The Seaweed Threatening the Atlantic
By Juni Kim, age 16
Thousands of beachgoers along the Atlantic Ocean have been watching a sudden influx of seaweed on the shores this summer. The influx of seaweed is killing sea life and threatening shorelines with significant economic and environmental damage. The culprit? A genus of brown algae known as sargassum is primarily responsible for these events, and scientists are baffled at the immense growth of sargassum, warning this may become the “new normal” for the algae.
Ecological Significance
“Everything in moderation” seems to be the environmental rule the Sargassum is breaking. Within the open ocean, sargassum is used by many species as both a habitat and as protection against larger predators. As the Sargasso Sea Alliance in a 2011 Paper states, "[The sargassum ecosystem] provides essential habitat for nurturing a wide diversity of species, many of which are endangered or threatened.” It’s when that “normal” level of algae expands that it becomes a threat to the ocean.
The Magnitude of Inundations
Many sources, including the University of South Florida's Optical Oceanography Laboratory, point to 2011 as the beginning of the sargassum inundation events. However, starting from 2011, these events have become more severe, breaking records every two or three years. According to the Nereus Program, a bloom in the summer of 2018 extended almost 1700 square kilometers. This bloom exceeded the prior average of around 300 square kilometers.
Impacts of Blooms/Inundations
As the Optical Oceanography Laboratory stated in a recent ESSA article, “many of the impacts of sargassum blooms stem from the decomposing process that occurs shortly after they inundate on coastlines. The aerobic bacteria that decompose the seaweed consume oxygen, causing surrounding species to suffocate. Decomposers of sargassum also generate noxious hydrogen sulfide, leading to numerous toxicity cases in humans. Due to the sheer density of the blooms, inundations also inhibit water sports and beachgoing, which presents a major threat to the tourism industry of these places.” (as an article by ESSA notes).
Causes and Proposed Human Impacts
Although human-induced climate change, along with an influx of nutrients, are widely believed to be a factor in causing inundations, as are analogous to other recent algal blooms, not enough is known about the blooms to stop or inhibit them. Agricultural fertilizers contain large amounts of nitrogen, which is known to stimulate algal growth. Although the extent of the human-generated effect on inundations is still unknown, scientists are still hopeful that they can reduce the severity of such inundations and their ecological and economic impacts by reducing the liberal usage of soil-enhancing fertilizers and nutrients.
Information/Sources
https://essa.com/the-great-sargassum-disaster-of-2018/#_ftn1
https://optics.marine.usf.edu/projects/SaWS.html
https://nereusprogram.org/works/the-sargassum-mass-bloom-of-2018/#_ftn9
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