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Plastic Seaweed Soup

July 4, 2022

Its a crying shame... plastic waste combined with naturally occuring seaweed are creating a horrific environmental nightmare in the Caribbean and out into the Atlantic. One of our scientists described it as "a plastic seaweed soup that's choking marine, terrestrial, and avian life."

Although Sargassum seaweed has a long history and cyclic appearance, in the last ten years unprecedented amounts have been expanding in geographic range. Human acitivity is clearly responsible for its increased abundance.

Plastic Seaweed Soup beached on the south coast of Belize
Plastic Seaweed Soup beached on the south coast of Belize

Along with coastal run-off from agriculture and urban activity, our scientists are attributing its exponential growth to fossil fuel burning, increased plastic pollution, and acid rain.

- Rising atmospheric CO2 from fossil fuel burning is serving as the primary nutrient for its rapid growth (carbon is the primary component of seaweed). The oceans are the major sink for CO2 and absorb most of it at the surface where this seaweed lives, thereby fueling its growth.

Most marine traffic aslo releases substantial amounts of CO2 near the ocean surface. The denser than air CO2 remains close to the seawater surface where it has a disproportionate affect on increasing the dissolved CO2 concentration of the seawater which further enhances growth.

- Floating plastics provide a matrix for the seaweed to associate with, which encourages growth and spreads it further via wind and surface currents. The plastics are also releasing plasticizers and other chemicals into the soup creating a toxic environment affecting microorganisms, other algae, fishes, birds, and marine mammals.

- Acid rain with pH 5 or less is also catalyzing its growth by adding more dissolved CO2 to the soup which enhances photosynthesis. Increased amounts of rain with lower pH is a direct result of more fossil fuel (hydrocarbon) burning.

Massive seaweed accumulating on resort beaches in central Belize
Massive seaweed accumulating on resort beaches in central Belize

Much of the soup washes up on coastlines creating additional problems. There, toxic amounts of H2S (hydrogen sulfide) gas is being released into the air by bacteria that decompose the seaweed. Its also creating gruesome looking sites on many beaches.

This compex problem is altering pelagic and coastal ecosystems over widespread areas and is now severely impacting tourism, economies, the environment, and the health of many different forms of life... including humans.

Would you like to contribute or comment? email: enclabs@enclabs.org

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