Allelopathy in Benthic and Littoral Areas: Case Studies on Allelochemicals from Benthic Cyanobacteria and Submersed Macrophytes
Elisabeth M. Gross
Abstract
Photosynthetic organisms in littoral and benthic habitats are in general situated in close proximity to their competitors. Benthic algae and cyanobacteria compete for space and grow adjacent to each other. Submersed macrophytes can be overgrown by epiphytic algae and are surrounded by other macrophytes and phytoplankton. Benthic cyanobacteria and submersed macrophytes face a similar challenge; they both have to compete for light and, therefore, for space with other photosynthetically active organisms. In the littoral system, thick epiphyte cover, scums of filamentous algae, and high phytoplankton densities can deprive submersed macrophytes of sufficient light. Allelochemicals found in cyanobacteria and macrophytes are mainly secondary metabolites. Allelopathic interactions of algae, although not referred to as such, were observed as early as 1917 by Harder.