Arctic facing threat of rapid ocean acidification, marine species affected

Severe ocean acidification is engulfing the Arctic Ocean, especially the Western Arctic Ocean. According to a new study, a host of marine species including shellfish and other important links in the food web are affected.

The study tracked the changes between the between the 1990s and 2010 when enhanced acidified waters conspicuously advanced 300 nautical miles northward from the Chukchi Sea.

In the ocean depth as well, the expansion of acidic waters stretched from sub-surface 325 feet to 800 feet plus.

Reasons of acidification

According to scientists, the acid incursion in oceans is the fallout of the excessive intake of atmospheric carbon dioxide. The resulting acidity of sea water is depleting the materials required by shellfish and also disrupting the food chain.

“Acidification has implications for marine life, particularly clams, mussels and tiny sea snails that may have difficulty building or maintaining their shells in increasingly acidified waters,” said Richard Feely, senior scientist at NOAA and the study’s co-author.

The study has been published in the journal Nature.

Co-author Wei-Jun Cai from the University of Delaware said the rate of acidification in the Arctic Ocean is almost double with that of Atlantic or Pacific oceans.

Expanding Pacific water

According to Di Qi, the paper’s lead author, acidification at the Arctic sea is exacerbated by the entry of Pacific Ocean waters into the Arctic during winters and abetted by ocean currents and depleting Arctic sea ice, which allows for expanding the acidic water levels.

During the study, the scientists used icebreaker Xuelong of China to sample the Arctic Ocean waters and in different expeditions. They monitored ocean acidification from 2008 to 2010.

Arctic’s melting sea ice is helping in the ingress of Pacific sea water into the Arctic Ocean, as retreating sea ice allows Pacific winter water to expand into the north.

According to Cai, melting sea ice functions as a thin water mass heightening the exchange of carbon dioxide with the atmosphere above.

Ocean system under threat

Meanwhile, the world’s oceans are in a big stress from global warming. According to a new research, if emissions continue to escalate, by 2050, most of the oceans will turn hot and acidic with changes hitting all marine organisms, mainly fish, which is the chief source of food for one-seventh of the global population.

Escalating ocean temperatures take in more carbon, and the resulting acidity hastens the destruction of many species.

If emissions are moderated, these organisms get the reprieve of adaptation and attain heat-resistant characteristics, with many schools of fish moving to cooler climes of the poles.

“We don’t understand very well how quickly marine organisms can adapt to change,” said Stephanie Henson, the study’s lead author and a principal scientist at the British National Oceanography Center in Southhampton, England.

Another study said there has been 13 percent growth in ocean warming than envisaged earlier, and the pace is growing. The assessment of this critical part of climate change was made possible by a new sensing device deployed since 2005. It is known as Argo float system that floats across oceans looking for temperature data from the surface as well as depths up to 2,000 meters.

When the device rises up to the ocean surface, it sends data to satellites to map the heat content. The device marks a great improvement over expendable bathythermographs, which were used earlier in assessing sea temperatures and deployed along important shipping routes.

Kalyan Kumar, Tech Times, 11 March 2017. Article.

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