Crabbe on Coral
Professor James Crabbe FIMarEST is a leading expert on coral at Wolfson College, Oxford University. He was part of a team that recently revealed that 44% of coral on the planet is critically endangered. But why should we care, and what is to be done? James explains.
Coral reefs are some of the most beautiful, diverse habitats on the planet. I’ve been studying corals for over 24 years, and they never cease to amaze me. But more than that, coral reefs are an essential part of our planet’s life support system and a major source of biodiversity.
For humans, coral reefs provide various ecosystem services such as protecting coastlines from storms and erosion, providing jobs for local communities, and offering recreation opportunities (such as diving and snorkeling). They are also a vital source of food and medicines.
What’s the problem?
It’s well known that climate change is causing catastrophic coral bleaching on reefs. When water is too warm, corals expel the algae (zooxanthellae) living in their tissues, causing the coral to turn completely white. Corals can survive a bleaching event, but they are under more stress, and are more likely to die, than unbleached corals.
But bleaching is not the only threat facing corals – the list of challenges can seem endless – meaning protecting reefs comes with a myriad of challenges. These include overfishing, destructive fishing practices, ocean acidification, sea-level rise, algal blooms, agricultural runoff, coastal development, marine pollution, coral diseases, invasive species, and damage by extreme weather.
I worked with an international team that surveyed 15,066 reefs between 2014 and 2017. The results revealed that 80% of reefs experienced significant coral bleaching and 35% experienced significant coral mortality, surpassing damage from any prior global bleaching event. Moreover, the study shows that 44% of 892 warm-water reef-building coral species are now at risk of extinction.
Our observations also highlighted that global warming’s widespread damage to coral reefs is accelerating, as well as underscoring the threat that anthropogenic climate change poses for the irreversible transformation of these essential ecosystems.
To assess extinction risk, we used the criteria of the International Union for Conservation of Nature (IUCN) Red List of Threatened Species. Reef-building corals were last assessed for the IUCN Red List in 2008 when one third of species were found to be threatened.
Finding solutions
The main solution to save corals from extinction is to cut greenhouse gas emissions, accompanied by initiatives to address the other threats.
But sadly, the current proposal to reduce CO2 by 450ppm will not bring the world’s temperature down enough to preserve coral reefs. For this, CO2 needs to be reduced to 350ppm, which is a huge mountain to climb. However, without drastically reducing emissions, corals will continue to decline, affecting other marine ecosystems, as well as communities and economies.
To conserve our coral reefs, we must work to get the right people around the table to discuss these critical issues. This is where NGOs at all levels have a huge part to play, by ensuring that those most affected, such as indigenous communities, have a voice. Above all, young people must be involved – it is their world and all the rest of us can do is pledge our support.
It’s easy to feel powerless as tales of woe concerning the world’s vital ecosystems continue to emerge. But, as a scientist, I can join the conversation to support the need for urgent action by the global community.
Within our Institution, I know many of us will also be in the same boat. I urge you all to continue to collaborate, innovate, and raise awareness to make a difference in your areas of expertise. Why not use the IMarEST communications team to help tell your story too?
Together we are stronger, and as an industry I do truly hope we get our message across. It is only by cooperating that we will achieve our sustainable development goals to maintain our oceans by 2030.