DO INVERTEBRATES MATTER - DETRITAL PROCESSING IN THE RIVER SWALE-OUSE

A litter bag experiment was used to examine the role of macroinvertebr ate communities in the processing of terrestrially derived (allochthon ous) organic material at headwater, mid-reach and lower reach sites on the River Swale-Ouse system, North Yorkshire, UK. Data from the study indicates that the role of macroinvertebrates in leaf litter processi ng within the River Swale-Ouse system is minimal, and not measurable b y the technique used. Thus it is unlikely that in this river system ma croinvertebrates have a significant effect on either the size of the r esident detrital pool or the rate of production of fine particulate or ganic matter. Highest numbers of both total invertebrates and shredder species were recorded in bags at the mid-reach site. This pattern con flicts with the river continuum concept model which presumes the great est abundance and role of shredder invertebrates in headwater streams. (C) 1998 Elsevier Science B.V.