Distribution and Diversity of Fungi across Tropical Coastal Ecosystems

Mangroves, as a biome, sustain highly productive ecosystems while been subjected to coastal dynamics. On the coast, estuarine sediments constitute an unusal habitat for fungi. Puerto Rico is bordered by mangroves and has the second largest estuary (Jobos Bay) managed as a national reserve. As fungi are considered primary decomposers of complex organic matter, we aimed to describe the heterogeneity and biogeography of fungi in those tropical coastal ecosystems. The composition of fungal communities was characterized by amplification of partial ITS from soil and sediment samples for Terminal Restriction Fragment Length Polymorphism (TRFLP). DNA extraction was performed on 91 samples, but the ITS was amplified in only 24 positive samples. A total of 1329 phylotypes (TRFs) were detected, representing 345 different TRFs (richness). Fungal community in mangroves oscillated between 23 (Vieques) and 152 (Maunabo) TRFs whereas in Jobos Bay oscillated between 18 (CNT18) and 79 (OTR37). Currently, no TRF was found in common among all samples. Only one sample detected 29% of the picks, suggesting potential endemism. Similarity analyses, based on the Sorensen index, illustrate the association with geographic proximity. The similarity index fluctuated between 19% and 72%, and was highest among neighboring sites. The application of TRFLP provides information on fungi diversity, and shows that the fungal community is distinctive for mangrove and sediments ecosystems. Evaluation of clonal libraries are in progress to identify specific taxa.