Fungal communities associated with early stages of decomposition of Spartina maritima (Curtis) Fernald were assessed in two geographically distinct salt marshes in Portugal by direct observation of fungal sporulating structures. Twenty-three fungal taxa were identified from 390 plant samples, 11 of which were common to both study sites. Natantispora retorquens, Byssothecium obiones, Phaeosphaeria spartinicola, Phoma sp. 1 and Stagonospora sp. were the most frequent fungal taxa in the studied communities. The fungal species Anthostomella spissitecta, Camarosporium roumeguerii, Coniothyrium obiones, Decorospora gaudefroyi, Halosarpheia trullifera, Leptosphaeria marina and Stagonospora haliclysta were recorded for the first time on S. maritima plants; with the exception of C. roumeguerii and L. marina, all of these species were also new records for Portugal. The differences between species composition of the communities associated with S. maritima were attributed to differences in abiotic conditions of the salt marshes. Although the fungal taxa were distributed differently along the host plants, common species to both fungal communities were found on the same relative position, e.g. B. obiones, Lulworthia sp. and N. retorquens occurred on the basal plant portions, Buergenerula spartinae, Dictyosporium pelagicum and Phoma sp. 1 on the middle plant portions and P. spartinicola and Stagonospora sp. on the top plant portions. The distinct vertical distribution patterns reflected species-specific salinity requirements and flooding tolerance, but specially substrate preferences. The most frequent fungi in both communities also exhibited wider distribution ranges and produced a higher number of fruiting structures, suggesting a more active key role in the decay process of S. maritima.
Keywords: Marine fungi; Salt marsh; Spartina maritima; Species-specific ecological requirements; Vertical distribution patterns.