Effects of Submerged Macrophytes on Demography and Filtration Rates of Daphnia and Simocephalus (Crustacea: Cladocera)

Macrophytes and cladocerans represent the main antagonistic groups that regulate phytoplankton biomass; however, the mechanism behind this interaction is unclear. In laboratory conditions, we separately evaluated the effects of three submerged macrophytes ( , , and ), as well as their exudates, and plant-associated microbiota (POM < 25 µm) + exudates on the population growth of cf. and cf. . Living , exudates, and POM < 25 µm + exudates exhibited the most robust positive effects on density and the rate of population increase ( ). Subsequently, we examined the effects of on the filtration and feeding rates of and revealing significant ( < 0.001) promotion of filtration and feeding in but not in . To elucidate the specific effects of this macrophyte on demography, we assessed selected life table variables across the same treatments. The treatments involving exudates and living resulted in approximately 40% longer survivorship and significantly ( < 0.01) enhanced fecundity. Our findings indicate that exudates from submerged macrophytes positively influence demography by increasing filtration rates, survivorship, and fecundity. This synergy suggests a substantial impact on phytoplankton abundance.