Ocean acidification combined with other climate change impacts like warming waters, deoxygenation, coastal erosion and melting ice is threatening the existence of many marine species. This is especially true for species such as clams, oysters, mussels, corals and phytoplankton that rely on calcium carbonate shells as protection. As ocean acidification reduces availability of carbonate ions that these organisms need for growth and survival it could result in decreased growth, calcification or even dissolution of their skeletons causing their survival or decline.
Human-caused ocean acidification stems from CO2 gas being absorbed into seawater. CO2 dissolves to produce weak acid called carbonic acid which, upon dissociation, produces hydrogen ions and carbonate ions which then determine its acidity (pH). If hydrogen ion concentration rises in an ocean environment then more acidity will result.
This process is taking place across the world’s oceans, though some regions seem to be progressing more rapidly than others. Polar seas and upwelling regions, where deep waters feed coastal surface waters with nutrients from below, tend to become more acidic and corrosive than other ocean regions.
Short-term natural fluctuations in ocean and coastal waters‘ pH can also significantly impede marine organisms’ ability to survive and flourish, altering how certain fish sense predators and find shelter. Changes to ocean chemistry could reduce clownfish ability to sense predators and shelter.
Weather conditions, prevailing wind patterns, or biological processes affecting ecosystem dynamics can all influence these fluctuations in various ways. In Puget Sound for instance, seasonal water flow changes and tide intrusions interacting with river plumes can produce drastic and rapid fluctuations in aragonite saturation state and pH levels (see image below).
Understanding the complex interactions between long-term climate change impacts and short-term natural variations is necessary to effectively manage and adapt to ocean acidification.
Duke University-led research has recently identified significant natural short-term increases in ocean acidity within North Carolina estuaries that occurred independently from global ocean acidification processes. This variation occurs alongside long-term ocean acidification.
We must also work in partnership with coastal communities – including fishermen, farmers and other business owners – to identify and implement innovative solutions to ocean acidification. This is especially crucial for those relying on marine life for their livelihoods. Helping these communities recognize the risks and take necessary actions, while providing them with resources for dealing with acidification and climate changes will be key in supporting sustainable solutions. Protecting local economies and strengthening community economies are effective ways of combatting climate change. Furthermore, taking this approach will also ensure the United Nations Sustainable Development Goal 14 of “conserving and enhancing benefits from oceans, seas, and marine resources” is met.