Aquatic plants during decomposition as an environment-forming factor for zooplankton: an experiment in microcosms
S. A. Kurbatova, I. Yu. Yershov, N. G. Otyukova, Ya. V. Stroynov, E. V. Borisovskaya
Papanin Institute for Biology of Inland Waters of RAS, Borok, Russia
Keywords: zooplankton, aquatic plants, hydrochemical parameters, bacterioplankton, phytoplankton pigments
Abstract
Aquatic vascular plants at different stages of their life cycle exhibit different physiological and metabolic activity, resulting in changing habitat conditions for hydrobionts. The hydrochemical parameters of the environment, the concentrations of phytoplankton pigments, the abundance of bacteria and zooplankton were studied in experimental ecosystems (microcosms), including actively vegetating and completing the vegetation of aquatic plants. In microcosms with actively vegetating hornwort Ceratophyllum demersum L. the concentration of Ptot, Mg2+ and BOD 5 increased, and Na+ and Ca2+ decreased. In systems with a dying arrowhead Sagittaria sagittifolia L. the concentration of K+ increased to the greatest extent, Ptot, Cl-, and BOD5 to a lesser extent, and the concentrations of SO42- and O2 dissolved in water decreased. In the presence of plants, higher concentrations of phytoplankton pigments were observed in comparison with the control. The quantitative indicators of bacterioplankton did not differ. The number and biomass of zooplankton in general and the dominant species Daphnia longispina in microcosms with plants exceeded these indicators in the control. The hornwort, which lost half of the biomass, but continued vegetation, had a stronger stimulating effect on the abundance of zooplankton than the arrowhead, which finished vegetation.
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