constituted the dominant phytoplankton and zooplankton communities, respectively. Further, Saturated fatty acids (SFAs) presented a relatively intuitive indication of the changes in the community structure of Cyanophyta. One of the MUFAs (C16:1) content reflected Bacillariophyta community structure changes. Additionally, there is a good indicational effect between C18:2ω6 and cladocerans, which exhibit a feeding phenomenon toward Cryptophyta. Rotifers obtained C20:2 through Pyrrophyta in order to get polyunsaturated fatty acids (PUFAs). EPA is indication of rotifers. The research results can provide theoretical support for understanding the mechanism of fatty acid transfer among plankton.