Climate change impacts on coral reefs: linkages between the warming ocean and coral bleaching

Environmental Sciences; Fluid Dynamics; Heat Transfer, Combustion

This study aims to quantify how variations in coral topography alters heat flux from the coral surface, while at the reef-scale how water temperatures and flow patterns impact coral bleaching.

Research Interests
  • Climate change
  • fluid dynamics
  • oceanography
  • coral reefs

Elevated sea surface temperatures caused by global warming is one of the major threats to coral reefs.  Corals survive within a small temperature range and at their upper temperature threshold require efficient heat transfer with the overlying water column to support key biological processes for survival. Continued heat stress typically leads to coral bleaching and in many cases, coral death. In many reef areas, it has been found that certain species of coral can survive elevated heat levels for substantially longer than other species. Although many biological processes play a role in coral bleaching, the ability for corals to dissipate heat along its surface is a main factor. Heat transfer rates are primarily determined by flow conditions, coral morphology, and the physics of the resulting fluid-structure interaction, which remains poorly understood. To investigate the interrelationship of these factors on fluxes of heat, we will measure hydrodynamic and heat flux characteristics over various coral surface morphologies. To derive heat transfer relationships, we will conduct multi-layer Stereo Particle Image Velocimetry (SPIV) on coral samples in a recirculating water flume (test section, 380 x 450 x 1520 mm; max flow speed, 1 m/s) located within the Department of Mechanical and Aerospace Engineering. The SPIV setup uses 30 micron glass beads and two continuous laser sheets to create a volumetric rendering of fluid flow over the coral surface. Additionally, we will conduct field measurements of ocean water temperatures and fluid circulation patterns and link these to coral surface temperatures and distributions of coral bleaching. This work will be conducted at the Smithsonian Tropical Research Station in Bocas del Toro, Panama and/or the Bermuda Biological Laboratory in Bermuda. Both of these locations have active research partnerships with faculty at the University of Virginia.

Desired outcomes

We seek to obtain initial datasets on coral-flow interactions and distributions of coral bleaching to develop a larger external grant proposal, likely to the National Science Foundation. In addition, our goal is to obtain enough data and findings for a peer-reviewed publication resulting from this work.