Scientists are investigating the unusual coral bleaching event around the French Polynesian island of Moorea in the central South Pacific Ocean.
What made this event unusual and drew the attention of ocean scientists was that it occurred in a year ( April and May 2019) with no El Nino conditions.
The team found that anti-cyclonic eddies caused the event. These currents elevated sea levels and led to a concentration of warmer waters on top of the reefs. This effect created an underwater marine heatwave that was not visible from the surface. The event highlights the importance of collecting data at the surface and deeper in the water column.
According to Prof. Alex Wyatt, the research team lead from the Department of Ocean Science at the Hong Kong University of Science and Technology:
“The present study highlights the need to consider environmental dynamics across depths relevant to threatened ecosystems, including those due to the passage of underwater ocean weather events. This kind of analysis depends on long-term, in situ data measured across ocean depths, but such data is generally lacking. Our paper provides a valuable mechanistic example for assessing the future of coastal ecosystems in the context of changing ocean dynamics and climates.”
