Bermuda has so far been spared the effects of an international coral bleaching event brought on by higher than usual sea temperatures.

In October, the United States-based National Oceanic and Atmospheric Administration (NOAA) declared the onset of a global coral reef bleaching event, damaging reefs in every ocean basis.

However apart from some fire coral bleached at the end of the summer, the Bermuda Institute for Ocean Sciences (BIOS) has said Bermuda’s reefs had not been harmed.

Coral bleaching is usually brought on by environmental conditions such as warming water stressing corals, forcing them to expel the algae that live inside. The algae usually provide the coral with both food and colour, causing them to turn pale white.

While corals can recover from such events, the longer stressful conditions continue the lower the likelihood of recovery.

The current bleaching event — the third recorded since 1998 — is believed to have been brought on by several events, including El Niño warming waters in the Pacific, a “stagnant” warm water formation affecting the Hawaiian Islands and record high temperatures in the Caribbean.

Coral reefs typically prefer water temperatures between 75°F and 82°F, with a lower limit of about 64°F — the average winter water temperature for the Island.

Regarding Bermuda’s status, a BIOS spokeswoman said: “Summer heat rarely has the chance to cause lasting bleaching damage in Bermuda. Compared to the Caribbean, Bermuda’s more temperate climate limits the window in which water temperatures can exceed the average annual high to induce bleaching.”

The spokeswoman said that Bermuda could provide a safe haven for some coral species in the event Caribbean reefs were unable to recover from a future bleaching event, noting that researchers at BIOS were using genetic techniques to determine if reefs in Bermuda and the Caribbean were capable of interbreeding despite the geographic distance.

“[BIOS coral reef scientist Gretchen Goodbody-Gringley] has found evidence that some populations can interbreed and exchange offspring, and that currents carrying coral larvae can connect reefs across the region,” the spokeswoman said.

“Thus, healthy reefs in Bermuda could help maintain coral diversity in the Atlantic, which is yet another reason to take good care of our reefs.

“Bermudians have already made great strides caring for corals. A major international study analysing how Caribbean reefs have changed over the past 40 years highlights Bermuda’s ban of fish pots, as well as the protection of parrotfish, as key mechanisms safeguarding reef health.

“Parrotfish grazing on the reef defend corals from seaweed that could otherwise smother corals in distress. As these fish have been removed from much of the Caribbean, algae tends to take over bleached coral and once thriving reefs are reduced to rubble and seaweed. Furthermore, the ability of corals to recover from any single bleaching events depends on their overall stress level. Limiting local pollution and maintaining a balanced ecosystem helps corals survive stress from climactic events.”