Scientists develop 'underwater umbrellas' to protect coral reefs from bleaching

Addressing Coral Bleaching

The Earth is currently experiencing its fourth global coral bleaching event. Projections indicate that by 2050, most coral reefs will suffer annual mass bleaching due to ocean warming. A new invention, dubbed "underwater umbrellas," aims to protect some of these vulnerable coral populations.

The 'Underwater Umbrella' Solution

Published in the journal Frontiers in Marine Science, a study details these underwater umbrellas, which are designed to shade corals and reduce their exposure to sunlight. Excessive solar radiation intensifies coral bleaching, particularly when combined with heat stress. Testing in the Caribbean demonstrated that shaded corals experienced less bleaching, with some even regaining color.

Karen Neely, a research scientist at Nova Southeastern University and lead author, noted that the current structures are effective for smaller areas like individual corals, nurseries, or small outplant sites. Future engineering could potentially scale this solution for larger reef areas.

Understanding Coral Bleaching

Coral bleaching occurs when corals expel symbiotic algae (zooxanthellae) due to environmental stressors such as changes in temperature, light, or nutrient availability. These algae provide corals with their color and primary food source. Without them, corals turn white and begin to starve.

While global action to reduce greenhouse gas emissions is necessary to reverse ocean warming, localized strategies like shading can mitigate immediate damage to coral reefs. The decimation of these ecosystems impacts marine species, coastal protections, and the multi-billion dollar fishing industry.

Inspiration and Design

Shading has emerged as a promising mitigation strategy, with experiments conducted in the Pacific Ocean using various designs. Neely's team drew inspiration from a colleague in Dominica who created similar umbrella-like structures during the 2023 marine heatwave. The shades are constructed from pipes with nylon cloths attached.