Underwater 'shades' tested to protect coral reefs from bleaching
Researchers have tested underwater 'umbrellas' in Florida Keys that reduce light exposure to corals, offering protection against heat stress and bleaching.
Scientists are employing a novel approach to shield coral reefs from the damaging effects of warming ocean waters, a phenomenon leading to widespread coral bleaching. In a recent experiment conducted in the Florida Keys, researchers deployed underwater "umbrellas" constructed from shade cloths, commonly used in agriculture and horticulture. These structures were positioned to float above individual coral colonies.
The experiment aimed to mitigate the impact of severe heat stress, which has intensified due to climate change. While the shade cloths did not lower water temperature, they significantly reduced the amount of light reaching the corals by approximately 60%. This reduction in light, particularly during peak summer days, helped minimize the synergistic stress caused by both heat and light, which triggers coral bleaching.
Coral bleaching occurs when corals lose the symbiotic algae living within their tissues, causing them to turn white. This loss is often initiated by heat stress. Despite experiencing one of the hottest summers on record during the study, corals protected by the shades exhibited less color loss than their unshaded counterparts, with some even recovering color. This indicates a potential for improved resilience.
Installation and removal of the underwater shades proved to be straightforward, and researchers observed no adverse effects on the surrounding marine ecosystem. While the method is currently focused on protecting individual or small groups of corals, its cost-effectiveness is notable. The study estimated the cost of shading a single coral at around $100, a fraction of the over $1,000 required for restoration.
Although shading is not a cure for the underlying climate crisis, it offers a tangible, immediate intervention to support coral survival. Researchers suggest this technique could be a valuable tool for managing critical reef areas and preserving marine biodiversity, emphasizing the need to protect existing coral structures as much as possible.