Human activities reduce coral energy reserves and lower stress resilience

A novel study led by the University of Hawai‘i at Mānoa has revealed that human activities are significantly depleting the energy reserves of coral reefs, leaving them more vulnerable to environmental stressors. Published in *Nature Communications*, the research highlights how contaminants from agricultural, industrial, and pharmaceutical sources accumulate in coral tissues, reducing their ability to withstand rising ocean temperatures and acidification.

The study analyzed 380 lobe corals (*Porites lobata*) and rice corals (*Montipora capitata*) from 16 sites around Maui, Hawai‘i. Researchers found that areas with high human activity showed elevated levels of 25 contaminants in coral tissues. These pollutants, including pharmaceuticals and industrial byproducts, were linked to diminished nitrogen and energy reserves, critical for coral survival. "Coral that has been exposed to human disturbances uses more of its energy to cope with stress, leaving less for growth and recovery," said lead author Zach Quinlan, a research biologist at the Hawai‘i Institute of Marine Biology.

Surprisingly, both coral species exhibited nearly identical metabolic trends despite their differing life strategies. "This uniformity suggests that human pressures are so pervasive that they override natural biological differences," Quinlan noted. The study also found that sites with the most severe coral cover declines after the 2016 bleaching event had the most disrupted metabolomes, with stress chemicals enriching and energy reserves shrinking.

The research identifies two primary mechanisms by which human activities harm coral resilience: the accumulation of anthropogenic molecules and the depletion of nitrogen and energy reserves under chronic stress. "Coral are essentially burning through their energy stores to survive pollution and other disturbances," said Megan Donahue, senior author and director of the Hawai‘i Institute of Marine Biology. "This leaves them ill-equipped to handle even minor environmental changes."

The findings underscore the urgent need for strategies to mitigate human impacts on marine ecosystems. The team proposes monitoring coral metabolomes as a tool to track hidden chemical stressors, a method they argue could revolutionize conservation efforts. "By understanding how contaminants affect coral physiology, we can better prioritize areas for protection and restoration," Donahue said.

Coral reefs face a dual threat from local pollution and global climate change, as highlighted in a separate review published in *Springer*. The study emphasizes that local stressors — such as sedimentation and chemical runoff — can exacerbate the effects of rising sea temperatures and ocean acidification. "No single solution will work for all reefs," the review states. "Tailored approaches that address both local and global challenges are essential."

The health of coral reefs is inextricably linked to human well-being. As the Coral.org report explains, reefs provide critical ecosystem services, including water filtration, food security, and coastal protection. Their decline threatens not only marine biodiversity but also the livelihoods of millions who depend on fisheries and tourism. "Healthy reefs are a lifeline for communities worldwide," the report states. "Their loss would have cascading effects on public health and economic stability."

Efforts to restore coral resilience are already underway. Quinlan and his team are experimenting with ways to replenish coral tissue nitrogen and energy reserves in controlled settings. If successful, these methods could offer new hope for protecting reefs against escalating environmental pressures. Meanwhile, scientists emphasize the need for reducing human impacts on marine ecosystems, as highlighted in the study's call to action.

The study serves as a stark reminder of the interconnectedness between human actions and ocean health. As climate change accelerates and coastal development expands, the survival of coral reefs, and the ecosystems they support, depends on immediate and sustained conservation efforts. "The evidence is clear," Quinlan said. "Reducing our environmental footprint is not just about saving corals. It’s about safeguarding the future of our planet."