Responses of four submerged macrophytes to freshwater snail density (Radix swinhoei) under clear-water conditions: a mesocosm study

Macrophytes play a key role in stabilizing clear-water conditions in shallow freshwater ecosystems. Their populations are maintained by a balance between plant grazing and plant growth. As a freshwater snail commonly found in shallow lakes, Radix swinhoei can affect the growth of submerged macrophytes by removing epiphyton from the surface of aquatic plants and by grazing directly on macrophyte organs. Thus, we conducted a long-term (11-month) experiment to explore the effects of snail density on macrophytes with distinctive structures in an out-door clear-water mesocosm system (with relatively low total nitrogen (TN, 0.66 ± 0.27 mg L-1) and total phosphorus (TP, 36 ± 20 μg L-1) and a phytoplankton chlorophyll a (Chla) range of 14.8 ± 4.9 μg L-1) based on two different snail densities (low and high) and four macrophyte species treatments (Myriophyllum spicatum, Potamogeton wrightii, P. crispus, and P. oxyphyllus). In the high-density treatment, snail biomass and abundance (36.5 ± 16.5 g...