The Bahamas Coral Gene Bank is a collaborative initiative spearheaded by the Perry Institute for Marine Science, involving The Government of The Bahamas, Atlantis Paradise Island, the Atlantis Blue Project Foundation, and the University of The Bahamas, with longstanding support from the Disney Conservation Fund.The Bahamas Coral Gene Bank at Atlantis Paradise Island holds living corals collected from Bahamian reefs, kept safe from disease and heat while the reefs they came from recover. Led by scientists from the Perry Institute for Marine Science and supported by the Atlantis Blue Project Foundation, it is a working laboratory, and keeping a coral alive inside it is daily, technical work. Gimel Morley explains a problem that comes up more often than most people would expect.
By Gimel Morley, Coral Aquarist Manager, Perry Institute for Marine Science
What Bleaching Actually Is
Coral bleaching is often associated with unusually warm ocean temperatures, but heat is only one of many stressors that can cause corals to lose the colorful algae, known as zooxanthellae, that live within their tissues.
Those algae are the reason a healthy coral has any color at all, and they are its main food source. They live inside the coral's tissue and hand over the sugars they make by photosynthesis. When a coral is stressed it expels them, and what is left is thin, transparent tissue over a white skeleton. The coral has not so much lost its color as lost the thing that was providing it.
In the wild, corals may bleach because of marine heatwaves, rapid temperature fluctuations, pollution, disease, or sudden changes in salinity following heavy rainfall.
Bleaching is a survival response rather than an immediate death sentence, allowing corals to conserve energy during stressful conditions. As NOAA puts it, a bleached coral is not a dead coral, but it is a coral under stress and at greater risk of dying. If the stress persists for too long, corals can starve, become more susceptible to disease, and eventually die.
That distinction has mattered enormously these past few years. NOAA confirmed a fourth global bleaching event in April 2024. By the time it was declared over in mid-2025, bleaching-level heat stress had reached 84% of the world's reef area, with mass bleaching recorded in at least 83 countries and territories. The Caribbean was among the hardest hit.
Why It Still Happens Indoors
Even in carefully managed land-based coral holding facilities, bleaching can still occur despite the ability to shield corals from the intense ocean heatwaves experienced during the summer. While the Bahamas Coral Gene Bank provides stable temperatures, corals remain highly sensitive to changes in their environment.
The holding systems at the Bahamas Coral Gene Bank. Stable temperature is only one of the variables that has to stay right. Photo: Atlantis Blue Project Foundation.
Small fluctuations in water chemistry, nutrient levels, alkalinity, lighting intensity, water flow, or dissolved oxygen can all trigger stress responses. Routine husbandry activities such as moving colonies, cleaning systems, transporting corals, or introducing new specimens may also contribute to temporary bleaching.
Light is a frequent culprit. A colony shifted from a shaded corner of a tank to a brighter one, or a fixture whose output has drifted as its diodes age, can deliver more light than the coral's algae are able to process. Water chemistry is the other common one. Nitrate and phosphate creeping upward while alkalinity drifts down will destabilise the partnership between coral and algae well before anything looks wrong to the eye.
The Same Coral, Six Months Apart
The two photographs below show a single colony in the collection, catalogue number JEWFISH_DSTO_001, on the same tile and under the same lights.
January 2026: pigmented tissue, polyps extended. Photo: Bahamas Coral Gene Bank.
July 2026: the same colony, bleached. Photo: Bahamas Coral Gene Bank.
The skeleton underneath has not changed and the tissue is still there. What is missing is the algae, and with them the coral's ability to feed itself.
Catching It Early
For coral aquarists, preventing bleaching extends far beyond simply controlling temperature. Although bleaching can still occur in captivity, the ability to quickly identify and correct the underlying causes greatly improves the chances of coral recovery.
Most of that work is unglamorous. Water gets tested on a schedule. Changes get logged, so that when a colony pales you can look back and see what moved and when. New corals are brought up to full light over weeks rather than hours. Colonies are fed, so they are not depending on photosynthesis alone, and a coral that has been eating well tends to ride out a wobble in conditions better than one that has not.
Recovery is possible because bleaching is rarely absolute. Corals can rebuild their algal populations from the symbionts still remaining in their tissue, or take them up again from the surrounding water. Removing the stressor is what gives them the opening to do it.
Why This Work Matters
Every colony in the gene bank is a piece of Bahamian reef held in reserve. Some are species that stony coral tissue loss disease has torn through in the wild, kept here in clean water the disease cannot reach. The point is not to keep corals in tanks indefinitely. It is to hold enough living genetic diversity, in good enough condition, to put back on the reef when conditions allow.
That is why a colony turning pale in a tank gets taken as seriously as a bleaching report from the reef. The difference is that indoors, the cause can usually be found and fixed.
About the Bahamas Coral Gene Bank
The Bahamas Coral Gene Bank at Atlantis Paradise Island is the first facility of its kind in the region. It is led by scientists from the Perry Institute for Marine Science, with funding and support from the Atlantis Blue Project Foundation, and it exists to protect Bahamian coral genetic diversity from disease and heat until it can be returned to the reef.
Help us protect coral reefs in The Bahamas.
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