How Algae Emissions Could Affect the Weather

Featured image by Jesse Allen and Robert Simmon, Public Domain

Paper: Unprecedented DMSP Concentrations in a Massive Dinoflagellate Bloom in Monterey Bay, CA
Authors: Ronald P. Kiene, Brent Nowinski, Kaitlin Esson, Christina Preston, Roman Marin III, James Birch, Christopher Scholin, John Ryan, and Mary Ann Moran

Tiny marine organisms have been showing up in higher and higher numbers in bodies of water. These organisms also emit sulfur-containing compounds – and if they emit enough sulfur, their emissions could affect the climate.

Monterey Bay, California is beloved for its sea life, from harbor seals to sea otters. But in 2016 a different kind of marine life swept across the bay in a red bloom: the plankton Akashiwo sanguinea. New research suggests that one of the waste products of this tiny, seemingly innocuous organism could add significant amounts of sulfur to the atmosphere and perhaps even affect cloud formation in the region. As the climate’s temperature ramps up, causing more algae blooms, these regional changes could even have consequences for our weather.

Dinoflagellates like A. sanguinea are single-celled protists. Most dinoflagellates get their energy from the sun via photosynthesis, but A. sanguinea is mixotrophic, so it can also digest other organisms. While the mechanisms behind sudden explosions in the number of plankton in an area – called blooms. – are not fully understood, they are thought to involve large influxes of nutrients like nitrogen and phosphorus to a body of water. In 2016, just such a bloom affected Monterey Bay.

Akashiwo sanguinea. By Minami Himemiya, CC BY-SA 3.0

While some algae blooms can be toxic, A. sanguinea hasn’t been shown to harm human health. However, algae blooms can have other unexpected consequences, like the chemical dimethylsulfonioproprionate (DMSP), which is produced by A. sanguinea. DMSP is used by the algae to maintain electrolyte balance and contains the element sulfur. The authors and others report that during algae blooms, concentrations of DMSP can reach extreme levels. What’s more, as DMSP degrades, the sulfur it contains is released to the atmosphere.

An algae bloom in Lake Erie. By Jesse Allen and Robert Simmon, Public Domain

At normal concentrations, the release of sulfur into the atmosphere wouldn’t be a problem. Naturally-occurring chemicals like DMSP are part of the global sulfur cycle, returning sulfur to the atmosphere. But once in the atmosphere, sulfur-containing chemicals aren’t inert. They play important roles in the chemistry of the atmosphere, creating aerosols that can reflect solar radiation and that can serve as nucleation centers for the water droplets that form clouds. Both of these roles increase the albedo (reflectivity) of the atmosphere, directly influencing the global climate. Therefore, studying new routes for sulfur to enter the atmosphere – like algae blooms – is necessary to understand the consequences for our planet.

To study the link between the 2016 algae bloom and the amount of the sulfur-containing chemical DMSP produced, the authors collected two weeks’ worth of water samples off the coast of Monterey Bay. They also used satellite images to measure the extent of the algae bloom from the air over time and measured the surface temperature of the water. Using the water samples, they measured the amount of DMSP dissolved in each water sample as well as the DMSP that was still contained in algae cells (particulate DMSP) by degrading the samples to produce the volatile sulfur byproduct of DMSP, dimethyl sulfide (DMS). DMS was separated from other gaseous byproducts, then the amount of sulfur was measured using flame photometry.

At peak levels, the concentration of DMSP measured in Monterey Bay reached a record high (4240 nanomolar). Most DMSP measured was actually still contained in algae cells, which the authors attribute to the eager consumption of external DMSP by bacteria in the water. The authors observe that the particular kind of algae that contributed to this bloom – A. sanguinea – might create more DMSP than other types of algae blooms. Since A. sanguinea is predicted to thrive as global temperatures rise, DMSP production will also continue rising, which could significantly impact the emission of sulfur into the atmosphere.

As the planet continues to warm, scientists are expecting algae blooms to become more and more common – a problem for beachgoers and seabirds everywhere. But the sulfur-containing chemicals these algae blooms release into the atmosphere could have consequences far beyond your local watershed. These chemicals could have unpredictable consequences for local and global climates as they influence the albedo of the atmosphere. Case studies of local algae blooms like this one add important data points that scientists can use to help understand bigger changes.

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How Algae Emissions Could Affect the Weather by Kristina Vrouwenvelder is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.