White patches of bleached coral visible on BREEF’s world-renowned Ocean Atlas sculpture
Record-breaking temperatures this summer have impacted many ecosystems across the globe. In The Bahamas increased ocean temperatures have caused a crisis for coral reefs because corals are very vulnerable to warming water. This marine heatwave is likely to have serious repercussions for The Bahamas as a low-lying archipelago dependent on the coral reefs for numerous ecosystem services. Coral reefs are home to numerous species of marine plants and animals, they play an important role sustaining fisheries and tourism, and coral reefs provide the first line of defence breaking wave energy from storms and hurricanes.
Divers, tour operators, and fishers throughout the Bahamian archipelago have observed large areas of white corals, noticing that the usual vibrant yellow, green and orange hues of healthy coral reefs have been replaced by bright white bleached coral. Scientists have been documenting the progression of coral bleaching around The Bahamas and around the world.
Ocean Atlas, the world’s largest underwater sculpture and now an iconic underwater feature visited by Bahamians and visitors from around the world every year, is also feeling the impacts of the elevated water temperatures and consequent stress to corals. BREEF created the Coral Reef Sculpture Garden in the waters off Western New Providence in 2014 as a beacon of hope for the ocean – to draw attention to the threats faced by Bahamian coral reefs, and to inspire action for coral reef conservation. Since installing Ocean Atlas and the other sculptures, they have become encrusted in live corals and are now habitat for a great diversity of species of marine life. The sculpture garden is also BREEF’s underwater classroom and it is a well-loved site where thousands of Bahamian children have had a chance to learn about marine conservation, and oftentimes take part in their first ever snorkeling experience.
Bleached staghorn coral at BREEF Underwater Sculpture Garden in July 2023
“It’s shocking to see the severe coral bleaching taking place on reefs around the Bahamian archipelago. Many people have a personal connection to Ocean Atlas. Seeing this dramatic bleaching occurring at such an iconic site resonates with people, and will hopefully inspire much-needed action.” stated BREEF Executive Director Casuarina McKinney-Lambert.
Coral bleaching occurs when corals expel the symbiotic algae living in their tissues. These algae, known as zooxanthellae, provide corals with up to 90% of their nutrition through photosynthesis, and they are also responsible for giving the corals their colour. When coral is stressed by elevated water temperature, the algae is expelled from the coral tissue, leaving the coral colourless and starving. If the stress and subsequent bleaching persist for too long, the coral will die. If the stress is removed, for example by water temperatures dropping, there is a chance for it to regain its zooxanthellae and its colour, and recover.
There has already been evidence of some coral mortality at the BREEF Coral Reef Sculpture Garden, including some of the corals that BREEF is growing in the coral nursery and some of the corals that have been outplanted to adjacent reefs. Some of the corals have bleached and died. Others, particularly those where the coral fragments were sourced from shallower sites, are still healthy.
Coral reefs, which consist of even more biodiversity than tropical rainforests, are incredibly important ecosystems. However, they have been facing numerous threats such as pollution, invasive species, coastal development, and overfishing and climate change that is causing coral bleaching. The Bahamas is home to 35% of all coral reefs in the wider Caribbean region. Despite covering less than 1% of the ocean floor, coral reefs support over 25% of all marine life. They provide valuable benefits like contributing to the development of medicines, offering protection from storms, and generating income through tourism and fisheries.
“Global climate action is absolutely essential to reduce the amount of greenhouse gases that are released into the atmosphere and warming the world. Although The Bahamas produces only a small amount of the greenhouse gases that are changing the climate, we are feeling a disproportionate amount the negative impacts of climate change- from climate-fueled hurricanes to catastrophic bleaching of our reefs.” stated BREEF Executive Director Casuarina McKinney-Lambert. “The Bahamas has an opportunity to take a lead in the shift away from fossil fuels, and encourage other countries to do the same.”
A spiny lobster/crawfish on top of bleached coral. Coral reefs sustain commercially important fisheries and bleaching coral threatens entire ecosystems and valuable species.
Coral propagation unit at BREEF Sculpture Garden May 2023 (L) and July 2023 (R)
Fish swim around coral bleached from heat stress in August 2023
Stressed coral can develop bright neon colouring in response to extreme heat.