Water Flow Reduces Bleaching and the Effects of Thermal Stress On Photosystem Function in The Coral Porites divaricata

EPA Grant Number: FP916403
Title: Water Flow Reduces Bleaching and the Effects of Thermal Stress On Photosystem Function in The Coral Porites divaricata
Investigators: Kinane, Sean W.
Institution: University of Florida
EPA Project Officer: Lee, Sonja
Project Period: January 1, 2004 through December 31, 2006
Project Amount: $102,656
RFA: STAR Graduate Fellowships (2004) RFA Text |  Recipients Lists
Research Category: Fellowship - Zoology , Academic Fellowships , Biology/Life Sciences


Porites divaricata often is found in very shallow areas with high solar irradiance, temperature, and water velocity. High temperature and solar irradiance contribute to coral bleaching and there is evidence that water motion may alleviate these affects. The objective of this research project is to explore the hypothesis that increased water motion alleviates bleaching and the effects of thermal bleaching stress on photosystem function in the coral Porites divaricata.


I tested the hypothesis that increased water motion reduces bleaching stress in P. divaricata using paired flume experiments with different water velocities under conditions of high temperature and solar irradiance. Whether water motion affected dynamic photoinhibition or chronic photoinhibition (photodamage) was examined. There was an increase in minimal fluorescence, indicating photodamage of the zooxanthellae photosynthetic apparatus. One measure of bleaching stress, decrease in photochemical efficiency of Photosystem II (Fv/Fm), is greater in “slow flow” (2-3 cm s-1) compared to “fast flow” (14-21 cm s-1) after 1 day of exposure to bleaching conditions. Water temperature also significantly affected Fv/Fm. Bleaching (loss of zooxanthellae cells from the coral) was significantly greater in corals in the slow flow treatment.

Supplemental Keywords:

fellowship, Porites divaricata, Photosystem II, water velocity, coral bleaching, water motion, photoinhibition, photodamage, photosynthesis, photochemical efficiency, zooxanthellae cells, thermal bleaching stress,, RFA, Scientific Discipline, Ecosystem Protection/Environmental Exposure & Risk, Aquatic Ecosystems & Estuarine Research, Oceanography, Aquatic Ecosystem, Ecological Risk Assessment, anthropogenic stress, nutrient dynamics, water flow, aquatic ecosystems, thermal damage, coral reef communities, ecosystem stress

Relevant Websites:

2004 STAR Graduate Fellowship Conference Poster (PDF, 1p., 912KB, about PDF)

Progress and Final Reports:

  • 2004
  • 2005
  • Final