One-third of Reef-Building Corals in risk

Clarice

One-Third of Reef-Building Corals Face Elevated Extinction Risk from Climate Change and Local Impacts

Science Express --
Published Online July 10, 2008

http://www.sciencemag.org/cgi/content/abstract/1159196

The conservation status of 845 zooxanthellate reef-building coral species have been assessed using IUCN Red List Criteria. Of the 704 species that could be assigned conservation status, 32.8% are in categories with elevated risk of extinction. Declines in abundance are associated with bleaching and diseases driven by elevated sea surface temperatures, with extinction risk further exacerbated by local-scale anthropogenic disturbances. The proportion of corals threatened with extinction has increased dramatically in recent decades and exceeds most terrestrial groups. The Caribbean has the largest proportion of corals in high extinction risk categories while the Coral Triangle (western Pacific) has the highest proportion of species in all categories of elevated extinction risk. Our results emphasize the widespread plight of coral reefs and the urgent need to enact conservation measures

searchlightsoul

Clara Clareando wrote:

One-Third of Reef-Building Corals Face Elevated Extinction Risk from Climate Change and Local Impacts

Science Express --
Published Online July 10, 2008

http://www.sciencemag.org/cgi/content/abstract/1159196

The conservation status of 845 zooxanthellate reef-building coral species have been assessed using IUCN Red List Criteria. Of the 704 species that could be assigned conservation status, 32.8% are in categories with elevated risk of extinction. Declines in abundance are associated with bleaching and diseases driven by elevated sea surface temperatures, with extinction risk further exacerbated by local-scale anthropogenic disturbances. The proportion of corals threatened with extinction has increased dramatically in recent decades and exceeds most terrestrial groups. The Caribbean has the largest proportion of corals in high extinction risk categories while the Coral Triangle (western Pacific) has the highest proportion of species in all categories of elevated extinction risk. Our results emphasize the widespread plight of coral reefs and the urgent need to enact conservation measures

The first corals appeared 542 Million years ago. They have survived literally millions of climatic oscillations, including the past 2.8 million years of glacial cycling. 125 thousand years ago, ocean temperatures were greater than present and the predicted temperatures for global warming, yet all modern corals survived this period unaffected. Now I'm not a global warming sceptic, but given this information which is preserved in the fossil record I can't see how any of the pojections you provide have any credibility because they are hoplessley short sited.

How then can this latest bout of climate change cause the extinction of corals when equal or greater events in the recent past did not?

SundaySilence

http://www.pbs.org/wgbh/evolution/extinction/massext/statement_03.html

ClimberInOz

I think the biggest risk is a reduction in the reef building corals, ot at the very least a change in the relative species abundance. I live on the Great Barrer Reef (not literally) and in close proximity to the Australian Institute of Marine Studies and James Cook University (where I did my undergrad in Marine Biology), two of the world's leading institutions when it comes to coral reef biology. As a result I have been lucky enough to speek to and/or attended lectures from some of the world's leading scientists on these issues.

I think that specific predictions are hard with climate change, although it is likely that there will be a measurable effect on coral reefs. Possibly more of a threat than increasing temperatures is oceanic acidification. As the ocean absorbs more anthropogenic carbon, it absorbs a greater quantity of hydrogen ions (H+). As a result ocean pH levels are decreasing, and the acidification is begining to reach a level where calcifying organisms are affected. This is because, as pH decreaes, so does the concentration of the Carbnate ion (CO3 2-) in seawater, which calcifying organisms need to construct calcium carbonate skeletons, shells etc.

The full effects of ocean acidification are still not known, but some very scary experiments have shown that even a small decrease in pH can cause a collapse in the number of calcifying species. The uncertainty is the killer- we could see a small change in calcifying species diversity or we could see a major collapse. There is also a strong consensus amongst scientists that ocean acidification is entirely anthropogenic.

Under worst case scenario, reefs will still exist, they just won't be dominated by the stereotypical reef building corals with CaCO3 skeletons. Another example of why, even though we cannot predict the exact consequences of climate change, a reduction in CO2 emmisions is critical from a precautionary position.

For more info:

http://oceanacidification.wordpress.com/

searchlightsoul

ClimberInOz wrote:

I think the biggest risk is a reduction in the reef building corals, ot at the very least a change in the relative species abundance. I live on the Great Barrer Reef (not literally) and in close proximity to the Australian Institute of Marine Studies and James Cook University (where I did my undergrad in Marine Biology), two of the world's leading institutions when it comes to coral reef biology. As a result I have been lucky enough to speek to and/or attended lectures from some of the world's leading scientists on these issues.

I think that specific predictions are hard with climate change, although it is likely that there will be a measurable effect on coral reefs. Possibly more of a threat than increasing temperatures is oceanic acidification. As the ocean absorbs more anthropogenic carbon, it absorbs a greater quantity of hydrogen ions (H+). As a result ocean pH levels are decreasing, and the acidification is begining to reach a level where calcifying organisms are affected. This is because, as pH decreaes, so does the concentration of the Carbnate ion (CO3 2-) in seawater, which calcifying organisms need to construct calcium carbonate skeletons, shells etc.

The full effects of ocean acidification are still not known, but some very scary experiments have shown that even a small decrease in pH can cause a collapse in the number of calcifying species. The uncertainty is the killer- we could see a small change in calcifying species diversity or we could see a major collapse. There is also a strong consensus amongst scientists that ocean acidification is entirely anthropogenic.

Under worst case scenario, reefs will still exist, they just won't be dominated by the stereotypical reef building corals with CaCO3 skeletons. Another example of why, even though we cannot predict the exact consequences of climate change, a reduction in CO2 emmisions is critical from a precautionary position.

For more info:

http://oceanacidification.wordpress.com/

I have heard alot about ocean acidification but in West Oz (I did zool at UWA) I haven't had the benefit of seeing much work on corals because the fauna is predominantly temperate (atleast in the SW). Again I really would question whether there should be as much doubt about what will happen in the future as there presently is.
I really see resources such as the fossil record being under utilised in predictions on global warming-especially by biologist-much to the detriment of the predictions they generate. In addition to this I think that people need to consider that modern biotas are more flexible and resistant to change than has been considered. There is very good evidence that some elements of modern systems, such as vertebrates can be resistant to quite significant climate change (papers by Barnonsky et al. and Prideaux et al. in Australia etc if you want to follow up). The past is the key to the future but I see a lot of arm waving when this doesn't need to be the case.

ClimberInOz

searchlightsoul wrote:

I have heard alot about ocean acidification but in West Oz (I did zool at UWA) I haven't had the benefit of seeing much work on corals because the fauna is predominantly temperate (atleast in the SW). Again I really would question whether there should be as much doubt about what will happen in the future as there presently is.
I really see resources such as the fossil record being under utilised in predictions on global warming-especially by biologist-much to the detriment of the predictions they generate. In addition to this I think that people need to consider that modern biotas are more flexible and resistant to change than has been considered. There is very good evidence that some elements of modern systems, such as vertebrates can be resistant to quite significant climate change (papers by Barnonsky et al. and Prideaux et al. in Australia etc if you want to follow up). The past is the key to the future but I see a lot of arm waving when this doesn't need to be the case.

I essentially agree. I guess the uncertainty comes mainly from the climate science. Until you can specify your climatic predictions, it is hard to predict the biological effects, especially when you consider the interconnectedness of ecological systems.

That being said, life will continue- relative species abundance may change but where there is a niche, something will fill it. With cean acidification the evidence is quite clear what will happen to calcifying corals when the pH drops to a certain level, it is just a question of if we will reach that level...

Did you continue working in your field when you graduated?