Assessing the Recalibration Interval for Nearshore Sediment Assemblages after Hurricane Irma: implications for Developing Long-term Records of Overwash Deposits

<p>Surface distributions are commonly collected to assist with overwash interpretation; however, many of these are first established immediately after a major overwash event as part of a post-event field survey. This study documents the impacts of Hurricane Irma, a Category 5 storm, on nearshore sediments off the coast of Anegada (British Virgin Islands) using distributions of <em>Homotrema rubra</em>, an encrusting foraminifer with a defined provenance in coral reef ecosystems. Over four sampling intervals spanning 2 years, from six months pre-Hurricane Irma to 18 months post-Hurricane Irma, surface sediment was collected from three shore-perpendicular transects on both the northern and southern shores of Anegada. Partitioning Around Medoids cluster analysis using the <em>Homotrema</em> data revealed that Hurricane Irma introduced an influx of well-preserved <em>fragments</em> into the reef flat (10% increase along the Windlass Bight transect and 13 % increase along the Soldier Point transect, the two northern transects) and homogenized the sediments, limiting the foraminifer’s utility as a known sediment transport indicator. The homogenization of sediments along the two northern transects (i.e., reef proximal) persisted for 7-18 months, at which point <em>Homotrema</em> distributions returned to near pre-Hurricane Irma conditions. However, the southern transect (i.e., absence of reef), where <em>Homotrema</em> concentrations are significantly less, failed to recalibrate within the time period assessed by this study. Post-event recalibration intervals will vary based on site and event, however, our results suggest that a waiting period of at least 18 months is recommended before collecting surface sediment samples from nearshore environments offshore Anegada.</p>

Name thesis:degree_name

Master of Science (MS)

Level thesis:degree_level

Masters Thesis

Year dc:date.available

2020

Author dc:creator

• Mitchell, Stephen

Contributors dc:contributor

• Dr. Davin Wallace
• Dr. Jessica Pilarczyk
• Dr. Jeremy Deans

• surface distributions
• Homotrema rubra
• Anegada
• taphonomy
• Partitioning Around Medoids cluster analysis
• recalibration interval
• Geology
• Oceanography
• Paleontology

Repository record dc:identifier

https://aquila.usm.edu/masters_theses/777

OAI identifier oai:identifier

oai:aquila.usm.edu:masters_theses-1829