One of the projects WWF-Belize has been supporting in Placencia is the work of Lisa Carne, a marine biologist whose been working on speeding up the recovery of damaged coral reefs in Belize. We met up with Lisa at a dive shop on the seafront for a fascinating trip to see her coral nurseries – a project she calls ‘Fragments of Hope’.
As we packed up the boat with our snorkelling gear, Lisa explained how the health of coral reefs around the world is rapidly declining – because of human pressures like pollution, overfishing and sedimentation, as well as natural threats such as hurricanes.
These pressures and hazards are problem enough for the coral reefs, but they’re made much worse by climate change, which it’s projected will increase sea surface temperatures and the frequency of hurricanes.
The Mesoamerican reef ecoregion, stretching about 1,000 kilometres down the Atlantic / Caribbean coast from Mexico to Honduras, has already been considerably affected by mass ‘bleaching’ events in the past.
Bleaching is caused when coral is stressed by higher than average sea temperatures. The stressed coral will often end up inadvertently losing its hold on the symbiotic (and often colourful) algae that lives on it, resulting in a loss of colour – hence the term bleaching.
Sometimes the algae, and therefore the colour, will return – but the stress can lead to increased incidences of disease, failed reproduction and partial or even complete death of whole coral colonies.
In response to this, Lisa has developed coral nurseries, where fragments of thermally tolerant corals are grown to be planted on damaged reefs.
How do you know if a coral is ‘thermally tolerant’, I wondered? Well, it turns out it’s pretty obvious after a bleaching event – the tolerant individuals either didn’t bleach or recovered quickly.
As I entered the water for our first snorkel, I was wondering how easy it would be to identify coral bleaching, but I soon developed my own methodology. If the coral colour was almost as pale as my never-see-the-sun British skin, then I reckoned it must have been bleached!
Lisa showed us one of the thermally tolerant coral which fisherman had seen survive a coral bleaching event in 2009. This individual is now being used by Lisa as a ‘mother’ coral. She trims its fronds and propagates those in a nursery to produce resilient clones. The trimming doesn’t hurt the mother coral – in fact, it’s used to reproducing in this way, as fragments are often broken off during high wave action storms.
Lisa mainly uses the Caribbean Acropora corals, commonly known as Elkhorn and Staghorn, as they are some of the fastest growing, reef-building corals. They were also the first corals to be listed as ‘critically endangered’ on the IUCN Red List, due to a decline of more than 98% within the Caribbean over the last 30 years. Eight other slower-growing coral species are also propagated to ensure the correct mix can be recreated at degraded sites.
To date, Lisa has planted over 4,000 fragments at Laughing Bird Caye National Park, with help from local tour guides, the Belize Fisheries Department and local NGOs.
Lisa took us to a site which uses three different techniques to propagate the coral fragments: ropes, metal dome frames and cement discs on tables.
The Staghorn corals are tied to ropes and metal frames, while the Elkhorn coral prefers the stability of being cemented to ‘cookies’ on a table. As we looked at the table garden I noticed one little fish that had already taken particular fancy to the growing coral and was aggressively patrolling his patch in front of my snorkel mask.
Although it sounds like a relatively straightforward process, expertise is needed to know where best to site your nursery (sheltered sites created by neighbouring stag boulder corals are preferred), and also to ensure you are growing fragments of more than one individual. Straight clones would be bad – you want genetic diversity to encourage sexual reproduction.
And that’s where WWF-Belize has stepped in. As well as supporting Lisa’s salary for four years, Nadia provided the critical funds needed to allow fragments of coral to be sent to the Universities of Florida and Pennsylvania to test the genetic make-up of the coral and its symbiotic algae.
Now Lisa knows that she is growing a mix of heat-resistant male and female corals. And once planted-out, they should go on to spawn and produce new resilient individuals. It’s this climate change-adaptation analysis – identifying the corals most resistant to bleaching and disease – which sets this coral nursery project apart from others around the world.
Lisa told us she allows the nursery fragments to grow to a healthy size and then, along with volunteers, ‘plants’ them within degraded patches of the coral reef.
The ropes are nailed to existing reef structures and the metal frame fragments and cookies are cemented, if fragments can’t be placed in natural nooks and crannies.
When out planting the fragments Lisa tries to follow the natural forms of the corals – and I certainly couldn’t tell which areas had been planted and which were natural!
Laughing Bird Caye was chosen as the pilot location for the restoration work as it’s a World Heritage Site and National Park, so the pressures of overfishing are somewhat reduced. This allows the corals time to fully recuperate, as an over-fished area often has more coral-eating snails – because their natural predator, the spiny lobster, has been removed.
It also made it an unbelievably beautiful place to visit. Excellent for snorkelling too, with a great array of fish and invertebrates, topped off with the picture-perfect white sand of the Caye, inhabited by pelicans and an osprey (though on this occasion the latter was disappointingly reclusive).
We pointed out to Lisa that one criticism of coral restoration projects like these is that they work on a local scale but it wouldn’t be feasible to replant the entire reef. Lisa said she understands this view, and so the next step is for her to check that the out-planted sites are spawning.
If Lisa can prove her new sites are helping to reproduce and create new corals, then strategically placed restoration sites should significantly improve the health of the reef.
But nature doesn’t make it easy for her. She has to wait for the right night, sometime between July and September, when it’s a full moon and the corals all take part in a mass spawning event. A site to see, I’m told.
So once Lisa gets the confirmation that her coral restoration sites are spawning, she intends to get serious about replicating the process throughout Belize’s other marine National Parks. Something I hope will take place in the very near future.
Keep up to date with Lisa’s ‘Fragments of Hope’ Facebook page