Seagrass can work as a sanitary service Science


Some seaweeds are associated with lower levels of pathogens that cause gastroenteritis in the water.
Reinhard Dirscherl / ullstein image via Getty Images

A few years ago, a series of illnesses hit members of Joleah Lamb’s diving team. Lamb, a marine ecologist at the University of California, Irvine, researched coral disease in Indonesia with colleagues when they contracted dysentery, a type of gastroenteritis. This common disease can be caused by swallowing water contaminated with bacterial pathogens such as e.g. Enterococcus. Although symptoms are usually mild, gastroenteritis can be fatal. Every year, gastroenteritis and related diseases kill millions of people around the world – especially children under the age of five.

Lamb and the experience of her colleagues led to a scientific discovery: concentration Enterococcus pathogens that can cause gastroenteritis are lower in some parts of the ocean than in others. Significantly, pathogens that cause gastroenteritis are less common among seagrass meadows.

In a recent study, a team led by Fortunato Ascioti, an ecologist at the University of Palermo in Italy, was based on Lamb’s insight to assess the global potential of seagrass as a coastal sanitation service. Ascioti’s effort, which was independent of Lamb’s work, found that if all seagrass meadows around the world provide this service to reduce pathogens, they could be responsible for reducing up to 24 million cases of gastroenteritis annually. Savings from seaweed sanitation in healthcare alone could be worth as much as $ 74 million globally.

Ascioti explains that the finding is a rough estimate of the sanitary potential of some seaweeds. There are more than 70 species of seaweed, he says, and only a few are known to have this effect. Based on current knowledge of these types of seaweed, Ascioti and his team calculated to avoid about eight million cases of gastroenteritis annually.

Lamb, who was not part of the global assessment research team, says that when it comes to evaluating seaweed, these projections of the potential reduction in gastroenteritis are annual conservative. “I would say that this is just an assessment of the value of the seaweed sanitation service, which reduces pathogens for only one type of disease,” she says.

This is because different seaweeds target different pathogens. Lamb’s study identified three species of seaweed, Enhalus acoroides, Thalassia hemprichiiand Cymodocea rotundatawhich are effective against gastroenteritis Enterococcus bacteria. But previous research has shown that Mediterranean is an endemic seaweed Posidonia oceanica may reduce concentration Escherichia coliwhile temperate water is habitat Zostera marina helps reduce pathogens in Vibrio gender.

Seaweed can also help purify water for other marine species, including those harvested as seafood.

Whether society can harness this sanitary power by planting seagrass meadows is a complex question, Lamb says, because scientists aren’t entirely sure how seagrass does this job.

“We don’t know, at least in tropical systems, if [seagrasses] play complementary roles with each other or if one species can have a pathogen-reducing effect, “says Lamb. Seagrass meadow density can also play an important role, he notes. Further research is needed to understand whether this service is retained in replanted meadows.

However, with the increase in the human population living in coastal areas, mitigating disease-causing pathogens will only become more important.

This article is from Hakai Magazine, an online publication on science and society in coastal ecosystems. Read more stories like this at

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