Bleaching occurs when corals expel the symbiotic photosynthetic algae that they rely on for food, often in response to environmental stress such as abnormal elevated temperatures. Reefs can recover from bleaching events, but the process is uncertain and can take years — frequently corals die from bleaching on a massive scale.
Such events are becoming worryingly common as climate change causes rapid warming and increasing ocean acidification. From a biodiversity perspective this is a disaster, because although they only account for a very small area of the ocean, coral reefs host an enormous amount of biomass and a dazzling array of species.
It is therefore not just a question of losing some interesting and colourful corals. The corals are the base of many critical ocean ecosystems, and when they die the whole system they support comes tumbling down. This can lead to rapid declines in fish stocks and major losses for tourism activities related to the reefs; around the world, hundreds of millions of people depend upon these ecosystems.
The losses are happening very fast. By the middle of this century coral reefs are expected to shrink to just ten percent of their pre-industrial extent. This is an ecological catastrophe, but there is a glimmer of hope: recent breakthroughs in both science and diplomacy suggest we may be able to create a refuge for these critical ocean ecosystems.
One cause for optimism stems from scientific discoveries in the Red Sea. Pioneering research by Professor Maoz Fine from the Hebrew University in Israel found that corals in the Gulf of Aqaba, which is bordered by Egypt, Israel, Jordan and Saudi Arabia, are remarkably resistant to heat stress. The region is heating twice as fast as global averages, but has not yet experienced any major bleaching events. We now know, from exhaustive experimentation, that the corals of the Gulf of Aqaba can tolerate as much as five degrees of warming above their summer maximum, far in excess of even the most pessimistic climate predictions.
These projections were made possible by projects such as the Red Sea Simulator, a large system of experimental aquaria in which researchers can control any environmental parameter they choose, including temperature, salinity, pH and pollution levels. A suite of sensors and measurements also permits monitoring of the corals' health, photosynthetic performance, protein content, oxidative stress and even how the genes they express change in response to rising temperatures.
The Transnational Red Sea Centre (TRSC), a scientific organisation based at EPFL, builds on Professor Fine's groundbreaking work. Our goal is to coordinate research efforts and help preserve one of the world's major reef ecosystems. The first step will be to establish the biodiversity baseline of the Red Sea's coral reefs: from 2022 to 2025 we will be carrying out expeditions across 4,500 km of coastline of the Red Sea system.
Beyond that, it will be crucial to give governments and scientists in the region the capacity to continually monitor their reefs. To that end, we are creating a monitoring system that combines low-cost GoPro cameras with machine learning-based video analysis. This will assess coral cover, what genera are present, whether they are healthy, and the presence of plastic and pollution.
Sophisticated sensors will help us monitor the photosynthetic performance of their algae, which is a key indicator of stress. Furthermore, we are developing new seascape genomics techniques that will help us determine the regions of the reefs that are best adapted to warmer climates and responsible for seeding the rest of the reef with heat-tolerant coral.
This is not science for science's sake: all of our efforts are directed towards gathering the information that will be required to preserve these reefs into the future. That is why we have committed to Open Science principles and make all of our data freely accessible. More importantly, we are actively translating this data into common formats that anyone can access and use for further analysis.
However, none of this will be of any use unless we can motivate the governments and the communities in the region to act on our findings. That is why our mission is as much one of diplomacy as it is of science. Our efforts will only succeed with regional-scale collaboration; if just one country in the area doesn't follow agreed protocols, the reefs of the entire region could be put at risk.
Nonetheless, we are optimistic. Promoting collaboration in this geopolitically complicated region is undoubtedly one of our biggest challenges. But in many ways, science can be an avenue for dialogue that would be impossible elsewhere. For once, everyone's interests are aligned and there is a common understanding of what we will lose unless the countries in the region work together. As such, our project is not only an experiment in how to save coral reefs, but also a demonstration of how science can help find ways out of political impasse.
Whether our project provides hope for coral reefs elsewhere in the world remains to be seen. Experiments into assisted evolution, where scientists attempt to “encourage” corals to develop greater tolerance for a warming world, will no doubt have much to learn from the corals of the Red Sea. Personally, I am not convinced that this approach will provide solutions fast enough to deal with the rapid changes our oceans are experiencing.
Perhaps more important will be the impact of the model that we develop at the TRSC. The Coral Triangle, which spans more than 6 million km2 of tropical waters around Indonesia, Malaysia, Papua New Guinea, the Philippines, the Solomon Islands and Timor-Leste, faces different but comparable challenges in terms of both science and diplomacy. In this region the corals have enormous genetic diversity, and while they do not exhibit the exceptional heat-tolerance of corals in the Red Sea, any help this region can get to prolong their life-time and perhaps save their reefs could be enormously important.