CISNet: Coral Bleaching, UV Effects, and Multiple Stressors in the Florida Keys

EPA Grant Number: R826939
Title: CISNet: Coral Bleaching, UV Effects, and Multiple Stressors in the Florida Keys
Investigators: Anderson, Susan L. , Santavy, Debbie , Zepp, Richard
Current Investigators: Anderson, Susan L. , Cherr, Gary N. , Brown, Heather , Machula, Jana , Hansen, Lara , Oliver, Leah , Zepp, Richard , Jackson, Susan
Institution: University of California - Davis
Current Institution: University of California - Davis , U. S. Environmental Protection Agency
EPA Project Officer: Packard, Benjamin H
Project Period: October 1, 1998 through September 30, 2001
Project Amount: $407,567
RFA: Ecological Effects of Environmental Stressors Using Coastal Intensive Sites (1998) RFA Text |  Recipients Lists
Research Category: Environmental Statistics , Aquatic Ecosystems , Ecological Indicators/Assessment/Restoration


Elucidating interactions between climate, anthropogenic stressors, and damage to significant natural resources is a primary goal of CISNet. We will evaluate the role that climate change may play in altering penetrance of UV radiation over coral reefs and potentially contributing to coral bleaching. Our studies will be conducted at intensively monitored sites in the Florida Keys National Marine Sanctuary (FKNMS). Thus, our work will add to ongoing investigations of stressors in coral related to coral disease and impaired water quality. Data available from programs in the FKNMS will also help us characterize temperature and light conditions at our sites in a cost-effective manner. Global climate change may contribute to coral bleaching because thermal stratification causes both increased temperature and increased penetration of UV light associated with photobleaching. Both of these stressors are believed to contribute significantly to coral bleaching.


The remote sensing component of the proposal will first characterize underwater solar UV irradiance and the factors that modify UV exposure in corals. Characterization of diffuse attenuation coefficients under stratified and unstratified conditions will help to determine whether increased stratification and photobleaching cause increased UV irradiance over corals. Secondly, we will develop continuous observations of chromophoric dissolved organic matter concentrations (CDOM) and algorithms that relate measured CDOM concentrations to sea surface UV irradiance (predicted by remote-sensing and land-based radiometers). These efforts could be utilized to predict sites affected by increased UV and may eventually be related to coral bleaching.

In the coral stressors component of the proposal, we will utilize biomarker techniques to examine UV-specific DNA damages (thymine dimers) in relation to coral bleaching. We will also use these techniques to characterize temperature and UV interactions under controlled conditions. A monitoring study will be conducted in the FKNMS using Mote Marine Laboratory-Pigeon Key Marine Research Center (PKMRC) as the base of investigations with additional sampling in the Key West area and the Dry Tortugas National Park. The primary goals of this investigation are to determine whether: 1) temperature or UV irradiance/ thymine dimers better predict the occurrence of coral bleaching in field populations and 2) levels of thymine dimers and coral bleaching vary significantly under stratified and unstratified conditions. If significant positive correlations between UV exposure, thymine dimers, and coral bleaching are observed, this would be the most thorough analysis we know of indicating that increased UV irradiance associated with climate warming may have damaging effects on corals. To our knowledge, no previous studies have employed state-of - the-art molecular techniques to quantify UV-specific DNA damages in coral, utilizing these responses as "ecosystem indicators". The proposed investigation involves extensive collaboration between the PI and federal researchers. Matching funds in excess of $100,000 per year are provided by EPA.

Expected Results:

This research should result in significant advances in our understanding of the etiology of devastating increases in coral bleaching in the Florida Keys, the third largest barrier reef in the world.

Publications and Presentations:

Publications have been submitted on this project: View all 25 publications for this project

Journal Articles:

Journal Articles have been submitted on this project: View all 6 journal articles for this project

Supplemental Keywords:

ecological effects, ecosystem indicators., RFA, Scientific Discipline, Air, Geographic Area, Ecosystem Protection/Environmental Exposure & Risk, Ecology, Ecosystem/Assessment/Indicators, Ecosystem Protection, climate change, State, Chemistry, Ecological Effects - Environmental Exposure & Risk, Monitoring/Modeling, Ecological Risk Assessment, Ecological Indicators, anthropogenic stresses, ecological effects, ecological exposure, anthropogenic stress, environmental monitoring, UV effects, biomarkers, stressors, thermal stratification, coral bleaching, natural stressors, climate, coastal zone, remote sensing data, Florida Keys, multiple stressors, CISNet Program, ecosystem indicators, biomonitoring, water quality, chromophoric dissolved organic matter, photobleaching, thymine dimers, Florida, FLA

Progress and Final Reports:

  • 1999 Progress Report
  • 2000 Progress Report
  • Final Report