Hurricanes and storms can wipe out coral recruitment process

ANI, May 4th 2008

A new study has revealed that hurricanes and storms limit the ability of corals to “recruit” new corals into their community.

The study, supported by Earthwatch Institute in the US, was carried out in Belize, a Central American country, by Earthwatch scientist Dr. James Crabbe in 2006 and 2007 with Edwin Martinez, Earthwatch Field Director in Belize, as well as with the help of young local scientists.

Coral Reefs, which can grow to be thousands of years old, form and grow when free-swimming coral larvae in the ocean attach to rocks or other hard surfaces and begin to develop.

But, the new study has determined that intense storms can wipe out this “recruitment” process.

“Increasing evidence now shows that storms are becoming more intense due to climate change,” said Crabbe. “Storms threaten the survival of the entire reef itself,” he added.

According to Crabbe, who is doing a lecture tour related to this work throughout 2008, “If the storms don’t destroy corals outright, they render them more susceptible to disease, and that is certainly apparent on the Belize reefs.”

A team from Earthwatch measured the size of more than 520 non-branching corals in two major coral reef areas in southern Belize: the Sapodilla Cayes Marine Reserve, a world heritage site in the second largest barrier reef in the world, and the Port Honduras Marine Reserve.

In addition to providing habitat for an array of marine life, non-branching massive corals robust and shaped like mounds, and sometimes called ‘brain corals’ buffer coastal zones from erosive wave energy.

Crabbe’s team determined the surface area covered by the corals and entered the growth rates of the corals into a computer model to determine when in history the coral colonies first settled.

They compared numbers of corals that started life in each year with hurricane and storm data, and as suggested by data from fringing reefs of Jamaica, the coral recruitment was much lower during storm years.

According to Crabbe, the study holds implications for marine park managers.

“They may need to assist coral recruitment and settlement by establishing coral nurseries and then placing the baby corals (larvae) in the reef at discrete locations, or by setting up artificial reef blocks to help the corals survive,” he said.

Status of Caribbean coral reefs after bleaching and hurricanes in 2005

The “Status of Caribbean coral reefs after bleaching and hurricanes in 2005” is an excellent account of the impact of mass bleaching and hurricanes that hit the Caribbean in 2005. As you will remember, sea temperatures rose sharply in this region in May 2005, intensifying until October by which time hotspots covered most countries in the eastern Caribbean.  This occurred during the hottest year on record for the northern hemisphere at that time, and resulted in a massive die off of corals.

As pointed out by the editors, Clive Wilkinson and David Souter, the 2005 event provided an important opportunity to study the impact of extreme thermal stress on coral reefs.  Via network of hundreds of scientists that were linked by the Internet and backed up by sophisticated monitoring tools, key information and insights would gained into the relationship between thermal stress, bleaching and coral mortality.

Overall, coral reefs in eastern Caribbean were severely damaged by anyone’s estimate in 2005.  What is perhaps most alarming is that the mortality ranged up to 50% in places like the US Virgin Islands and the Greater and Lesser Antilles.  This came on top off a rapid deterioration of reefs that has been occurring over the past few decades.  The coral cover of most (if not all) coral reefs in this region have been sliding rapidly downwards.

This is a useful collection of papers which I recommend that you read (link).  My good friend Billy Causey, who has a long and proud history of fighting for the protection of Florida’s coral reefs, provides a very useful account of the history of bleaching in his region. There is also some useful information as well on the hurricane story, including on what drives their intensity and how they impacted reefs in 2005.

Hurricanes and global warming devastate Caribbean coral reefs

The Guardian, January 24 2008

Storm damage from waves and death of vital algae likely to become more common, report warns

Warmer seas and a record hurricane season in 2005 have devastated more than half of the coral reefs in the Caribbean, according to scientists. In a report published yesterday, the World Conservation Union (IUCN) warned that this severe damage to reefs would probably become a regular event given current predictions of rising global temperatures due to climate change.

According to the report, 2005 was the hottest year on average since records began and had the most hurricanes ever recorded in a season. Large hotspots in the Atlantic and the Gulf of Mexico powered strong tropical hurricanes such as Katrina, which developed into the most devastating storm ever to hit the US.

In addition to the well-documented human cost, the storms damaged coral by increasing the physical strength of waves and covering the coast in muddy run-off water from the land. The higher sea temperature also caused bleaching, in which the coral lose the symbiotic algae they need to survive. The reefs then lose their colour and become more susceptible to death from starvation or disease.


Carl Gustaf Lundin, head of the IUCN’s global marine programme, said: “Sadly for coral reefs, it’s highly likely extreme warming will happen again. When it does, the impacts will be even more severe. If we don’t do something about climate change, the reefs won’t be with us for much longer.” Some of the worst-hit regions of the Caribbean, which contains more than 10% of the world’s coral reefs, included the area from Florida through to the French West Indies and the Cayman Islands. In August 2005 severe bleaching affected between 50% and 95% of coral colonies and killed more than half, mostly in the Lesser Antilles.

The IUCN report highlights pressures on coral reefs in addition to those of overfishing and pollution identified in recent years. A recent study found that reefs near large human populations suffered the most damage.

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