Coral reefs affected in Galapagos

Coral reefs affected in Galapagos

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The Galapagos Islands currently have only one coral reef. The population of the animals have suffered several reductions since the 1970s, mainly due to events such as "El Niño" event.

The ocean around the Galapagos Islands has been warming since the 1970s, according to a new analysis of the natural temperature archives stores in coral reefs. Coral tissue loss amounted to 95% across the Archipielago. Also at that time, all coral reefs in the central and southern islands disappeared following severe degradation and eventual collapse due primarily to intense bioerosion and low recruitment.

Diane Thompson (left), Roberto Pepolas (center) and Alexander Tudhope (right) use a hydraulic drill to take a core from a Porites lobata coral head near Wolf Island in the Galapagos.
Credit: Jenifer Suarez, courtesy of the Cole lab.

Six sites in the southern islands have demostrated low to moderate coral community (scattered colonies, but no carbonate framework) recovery. The iconic pocilloporid reef at Devil's Crown (Floreana Island) experienced recovery to 2007, then severe mortality during "La Niña" cooling event, and is again undergoing rapid recovery. Notable recovery has occurred at the central (Marchena) and northern islands (Darwin and Wolf).

"People didn't know that the Galapagos or eastern Pacific was warming. People theorized or suggested it was cooling" said Gloria Jimenez, a UA doctoral candidate in geosciences.

Scientists thought strong upwelling of colder deep waters spared the region from the warming seen in other parts of the Pacific, she said.

"My colleagues and I show that the ocean around the northern Galapagos Islands is warming and has been since the 1970s" Jimenez said. The research is part of her doctoral work.

The very strong "El Niño" of 1982-83 temporarily warmed the surrounding ocean so much that most of the corals in the southern part of the Galapagos died, said co-author Julia Cole, who collected the coral cores while she was a faculty member at the UA.

On a global scale, co-author Peter Glynn says, the increase in water temperature, related to climate change, is the biggest threat to corals. These animals are one of the most vulnerable to changes in oceans conditions, since they live in areas with temperatures that approach the maximum they can tolerate. An increase of one or two degrees can cause whitening and death.

After more than 30 years of stuides in the islands, Glyn belives that the main threats to corals in this area continue to be related to overfishing, pollution, tourism and the increase of human population on the islands.

Info by: http://www.elcomercio.com/tendencias/fenomenodeelnino-corales-arrecife-galapagos-planetaeideas.html
https://www.sciencedaily.com/releases/2018/02/180221131836.htm
https://www.sciencedirect.com/science/article/pii/S0025326X18304004