Microbial community structure and dynamics in restored subtropical seagrass sediments

摘要

Microorganisms in seagrass sediments facilitate many key ecosystem processes, yet current knowledge of microbial facilitation of seagrass community recovery following disturbance or restoration is limited. We studied microbial community responses to restoration of a subtropical seagrass meadow disturbed by vessel groundings in south Florida, USA, and relationships between microbial communities and sediment properties at the study sites using terminal restriction fragment length polymorphism. Two restoration methods were evaluated: the installation of bird roosting stakes as a means to provide a nutrient source, and placement of sand fill into excavations to prevent erosion. Both disturbed and restoration sites had less complex microbial community structure than undisturbed reference seagrass sediments. Microbial community structure varied little between disturbed and fertilized sites, but was distinct in filled sites. Sediment bulk density, sediment organic matter and total phosphorus content, porewater ammonium, soluble reactive phosphorus, and dissolved sulfide concentrations were important environmental predictors of microbial community structure across the restoration treatments. We show that community structure and diversity varied with sediment depth, among restoration treatments, and through time. Our results indicate that microbial communities in seagrass meadows are changed by physical disturbance of the rhizosphere, and that common restoration techniques lead to the formation of distinct microbial communities during the first year of recovery.