Panic! panic!  "Rising acidity levels threaten ocean's food chain" 


All sorts of fun here.

1). Reducing the frequency of one creature will not generally "threaten" any food chain.  Food chains are complex and the only likely effect is that another species will become more abundant.  And in fact no food-chain analysis is attempted.

2). The academic journal article is appended and we find that the chief data-gatherer was from the notoriously crooked UEA.  Their frank admissions of manipulating the data (as revealed in the ClimateGate emails) must make us ask for independent replication of any findings emanating from there.

3). The study compares EXISTING ocean regions and finds that some tiny snails have thicker calcium carbonate shells where there is a LOT of calcium carbonate in the water.  Why that is a surprise and what it tells us about climate I have no idea.

4).  If the theory is that global warming will put more CO2 into the water then I have good news for them -- though why basic physics should be news I also have no idea.  Henry's law tells us that warmer water will OUTGAS CO2, so there will in fact be less of that naughty CO2 in the ocean under global warming.

5).  I could go on ....

The shells of some marine snails in the seas around Antarctica are dissolving as the water becomes more acidic, threatening the food chain, a study published in the journal Nature Geoscience said on Sunday.

The tiny snails, known as ``sea butterflies'', live in the seas around Antarctica and are left more vulnerable to predators and disease as a result of having thinner shells, scientists say.

The study presents rare evidence of living creatures suffering the results of ocean acidification caused by rising carbon dioxide levels from fossil fuel burning, the British Antarctic Survey said in a statement.

``The finding supports predictions that the impact of ocean acidification on marine ecosystems and food webs may be significant.''

The tiny snail, named for two wing-like appendices, does not necessarily die as a result of losing its shell, but it becomes an easier target for fish and bird predators, as well as infection.

This trend may have a follow-through effect on other parts of the food chain, of which they form a core element.

The world's oceans absorb more than a quarter of man-made carbon dioxide emissions, which lower the sea water pH.

Since the beginning of the industrial era, our oceans have become 30 per cent more acidic, reaching an acidity peak not seen in at least 55 million years, scientists say.

Scientists discovered the effects of acidification on the sea butterflies from samples taken around the Scotia Sea region of the Southern Ocean in February 2008.

Oceans soak up about a quarter of the carbon dioxide released into the atmosphere each year and as CO2 levels in the atmosphere increase from burning fossil fuels, so do ocean levels, making seas more acidic.

Ocean acidification is one of the effects of climate change and threatens coral reefs, marine ecosystems and wildlife.

The study involved researchers from the British Antarctic Survey, Royal Netherlands Institute for Sea Research, the US National Oceanic and Atmospheric Administration (NOAA) and other institutions found.

"The corrosive properties of the water caused shells of live animals to be severely dissolved and this demonstrates how vulnerable pteropods are," said lead author Nina Bednarek, from the NOAA.

"Ocean acidification, resulting from the addition of human-induced carbon dioxide, contributed to this dissolution."

Until now, there has been little evidence of the impact of ocean acidification on such live organisms in their natural environment and the study supports predictions that acidification could have a significant effect on marine ecosystems.

The researchers examined surface water, where wind causes cold water to be pushed up from deeper water, because it is usually more corrosive to a particular type of calcium carbonate which the sea snails use to build and maintain their shells.

"We know that the seawater becomes more corrosive ... below a certain depth which occurs at around 1,000m. However, at one of our sampling sites, we discovered that this point was reached at 200m depth. Marine snails - pteropods - live in this top layer of the ocean," Bednarek said.

Climate models forecast more intense winds in the Southern Ocean this century if CO2 continues to increase, which will make the mixing of deep water with more acidic surface waters more frequent, the study said.

This will make calcium carbonate reach the upper surface layers of the Southern Ocean by 2050 in winter and by 2100 all year round, said the study's co-author Dorothee Bakker, research officer at the University of East Anglia.

If CO2 levels continue to rise in the future, surface waters could be almost 150 per cent more acidic by the end of this century, which has not been experienced for more than 20 million years.

SOURCE

Extensive dissolution of live pteropods in the Southern Ocean

By N. Bednarsek et al.

Abstract

The carbonate chemistry of the surface ocean is rapidly changing with ocean acidification, a result of human activities. In the upper layers of the Southern Ocean, aragonite-a metastable form of calcium carbonate with rapid dissolution kinetics-may become undersaturated by 2050 (ref. 2). Aragonite undersaturation is likely to affect aragonite-shelled organisms, which can dominate surface water communities in polar regions. Here we present analyses of specimens of the pteropod Limacina helicina antarctica that were extracted live from the Southern Ocean early in 2008. We sampled from the top 200m of the water column, where aragonite saturation levels were around 1, as upwelled deep water is mixed with surface water containing anthropogenic CO2. Comparing the shell structure with samples from aragonite-supersaturated regions elsewhere under a scanning electron microscope, we found severe levels of shell dissolution in the undersaturated region alone. According to laboratory incubations of intact samples with a range of aragonite saturation levels, eight days of incubation in aragonite saturation levels of 0.94-1.12 produces equivalent levels of dissolution. As deep-water upwelling and CO2 absorption by surface waters is likely to increase as a result of human activities2, 4, we conclude that upper ocean regions where aragonite-shelled organisms are affected by dissolution are likely to expand.

SOURCE

Posted by John J. Ray (M.A.; Ph.D.).