Plankton May Be Better Equipped to Survive Ocean Acidification Than Previously Thought

phytoplankton bloom photo

A phytoplankton bloom in the Baltic sea near the island of Gotland.; Photo by Remus Shepherd via Flickr CC

Ocean acidification, or the changing of the pH balance of the ocean as it absorbs ever more carbon dioxide from the atmosphere, is a serious threat to many forms of sea life. One form which it seems to be threatening is phytoplankton, essentially the first rung of the food chain in the ocean and the basis of life for everything from tiny fish to whales. New research has uncovered that while phytoplankton populations do suffer from acidification, the tiny organisms might be better equipped than we thought to deal with the change. Ars Technica reports that coccolithophores -- a type of ultra tiny phytoplankton that creates a calcite shell, the remains of which form chalk -- inspired researchers at University of Copenhagen to look into how these creatures might fare in more acidic waters. The researchers came up with a novel way to measure the mass of a single cocolith (the shell of coccolithophores) as it dissolves in acidic seawater to within one-trillionth of a gram. They found that the minute creatures are resistant to dissolution.

The good news is that at least one type of phytoplankton can hold up longer than expected as the ocean's pH balance shifts. The bad news is, the ocean's pH balance is indeed shifting and not many organisms with calcium carbonate shells will be able to hold up as well -- from oysters to sea urchins to lobsters to corals.

plankton needlefish photo

Needlefish swimming among plankton; Photo by Tom Verre via Flickr CC

Ars Technica reports, "Some marine plankton and invertebrates build shells from aragonite--a form of calcium carbonate which dissolves more easily than calcite--and these organisms will be the first to feel the effect of increasing ocean acidity. Calcite-secreting organisms which aren't as resistant as coccolithophores will be next. Near pH 7.8, coccolithophores (and any other groups that stabilize calcite similarly) will be in trouble as well. Projections vary with scenarios of future emissions, but most put the average ocean pH at 7.8 before the end of this century."

That means that phytoplankton is in serious trouble by 2100, and so too are the countless species of marine organisms that feed off of them, and in turn feed other species. What's worse, phytoplankton are also a carbon sink, taking in CO2 and taking it with them as they drift to the bottom of the ocean when they die. Less phytoplankton means less CO2 being locked away.

Dawn Martin of SeaWeb pointed out in a recent conference called BLUEMind that one of the most important stories about the environment that we're failing to tell in a way that grabs people's attention is the story of ocean acidification. It is a huge, and very scary issue. With phytoplankton, we're talking about the bottom of the food chain being wiped out. Researchers may have found that a prolific type of phytoplankton can hold out longer than others, but that doesn't mean it's invincible.

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More on Ocean Acidification
Ocean Acidification - What It Is and How It's Changing The World
World Premiere of Acid Test: The Global Challenge Acidification on Planet Green
What You Need to Know About Ocean Acidification

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