cordgrass (Spartina alterniflora) in a salt marsh system, showing the proportion of carbon lost to dissolved organic matter (DOM), fine participate organic matter (FPOM), and incorporation into bacterial and fungal biomass. Source: Modified from Gessner et al. (1997).

The role of fungi in aquatic ecosystems has not been studied as intensively as it has in terrestrial ecosystems. Wong et al. (1998) reiterate this in their review, saying that although fungi are the dominant decomposers in these systems we know little about the mechanisms of decomposition or the interactions between fungi and between fungi and other organisms. Resource succession by saprotrophic fungi has been identified (Gessner et al., 1993), however, but we know very little about the relationship between fungal biodiversity and ecological function. It would appear, however, that resource quality of plant material dictates the community structure of the aquatic saprotrophic fungi colonizing it, and there may be many parallels between aquatic and terrestrial systems in the way in which materials are processed and utilized (Wagener et al., 1998). Gulis (2001) performed a multivariate analysis of 146 samples from 92 aquatic systems to show that the fungal species assemblage on wood and grass leaves has a different composition from those on tree leaf litter (Fig. 2.9). He did not, however, correlate the differences in fungal communities, resource quality, and rates of decomposition, nor any of these factors with physiological function (enzyme function, etc.) of the individual species or communities. This information is one of the aquatic decomposition system functions that is still to be explored.