From Space to Seabed: Researchers use satellites to analyze global reef biodiversity

February 13, 2024

Written by Liz Thompson

This new technique can aid in coral reef protection and restoration efforts.

Researchers used Earth-orbiting satellites to map coral reef biodiversity at a global scale to show that areas of high habitat diversity also have high species diversity. This new satellite mapping technique, developed by researchers at the Khaled bin Sultan Living Oceans Foundation (KSLOF) and the University of Miami Rosenstiel School of Marine, Atmospheric, and Earth Science, can help guide future efforts to identify and protect highly biodiverse reefs.

“As remote sensing technology becomes more advanced, and we continue to use satellite imagery to map ecological habitats, we must understand the biological and ecological meaning of these products,” said Sam Purkis, Chief Scientist at KSLOF and Professor and Chair of the Department of Marine Geosciences at the Rosenstiel School and the senior author of the study. “We showed that these maps can be used as a proxy for biodiversity, and therefore they can be used to guide ecosystem protection and restoration.”

The conventional approach of conducting SCUBA-diver surveys to measure the biodiversity of coral reefs is both time-consuming and expensive. So, the research team set out to find a new method utilizing remote sensing to produce habitat maps at a global scale.

To conduct the study, they extracted the diver-measured diversity of reef fish and coral species from our Global Reef Expedition dataset, which includes data from more than 1,000 reefs across the Pacific, Atlantic, and Indian Oceans. KSLOF maps cover approximately one-quarter of Earth’s shallow-water tropical coral reefs.

World Reef Map Coral Reef Map — *The study used maps detailed habitat maps created on the Global Reef Expedition, as well as data we collected underwater using SCUBA surveys.*

The scientists then used these maps to audit the complexity of the patterning of seabed habitats, which, they showed, to be correlated with the species diversity of the organisms that inhabited them. This relationship held across the Atlantic, Pacific, and Indian Oceans, and can therefore be used as a proxy for reef biodiversity.

Satellite imagery of the Neulka Islands (New Caledonia), along with the three types of satellite-derived habitat maps considered in our study. (a) True-color image from Maxar WorldView-2. The Khaled bin Sultan Living Oceans Foundation Global Reef Expedition benthic habitat maps for the Neulka Islands at 4×4 m resolution (b) contain 14 of the total 37 Indo-Pacific classes. The Allen Coral Atlas (“ACA”) offers two map types at 5×5 m resolution – benthic (c) and geomorphic (d). The full six ACA benthic classes are shown, while nine out of 12 geomorphic classes are present at this site.

“We show how the biodiversity of these ecosystems can instead be retrieved from satellite maps of the seabed,” said Anna Bakker, a Ph.D. student in the Rosenstiel School’s Department of Marine Geosciences and lead author of the study.“ This discovery offers the opportunity of assessing reef biodiversity, at a global scale, from orbit.”

The results from this study can aid in marine spatial planning and the designation of marine protected areas to protect reefs with high biodiversity.

Generating dynamic habitat windows in the Fulaga Atoll (Fiji). The 10 ha insets on the left portray the satellite imagery and the three satellite map types within that area: the Khaled bin Sultan Living Oceans Foundation Global Reef Expedition (“KSLOF- GRE”) habitat maps, and the Allen Coral Atlas (“ACA”) benthic and geomorphic maps.

“The breadth and importance of the data collected on the 10-year Global Reef Expedition allowed for this truly global-scale study on the biodiversity of fish and corals in three different ocean basins,” said Alexandra Dempsey, CEO of KLSOF and a contributing author to the study. “This study exemplifies the Khaled bin Sultan Living Oceans Foundation’s commitment to novel approaches towards coral reef conservation and its role in supplying critical data on our ocean’s reefs.”

Using satellites to map coral reef biodiversity

The study, “Remotely sensed habitat diversity predicts species diversity on coral reefs,” was published in the journal Remote Sensing of Environment. The study’s authors include: Anna Bakker, a Ph.D. student in the Rosenstiel School, Sam Purkis, Chief Scientist at KSLOF and Professor and Chair of the Department of Marine Geosciences at the Rosenstiel School, Arthur Gleason from the University of Miami’s Department of Physics, Alexandra Dempsey from the Khaled bin Sultan Living Oceans Foundation, and Helen Fox and Rebecca Green from the Coral Reef Alliance.

View the scientific paper

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