Tag Archives: Caribbean

Hurricanes and global warming devastate Caribbean coral reefs

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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.

Impacts

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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Humans Have Caused Profound Changes In Caribbean Coral Reefs

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ScienceDaily, January 9th

Coral reefs in the Caribbean have suffered significant changes due to the proximal effects of a growing human population, reports a new study.

“It is well acknowledged that coral reefs are declining worldwide but the driving forces remain hotly debated,” said author Camilo Mora at Dalhousie University, Halifax, Canada. “In the Caribbean alone, these losses are endangering a large number of species, from corals to sharks, and jeopardizing over 4 billion dollars in services worth from fisheries, tourism and coastal protection,” he added.”The continuing degradation of coral reefs may be soon beyond repair, if threats are not identified and rapidly controlled,” Mora said. “This new study moves from the traditional localized study of threats to a region-wide scale, while simultaneously analyzing contrasting socioeconomic and environmental variables,” he added.

The study monitored coral reefs, including corals, fishes and macroalgae, in 322 sites across 13 countries throughout the Caribbean. The study was complemented with a comprehensive set of socioeconomic databases on human population density, coastal development, agricultural land use and environmental and ecological databases, which included temperature, hurricanes, productivity, coral diseases and richness of corals. The data were analyzed with robust statistical approaches to reveal the causes of coral reef degradation in that region.

The study showed clearly that the number of people living in close proximity to coral reefs is the main driver of the mortality of corals, loss of fish biomass and increases in macroalgae abundance. A comparative analysis of different human impacts revealed that coastal development, which increases the amount of sewage and fishing pressure (by facilitating the storage and export of fishing products) was mainly responsible for the mortality of corals and loss of fish biomass.

Additionally, the area of cultivated land (a likely surrogate for agrochemical discharges to coral reefs) was the main driver of increases in macroalgae. Coral mortality was further accelerated by warmer temperatures.

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Parrotfish key to saving Caribbean reefs

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Recent research published in the journal Nature by Peter Mumby and co-authors at the University of Exter (United Kingdom) and University of California shows that in the Caribbean, the parrotfish (see image on the left) plays a key role in preventing coral reefs from being dominated by macro-algae (Link to abstract). Following the mass mortality of sea-urchins across the Caribbean reefs in the early 1980’s due to an unknown disease, the majority of the grazing of macro-algae is conducted by the humble parrot fish (Link to Reuters article). Dr Mumby gave a fascinating seminar earlier this year at the University of Queensland entitled “Marine Protected Areas & Coral Reef Ecosystem Resilience” detailing this and other research from his team in this area:

http://152.98.194.2/seminars/petermumby/PeterMumby.mp4