Impacts of Hurricane Irma on Florida Bay Islands, Everglades National Park, USA

G Lynn Wingard,S E Bergstresser,M C Jones,M E Marot,A Daniels,B L Stackhouse,K Hoefke,K Keller

doi:10.1007/s12237-019-00638-7

Abstract

Hurricane Irma made landfall in south Florida, USA, on September 10, 2017 as a category 4 storm. In January 2018, fieldwork was conducted on four previously (2014) sampled islands in Florida Bay, Everglades National Park to examine changes between 2014 and 2018. The objectives were to determine if the net impact of the storm was gain or loss of island landmass and/or elevation; observe and quantify impacts to mangroves; and identify distinctive sedimentary, biochemical, and/or geochemical signatures of the storm. Storm overwash deposits were measured in the field and, in general, interior island mudflats appeared to experience deposition ranging from ~ 0.5 to ~ 6.5 cm. Elevation changes were measured using real-time kinematic positioning and satellite receivers. Comparison of 2014 to 2018 elevation measurements indicates mangrove berms and transitional areas between mudflats and berms experienced erosion and loss of elevation, whereas interior mudflats gained elevation, possibly due to Hurricane Irma. Geographic information system analysis of pre- and post-storm satellite imagery indicates the western-most island, closest to the eye of the storm, lost 32 to 42% (~ 11 to 13 m) of the width of the eastern berm, and vegetated coverage was reduced 9.3% or ~ 9700 m2. Vegetated coverage on the eastern-most island was reduced by 1.9% or ~ 9200 m2. These results are compared to previous accounts of hurricane impacts and provide a baseline for examining long-term constructive and destructive aspects of hurricanes on the islands and the role of storms in resiliency of Florida Bay islands.

Highlights

Hurricanes have played a significant role in shaping the existing Greater Everglades ecosystem of south FloridaCommunicated by Stijn Temmerman Electronic supplementary material The online version of this article contains supplementary material, which is available to authorized users.1 U.S Geological Survey, Florence Bascom Geoscience Center, Reston, VA, USA2 U.S Geological Survey, St
The constructive aspects of Hurricane Irma in the open central areas of the islands are evident from the overwash deposits, the mudflat core tops, and the elevation gains measured on the mudflats at Bob Allen and Russell Keys
Considering the reduction in vegetated landmass and the degradation of the eastern berm following Irma, Jim Foot may be an excellent place to examine changes over the decade. When it made landfall on September 10, 2017 as a category 4 storm, Hurricane Irma had a substantial impact on four islands investigated in Florida Bay, Everglades National Park, Florida

Summary

Introduction

Research is needed to address whether storms contribute to build-up and resiliency of the coastal ecosystem through deposition and nutrient supply or whether damage to the coastal mangroves causes persistent change that results in regime shifts over decades Both destructive and constructive effects of hurricanes have been described (Cahoon 2006; Twilley 2007; Smith et al 2009; Whelan et al 2009; Castaeda-Moya et al 2010; Breithaupt et al this volume), and recognition of the net long-term (decadal to centennial-scale) impacts of these storms is imperative for future planning in the coastal region (Greening et al 2006). Their findings highlight the importance of understanding whether the net effect of storms on the coast is constructive or destructive as resource

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