Estuarine ecosystems are important in terms of biodiversity processes because there are intense interactions between the river and sea environments. Phytoplankton and zooplankton have been shown to be ecological indicators of the water quality status in estuary ecosystems. Therefore, a comprehensive evaluation of the effects that multiple pressures have on the phytoplankton and zooplankton communities in estuarine ecosystems is essential. In this study, water samples from 29 stations were collected from the Liaohe Estuary over three different seasons, and abiotic factors (i.e., phytoplankton and zooplankton) were obtained and compared. The results showed that there were significant temporal and spatial variations in the phytoplankton and zooplankton communities from the Liaohe Estuary. The correlation analyses showed that water temperature was the most important factor regulating the variation in phytoplankton communities, whereas the main driving force for the zooplankton was nutrient concentrations. Large amounts of nutrients entered the estuary in spring and summer due to intensive human activities in the Liaohe River basin. The inflows by the Liaohe River introduced some phytoplankton and zooplankton into the estuary, such as Coscinodicus asteromphalus, Chaetoceros decipiens, and Schmacheria poplesia. The impacts of Liaohe inflows on the estuary region gradually decreased as the distance from the inlet increased and this change was mediated by marine diffusion. The results from this study will improve knowledge about planktonic communities in estuarine ecosystems and provide a theoretical foundation for estuary environmental management.

河口生态系统在生物多样性过程方面很重要，因为河流和海洋环境之间存在着密切的相互作用。浮游植物和浮游动物已被证明是河口生态系统水质状况的生态指标。因此，全面评估多种压力对河口生态系统中浮游植物和浮游动物群落的影响至关重要。在这项研究中，在三个不同季节从辽河口采集了29个站的水样，并获得了非生物因子（即浮游植物和浮游动物）并进行了比较。结果表明，辽河口的浮游植物和浮游动物群落存在明显的时空变化。相关分析表明，水温是调节浮游植物群落变化的最重要因素，而浮游动物的主要驱动力是养分浓度。由于辽河流域人类的密集活动，春季和夏季大量营养进入河口。辽河的流入将一些浮游植物和浮游动物引入河口，例如astercosphacus asteromphalus，Chaetoceros decipiens和Schmacheria poplesia。辽河入海口对河口区域的影响随着距入海口距离的增加而逐渐减小，而这种变化是由海洋扩散引起的。这项研究的结果将提高对河口生态系统中浮游生物群落的了解，并为河口环境管理提供理论基础。