Abstract:
When Hurricane Irma made US landfall on the Florida Keys on September 10, 2017, the category 4 storm became the first major hurricane to hit the state since 2005. This study investigated the impacts that Irma had on seagrasses in Florida Bay – an estuary at the southern outlet of the Florida Everglades that is crucial to the environment and economy of South Florida but that is threatened by anthropogenic impacts on water quality. A massive seagrass die-off in 2015 left the bay with hypersaline water and sulfide-saturated sediment that was held in place by the bay’s network of carbonate mud banks. The promise of rainfall and storm surge from a major hurricane offered a chance to refresh the bay and begin the process of recovering from the die-off. By comparing seagrass density and community composition from after the 2015 die-off to after Irma, I found that seagrass cover has become more uniform and that species richness has increased throughout the study area. Seagrass density was lost in some shallow sections of the study area, but pioneer species Halodule wrightii had begun colonizing the disturbed areas, indicating that water quality had changed enough to support the less salt-tolerant species. The positive changes in seagrass density, distribution, and diversity after Hurricane Irma indicate that the storm may have flushed out the hypersaline water left after the 2015 die-off that had been limiting seagrass recovery for two years.
