WITNESS: Investigating ocean acidification (Part 2)

Irish marine scientists from the National University of Ireland, Galway and funded by Ireland's Marine Institute, aboard the research vessel The Celtic Explorer
In the second part of his WITNESS blog investigating the dangers of increasing ocean acidification, CONOR PURCELL learns that increase rates are already 10 times higher than at any time in the last 55 million years which, naturally, does not bode well for all ocean ecosystems
Ocean acidity has already increased by 26% since the start of the industrial revolution. If we continue to burn fossil fuels at our current rate, marine scientists predict an increase of 170% by the end of this century

The continental shelf rolls out for some hundreds of kilometres west of Ireland's Galway coast, before the Rockall Trough. Here the seafloor falls sharply off the shelf down to abyssal depths of over 3000 metres. Continentals shelves like this are host to a range of marine ecosystems, including cold water corals; a much less discussed variety compared to their warm water cousins.

 According to Dr Tríona McGrath, a marine scientist at the National University of Ireland Galway, and funded by Ireland's Marine Institute : "The Rockall Trough hosts an array of cold water coral ecosystems, interacting with a range of water masses along the Irish continental margin, Rockall Bank and Porcupine Bank. These deep water reef structures support a rich biodiversity and are particularly vulnerable in a more acidic ocean."

The cold water corals of the North Atlantic are vital for fisheries and act as sources of biodiversity. To look at how increasing carbon dioxide will affect these ecosystems and the fisheries they support, oceanographers are now measuring the carbonate system in the surrounding water, with a particular focus on ocean acidification. That was the aim of a team from Ireland's Marine Institute as they boarded the Celtic Explorer research vessel in February of this year.

Dr Evin McGovern, also from the Marine Institute, points out that "not many people are aware of the Irish coral reef biodiversity hotspots which we are only beginning to fully map and understand.

"These deep sea corals, primarily Lophelia pertusa, occur on the shelf and seamount slopes and canyons, usually between 200m and 1000m depth, and differ from tropical coral reefs in that, living in the dark they do not have photosynthetic algal symbionts."

 And coral is only part of the looming problem relating to increasing ocean acidification. In the future, it is projected that more acidic oceans will adversely impact on entire food chains related to the ocean. Ocean acidification projections for the end of the century do not look good.

 "There has already been an increase in ocean acidity of 26% since the start of the industrial revolution, which is directly due to humans emitting carbon dioxide to the atmosphere," explains Dr McGrath. "If we continue to burn fossil fuels at our current rate, it is projected there will be an increase in ocean acidity of 170% by the end of the century.

"This rate of acidification is 10 times faster than any acidification event in the oceans for over 55 million years, and quite likely for over 250 million years."

It is the rate at which this change is taking place where the real concern lies. Will our marine life and ecosystems be able to adapt to such a fast rate of change in the surrounding seawater?

All this depends on how we collaborate on an international level through divestment from fossil fuels. But such seemingly obvious steps are often met with challenges which can be the cause of frustration for many scientists.

According to Dr McGovern, "the role of the science community is to provide the factual evidence, including projections for future changes based on our best understanding, and also to advise on the uncertainties associated with these."

However, in this new era there is an alarming (and well documented) amount of rejection of the relationship between human introduced atmospheric carbon dioxide and global warming amongst some world leaders.

McGovern says: "our research in Ireland contributes to a global effort in this field. Maybe those politicians who deny climate change should join a mid-winter research survey in the north Atlantic to see how hard won this high quality data is before they dismiss it on a whim."

This Author

Conor Purcell is a Science & Nature Writer with a PhD in oceanography. He can be found on twitter @ConorPPurcell and some of his other articles at cppurcell.tumblr.com



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