Ecological Health Assessment Based on O/E Model and Chemical-Biological Composite Index in the Last Two Decades of the Poyang Lake Area In China

Abstract

Due to the excessive exploitation of lake water resources, lake ecosystems have been gradually degraded, and some lakes have even lost their ecological service functions. Therefore, the objective evaluation of the health status of lake ecosystems and the strengthening of lake ecological protection and restoration are important tasks in water environment management. In this study, several biological and water quality surveys on water ecological conditions were carried out in 11 key sections of Poyang Lake area from 1998 to 2022, and the ecological health of Poyang Lake area was evaluated by use of the O/E model and the chemical-biological index method according to the status of the water quality and the structure of the benthic fauna in the four seasons, respectively. The results showed that the benthic community structure is simple, and the biodiversity is low, which is mainly dominated by Insecta in Arthropoda and Oligochaeta in Oroidea, accounting for 84.3% and 42.4% respectively; The results of the O/E index evaluated under the threshold of probability of capture (pc) ≥ 0.5 showed that the health grade of all sections was in sub-healthy or average, which was consistent with the results of the chemical-biological composite index evaluation. The dual evaluation method of O/E model and chemical-biological composite index adopted in this study integrates more than twenty years of long time scale data, this method combined with long time scale data has not been studied before, and its advantage is that it can more objectively show the change rule of the ecological situation of the Poyang Lake area for many years, and at the same time, the results of the study can provide theoretical basis and technical support for the evaluation of the quality of the water environment in the Poyang Lake area.

Keywords: Ecosystems, Long time scale, Benthic community, Chemical-biological index