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Imperiled treasure: A coral reef called Varadero (commentary)

  • Accidentally discovered in 2013, the mysterious Varadero coral reef is entirely hidden beneath a thick layer of brown and murky sediment from Colombia’s Magdalena River.
  • A few feet below the surface, the sediment fades to reveal a vast underwater seascape of giant Caribbean corals called Orbicella. After the collapse of the staghorn and elkhorn corals in the 1980s, these boulder star corals have become the major ecosystem architects here, creating homes for snappers, parrotfish, groupers, and sea urchins.
  • Taken together, our group has visited some of the world’s best reefs, but we’ve never seen one like Varadero.
  • This post is a commentary. The views expressed are those of the author, not necessarily Mongabay.

“We are going to a place where the reef shouldn’t be there,” Dr. Valeria Pizarro enticed us.

The mysterious coral reef, Varadero, lies tucked away in the entrance to the Cartagena harbor. Accidentally discovered in 2013, it is entirely hidden beneath a thick layer of brown and murky sediment from Colombia’s Magdalena River. Our boat was carrying a small group of scientists and conservationists, and we would soon be among only a handful of people ever to observe the reef firsthand.

Pizarro smiled as she pulled on her wetsuit: “You’re going to be amazed. It’s the best reef I’ve ever seen in the Caribbean.”

As scientists attending the world’s largest conference on conservation biology that same week in Cartagena last July, we desperately wanted things to be hopeful about. Unprecedented coral death from superheated oceans combined with degradation from growing human coastal populations has made it a depressing time to be a conservation biologist.

We entered the water with our masks, fins, and air tanks. A few feet below the surface, the sediment fades to reveal a vast underwater seascape of giant Caribbean corals called Orbicella. After the collapse of the staghorn and elkhorn corals in the 1980s, these boulder star corals have become the major ecosystem architects here, creating homes for snappers, parrotfish, groupers, and sea urchins.

Varadero is home to the elkhorn coral (Acropora palmata), one of the most important reef-builders in the Caribbean, which has been decimated by disease since the late 1970s. Currently listed on the US Endangered Species List, scientists race to understand why this sensitive population occurs in the sedimented and hot waters of the Cartagena harbor. Photo Credit: V. Pizarro.

We swam between mountain ridges of corals, diving between healthy corals growing towards the dappled sunlight streaming from the surface, our arms outstretched in amazement and eyes filled with tears of joy.

Taken together, our group has visited some of the world’s best reefs, but we’ve never seen one like Varadero. As we dove from one mountain of coral to another, we could only look at each other in silent wide-eyed amazement. To all of us, this place was astounding.

In the context of the Caribbean, Varadero is an oddity. Since the 1970s, Caribbean corals have declined by 80 percent, killed off by a relentless combination of disease, overfishing, pollution, climate change, and — most recently — the arrival of invasive lionfish, an insatiable predator from the Indo-Pacific.

The harsh conditions that Varadero’s corals have survived for hundreds of years create even more mystery to their story. Pizarro’s temperature records show the reef can heat up to 35°C (or 100°F), several degrees higher than the survival limit for most corals.

Freshwater, sediment, and sewage pollution from the nearby Magdalena River are usually toxic to coral. Industrial shipping lanes and rapid coastal development, like that surrounding Varadero, usually crush corals into sand-smothered ruins. But somehow, these reefs are still here.

Varadero’s resilient reefs can provide important clues about how corals might survive climate change and pollution. Scientists want to understand the genetics, evolution, and ecology of these corals (and the myriad creatures associated with them) in order to discover how they have persisted and even thrived when so many other corals have perished.

Transplanting Varadero’s corals to other Caribbean reefs could provide genetic material enabling them to adapt to climate change. But it’s not just scientists who are interested in this remarkable place: For decades, these reefs have been well known to local fishermen who harvest the valuable snappers and groupers that hide among the healthy giant corals.

Scientists attending the International Congress for Conservation Biology are among the first divers to explore the remarkable coral reef Varadero, located in the Cartagena harbor. Threatened by a proposed shipping lane expansion in 2018, a group of Colombia coral reef scientists and concerned citizens are hoping the Colombian government will provide protection for the newly discovered Varadero reef. Photo Credit: E. Darling.

The Varadero coral reef also presents an opportunity to boost Colombia’s growing ecotourism industry. In Cartagena alone, tourism accounts for 38 percent of the economy, with more than two million visitors annually. Tourists pack into speedboats heading out to the less healthy reefs of the Rosario Islands, unaware of Varadero’s giant, ancient corals just 10 minutes away from Cartagena Harbour.

Colombian scientists and conservationists have petitioned their country’s government and national parks officials to expand the Rosario Islands National Natural Park to include the newly discovered Varadero reef. At the closing ceremony of our conservation meetings, Julia Miranda Londoño, the Director of the National Natural Parks Unit, said the agency would consider the evidence and consult with all stakeholders on a path forward.

For Varadero’s corals, the clock is ticking. One of the stakeholders to be consulted is Colombia’s powerful shipping industry, which plans to dredge the Varadero reef tract and expand access to the Cartagena Harbour early next year. Experts like Dr. Pizarro say that modernizing Cartagena Harbour by adding a second shipping lane would destroy more than 50 percent of this reef.

Local fishing communities affected by the dredging would be provided compensation by the government, but their way of life would be changed forever. That is why pressure is gathering among key stakeholders who seek a more balanced solution that preserves ecotourism and local fishing livelihoods. Faced with this reality, Pizarro says the situation is stark: “We have to fight to protect the reef. That’s it.”

To learn more about the Varadero Reef, Dr. Valeria Pizarro, and the Colombian coral reef scientists fighting to understand and protect one of the Caribbean’s last coral jewels, follow #SalvemosVaradero and #SaveVeradero on social media. You can also watch a short film on the ‘Heroic Reef’ and sign the petition to “Save Veradero” here.

A healthy Caribbean coral reef with large, old colonies of star corals (Orbicella spp.) and brain corals (Diploria spp.) create underwater architecture for diverse reef communities. Varadero’s coral reef has remarkably high amounts of living coral and low levels of coral disease, which typically plague other Caribbean reef environments. Photo Credit: V. Pizarro.

CITATIONS

Dr. Emily Darling is a Banting Postdoctoral Research Fellow at the University of Toronto and an Associate Conservation Scientist with the Wildlife Conservation Society. Dr. Kim Terrell is the Director of Research and Conservation at the Memphis Zoo. Dr. Elisa Bayraktarov is a Postdoctoral Research Fellow at the University of Queensland. They visited the Varadero coral reef in July 2017 during the International Congress for Conservation Biology — the world’s largest gathering of conservation biologists hosted by the Society for Conservation Biology.