Oceans on Acid - Sailors for the Sea

Oceans on Acid

By: Hilary Kotoun, Social Impact Director, Sailors for the Sea | February 2, 2015

Take a big breath and hold it. The oxygen you inhale is absorbed by the blood and carried throughout your body. Meanwhile, carbon dioxide is carried back to your lungs and is released. But wait – keep holding your breath. Your lungs will ache as you keep yourself from exhaling. Trigger impulses from your brain will signal your body to ensure normal respiration. This trigger – the urge to breathe – is not caused by the lack of oxygen in your body, but rather a build up in carbon dioxide and a change in your body’s pH.

Okay, you can exhale now. Breathe. 

Much like your body just experienced – the ocean’s pH is dropping

Pteropods, often nicknamed sea butterflies, are free-swimming sea snails about the size of a small pea. Their name is Greek meaning “winged-foot”
Pteropods, often nicknamed sea butterflies, are free-swimming sea snails about the size of a small pea. Their name is Greek meaning “winged-foot” their thin, transparent shells are made from calcium carbonate. Pteropods are an important source of food, eaten by marine from the tiny krill to salmon and even whales.

Seawater is naturally alkaline, with a healthy pH around 8.2. But since the industrial revolution, this number has dropped 30% and the ocean has become more acidic. In the last two centuries alone, the ocean has absorbed 525 billion tons of carbon dioxide emitted through the burning of fossil fuels. Scientists say the concentration of carbon dioxide in the atmosphere is higher now than it has been in the last 650,000 years and that this recent change in chemistry is happening faster than any known change in ocean chemistry in the last 50 million years.

To preserve ocean health we must curb our carbon dioxide emissions.

There exists a strong connection between the ocean and the atmosphere. A golden rule to remember is that what gets emitted into the air eventually makes its way into the ocean. Right now that number is about 22 million tons of carbon dioxide per day, or one third of all carbon emissions. This conceivably has “delayed” the current impacts of global warming, but it does not mean the problem has disappeared. When carbon dioxide reacts with seawater it forms carbonic acid – the same acid that creates fizz in soft drinks, and also the root of where many problems in the ocean may stem from in the coming years.  

The marine environment is teeming with organisms that depend on protective shells to survive.

 modified from Feely et al. 2009
The correlation between rising levels of CO2 in the atmosphere (red) at Mauna Loa and rising CO2 levels in the Ocean (blue) and falling pH (green) in the nearby ocean at Station Aloha. As CO2 accumulates in the ocean, the water becomes more acidic (the pH declines). (Figure source: modified from Feely et al. 2009).

Calcium carbonate is a key element for sea creatures to build their shells. From coral to oysters, lobsters to certain varieties of plankton – shells are the only line of defense for many creatures in the ocean. When excess carbonic acid is present, the formation of calcium carbonate becomes difficult and can dissolve shells that have already been formed.  

Because so many of these organisms serve as the basis of the marine food web, this breakdown may have sweeping effects in years to come. Some one billion people rely on marine animals currently as their primary protein source. When we mess with ocean chemistry and threaten the smallest organisms in the sea, we ultimately have an impact on all of humanity.

Coral Reefs

Corals need calcium carbonate to survive. Often described as the “rainforests of the ocean”, they contain over 25 percent of the world’s fish biodiversity. However scientists have found that increasing acidity significantly reduces the ability of reef-building corals to produce skeletons. On top of the many species they house, coral reefs provide many coastal communities with a natural protection from storm surges and hurricanes. Additionally, coral reefs make up a large portion of the tourism industry in tropical destinations. In the United States alone this includes revenue of $1.2 billion per year in the Florida Keys, and $360 million per year in Hawaii.

Imagine if the pH in your blood changed, causing your bones to dissolve.

Sea Butterflies

pteropod shells dissolve in acidified ocean water
These photos show what happens to a pteropod’s shell in seawater that is too acidic. The left image shows a shell collected from a live pteropod from a region in the Southern Ocean where acidity is not too high. The shell on the right is from a pteropod collected in a region where the water is more acidic (Photo credits: (left) Bednaršek et al. 2012; (right) Nina Bednaršek).

Pteropods are free-swimming transparent sea snails with a small shell. Often called the “potato chips of the sea” due to the critical part they play in the arctic marine food chain, these beautiful, tiny creatures are essential to the diet of everything from krill, to salmon, and even whales. A recent study of pteropods in the Pacific Ocean between Central California and the Canadian border found that more than half of the creatures had damaged shells due to acidity. This creates disturbances in the food chain, of which the implications are immense, but still not fully understood.

While the impacts of ocean acidification are still being explored, scientists are finding that even creatures at the bottom of the ocean are beginning to experience issues due to changes in acidity.

The Pacific Northwest has been hit hardest by ocean acidification. Their oyster farms, valued as a $110 million operation, have become the poster child to explain the dangers ocean acidification pose to the fishing industry. In addition to potentially wiping out the farms if waters become too acidic, researchers have found that the pH of the ocean may impact the size of the oyster. 

The oceans function as our planet’s life support system

Two of the most important factors for an organism to survive in the ocean are temperature and acidity and as we continue to emit carbon dioxide we alter both of these conditions. The sooner we reduce global carbon emissions, the sooner we are able to prevent these harmful trends.

The ocean moderates our climate and filters pollution. It supplies us with a rich diversity of food, minerals, and medicines. We also use it as a source of comfort, relaxation, recreation, and inspiration. However, due to a steady unchecked decline our oceans are in trouble, which in turn poses a threat to marine life, coastal and pelagic ecosystems, our economy, coastal cultures and societies.

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