You really should be giving more thought to algae. Sure, algae are tiny; some are just a single cell. But as two Dartmouth professors explained during the Irving Institute's March faculty seminar, algae's impacts on health—of both the planet and individuals—can be huge.
How huge? Consider: One type of algae may help us ease climate change. Another creates a toxin that could give you a fatal disease.
Carbon Dioxide, Meet Clay
Mukul Sharma, Professor of Earth Sciences. (Photo by Andrila Hait Chakrabarti)
The March faculty seminar began with a presentation by Mukul Sharma, Professor of Earth Sciences, entitled "Carbon Dioxide Removal with Co-Benefits." Removing carbon dioxide from the atmosphere is important, because an overabundance of this gas is contributing to climate change. And, as Sharma explained, it can be done with two lowly elements: algae and clay.
Algae, a member of the phytoplankton family, creates its own nutrition via photosynthesis, much as trees and other terrestrial plants do. However, algae also serve as a food for zooplankton, a type of plankton that must consume other organisms to thrive, much as animals (including humans) do.
That's where clay comes in. To be more precise, industrial clay. This substance, mined from the earth, is used as a raw material by manufacturing, agriculture and other industries. Importantly, clay contains iron. And, as a punning Sharma explained, "It's dirt cheap."
Sharma detailed an approach for using clay to capture atmospheric carbon dioxide and moving it safely to the bottom of the ocean.
Under this approach, industrial clay is spread over the ocean's surface. Then, when phytoplankton die, this clay causes their remains, known as "flocks," to sink deeper into the sea. Clay does this in two ways. One, it prevents bacterial decomposition in the upper ocean. And two, as experiments have shown, clay also aggregates the flocks, causing them to settle down faster.
Deeper in the ocean, the flocks are eaten by zooplankton. In their hunt for food, oceanic zooplankton change their depth in the water by as much as 100 meters a day. When these plankton descend, they take some of the carbon they've eaten deeper into the sea, mainly by defecating. Zooplankton feeding on clay-bearing flocks egest fecal pellets that are denser and could rapidly sequester carbon deeper into the ocean.
While more experiments are needed, the potential is great, Sharma said. The ocean has a large capacity to hold carbon.
"We've discovered a pathway that brings carbon to the deep ocean," Sharma says. "And one that could potentially reduce atmospheric carbon dioxide for less than $10 a ton."
A Trigger for ALS
The second faculty seminar of March was presented by Elijah Stommel, Professor of Neurology at the Geisel School of Medicine and a neurologist at the Dartmouth-Hitchcock Medical Center. In his presentation, "Harmful Algal Blooms (HABs) and Amyotrophic Lateral Sclerosis," Stommel explored the likely connection between ALS and a toxin produced by certain algae.
ALS—also known as Lou Gehrig's disease—is a serious disorder of the nervous system. There are many different forms of ALS, as well as different causes. But all initially develop slowly, then move with lethal intensity. Once symptoms begin, ALS patients often die within just two to five years.
As Stommel explained, ALS appears to have both genetic and environmental components. That is, a person may have a genetic propensity for the disease. But to get ALS, they probably also need to be exposed to certain environmental toxins.
"If one of your first-degree relatives gets ALS, you have an eight-fold higher chance of getting it yourself," Stommel explained. "So the risk is likely a combination of genetic susceptibility and environmental exposures over time."
Among the likely environmental factors are cyanobacterial toxins, substances created by a type of blue-green algae. These toxins are quite poisonous. "If your dog eats it," Stommel said, "they'll die in five minutes."
A link between this toxin and ALS was discovered in the Pacific island of Guam. There, in the years after World War II, the ALS rate was 200-fold greater than that for the rest of the world. One suspect was a local flour made from the root of a cycad plant. The roots are inhabited by cyanobacteria that have a symbiotic relationship, and the resulting flour contained the cyanobacteria-derived toxins. Years later, when people in Guam switched to a different diet, local ALS rates plummeted.
More recently, graduate students working with Stommel found a cluster of ALS cases around Lake Mascoma in western New Hampshire. There, ALS rates were 25- to 30-fold higher than that for the rest of the country. In one instance, two unrelated people living on the same property house—one, the house's owner and the other, the gardener—both contracted ALS within a couple years of each other. The property was on the eastern shore of Lake Champlain that had frequent HABs.
Stommel and his researchers uncovered a culprit: Lake Mascoma has recurrent annual blooms of cyanobacteria. A local fisherman caught a carp in the lake, and the fish was found to contain a cyanobacteria toxin, Beta-methylamino-L-alanine (BMAA). Researchers have also detected BMAA in the air around the lake.
Stommel and colleagues then used satellite imagery to map the water quality parameters favoring cyanobacteria. They overlaid the ALS cases with the water quality and found a statistically significant correlation between where the ALS patients lived and where the HABs were found. Also, most patients lived east of the lake. That checked out, because the local prevailing winds in summer come from the west and southwest, exposing residents to aerosols containing cyanobacteria and their toxins.
Another study has found ALS clusters on the eastern shore of Lake Champlain, situated on the border between Vermont and New York State. That lake also has large algal blooms, and they're increasing due to warmer temperatures, climate change, and nutrient pollution, mostly runoffs of nitrogen and phosphorus.
So consider the lowly algae. It may be tiny. But your health, and that of the planet, may depend upon it.
Learn more: Watch a video of the Irving Institute's March faculty seminar.
Peter Krass is a contributing writer and editor to the Irving Institute.