Navtej Kohli blog brings another news update on Global Warming. Sea is turning acidic. A report on Navtej Kohli blog:
Increasing carbon dioxide emissions could leave species such as coral and sea urchins struggling to survive by the end of the century because they are making the oceans more acidic, research led by British scientists suggests.
The study of how acidification affects marine ecosystems has revealed a striking impact on animal and plant life. The findings indicate that rising carbon emissions will alter the biodiversity of the seas profoundly, even before the effects of global warming are taken into account.
Greater concentrations of carbon dioxide in the atmosphere mean that more of the gas becomes dissolved in seawater, increasing its acidity. This will have good consequences for some species, but be catastrophic for others.
Dr Hall-Spencer's team investigated the likely effects of acidification by studying natural underwater vents off the coast of Italy, where carbon dioxide bubbles up through the sea floor. This makes the water around the vents significantly more acidic than it is in surrounding areas.
The study shows that certain species are very badly affected by rising acidity. Corals of the Caryophyllia, Cladocora and Balanophyllia varieties, for example, were common in on the sea bed in the region, but absent close to the vents. Sea urchins and sea snails were also affected badly by the high acidity.
Other species, including sea-grass and a type of algae known as Sargassum, thrived as the extra carbon dioxide has a fertilizing effect. This extra growth, however, can be damaging to other sea life - Sargassum is an alien invasive species, carried to the region in the ballast of shipping.
The research team is the first to use natural underwater carbon dioxide vents to assess how acidity caused by the gas influences sea life. “Our field studies provide a window on the future of the oceans in a high CO2 world,” Dr Hall-Spencer said.
This appraisal of life in a more acidic ocean was if anything conservative, Dr Hall-Spencer said, because it mimicked future ecosystems only partially.
The acidity around carbon dioxide vents can be reduced by rough conditions, which dilute the water - something that would not happen if the whole ocean was highly acidic.
The researchers also noted that while fish continued to swim through more acidic waters, they avoided breeding or spawning in them. “That isn't a problem at the moment, as they can go elsewhere,” Dr Hall-Spencer said. “But in a more acidic ocean there will be no escape.”
Global warming will also have an independent impact on sea life, by raising ocean temperatures.
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