Original paper

Die Struktur der makrobenthischen Biomasse in einem voralpinen Schotterbett am Beispiel der mittleren Loisach

[The structure of macrobenthic biomass in the gravel bed of the pre-Alpine Loisach River]

Wachs, Bodo


In order to assess the zoobenthic drift in the pre-Alpine river Loisach at river-km 51.4 qualitative and quantitative determinations of benthos abundance were carried out between 1979 and 1982. These ecological investigations provided information on the area-specific presence of wet mass, dry mass and organic dry mass as well as the total phosphorus and total nitrogen content of benthos collected from the gravel bed which is characteristic for pre-Alpine streams. This environment is kept in nearly constant motion by bed-load transport. In the substrate of such a riverbed one generally observes considerable mixing of epirheic benthos with organisms typical for the psammal. During periods of high-water many zoobenthic organisms in the gravel bed can move into the sand-pore-system of the hyporheal so that a high-water-wave only carries certain species into the Kochelsee which is located downstream from the sampling site. The investigations presented in this contribution were carried out as part of a special research program of the Technical University of Munich (SFB 81 / Projekt A5); one goal of this program was to establish the material balance of a thoroughly flushed pre-Alpine lake (Kochelsee).


macrobenthic biomassenvironmentRiver LoisachKochelseeGermany