RAPID: Storm-related sediment export during hurricanes Irma and Maria along the northwestern insular shelf of St. Croix, US Virgin Islands

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Hurricane Irma and Maria, both category 5 storms, that struck the Caribbean in the summer of 2017 caused severe damage to many islands not only destroying a significant amount of civil infrastructure but also impacting many shallow submarine environments. This research project collects time-critical, ephemeral data consisting of observations of erosion, sediment redistribution, and coral reef structure damage at Cane Bay on St Croix in the US Virgin Islands. This location was picked because it was at or near the center of both Hurricane Irma and Hurricane Maria when they were at their maximum strength. It is also the location of another major hurricane strike (i.e., Hurricane Hugo) in 1989. Data like that collected for the present project were also collected for Hurricane Hugo, allowing comparisons to be made and comprehensive modeling of the impact major storms have on carbonate production, bioerosion, and sediment export in a modern reef system. Land and marine photographic images, as well as other data will be collected to provide high quality measurements of sediment removal by each storm. These data, as well as historical data from Hurricane Hugo, will be used to model storm related sediment transport in the area over the past century. Broader impacts of the work include partnership with researchers at the US Geological Survey, production of an educational video based on overcoming reef-building misconceptions, and improving knowledge of the impacts of major storms on coral reefs which will help inform and improve reef management.Carbonate production and carbonate cycling in modern reefs is due to a balance between the secretion of calcite by corals and coralline algae and the breakdown and removal of the physical structure of the reef by biological and physical means. While the biologically related components of this equation have been intensively studied, a missing part of the equation is sediment export, a parameter that is presently poorly understood and quantified. A key set of data documenting sediment export in a reef system was collected in Cane Bay at St. Croix in the US Virgin Islands just after Hurricane Hugo. Additional data was collected during fair weather conditions on the island for comparison. This new project collects similar data to that collected after Hurricane Hugo. It will allow a quantitative comparison between the various storms and an assessment of sediment export. Goals will be to characterize sediment removal from the northwestern insular shelf of St. Croix. Modeling, to be carried out by a collaborator from the US Geological Survey, will be focused on determining the relative roles of bottom shear versus storm surge during major storms in exporting sediment from coral reefs in tropical carbonate systems.