Reduction of Microcystis blooms in a hypertrophic reservoir by a combined ecotechnological strategy

• Published in: Hydrobiologia Vol. 408-409; p. 31
• Main Authors: Deppe, Thomas, Ockenfeld, Klaus, Meybohm, Andreas, Opitz, Michael, Benndorf, Jürgen
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Nature B.V 01.08.1999
• Subjects: Carbon dioxide; Epilimnion; Germany; Germany, Saxony; Microcystis aeruginosa; Phytoplankton; Plankton; Reservoirs; Water bodies; Water treatment; Germany, Sachsen, Bautzen Reservoir
• ISSN: 0018-8158; 1573-5117
• DOI: 10.1023/A:1017097502883

In Bautzen reservoir, a shallow, hypertrophic water in Eastern Saxony, biomanipulation led to structural changes in the phytoplankton community but did not reduce algal biomass. To supplement the top-down management, a new type of water treatment technology was tested during two seasons (May-August 1996/1997), aiming at the bottom-up control of mass developments of the cyanobacterium Microcystis aeruginosa.The technology is based on a combined lake-internal phosphorus precipitation and a transport of hypolimnetic water rich in free carbon dioxide into the upper layers. During the treatment periods, there were found both an increase of CO^sub 2^concentrations in the mixed layer and an extension of the period in which free CO^sub 2^was detected in the epilimnion. The concentrations of phosphorus could be lowered drastically in the whole water body. Microcystiswas almost totally suppressed (1996) or appeared with a delay (1997) compared to the regular annual pattern observed before the treatment. In contrast to the preceding year (1995), diatoms played a major role in the summer phytoplankton during the treatment years (1996/1997). The two application periods are compared with respect to the influence of meteorologically determined variables.[PUBLICATION ABSTRACT]