https://phys.org/news/2018-10-fish-coral.html

The international team of researchers spent more than 600 hours underwater observing butterflyfish over a two-year period encompassing the unprecedented mass coral bleaching event of 2016. Led by Dr. Sally Keith of Lancaster University, previously Center for Macroecology, Evolution and Climate, the team examined 17 reefs across the central Indo-Pacific in Japan, the Philippines, Indonesia and Christmas Island (Indian Ocean).

During the initial data collection, the researchers were unaware that the catastrophic bleaching event was on the horizon. Once underway, the researchers realised that this serendipitous 'natural experiment' placed them in a unique position to see how fish changed their behaviour in response to large-scale bleaching disturbance.