EVIDENCE FOR POSITIVE INTERACTIONS BETWEEN EPIPHYTIC ALGAE AND HETEROTROPHIC DECOMPOSERS DURING THE DECOMPOSITION OF TYPHA-LATIFOLIA

The effect of epiphytic algae on the decay of Typha latifolia was exam ined by the use of small, closed microcosms incubated under field cond itions for 70 days. Scanning electron micrographs of the microbial ass emblages on the surface of decaying T. latifolia litter clearly illust rated that the growth of heterotrophic microbes was enhanced in treatm ents intended to maximize algal abundance. Additionally, maximum algal abundance resulted in significantly greater decay of T latifolia (+8 to +23%) and reduction of total phosphorus (-41 to -50%) in the water surrounding the decaying litter. Heterotrophic microbes may have been stimulated by either autotrophic release of oxygen and/or dissolved or ganic carbon (DOC); however, oxygen and DOC concentrations showed no c lear pattern with respect to algal treatments.