Hanauma Bay is a marine sanctuary near Honolulu that is a popular snorkeling spot and is home to vibrant marine life and well-preserved corals. Its popularity grew in the 1970’s and 1980’s and its visitor attendance peaked at an estimated 10,000 people a day. A new management plan in 1990 reduced visitation, improved facilities, established an education program, and banned the feeding of fish. In 2019, average daily attendance was still about 3,000 people – about a million a year – and the impact on the reef ecosystem was considerable.
In 2020, because of the Covid pandemic, the preserve was completely closed to the public for seven months. This provided a unique natural experiment to study the effect of removing human interference from a natural ecosystem.
Researchers from the Hawaii Institute of Marine Biology found that the reef in Hanauma Bay quickly returned to having better water quality, more monk seal sightings, greater fish abundance, and significant changes in fish behavior. The fact that the ecosystem responded quickly indicated that everyday human presence can have a real and measurable effect on reef health.
The research serves as a valuable case study for marine managers around the world. Putting limits on the number of visitors to reefs – especially those that are currently unregulated – could help restore lost ecological function and reduce human-induced pressure while still maintaining access. Tourism to reefs generates billions of dollars annually, so there needs to be ways to protect reefs without making them entirely off limits.
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When crowds left, reefs came alive at Hanauma Bay
Photo, posted December 13, 2011, courtesy of Dalton Reed via Flickr.
Earth Wise is a production of WAMC Northeast Public Radio