Rapid shredding of leaves by crabs in a tropical African stream

摘要

Plant debris is now well established as a major source of energy in the low order streams of naturally forested landscapes (Cummins & Klug 1979, Giller & Malmqvist 1998). Initially leaves form poor quality food, but once conditioned by microbial colonisers, they attract a guild of invertebrates, the shredders, which progressively breaks apart the softened tissue, revealing the skeleton of veins before finally demolishing this also. Shredding rates vary with plant species and other conditions, but in temperate regions, where the process has been most studied, rates are maximally up to 1% per day for tree leaves (Giller & Malmqvist 1998). Soft aquatic plant species are shredded at up to 3% per day. Shredders in temperate regions include cranefly larvae, lim-nephilid caddisfly larvae, nemourid stonefly nymphs, astacids and amphipods, among others.