Spatial niche differentiation and key driving factors of dominant benthic macroinvertebrates in Qinhuangdao City, China

Climate change and human activities have led to serious challenges and threats to the global water environment. Protecting suitable benthic niches and clarifying the drivers of niche changes can effectively regulate the intensity of human activities and cope with the impacts of climate change. This study took the sampling data of Qinhuangdao in 2023 as the basis, and used the dominance model to select dominant taxa. Then, it calculated the niche breadth and overlap of the dominant benthic macroinvertebrate using niche models. What's more, it combined canonical correlation analysis to analyze the correlation between environmental factors and benthic macroinvertebrate density and biomass. Finally, partial correlation analysis was used to identify key driving factors. The results showed that 13 dominant taxa were selected for the dominance model, Unio douglasiae and Orthetrum coerulescens had the greatest dominance. For water quality physical metrics, all dominant taxa had the highest mean niche breadth along the conductivity gradient (2.51) and the greatest mean niche overlap along the turbidity gradient (4.82). For water chemistry indicators, the niche breadth of dominant taxa was highest along the biochemical oxygen demand gradient and lowest along the hexavalent chromium gradient. Key drivers of niche breadth and overlap spatial differentiation for dominant taxa were chemical oxygen demand for Cr (COD_Cr), biochemical oxygen demand (BOD) and water temperature (WT). High concentrations of COD-Cr and BOD can change the competition and food chain structure among benthic macroinvertebrates, thus affecting the niche breadth and overlap of benthic communities. WT has a direct impact on the physiological and ecological processes of benthic macroinvertebrates. In estuaries and sandy beaches, the key drivers of benthic niche may be organic carbon and chlorophyll α. This study provides a scientific basis for benthic conservation and ecological restoration in Qinhuangdao, and a reference and guidance for similar benthic macroinvertebrates around the globe to cope with climate change, regulate human activities, and enhance biodiversity.