CORAL BLEACHING - A POTENTIAL BIOMARKER OF ENVIRONMENTAL-STRESS

Coral bleaching refers to the loss of symbiotic algae by host corals, or to the loss of pig mentation by the algae themselves, causing coral s to appear white or ''bleached.'' Some corals may regain algae or pig mentation and survive, but when bleaching is severe the host coral die s. Coral bleaching events have increased dramatically in the last two decades, and coral reefs throughout the world have been extensively de graded as a result. This article reviews coral bleaching for investiga tors working in the field of toxicology and environmental health, a gr oup of scientists not normally exposed to this issue. Several environm ental stressors have been correlated with bleaching, including fluctua tions in sea surface temperatures and salinity, increased sedimentatio n, increased solar radiation, and contaminants such as oil and herbici des. Molecular mechanisms of bleaching are only beginning lo be invest igated and are thus far poorly understood. Toxicologists have the pote ntial to make significant contributions toward understanding anthropog enic aspects of coral bleaching and elucidating molecular mechanisms o f this important environmental problem.