[Coral-List] Modern sea-level rise and coral reefs

Mike Field mfield at usgs.gov
Fri Nov 19 16:38:12 EST 2010

Coral reef colleagues,

We have just completed a study assessing the potential impact of  
anthropogenic-driven sea-level rise on coral reefs. The study is  
published in the Journal of Coastal Research, a journal many coral- 
listers might not access, and so I am passing on information here. The  
conventional wisdom about 21st century SLR and coral reefs has seemed  
to be that it would “simply add a bit more space for coral growth”. We  
found differently.

Poor water quality (turbidity) on shallow reef flats of fringing coral  
reefs is often caused by frequent re-suspension of fine-grain sediment  
by trade-wind waves. Water depth is a fundamental control on the  
bottom stresses and resultant suspended sediment concentrations (SSC).  
Deeper water—even 20 cm deeper—will likely lead to higher SSC, and  
resuspension will likely occur earlier in the day and last longer, all  
during periods of optimal photosynthesis. We estimate that on the  
island of Molokai, for example,the time that thresholds of  
"acceptable" SSC (<10 mg/L) are exceeded will rise from 9% to 37%.  
Granted these impacts may not compare in magnitude or extent with  
those caused by the other, major climate-change related impacts of  
thermal stress and acidification, but they are factors that might be  
useful in planning/managing protected areas.

The full reference is:

Ogston, A. S. and Field, M. E., 2010, Predictions of Turbidity Due to  
Enhanced Sediment Resuspension Resulting from Sea-Level Rise on a  
Fringing Coral Reef: Evidence from Molokai, Hawaii. Journal of Coastal  
Research, Vol. 26, No. 6, p 1027-1037.

If you would like a pdf copy of the manuscript, please send an email  
to Andrea Ogston (ogston at oceans.washington.edu) or to me (mfield at usgs.gov 


Michael E. Field
US Geological Survey
Pacific Science Center
400 Natural Bridges Drive
Santa Cruz, CA 95060
(831) 427-4737;   FAX: (831) 427-4748


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