Hyphomycetes and macroinvertebrates colonizing leaf litter in two Belgian streams with contrasting water quality

Abstract

Breakdown, hyphomycete and invertebrate colonization of beech (Fagus .sjlvcitic.u L.) and poplar (Pop~i/u.s rzigm x c,uroinc.rican Dode juinier) leaves were ctudied in two headwater streams with contrasting water chemistry. Breakdown of both species was slower in stream B, a headwater stream containing herbicides and low concentrations of metal ions. This was related to lower conidial production of aquatic hyphomycetes and lower biomass of G'arnmnr~i.~ sp., a shredder that dominated invertebrate assemblages on leaf packs. Differences in processing ratec, colonization by aquatic hyphomycetes, and shredder assemblages appeared to be related to stream water chemistry. Although the herbicide and metal concentrations in stream B were rather moderate, the activity of aquatic hyphomycetes and shredderc may have been adversely affected.