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Coral reef of Varadero is a coral reef located in the Bay of Cartagena, Colombia. Its paradoxical existence, harboring high coral cover and diversity despite the poor water quality and sediments discharged during the last 500 years by the Canal del Dique into the Bay, has drawn special interest by the scientific community and local and international media. The persistence of the Varadero reef is currently threatened by a project to modernize Cartagena’s port, not only by the direct damage produced by the dredging of a new shipping lane through the reef, but also by the deterioration of water conditions associated with the operation and maintenance of the channel.
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Location
The coral reef of Varadero (10⁰18’10”N, 75⁰34’55”W) is a 1 km2 shallow water reef located SW of the Bay of Cartagena. It lies in the northern limit of the Natural Park Corales del Rosario y San Bernardo, Colombian Caribbean. It’s located approximately 6 kilometers to the east of the main mouth of the Canal del Dique, a canal of 118 kilometers connecting the Cartagena Bay to the Magdalena River. The annual water discharge and sediment load of the Canal del Dique has a mean of almost 400 m3 per second and 6 million tons per year, respectively, conferring the whole bay an estuarine character. The influx of human activity accompanied by the presence of this canal increased the bay water’s turbidity, nutrient levels, and sedimentation during last decades, may have caused the acute damage of the coral reefs and seagrass beds in the area. Reefs outside the bay, including those of the Rosario Islands, have also been negatively impacted mainly after the increased sedimentation rates from the Magdalena River and the construction of new canals from El Dique to the south of the Bay of Cartagena
Ecological Significance
Roughly 1 km2 in size, Varadero boasts approximately 80% coral cover. Reaching more than 3 meters in diameter, many of the massive colonies found in the reef of Varadero belong to the genus of the hermatypic coral Orbicella. This reef is estimated to contain a richness of over 30 scleractinian coral species. To adjust to the low light levels resulting from the water’s polluted state, some corals have utilized a flattened, plate-like growth strategy to optimize light exposure for its photosynthetic algal endosymbionts of the genus Symbiodinium. With the rapid decline of coral reefs in the Caribbean, scientists are examining reefs, such as in Varadero, to understand reef resilience.