Researchers have unveiled a promising strategy to shield coral reefs from the impacts of marine heatwaves.

But the experts say it will require simultaneously addressing human-caused disturbances on both land and sea. 

A new study, published in Nature, sheds light on the potential of integrated management approaches in fortifying coral reefs against the challenges posed by climate change.

Coral reef ecosystems have long borne the brunt of human interventions, both on the land and in the oceans. 

Land-based factors like urban runoff and wastewater pollution, as well as sea-based issues like overfishing, have relentlessly contributed to the decline of these vital underwater habitats. 

Compounded by the alarming rise in ocean temperatures due to marine heatwaves, corals face the dual threat of bleaching and mortality.

Lead authors Jamison Gove, Gareth Williams, and their team embarked on an ambitious mission to assess the intricate relationship between human activities and reef health across Hawaiʻi from 2003 to 2019. 

The focal point of their investigation was the unprecedented marine heatwave of 2015, during which ocean temperatures soared 2.2°C above normal levels. 

The team scrutinised the impacts of urban runoff, wastewater pollution, and fishing restrictions - human-induced pressures that have direct repercussions on the marine environment. 

Over the study period, they observed fluctuating patterns in coral reef cover, with certain regions experiencing growth, decline, or stability.

Remarkably, reefs that were shielded from both land- and sea-based human impacts exhibited a noteworthy trend: heightened coral cover prior to the heatwave and reduced coral loss during the heatwave crisis. 

Additionally, reefs populated by herbivorous fish and subject to fewer land-based human interventions displayed a marked increase in reef-builder cover - a critical factor for sustaining coral growth - four years after the heatwave disturbance. 

In contrast, reefs with diminished fish populations and greater exposure to land-based pressures demonstrated a decline in both areas.

The researchers went a step further by employing computational models to explore potential scenarios. 

Their simulations unveiled a striking revelation: by curtailing human impacts on land and sea, the probability of a reef exhibiting high reef-builder cover four years post-disturbance skyrocketed by three- to sixfold. 

The implications are profound, indicating that a holistic land–sea management approach could prove instrumental in safeguarding coral reefs amid a rapidly changing climate.

The full study is accessible here.