Resistance, resilience, and recovery of salt marshes in the Florida Panhandle following Hurricane Michael

Katherine A Castagno,Kiera O’Donnell,Steven B Scyphers,Alison A Bowden,Michael W Beck,Tori Tomiczek,Christine C Shepard

doi:10.1038/s41598-021-99779-8

Abstract

Characterizing the fragility, resistance, and resilience of marshes is critical for understanding their role in reducing storm damages and for helping to manage the recovery of these natural defenses. This study uses high-resolution aerial imagery to quantify the impacts of Hurricane Michael, a category 5 hurricane, on coastal salt marshes in the Florida Panhandle, USA. Marsh damage was classified into several categories, including deposition of sediment or wrack, fallen trees, vegetation loss, and conversion to open water. The marshes were highly resistant to storm damages even under extreme conditions; only 2% of the 173,259 km2 of marshes in the study area were damaged—a failure rate much lower than that of artificial defenses. Marshes may be more resistant than resilient to storm impacts; damaged marshes were slow to recover, and only 16% of damaged marshes had recovered 6 months after landfall. Marsh management mattered for resistance and resilience; marshes on publicly-managed lands were less likely to be damaged and more likely to recover quickly from storm impacts than marshes on private land, emphasizing the need to incentivize marsh management on private lands. These results directly inform policy and practice for hazard mitigation, disaster recovery, adaptation, and conservation, particularly given the potential for more intense hurricane landfalls as the climate changes.

Highlights

Hurricane Michael made landfall in Mexico Beach, FL, on October 10, 2018, as a category 5 hurricane
Based on comparative analysis of aerial imagery, the marshes in the Florida Panhandle were overwhelmingly undamaged by Hurricane Michael
Of the 173,259 k m2 of marsh analyzed across Bay, Gulf, and Franklin counties, only 1.9% (3371 km2) was classified as damaged after Hurricane Michael

Summary

Introduction

Hurricane Michael made landfall in Mexico Beach, FL, on October 10, 2018, as a category 5 hurricane. Natural and nature-based features (NNBF), including salt marshes, are increasingly being leveraged for coastal protection to build resilience to storms and rising sea levels[17,18] This understanding of how marshes are affected by and recover from major storm events can be incorporated into nature-based and hybrid shoreline stabilization and coastal protection designs. Building this knowledge base is important as climate models suggest that hurricanes will increase in intensity as the climate continues to change[19]. Damage was determined visually using aerial imagery from Google Earth, which provided high- resolution aerial imagery from directly after Hurricane Michael’s landfall (11–12 October 2018) and prior to Hurricane Michael (October 2017, February 2017, October 2015). 30 m by 30 m marsh grid cells were classified into one of eight categories: no damage, deposition of vegetation or sediment, Scientific Reports | (2021) 11:20381 |

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