The influence of Myriophyllum verticillatum and artificial plants on some life history parameters of Daphnia magna

Abstract

Submerged macrophytes are known to serve as refuge for zooplankton but also seem to suppress the zooplankton growth. Thus, there is a conflict between the positive and negative role of macrophytes for zooplankton. We tested the influence of physical structure using artificial macrophytes, chemicals released by a macrophyte (Myriophyllum verticillatum), as well as the combined effects of these two factors on the life history of Daphnia magna. Daphnids matured at a smaller size and produced fewer eggs but larger individual offspring in the presence of artificial and real plants. Thus, under conditions with plants, we observed a trade off between number of eggs produced and the individual size of the offspring. Daphnids grown in the presence of exudates without plants were larger at maturity and showed no reduction in clutch size as compared with the control. We suggest that the macrophytes (real and artificial) negatively affected the daphnids in two ways: (1) food particles were settling down faster on the plant structures and this reduced the available food for Daphnia, (2) the plant structures were obstacles for the daphnids causing them to spent more energy during swimming. Both effects resulted in a reduced somatic growth, whereas the increased individual offspring size was probably a response to the reduced food level. Daphnia was not negatively affected by Myriophyllum exudates.

Reduction of zooplankton communities in small lake outlets in relation to abiotic and biotic factors

“…It is well-known that submerged macrophytes can be an effective place for large crustaceans to hide from predatory fish (Lauridsen et al 1996, Cerbin et al 2007). Additionally, adult copepods are able to escape from fish into the dense vegetation of macrophytes (Gliwicz 1985, O'Brien 1987.…”

Zooplankton communities of two lake outlets in relation to abiotic factors

“…In Korytnica, the type of water vegetation growing between the first two sites could be responsible for the greater body length of Cladocera at K2 than at K1. It is well known that submerged macrophytes can be an effective hiding place for zooplankton from predatory fish [32,33]. Thus, the dense vegetation over this section of Korytnica could protect larger Cladocera well.…”

Analyzing the effects of four submerged macrophytes with two contrasting architectures on zooplankton: A mesocosm experiment

“…These different effects of macrophytes on zooplanktons seemed to mostly depend on zooplankton species and not on macrophyte architecture. Many studies have also confirmed that the preferences of different organisms to submerged macrophytes are different (Lalonde and Downing, 1992;Kuczynska-Kippen and Cerbin, 2003;Cerbin et al, 2007;Cremona et al, 2008).…”

“…Greater macroinvertebrate (e.g., gastropods) biomass sometime appeared on macrophytes with a simpler architecture than macrophytes with a complex architecture (Lalonde and Downing, 1992), and this could be related to substrate preferences of Gastropoda toward the tape grass V. americana (Cremona et al, 2008). Daphnia magna is unlikely to prefer to M. verticillatum than other macrophytes because of maturing at a smaller size and producing fewer eggs under the influence of M. verticillatum (Cerbin et al, 2007). Therefore, various organisms exhibited different responses and preferences on different macrophytes, and these responses and preferences might mostly depend on organism species rather than on macrophyte architecture.…”