Disturbance and recovery of microbial community structure and function following Hurricane Frances

Summary Disturbance and recovery influence microbial community structure and ecosystem functions in most natural environments. This study from a hypersaline Bahamian lagoon details the response of a benthic cyanobacterial mat to disturbance by Hurricane Frances, a category‐4 storm. Clone libraries of cyanobacterial small subunit r‐RNA genes and nitrogenase genes revealed significant shifts in cyanobacterial and diazotroph community composition following the hurricane. Post‐hurricane clone libraries were dominated by sequences that had been rare in pre‐hurricane communities. In spite of this dominance shift, re‐colonizing mat communities performed nitrogen fixation and photosynthesis at rates within the normal range of variation measured in the mat at similar salinities. There was a tendency for nitrogen fixation rates from mats re‐colonizing sites with hurricane‐related sand deposition to be higher than those from mats re‐colonizing sites without significant sand deposition. This suggests that the altered communities responded to a carbon : nitrogen imbalance that was particularly pronounced in areas subjected to disturbance by sand burial. The post‐hurricane dominance of organisms that had been previously rare suggests that pre‐hurricane diversity and functional redundancy contributed to the rapid recovery of ecosystem function in the post‐disturbance environment.