In an unlikely ‘positive’ twist on COVID lockdowns, the rapid recovery of a reef offers a blueprint for balancing conservation and tourism worldwide. Researchers in the US now say that limits on visitors could protect coral ecosystems without harming tourism – and may even boost the industry in the long run.
Hanauma Bay Nature Preserve, a popular snorkelling spot in Hawaii, saw a remarkable transformation during the pandemic shutdown. Normally attracting around a million visitors a year, the bay’s seven-month closure allowed nature to bounce back in surprising ways.
A new study from the Hawaii Institute of Marine Biology (HIMB), published in Nature Ocean Sustainability, reveals that the water became clearer, fish populations swelled, and endangered Hawaiian monk seals began appearing more often. Researchers describe the closure as a “natural experiment” exposing just how much everyday tourism pressures shape the bay’s ecosystem.
Scientists from HIMB’s Elizabeth Madin Lab collected data before, during, and after the shutdown. They tracked water quality, fish populations and behaviour, and monk seal sightings. The difference was immediate. Herbivorous species such as parrotfish more actively grazed algae, while overall fish density rose to healthier levels.
“These kinds of changes happened quickly,” explains lead author Dr Elizabeth Madin in a statement on the findings, “suggesting that everyday human presence can have a real and measurable impact on reef health.”
Anthropical impacts on biodiversity have become the subject of more intense scrutiny. Earlier this year, researchers from the University of Zurich’s Department of Evolutionary Biology and Environmental Studies published findings (Nature 641) about the global human impact on biodiversity.
“Critically, the direction and magnitude of biodiversity changes vary across pressures, organisms and scales at which they are studied,” note the authors, whose global analysis reveals the “general impact and key mediating factors of human pressures on biodiversity”, and offers a benchmark for conservation strategies.
Rapid rebound
When freed from human pressures, sensitive marine ecosystems can rebound, and much faster than expected, according to the Hawaiian team. For Hanauma Bay, the recovery underscores the importance of smarter management to balance tourism with conservation.
Their work also highlights a potential win-win for nature and the economy. Visitor caps and stricter controls could ease ecological strain while maintaining reasonable access. A 2022 survey by Reef-World Foundation suggests tourists are willing to pay more for sustainable offerings – protecting ecosystems while at the same time strengthening the industry that depends on them.
The forced closure, or “anthropause”, offered unique insights on how marine managers can achieve this delicate balancing act. If you give reefs a much-needed break, they can recover and even thrive, the researchers suggest. The big challenge now is finding ways to let visitors in without shutting nature out.
“Using the COVID-19 anthropause to better understand the impacts of human presence on reef systems can provide important clues to how these ecosystems, and the resources they provide for coastal inhabitants, will conceivably change over time as human presence changes,” the research paper concludes.
