Bleached Coral
Roatan’s Coral Suffer from Stress

November 11th, 2011
by Thomas Tomczyk

[private]

An octopus on bleached coral around Dixon Cove

An octopus on bleached coral around Dixon Cove

A very hot summer with few storms followed by lots of rain have had an affect on not only the island of Roatan but also on its surrounding reefs. Several divers around Roatan have noticed a coral bleaching phenomena. “The lack of storms and rise in temperature are likely the causes,” says Nick Bach of Roatan Marine Park.

Bleaching of coral is the loss of intracellular endosymbionts that give coral its coloration. This bleaching makes the coral more fragile, less able to continue sustaining itself and to maintain its parasitic control. Coral bleaching is the response of corals to stress caused by increased water temperature, changes in water chemistry, sedimentation, bacterial infections or other causes which are less likely to occur at this time on Roatan.

Bleaching doesn’t always mean that the coral has died. The organism has a chance to recover, but that window is pretty tight. “If algae are growing on the coral it probably means that the coral is dead,” says Bach.

“There has been bleaching, but it’s been very localized,” says Chris Benson, owner of Tranquil Seas Dive Center who has been diving consistently around Roatan the last few years. Benson has noticed some extended bleaching off Saint Helene Island, Los Fuertes, Dixon Cove and Brick Bay especially. Benson believes it’s a combination of runoff that increases heat absorption as well as changes to the reef’s geometry at channels that act like retention walls to runoff sediment from the island’s shores. This sedimentation and runoff from numerous construction projects has likely added to the stress on the reef.

Some island reef areas haven’t been affected by bleaching, but the added sedimentation could lead to dying of coral in the next couple of years. “Over the last couple of years on the back reef and the channel between Pristine Bay and Blue Ocean Reef the visibility has gone from maximum quality of ten to low of three,” said Benson.

“I’ve seen sponges die off. This happened at Barbarat Bank, West Bay, West Bay Point, Blue Harbour. This year I have seen small coral colonies die within just a few months,” said Benson. “On the positive side, other places thrive.” [/private]

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