Study: Persistent, Highly Acidified Water All Along US West Coast; Some Hot Spots With pH As Low As Any Oceanic Surface Waters In World

There are now persistent, highly acidified stretches of water found all throughout the California Current System along the West Coast of the US, a 3-year survey of the region has found.

Image via Oregon State University

Some of the hot spots found during the survey were apparently home to pH levels as low as any ever recorded in any oceanic surface waters anywhere around the world. These hot spots will continue becoming more acidified and more prevalent during the coming years, the researchers note, because atmospheric carbon dioxide levels continue to rise rapidly.

Despite this fact, the researchers also note that there are refuges of moderate pH environments that are prevalent enough that it seems to be possible that they could serve as safe havens over the coming decades and possibly centuries.

“The West Coast is very vulnerable. Ten years ago, we were focusing on the tropics with their coral reefs as the place most likely affected by ocean acidification. But the California Current System is getting hit with acidification earlier and more drastically than other locations around the world,” commented lead author Francis Chan, a marine ecologist at Oregon State University.

The press release provides more: “A team of researchers developed a network of sensors to measure ocean acidification over a three-year period along more than 600 miles of the West Coast. The team observed near-shore pH levels that fell well below the global mean pH of 8.1 for the surface ocean, and reached as low as 7.4 at the most acidified sites, which is among the lowest recorded values ever observed in surface waters.

“The lower the pH level, the higher the acidity. Previous studies have documented a global decrease of 0.11 pH units in surface ocean waters since the beginning of the Industrial Revolution. Like the Richter scale, the pH scale is logarithmic, so that a 0.11 pH unit decrease represents an increase in acidity of approximately 30%.

“Highly acidified ocean water is potentially dangerous because many organisms are very sensitive to changes in pH. Chan said negative impacts already are occurring in the California Current System, where planktonic pteropods — or small swimming snails — were documented with severe shell dissolution.”

To be clear, these pteropods serve in many ways as the foundation of other species populations, such as herring, salmon, etc. — if they see a significant population decline, then other species will decline as well.

With regard to the survey itself, something that’s very interesting was the stability of the ocean acidification that was observed.

“The highly acidified water was remarkably persistent over the three years,” Chan noted. “Hotspots stayed as hotspots, and refuges stayed as refuges. This highly acidified water is not in the middle of the Pacific Ocean; it is right off our shore. Fortunately, there are swaths of water that are more moderate in acidity and those should be our focus for developing adaptation strategies.”

With regard to where to go from here, the researchers argue that refuge sites should be identified and better managed.

“Even though we are seeing compromised chemistry in our ocean waters, we still have a comparably vibrant ecosystem,” Chan concluded. “Our first goal should be to not make things worse. No new stresses. Then we need to safeguard and promote resilience. How do we do that? One way is to manage for diversity, from ensuring multiple-age populations to maintaining deep gene pools.

“The greater the diversity, the better chance of improving the adaptability of our marine species.”

The new research is detailed in a paper published in the journal Nature Scientific Reports.