Neal Cantin: The role of light in coral bleaching and recovery

Neal E Cantin a
a Australian Institute of Marine Science, Townsville QLD 4810, Australia
Coral bleaching refers to the abrupt breakdown of the typically beneficial symbiotic relationship between the coral host and the algal symbiont, Symbiodinium sp., which provides coral tissues with the healthy colour expected within vibrant reef habitats. Environmental stressors, individually or combined that can cause corals to bleach and turn completely white include temperature (hot or cold events), high light and low salinity from freshwater flood events. However, widespread mass bleaching events that impact large areas of reefs on regional scales consistently occur during abnormally high temperature anomalies that last for extended periods of time. Bleaching severity and mortality is enhanced with prolonged warming events that coincide with calm (low wind) conditions that increase water clarity and light intensity. The combination of accumulated heat anomalies and high light intensity reduce the photosynthetic productivity of Symbiodinium spp. and increase the production of toxic reactive oxygen within the tissues of the coral host, which leads to bleaching in an attempt by the animal to protect itself from the damage produced by the symbiont. Climate change continues to increase the rate of ocean warming and the likelihood of more frequent, intense thermal stress events. Strong El Nino phases, of the El Nino-Southern Oscillation, similar to the 2016 event in Australia are typically accompanied with weaker monsoon conditions, which means reduced winds, cloud cover and higher light intensity, which enhance the air-sea heat flux. This talk will discuss the role of light in relation to coral physiology, climate patterns and ocean warming to enhance interventions that seek to reduce the effect of light intensity on the coral bleaching response.
KEYWORDS:
Light, Coral Bleaching, Temperature, Stress, Climate Change,