Microbial dynamics associated with decomposing Typha latifolia litter in two Lake Erie coastal wetlands: Effects of sedimentation and hydrology.

R. Su¹, R. Amonette², K.A. Kuehn¹, R.L. Sinsabaugh^2,3, and R.K. Neely¹. ¹Department of Biology, Eastern Michigan University, Ypsilanti, Michigan 48197, ²Department of Earth, Ecological and Environmental Science, University of Toledo, Toledo, Ohio 43606, ³Present address: Department of Biology, University of New Mexico, Albuquerque, NM 87131

This study examined the interactions between microbial activity and sedimentation on Typha latifolia decomposition in two Lake Erie coastal wetlands with distinct differences in hydrologic regimes (seasonally-dry vs. permanently inundated). The objective of this investigation was to assess the effects of differing hydrology and increasing sedimentation on the biomass, productivity and respiration rates of microorganisms (fungi and bacteria) associated with decomposing T. latifolia litter. Sediment additions did not have a significant effect on microbial assemblages associated with T. latifolia . However, differences in hydrologic regimes between study sites had a major influence on microbial colonization and growth. Bacterial biomass associated with litter was consistently greater at the permanently inundated wetland site than the drier site (800 vs 290 µgC/g detrital C, respectively). In contrast, fungal biomass and rates of fungal production were greater at the seasonally-dry wetland site versus the inundated site (e.g., fungal biomass: 80 vs. 33 mgC/g detrital C, respectively). Rates of microbial respiration were similar between the two sites initially, but increased at the inundated site towards the end of the study period. Results obtained in this investigation point to contrasting patterns in microbial dynamics during macrophyte decay as a result of wetland hydrology.