Contrasting zooplankton communities in coastal rivers of eastern and western Guangdong, China: Relationships with environmental factors

This study compared zooplankton community structure and its relationship with environmental factors in coastal rivers of eastern and western Guangdong, based on a survey of 18 sampling sites across 9 rivers in March 2021. The study found significant differences in key environmental parameters (water temperature, pH, dissolved oxygen) between the rivers in eastern and western Guangdong. However, no corresponding geographical pattern was detected in the α-diversity indices of the zooplankton communities. Notably, zooplankton diversity in western Guangdong rivers was significantly positively correlated with salinity and total phosphorus (TP), with the Pielou evenness index showing particular sensitivity to TP. Self-organizing map (SOM) analysis demonstrated distinct geographical clustering patterns in zooplankton communities between the two regions. Furthermore, the random forest model identified 15 bioindicators whose abundances were closely associated with environmental factors such as water temperature and nutrient levels. The study highlights that rivers in eastern Guangdong are predominantly influenced by industrial pollution and hydrological regulation, whereas those in western Guangdong are more affected by agricultural non-point source pollution. These findings elucidate the differential regulatory mechanisms of abiotic factors and human activities on zooplankton communities, providing a scientific basis for the conservation and management of coastal river ecosystems in Guangdong Province.