Ocean Acidification on the rise

by Ciaran McLarnon

Climate change is becoming big news again; with the problem being blamed for the wildfires and drought in the western states of the United States. On 6th August there were reports that climate change may have also contributed to the 2010 heat wave in Russia. The view that climate change makes a significant contribution towards the increased occurrence of such events was also proposed by Professor Christopher Field of the Departments of Biology and Environmental Earth System Science at Stanford University when he addressed the United States Senate Committee on Environment and Public Works on behalf of the IPCC 1. The testimony that he gave on 1st August showed that climate change is a serious problem that requires immediate mitigation. In addition to these reports climate change is also creating challenges for the management of the oceans that have impacts on fisheries and all marine wildlife.

Reported by the BBC on 10th August, increased UVB radiation reaching the surface of the planet as a result of climate change could be having a damaging effect on marine life2. The oceans are currently the most important carbon sink, absorbing as much as 50% 3of the carbon produced by man. This is a vital resource if we are to reduce the effects of climate change, but even the oceans are not immune from the effects of the vast amounts of carbon that we produce. The amount of CO2 absorbed by the oceans leads to increased acidification of the seas, and as recently as 6th August the British Antarctic Survey warned of the negative effects of this phenomenon 4.

The problem is that when the oceans absorb carbon this reacts with the water to form carbonic acid, lowering the pH of the water and creating many problems the organisms that live within the water. The principle difficulty is that this acidification slows the rate of calcium carbonate uptake 5. This means shellfish can’t make their shells strong enough, coral are unable to build the foundations on which to make their reefs and many other forms of marine life suffer as a result.

Together with the rising sea temperatures and increase in solar radiation that also occur as a result of climate change, ocean acidification can also have other effects on organisms that contribute to stresses on Marine ecosystems. In addition to the effects on the uptake of calcium carbonate, ocean acidification will also affect the metabolisms of most marine organisms and the role of oceans in the global carbon cycle.

Studies have shown that the metabolism of oysters is affected by temperature and pH 6, and these effects could also be found in molluscs and other coastal invertebrates such as barnacles and many of the amphipod species.

Recent analysis 7 has shown that the ocean acidification is occurring at a faster rate as the rate of fossil fuel consumption increases. These findings suggest we cannot use the ocean as a carbon sink and have to consider the impacts our energy needs could have on the oceans in some areas.

Coastal areas are among those areas most susceptible to acidification 8. These areas give people the first and most frequent access to the sea, and are areas of high economic and ecological value. It is therefore vital that these areas are maintained ecologically within the mould that was cast several thousand years ago.

Acidification does not just affect shellfish and smaller marine organisms, ocean dwelling mammals will also be affected. Animals like sea otters, bottlenose dolphins and grey whales are at or near the top of their respective food-chains, and therefore essential in regulating those ecosystems. Naturally any decline in prey numbers will lead to a decline in the numbers of these already too rare species.

The impact on fisheries of acidification has also been reported, and the impacts on an industry that is already in decline could be very severe. Intensive fishing methods have decreased many catches, and fisheries are now realising that ocean acidification gives them a new problem to contend with 9. Many fish, such as Salmon and Eels, migrate long distances to mate and lay eggs. The higher temperatures mean higher energy requirements for the fish, and many do not have the resources that are required to complete this difficult journey. This decline will lead to a decline in the yield of a fishery, and is just one of many effects that could impact the numbers of fish in the ocean.

There are plans to mitigate climate change using the oceans, but these plans depend on the integrity of the ocean. There already have been tests of an idea to enrich the sea with iron filings 10 that would encourage phytoplankton growth, and therefore the size of this carbon sink. This plan could work, but there is a limit to how much we can acidify the oceans.

A review on New Environmentalist of the Alternative Rio +20 conference highlights the sea is an under-appreciated and yet vital resource 11. There are many parts of the land that need our help, and the oceans could help us to achieve this. But it would seem that the oceans are close to their breaking point.

Unfortunately, the most effective way to reduce ocean acidification is to reduce carbon emissions. So in order to use the oceans to absorb the extra carbon that we produce we must reduce the amount of carbon that we produce. Off-setting carbon is not an option to deal with this problem; this may be the first signal that real action is needed against climate change.

 

  1. Christopher Field’s report to the United States Congress:

http://epw.senate.gov/public/index.cfm?FuseAction=Files.View&FileStore_id=fe138741-9ce8-4444-9912-c2004ae9e955

http://news.stanford.edu/news/2012/august/field-capitol-hill-080112.html

http://www.guardian.co.uk/environment/2012/aug/01/climate-change-extreme-weather-congress

  1. BBC report on UVB increasing mortality in Marine Life:

http://www.bbc.co.uk/nature/19170802

  1. Ocean’s importance as carbon sink:

http://news.nationalgeographic.com/news/2004/07/0715_040715_oceancarbon.html

http://oceanworld.tamu.edu/resources/oceanography-book/carboncycle.htm

  1. British Antarctic Survey warns of Ocean Acidification:

http://www.publicserviceeurope.com/article/2309/the-ramifications-of-ocean-acidification-a-warning

  1. The effects of ocean acidification on calcium carbonate:

http://www.akmarine.org/our-work/address-climate-change/ocean-acidification

http://www.epa.gov/climatechange/science/indicators/oceans/acidity.html

  1. Effect of Acidification on Oyster metabolism:

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2953406/

  1. Ocean Acidification is increasing at a faster rate:

http://www.mathaba.net/news/?x=630314

http://www.newscientist.com/article/dn21534-oceans-acidifying-at-unprecedented-speed.html

  1. Acidification is can be more evident in Coastal Areas:

http://www.piscoweb.org/research/coastal-oceans/ocean-acidification/oa-consortium-approach

  1. The fishing industry and ocean acidification:

http://www.scor-int.org/High_CO2_II/Presentations/Fossa.pdf

http://www.scientificamerican.com/article.cfm?id=ocean-acidification-threatens-global-fisheries

  1. Plans to enrich oceans with iron filings:

http://www.guardian.co.uk/environment/2012/jul/18/iron-sea-carbon

http://www.businessgreen.com/bg/news/2028150/researchers-swim-unison-ocean-iron-fertilisation

  1. Alternative Rio +20 report on Oceans:

http://www.newenvironmentalist.co.uk/?page_id=670

To read more on Ocean Acidification try these links:

http://www.annualreviews.org/eprint/QwPqRGcRzQM5ffhPjAdT/full/10.1146/annurev.marine.010908.163834

http://oceanrep.geomar.de/7878/1/965_Raven_2005_OceanAcidificationDueToIncreasing_Monogr_pubid13120.pdf

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