DECOMPOSITION IN FRESHWATER ECOSYSTEMS

Abstract

SUMMARY This review examines the sources and composition of organic matter and the decomposition of particulate and dissolved organic matter (POM and DOM) in freshwater ecosystems. The main points to emerge from the review are listed below. Terrestrial plant material is an important source of allochthonous POM in lotlc systems. In lentic systems important autochthonous sources of DOM are the algae and aquatic macrophytes. Little Is known about dissolved organic carbon (DOM) compounds in freshwaters and they are not easily categorized chemically. The decomposition of wood is largely a surface phenomonon carried out by fungi since gallery-forming insects are lacking. Difficulties arise in describing decomposition of plant material in rivers because of methodological problems. The data generally show that leaching of DOM is followed by microbial breakdown and further processing by invertebrates. The microbes are mainly hyphomycete fungi but bacteria can play a significant role in later stages. In lentic syst...