Sustainability: Assessing the impact of tourism on Hawaiian coral reefs

The most popular Hawaiian coral reefs may be being degraded by the tourists they attract, a paper in Nature Sustainability suggests.

Coral reefs are popular for their biodiversity and beauty, and are also vital ecosystems, nurturing fisheries and protecting coasts. Reef tourism can incentivize conservation by generating funds and supporting local livelihoods focused on protecting the reefs: tourism is cited in the UN 2030 Agenda for Sustainable Development goals as a means to promote sustainable use of marine and coastal resources. However, tourists can harm live corals directly or indirectly, such as by polluting the surrounding sea.

Bing Lin and colleagues combined over 250,000 Instagram posts from between 2018 and 2021 from tourists visiting Hawaiian reefs with airborne maps of live coral cover. They used artificial intelligence to analyse reef map images at a 2 metre resolution and 16 metre depth. They show that accessible sites with more live coral cover were visited more often, but, at the most popular sites, corals closer to the shore were more degraded compared to those at less popular sites. The authors note that the amount of pollution in the water was not found to be the primary reason for degradation and suggest instead that tourist visitation itself was the cause, such as through reef contact and trampling by divers and snorkellers.

Global and large-scale impacts, such as climate change, are known causes of declining coral reefs. However, the authors argue that their research shows that local impacts matter and should be considered so that coral reefs can be sustained.