Aquatic hyphomycete communities across a land-use gradient of Panamanian streams

Aquatic hyphomycetes play an essential role in the conditioning and breakdown of imported leaves, needles and other plant detritus in running waters. Most research on their diversity and function has been done in temperate regions and very little in South and Central America. Current knowledge suggests that fungal diversity in tropical streams is comparable to that in temperate waters. Due to increasing anthropogenic stress threatening stream communities in the tropics, we risk losing irreplaceable information. We investigated aquatic hyphomycetes on leaves decaying in 15 streams in the Republic of Panama. The streams were classified as pristine, rural, or urban. Multivariate analyses of physico-chemical and riparian vegetation parameters separated the pristine streams from the other two groups. Pristine streams generally had the lowest levels of several inorganic nutrients and turbidity and the widest buffer zones of riparian vegetation. Multivariate analysis of aquatic hyphomycete communities separated the pristine streams from rural and urban streams. Both numbers of fungal species and conidia released per unit leaf mass were generally highest in pristine streams. A total of 34 fungal taxa was recovered. Of these, 32 were assigned to described aquatic hyphomycete taxa, with 29 being new records for the Republic of Panama.