A diverse group of fungi decompose wood in water, providing a significant fraction of the energy and nutrients that support freshwater and saltwater foodwebs. In this project, we explore how groups of fungal species assemble and, as a group, decompose wood. Are particular species important for decomposition to occur, or instead are the genes necessary for decomposition shared among many species, such that fungal species are interchangeable? We have established a decomposition experiment along a freshwater-saltwater gradient in three river systems on the island of Coiba, on the Pacific coast Panama. Our experiment is being used to relate the diversity and species composition of fungi to (i) the activity of genes associated with wood-degrading enzymes, (ii) changes in wood chemistry though the decomposition process, and (iii) to explore how salinity influences fungal gene expression, fungal species interactions, and substrate use. Results from this study will help us understand fungal community organization, which will tell us whether wood decomposition is likely to be robust to diversity loss, or whether particular fungal groups are critical for decomposition.

We also expect that our work will reveal novel genes and genetic pathways that have evolved in aquatic fungi and that have application for cellulosic biofuel research and bioremediation. Culture-grown fungi are also being screened for activity against cancers and tropical diseases.