Coral reefs in West Hawaiʻi are showing signs of recovery from the global El Niño event in 2015.

According to The Nature Conservancy, approximately 60-percent of corals in West Hawaiʻi underwent bleaching during the event, and some reefs experienced up to 90-percent mortality. Corals bleach under stress, and severe or prolonged stress can lead to death.

Researchers surveyed more than 14,000 coral colonies at 20 sites along West Hawaiʻi's coastline.

Over the past three years, researchers with The Nature Conservancy, state Department of Land and Natural Resources - Division of Aquatic Resources, and the National Oceanic and Atmospheric Administration have studied those same sites to see what species were most resilient to the changes, and how the reef recovered.

Eric Conklin is the Director of Marince Science for the Nature Conservancy.

He says Hawaiʻi was lucky compared to other reefs affected by the 2015 event.

Conklin says corals are resilient, and can adapt to the changing ocean temperatures. But they are only resilient when there is minimal exposure to human impacts - such as over-fishing and runoff pollution.