Fungi and cellulolytic activity associated with decomposition of Bauhinia purpurea leaf litter in a polluted and unpolluted Hong Kong waterway

Abstract

A survey of fungal succession on decomposing Bauhinia purpurea L. leaves in the unpolluted Tai Po Kau Forest Stream (TPKFS) and the animal waste polluted Lam Tsuen River (LTR) was carried out during the winter of 1988 and the summer of 1989. In situ cellulolytic activity of the TPKFS leaf litter was also investigated. Most of the 28 aquatic hyphomycete species found were cosmopolitan or frequently reported in temperate regions. Clavariopsis aquatica De Wildeman, Lunulospora cymbiformis Miura, and Flagellospora penicillioides Ingold were the dominant species at both sites. Among the 49 geofungi species recorded, lymaphilic species were commonly observed in the polluted LTR (e.g., Geotrichum candidum Link ex Leman, Fusarium oxysporum Schlecht, and Mucor racemosus Fres.) and lymaxenes in the TPKFS (e.g., Humicola spp., Trichoderma spp. and Gliocladium roseum Bain.). Species richness of aquatic hyphomycetes was higher in the TPKFS (27 species) than in the polluted LTR (14 species), whereas for the associated geofungi, it was higher in the LTR (35 species) than in the TPKFS (28 species). Conidial production was also higher in the TPKFS. Aquatic hyphomycetes and geofungi showed a complementary sequence of dominance in winter and summer, respectively, in the clean TPKFS. Higher cellulolytic activity occurred in the winter than the summer leaf litter. Key words: aquatic hyphomycetes, geofungi, leaf litter, pollution, cellulolytic activity.