Emerging facts about protective plants

Posted on December 15, 2009

It’s well known that submerged aquatic vegetation can provide valuable refuge for animal plankton and small fish by reducing the foraging efficiency of larger predators.  However, in many water bodies, such as turbid lakes, light levels are low and submerged plants are scarce.  In these systems, emergent and floating-leaved plants can be abundant,  but little is known about their ability to provide refuge.  In Frederiksborg Slotssø, a small turbid Danish lake,  densities of water fleas and copepods  were higher in and around beds of emergent and floating-leaved plants than in open water, seemingly because of the reduced risk of fish predation.    The higher numbers of planktonic grazers reduced algal densities  and this improved water clarity in the vegetated areas.  The study highlights the ecological role played by non-submerged aquatic plants in moderating predation pressure and enhancing water quality.

Reference:  Cazzanelli, M., Warming, T.P. & Christoffersen, K.S.  2008.  Emergent and floating-leaved macrophytes as refuge for zooplankton in a eutrophic temperate lake without submerged vegetation.  Hydrobiologia  605, 113–122.