What colour should corals be?

Contrary to famous images of corals in a limitless palette of colours, snorkelers are starting to tell stories of mysterious fields of white corals. This is, in fact, an ecosystem showing signs of major global stress, the most explicit of symptoms being the loss of colours. The stress of changes in conditions due to increased ocean temperature and pollution causes corals to expel a symbiotic algae living in their tissues, which is seeing them turn completely white. According to the International Union for the Conservation of Nature, staghorn coral populations, the most widespread coral, have declined more than 80% over the past 30 years.


Caroline Sorbier

Guillaume Beaudoin is a sea hitchhiker and a Montréal-based cinematographer, photographer and director. Since he first took part in the Ocean CleanUp expedition in 2015, founded by a 21-year-old who aims to clean 50% of the Great Pacific Garbage Patch in the next 5 years, he has hardly stopped sailing around and he is now making his way across the South Pacific Ocean for his documentary series Across the salty roads. From boat to boat, island to island, he meets and reports on local communities who are affected by and fighting against environmental issues. Amongst the many people he’s met during his travels, Cody Clement and Denis Schneider are two coral gardeners who are doing extensive work in coral protection.

Photo: Guillaume Beaudoin Photo: Guillaume Beaudoin


Cody Clement is a Biology Ph.D student from UC Berkeley and specialised in coral reef gardening. Cody compares corals to canaries in the coal mines, used as an early-warning signal to detect toxic gases. Canaries would drop dead if the environment was toxic, which is exactly the response of corals in polluted and warmer water, warning us of its toxicity levels. In the Fiji Islands, this toxic environment is the result of a cocktail of stressors such as overfishing, contaminated waste water and erosion.

Photo: Guillaume Beaudoin Photo: Guillaume Beaudoin

“The good news is that we have these coral planting efforts going on all around the world trying to rehabilitate corals. We are seeing more marine protected areas being set up throughout the Pacific,” says Cody.

Photo: Guillaume Beaudoin Photo: Guillaume Beaudoin

Fins, mask and snorkel on, Guillaume followed Cody under the water and discovered a whole experimental nursery of hundreds of coral slips screwed into immersed platforms. What Cody found out is that when mixing species of coral together, they seem to grown stronger: the fundamental and yet evident virtue of the concept of biodiversity is clear in this project.

Photo: Guillaume Beaudoin Photo: Guillaume Beaudoin


Guillaume later set sail in the direction of Bora Bora, a small island in the northwest of Tahiti in French Polynesia where Denis Schneider was awaiting him, a French marine biologist who uses the Bio-rock methods, a solar-based technology providing energy to a low-voltage electric field which in return strengthen corals against the impacts of global warming.

“We allow the corals to grow more because of the iron, calcium and magnesium flourishing on these structures that constitute the coral diet,” explains Denis.

Denis is one of many coral gardeners who have made it their mission to grow coral nurseries. No coral means no fish, and no fish means no snorkelling, so tourism also largely benefits from these technologies implemented in eco-tourism resorts all around the island.

Photo: Guillaume Beaudoin Photo: Guillaume Beaudoin

Other techniques are flourishing such as coral breeding or “assisted gene flow”, which involves moving species of coral resistant to higher temperature into places where corals are dying. However, a study on the cost and feasibility of marine coastal restoration found coral reef restoration to be highly expensive, with costs as high as US$1.8 million per hectare. As much as these techniques are encouraged, researchers pledge for governments to cut carbon dioxide emissions down and tackle ocean pollution so that corals can naturally grow instead of having to be saved.

Interview by Caroline Sorbier.

Guillaume is currently onboard of the Ocean Clean Up Boat, this world first ocean clean up system has just been launched after 5 years of research.
The boat and its massive net are now heading from San Francisco to Great Pacific Garbage Patch, 1,200 nautical miles offshore.

You can follow the story on Across the Salty Road page.

This article was published in The Beam #6 — Subscribe now for more.

This article is also available to view on our Medium page.