Study Shows How Biodiversity of Coral Reefs around the World Changes with Depth
Published:12 Apr.2023    Source:California Academy of Sciences

In a paper published today in Current Biology, researchers from the California Academy of Sciences Hope for Reefsinitiative, along with Brazilian collaborators from the University of São Paulo, Federal University of Espírito Santo, and the Instituto Nacional da Mata Atlântica, show that mesophotic coral reefs function much differently than their shallower counterparts and are unlikely to offer a refuge for shallow water fishes trying to escape climate-change driven warming on the ocean's surface.

The research is based on hundreds of dives totaling more than a thousand hours underwater at sites across the Pacific and the Atlantic, with researchers collecting an unprecedented amount of data on what species occur on coral reefs at a range of depths, from the shallows to the low-light mesophotic zone between 100 and 500 feet (30 to 150 meters) beneath the surface.
Coral reefs are among the most vibrant and vital ecosystems on our planet, supporting a quarter of all marine life and the livelihoods of more than a billion people worldwide. Therefore, better understanding coral reef biodiversity -- an indicator of broader ecosystem health and resilience to stressors like climate change -- is critical for creating a thriving, regenerative future for life on Earth.
For the researchers, this discovery points to the presence of a strong ecological filter between shallow and deep coral reefs that could prevent shallow water species from seeking colder, deeper reefs in the face of climate change. The findings make a strong case for expanding marine protections for coral reefs to greater depths, they conclude.