Ocean acidification will affect coastal communities, particularly those that rely exclusively on small scale fisheries, a four-year study supported by the IAEA found. With populations around the globe dependent upon the sea for their livelihood and primary source of food, ocean acidification — a consequence of rising carbon dioxide (CO2) emissions — could have serious societal and economic consequences for them.
“One of the resounding messages to arise is the importance of examining the impacts of ocean acidification at the local or community level,” said Peter Swarzenski, Head of the IAEA Radioecology Laboratory Section. “Global or national-level data can provide a broad overview but may not fully describe the impacts to individual communities that rely on small-scale artisanal fishing or aquaculture operations, particularly in developing nations.”
While the full effect of ocean acidification on marine organisms is still unknown, research indicates it could have a negative impact on growth rates and reproductive processes across a broad variety of species. This could have repercussions on the entire ecosystem. For example, preliminary research has shown that ocean acidification can have a negative impact on mussels in their early life stages, hampering their development.
Under the IAEA project, scientists from Canada, Chile, Ghana, Kenya, Kuwait, Namibia, Peru, the Philippines and the United States compared the findings of their research carried out in their respective countries and extracted trends. Their studies covered a wide range of species including scallops, oysters, sardines and shrimp.
“The breadth of this coordinated research project was new, unexplored territory for the IAEA,” Swarzenski said. “The project extended beyond the biological and physical sciences and explored the social and economic impacts of ocean acidification on coastal communities.”
Their research went from analysing organisms under various pH (or acidity) levels in laboratories to monitoring actual coastal conditions. Researchers assessed fisheries and coastal communities to evaluate the degree of human reliance on key fish species as a source of food and revenue.
For example, researchers in Chile measured seawater properties such as pH, alkalinity, salinity, temperature and nutrients in an artisanal mussel-seed farm in Northern Patagonia. The project helped increase their knowledge and laid the basis for an ocean acidification network in Patagonia, which will ensure the sustainability of the project. Other research looked at how factors such as wind intensification can lead to further ocean acidification, as well as the impact of harmful algal blooms and seasonal variations in river discharges.
In other countries, including Ghana, research focussed on the composition and abundance of fish catches in artisanal and semi-industrial fisheries and in aquaculture production. The Ghanaian research project also studied the socioeconomic situation in Benin, Gambia and Togo.
Why ocean acidification matters
The IAEA uses isotopic and nuclear techniques to better understand biological processes in the environment. In the context of ocean acidification, its researchers examine the effects of high CO2 levels on calcification processes of invertebrates such as corals, shrimp and bivalves using the radioisotope calcium-45 to measure calcification rates. Both radioisotopes and stable isotopes of other elements are used to study acidity levels in the geological past or to determine if current changes in pH affect how marine species absorb pollutants such as heavy metals.
THE SCIENCE BOX
What is ocean acidification?
Some of the CO2 released into the atmosphere gets absorbed by the oceans. The CO2 reacts with water molecules (H2O) to form carbonic acid. Carbonic acid is a weak acid, but even slight changes in ocean acidity can have dramatic impacts on some organisms and cause knock-on effects throughout the food chain.
Below a certain pH and corresponding carbonate ion concentration, conditions become corrosive to calcium carbonate, which is used by many organisms to build shells and skeletons. Some corals, pteropods, bivalve molluscs and calcifying phytoplankton may be particularly sensitive to these changes in seawater chemistry. Plus, energy spent overcoming lower pH conditions may reduce the energy available for other physiological processes such as reproduction and growth.
These knock-on effects can affect humans too, with impacts on the livelihoods and food security of billions of people.
Sarah Jones-Couture, IAEA Environmental Laboratories, 25 August 2016. Article.
