Ecological Indicators (Jan 2021)
Joint effects of habitat indexes and physic-chemical factors for freshwater basin of semi-arid area on plankton integrity – A case study of the Wei River Basin, China
Abstract
As the largest tributary of the Yellow River and a large semi-arid area, the ecological status of the Wei River Basin, China, has become an important issue of concern. Habitat, water quality and biological pressure are the factors affecting the structure and function of rivers. However, it is a challenging task to determine the joint rather than isolated influence of factors on the watershed. Plankton is sensitive to the status of water system, so it is used to analyze the interaction between habitat indexes and physic-chemical parameters of water body. In this study, plankton and water samples were collected from 21 sampling sites in the whole Wei River Basin in October 2019. The planktonic index of biotic integrity (P-IBI), biomass, abundance, diversity index and trophic status were established. The integrity of plankton in the basin was evaluated. Redundancy analysis (RDA) was used to assess the correlation and variability between 23 physicochemical factors and habitat indexes of planktonic community. The results show that the applicability and accuracy of P-IBI are good. The planktonic integrity of the ecosystem in the basin is “critical”. The upper and lower reaches of the main stream are better than those of the middle reaches, while the upper reaches of the two major tributaries are in poor condition due to the influence of cities and industries. Wei River system is better than Jing River and Beiluo River system. Physical and chemical factors, including dissolved oxygen, turbidity, phycocyanin and chlorophyll, are the main driving forces affecting the integrity of plankton in the study area. Relatively speaking, the contribution of physicochemical parameters to P-IBI was greater than that of habitat indexes, and there was a shared explanatory variance between them. The abundance level can best reflect the isolation effect of two aspects of the environment. The results show that the planktonic index of biotic integrity is a potential tool to reflect the interaction of habitat conditions and physical and chemical factors. The whole basin scale research is helpful to promote habitat restoration and water conservation.
