Scientists are turning seawater into a ‘blood test’ that could reveal coral reef damage before it becomes visible

Before major surgeries and operations, doctors often detect diseases in humans using minimally invasive methods like a blood or urine test, before symptoms become severe. Now, researchers at the Woods Hole Oceanographic Institution (WHOI) are applying a similar concept to coral reefs. They have shown that the water surrounding reefs contains chemical and microbial signals that could reveal changes in ecosystem health long before these changes become visible.In a new study, WHOI scientists combined the principles of chemistry, biology and ocean physics to examine how dissolved molecules, microorganisms and water movement interact across coral reefs and a nearby seagrass meadow in the American Virgin Islands. The findings have revealed that each sample site has its own distinct chemical and microbial signature and that ocean currents play a major role in shaping those patterns on timescales as short as a few hours.For the research, researchers collected seawater from two neighbouring coral reefs and a nearby seagrass meadow over four days, sampling at dawn and midday. They measured dissolved compounds known as metabolites, or small molecules produced and consumed by marine organisms,...