Can anything be done to preserve coral reefs? Rachel Jones, project manager for ZSL’s marine and freshwater conservation programme, outlines the threats they face, and how we are working to defend these vulnerable ecosystems.
Coral reefs are one of our most iconic habitats, yet human activities threaten their future. Like rainforests, coral reefs harbour a huge amount of biodiversity. Despite representing only 1% of marine habitat, they provide a home for nearly a quarter of all marine species, including the living coral polyps themselves, whose mineral skeletons gradually form the reef structures. And around 500 million people worldwide rely on coral reefs for food, protection from storms and high tides, and tourism income.
Coral under threat
Coral reefs have evolved over billions of years, but they’re incredibly sensitive to human impacts. These range from local issues including overfishing, illegal wildlife trade, pollution and coastal development to global pressures such as climate change. With more carbon dioxide in the atmosphere, sea temperatures rise. When this occurs, corals become stressed and expel the algae that gives them their distinctive colours. This makes the coral turn white – an event known as bleaching. If it continues unchecked, the coral will die.
While we can’t stop all coral bleaching, we can help to relieve local pressures, such as overfishing and pollution, to make coral reefs more resilient to threats. Well-protected reefs can recover from bleaching over time; while some coral may die off, healthy survivors continue to produce larvae, which gradually recolonise the reef. But if water temperatures continue to rise, bleaching events will happen more frequently. If these events outpace the recovery time of the coral, reefs will die.
What we are doing
This year, I coordinated a team from ZSL, the Chagos Conservation Trust and other organisations on an expedition to the Chagos Archipelago, funded by the Bertarelli Foundation. The archipelago is in the British Indian Ocean Territory and currently one of the world’s largest Marine Protected Areas.
The team surveyed and videoed the coral reef, to assess the damage caused by bleaching. They found that while much of the coral in shallower waters had died off in recent bleaching events, corals at greater depths had survived, while new colonies were starting to grow back and replace dead ones – boding well for long-term recovery. Next, we will be scanning some of the coral skeletons held at the Natural History Museum, so we can assess how these species have been changing over time.
We also work with the UK Customs team at Heathrow Airport to confiscate and house illegally traded corals. The ZSL Aquarium is home to the biggest collection of live corals in the UK, with around 120 species.
Meanwhile, in December, scientists from across Europe will be gathering for a major coral symposium organised by Oxford University and ZSL. It will be a fantastic opportunity for researchers to come together to discuss what can be done to secure the future of the world’s invaluable and incredible reefs.
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