Environment of planktic crustaceans as changed by hornwort: Effect on abundance of Daphnia

The effect of submersed hydrophyte Ceratophyllum demersum L. on the abundance of Daphnia longispina O.F. Muller has been studied. The experiments demonstrated that the hydrochemical characteristics in overgrowths of Ceratophyllum are within the limits of tolerance for D. longispina. The concentrations of waterborne phosphates, chlorophyll a, and bacterial biomass increase in the presence of hornwort. In plant overgrowths, Daphnia is suppressed due to the restriction of its movement. In a medium containing only metabolites of Ceratophyllum, the abundance of Daphnia longispina increases due to the enrichment of food resources.