Mollusk | Chapter 8 | Extinction

In 1911, Alabama’s Coosa River was 281 miles of sparkling waters and thriving life. Fish were abundant, feeding the hardscrabble communities that lived on its shores. Up and down the Coosa, mussel beds sat in the rich, churning waters. Snails scraped the shining rocks clean of algae.

The river was full of life, but the humans on its banks struggled under dismal conditions. Nearly the entire state of Alabama lived without electricity, in darkness and hard toil. There was little industry. At the end of the Coosa, the great waterfall of the Devil’s Staircase blocked both travel and trade. While the northern states continued to industrialize following the American Civil War, Alabama lagged behind.

Everything changed when James Mitchell became president of the Alabama Power Company in 1912. For Mitchell, bringing electricity to Alabama was a matter of survival. The country was on the brink of another terrible war, and all seemed doomed to chaos and violence.

“To make money is all right; to build industry is fine,” Mitchell told his friends, “but to build an industry that saves mankind from toil which it can well be spared, that reduces the labor and drudgery of women, that provides leisure for education and culture – truly is a much finer thing.”

James Mitchell.

James Mitchell.

Mitchell wanted to create a better world, and he thought that meant damming the Coosa for hydropower.

Waters flooded into the first of the Coosa’s vast dams in December 1913, turning shallow rivers into deep, still reservoirs. Local ecologists scrambled up from the mussel beds where they had been frantically collecting everything they could. “We worked until the last possible moment,” one of them wrote. By the time they left that day, the water was bursting the riverbanks and rising up the valley.

In the dark depths of the new reservoirs, the snails and mollusks began to die.

Freshwater mussels can live for a hundred years. Because of their long lifespans, it took us decades to realize that the shelled nymphs of the Coosa River were no longer reproducing. The mussels and snails needed the warm, churning freshness of the shallow rapids. In the deep, freezing waters of the reservoir, they could no longer sense the changing seasons. The algae they ate stopped growing.

For millennia, the mollusks of the Coosa River evolved to thrive despite every disaster the planet threw at them. But they could not survive us.

Even after we realized what we’d done, we dammed with abandon. Less than 2 percent of the winding, twisting lengths of U.S. rivers are still free flowing.

Dam on the Coosa River.  Mike Kline

Dam on the Coosa River. Mike Kline

In the distant future, if our descendants dig up our fossil record, they’ll marvel at the collapsed high rises of Manhattan, the underground network of train tunnels, and the endless mesh of highways.

In Alabama, they’ll look out over what used to be hundreds of miles of deep, cool water reservoirs formed by dams that slaughtered species and sparked entire states into light.

The Coosa is just one small story of loss among millions. Humans have changed the world faster than any other animal. The answers to many of the human questions of “will this work” are “yes” on the human scale, but a definitive “no” in the longer term.

There have been five great extinctions since animal life began on earth 1.8 billion years ago. The rise of humans has brought about the sixth. Plants and animal species are going extinct before we can even document them. When their last survivor dies alone, we lose an entire universe.

More Extinction

41 percent of the extinctions since we began documentation in the 1500s have been mollusks, far more than any other group.
Extinction is a natural phenomenon, occurring at a rate of about one to five species per year. Scientists estimate we’re now losing species at 100 to 1,000 times the normal rate.
Scientists believe that about 99 percent of all species that ever lived are now extinct.
Our decisions about technology all have repercussions. Building dams for hydropowered electricity hurts the freshwater mollusks, but burning fossil fuels for electricity hurts marine mollusks.
The ocean absorbs a third of the carbon dioxide in the atmosphere, which causes a chemical reaction that acidifies the water. As our oceans acidify, the water eats away at the mollusks’ shells.
Pteropod or “sea butterfly” shell in normal ocean.

Pteropod or “sea butterfly” shell in normal ocean.

Pteropod shell in acidifying ocean.  Nina Bednarsek, NOAA

Pteropod shell in acidifying ocean. Nina Bednarsek, NOAA