沉水植物菹草腐解会向水体释放大量营养物质，对水生态系统产生负面影响。为了探究滤食性底栖动物三角帆蚌对沉水植物腐解后水质恶化的减缓作用，于2023年5—7月以不同规格、不同密度的蚌与菹草组合进行了45 d试验箱模拟实验，监测水质指标的及浮游植物群落结构的变化。结果发现，经三角帆蚌的滤过，在一定程度上可以降低水体中的总氮（total nitrogen, TN）、总磷（total phosphorus, TP）、化学需氧量（chemical oxygen demand, COD）以及叶绿素a（chlorophyll a, CHLA）。为探究其三角帆蚌的密度效应与规格效应，投放低、中、高密度的三角帆蚌。实验结果显示不同规格密度的三角帆蚌均可以显著控制浮游植物的生物量，且三角帆蚌对浮游植物的群落结构有显著影响。其中，投放小规格（壳长4 cm）低密度（1 g/L）的三角帆蚌对水体的改善和浮游植物生物量的控制最好。

The decomposition of submerged plants such as Potamogeton crispus releases a large amount of nutrients into the water body, which has a negative impact on aquatic ecosystems. To investigate the slowing effect of filter feeding benthic animal, the Hyriopsis cumingii, on the deterioration of water quality after the decomposition of submerged plants, a 45 day experimental chamber simulation experiment was conducted from May to July 2023 using different specifications and densities of clams and seagrass combinations to monitor changes in water quality indicators and phytoplankton community structure. It was found that filtration through the Hyriopsis cumingii can reduce the total nitrogen (TN), total phosphorus (TP), chemical oxygen demand (COD), and chlorophyll a (CHLA) in the water to a certain extent. To investigate the density effect and size effect of its Hyriopsis cumingii, low, medium, and high-density triangular sail clams were released. The experimental results show that different sizes and densities of Hyriopsis cumingii can significantly control the biomass of phytoplankton, and Hyriopsis cumingii have a significant impact on the community structure of phytoplankton. Among them, releasing small-sized (shell length 4 cm) low-density (1 g/L) Hyriopsis cumingii has the best effect on improving water quality and controlling phytoplankton biomass.