Biodegradation study of eucalyptus (Eucalyptus camaldulensis) and oleander (Nerium oleander) leaves in waters of the Aïn Chkef river in Morocco
This work deals with the overall process and the positive and negativeeffects of the breakdown of leaves, which is a major feature of thefunctioning of heterotrophic aquatic systems. The aim of the study wasto evaluate the relationship between the stream and the adjacentterrestrial ecosystem, since is at the land/water interface thatimportant features of ecosystem functioning can be found. We have usedthe technique of mesh bags with 0.5 cm openings that allow for easyaccess by a large proportion of the aquatic invertebrates thatcontribute to the degradation of leaves in water. We have alsointroduced two or three stones in order to anchor the mesh bags on thestreambed. Regarding the degradation of the leaves, we found that theoleander leaves decompose and lose their weight faster than theeucalyptus leaves, this loss being very rapid, reaching a value of 70%of the initial weight after 30 days. The initial weight loss could berelated to leaf leaching, which depends on the texture and structure ofthe leaves and the action of invertebrates, especially of molluscs(macerators) and Diptera (filterers) that contribute in large measureto the degradation of the leaves. This period of weight loss is quiteshort for oleander leaves (15 days), while it is relatively long forthose of eucalyptus (30 days), the colonization of which byinvertebrates, both in number and biomass, remains lower than that ofoleander bay leaves.