Coral can recover from climate change damage

[OKIsItJustMe]

http://www.exeter.ac.uk/news/featurednews/title,52379,en.php

Coral can recover from climate change damage

A study by the University of Exeter provides the first evidence that coral reefs can recover from the devastating effects of climate change.

Published Monday 11 January in the journal PLOS One, the research shows for the first time that coral reefs located in marine reserves can recover from the impacts of global warming.

Scientists and environmentalists have warned that coral reefs may not be able to recover from the damage caused by climate change and that these unique environments could soon be lost forever. Now, this research adds weight to the argument that reducing levels of fishing is a viable way of protecting the world’s most delicate aquatic ecosystems.

Increases in ocean surface water temperatures subject coral reefs to stresses that lead quickly to mass bleaching. The problem is intensified by ocean acidification, which is also caused by increased CO2. This decreases the ability of corals to produce calcium carbonate (chalk), which is the material that reefs are made of.

Approximately 2% of the world's coral reefs are located within marine reserves, areas of the sea that are protected against potentially-damaging human activity, like dredging and fishing.

The researchers conducted surveys of ten sites inside and outside marine reserves of the Bahamas over 2.5 years. These reefs have been severely damaged by bleaching and then by hurricane Frances in the summer of 2004. At the beginning of the study, the reefs had an average of 7% coral cover. By the end of the project, coral cover in marine protected areas had increased by an average of 19%, while reefs in non-reserve sites showed no recovery.

Professor Peter Mumby of the University of Exeter said: "Coral reefs are the largest living structures on Earth and are home to the highest biodiversity on the planet. As a result of climate change, the environment that has enabled coral reefs to thrive for hundreds of thousands of years is changing too quickly for reefs to adapt.

“In order to protect reefs in the long-term we need radical action to reduce CO2 emissions. However, our research shows that local action to reduce the effects of fishing can contribute meaningfully to the fate of reefs. The reserve allowed the number of parrotfishes to increase and because parrotfish eat seaweeds, the corals could grow freely without being swamped by weeds. As a result, reefs inside the park were showing recovery whereas those with more seaweed were not. This sort of evidence may help persuade governments to reduce the fishing of key herbivores like parrotfishes and help reefs cope with the inevitable threats posed by climate change”.

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[kristopher]

1. What about the reduction of light due to sea level rise?

It is my understanding that is the most severe threat. Coral are extremely slow growing and light intensity dependent. As sea level rises due to AGW the amount of light will diminish far too rapidly for the coral to adapt, leading to certain death for most species.

[OKIsItJustMe]

2. Healthy reefs can build upward

See “http://en.wikipedia.org/wiki/Atoll">Atoll” (for example.)

[Warpy]

3. Since corals reproduce not only by budding

on site but by releasing either eggs and sperm into the water or fertilized zygotes into the water, new corals are likely to grow in newly shallow waters and old corals will likely bud aggressively in order to follow the rising sea level.

Remember, the continental shelves were once largely above water, supporting corals. Corals have developed alternate reproduction cycles in order to survive fluctuating sea levels over the ages. They're not going to go away because of that.

What is more worrying is the acidification of the sea, but that has also happened before, usually during periods of vulcanization.

Corals are some of the toughest, most resilient critters out there. While it is sad seeing some established reefs disappear, over many hundreds of years new ones will arise.

[TxRider]

4. The first evidence?

Not hardly, coral has survived far worse over millions of years with both higher and lower sea levels and higher an lower temps. No reef is permanent in the long run however