Leaf-conditioning by microorganisms.

Many detritus-feeders prefer dead leaves which are colonized by microorganisms-i.e. conditioned leaves, over freshly fallen or sterile leaves. Traditionally, this has been attributed to the build-up of microbial cells on the substrate. Two experiments show that changes in the leaf itself, brought about by microbial excretions and secretions, or by a hydrolytic agent (hot HCl), can also increase its palatability to the detritus-feeding amphipod Gammarus pseudolimnaeus.