Tuesday, May 27, 2008 - 10:15 AM
145

Breakdown of leaves and wood in streams affected by mine drainage

Dev K. Niyogi1, Jon S. Harding1, and Kevin S. Simon2. (1) School of Biological Sciences, University of Canterbury, Private Bag 4800, Christchurch, 8140, New Zealand, (2) School of Biology and Ecology, University of Maine, 5722 Deering Hall, Orono, ME 04469

Drainage from coal mines imposes several stressors on biota in receiving streams.  Low pH, dissolved metals, and metal oxide precipitates can all influence stream organisms and the ecosystem processes they drive.  We examined the breakdown of leaves and wood in streams affected by active and abandoned coal mines on the west coast of the South Island, New Zealand.  The breakdown rate of beech leaves was lower in streams affected by mining, mainly because of a reduction in shredding invertebrates in the streams.  Microbial processing of leaves and wood, on the other hand, was often high in streams affected by mining, including those with pH less than 3.  Other factors such as nutrients and metal oxides had greater influence on microbial activity than low pH.  Both invertebrate diversity (in leaf packs) and fungal diversity (on leaves and wood) declined in streams affected by mining.  No shredders were found in the most acidic streams.  Molecular analyses revealed distinct fungal communities across the pH gradient.  Streams affected by mining allow a view of the functional role of key taxa as well as diversity in the communities involved in decomposition.


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