Wegner, C.E. and Ellis, J.T., 2017. The influence of sea-level rise on wave-energy dissipation and wave-driven currents at Buck Island Reef National Monument.
Modern Caribbean reefs have undergone significant degradation in the past century because of various anthropogenic stressors, which include climate-change-related impacts, hurricanes, and, potentially, sea-level rise. Degraded reefs will be unable to maintain sufficient vertical accretion with substantial increases in sea level, which will alter the hydrodynamics of these systems. A reduction in wave dissipation by reefs has the potential to shift the shorelines behind the reefs, potentially resulting in economic and habitat losses for tropical shorelines. This study focused on a barrier reef with low, live coral cover (<10%) and accretion rates comparable to current rates of sea-level rise in the region (∼1.7 mm/y). Tides served as a proxy for sea-level rise, with the spring high tide representing a future low tide. These findings indicate that at low tide, infragravity wave frequencies (0.004–0.04 Hz) dominate in the lagoon and are a function of wave breaking on the reef. At high tide, the infragravity waves are less prominent. Current velocities were higher at high tide, averaging 0.14 m s−1 vs. 0.11 m s−1 at low tide. The spectral current characteristics correlate with the infragravity wave frequencies and suggest that these waves are a driving force in lagoon circulation. Wave-energy transmission increased at high tide by 20–30% throughout the sampling period. These results suggest that with sea-level rise, infragravity band waves will be reduced and affect the stresses on the sea bed and sediment-transport processes, also allowing larger and more energetic waves to reach the shoreline.