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. While environmental flow regulation is widely applied to enhance aquatic habitats, its effectiveness needs to be evaluated. In this study, a hydrodynamic-water quality model was used to simulate the fields of flow, temperature, and pollutants. The Ecological Niche Modeling at the MetaLand EcologyLab (ENMTML) was utilized to evaluate the area of suitable habitats for aquatic organisms under both environmental flow regulation and no environmental flow regulation conditions. The typical Baiyangdian Wetland in northern China was taken as the study area, and the important economic fish, Cyprinus carpio, served as the indicator of aquatic species. The effectiveness of environmental flow regulation was evaluated from December 1, 2017, to June 30, 2018. The results indicated that the variables of water depth, dissolved oxygen (DO), ammonia nitrogen (NH4+-N) and Chlorophyll a (Chla) were the major environmental factors determining the variability of the suitable habitat area for Cyprinus carpio. The environmental flow regulation capacity of the Baiyangdian Wetland was 2.6 [Formula: see text] 108m3, which produced a suitable habitat area of 135.538km2 at the end of the water supply period. Compared with the no environmental flow regulation condition, the highly and moderately suitable habitat areas for Cyprinus carpio were enlarged by 56.30km2 and 34.11km2, respectively. The outcome provides not only a basic reference for wetland management, but also a scientific perspective for understanding the impact of environmental flow regulation on aquatic organisms. The proposed method demonstrates the important potential of evaluating the effectiveness of environmental flow regulation on aquatic organisms in wetlands.