Impacts of environmental flow regulation on survival of aquatic organisms: a case study of Cyprinus Carpio in Baiyangdian, China

Abstract

Decreasing water volume and increasing pollutants in wetlands pose challenges to aquatic life.Environmental ow regulation is a widely used to improve the living environment of aquatic organisms, but it's effectiveness needs to be evaluated. In this study, the hydrodynamic and water quality models are used to simulate the elds of ow, temperature and pollutants and the Ecological Niche Modelling at the MetaLand EcologyLab (ENMTML) is utilized to evaluate the area of suitable habitats of aquatic organisms in the cases of environmental ow regulation and no environmental ow regulation conditions. The typical wetland of Baiyangdian in northern China is selected as the studied area and the important economic sh Cyprinus carpio is select as the indicator aquatic species to show the effectiveness of environmental ow regulation. The study period is from December 1, 2017 to July 1, 2018. The results indicate that for Cyprinus carpio in Baiyangdian Wetland, the variables of water depth, dissolved oxygen (DO), ammonia nitrogen (NH4+-N) and Chlorophyll a (Chla) are the major environmental factors which determines the variability of suitable habitat extent. The environmental ow regulation amount for the Baiyangdian Wetland is 2.6 10 8 m 3 , which produces a suitable breeding habitat area of 135.532 km 2 at the end of the water supply period. Comparing with no environmental ow regulation case, the suitable habitats areas is enlarged by 56.29 and 31.83 km 2 of the highly and moderately suitable habitats for Cyprinus carpio, respectively. The outcomes of this study provide not only a basic reference for wetland management, but also a scienti c perspective understanding of the environmental ow regulation on aquatic organisms. The proposed method combining MIKE 21 model with the ENMTML package is shown to have the potential to evaluate the effectiveness of environmental ow regulation in wetlands.