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Seagrasses Can Protect Humans

Barbora Adamková, GRID-Arendal

By Blue Forests Project

March 6^th, 2017

The most common coastal ecosystem on Earth, so long overlooked, may finally get its time to shine. Seagrasses are able to protect corals, other sea creatures and humans from harmful pathogens.

Scientists in Indonesia were inspecting coral reefs that had been infected with bacteria and fungi. By the end of their scuba diving workshop they all got sick with dysentery. This was the motivation for marine biologist Drew Harwell that led to a study published in the journal Science. "It got me thinking about human health and environmental health and how they are linked," Harvell explained.

She shared her thoughts with marine disease ecologist Joleah Lamb, which began the investigation. It proved that the amount of oxygen released by seagrass meadows is enough to kill pathogens. In addition, seagrass habitat also provides nursery for marine invertebrates, which produce bacteria-killing compounds.

The researchers obtained DNA from seawater, which turned out to contain 18 kinds of disease causing bacteria. In comparison, the water from the seagrass meadows contained only half of them. The same result was found on coral reefs around the islands, as they are often linked with seagrass meadows. Reefs next to seagrass habitat were twice as healthy as those without. The exact mechanisms of the pathogens protection remain to be discovered, but the implications could be globally significant.

"Millions of people rely on healthy coral reefs for food, income and cultural value," emphasises Lamb.

Seagrasses benefit the health of coral reefs, fish and humans too. Photos Credit: Steven Lutz/GRID-Arendal

Seagrasses benefit the health of coral reefs, fish and humans too. Photos Credit: Steven Lutz/GRID-Arendal

Seagrasses benefit the health of coral reefs, fish and humans too. Photos Credit: Steven Lutz/GRID-Arendal

Seagrasses benefit the health of coral reefs, fish and humans too. Photos Credit: Steven Lutz/GRID-Arendal

Seagrasses benefit the health of coral reefs, fish and humans too. Photos Credit: Steven Lutz/GRID-Arendal

Seagrasses benefit the health of coral reefs, fish and humans too. Photos Credit: Steven Lutz/GRID-Arendal

The research showed that clear blue coloured ocean water was in reality filled with dangerous micro bacterial organisms. The newly discovered capacities of seagrasses can increase our understanding of the benefits they provide. “There could be a huge potential in how valuable they become,” said Lamb. However, seagrass meadows are disappearing at an alarming rate of one football field every half an hour, which highlights the need for greater protection.

Drew Harvell, professor of Ecology and Evolutionary Biology at Cornell University, explains the findings of her research team on how the presence of seagrass mitigates the effects of human sewage in ocean ecosystems.

Journal Reference:

Joleah Lamb et al. Seagrass Ecosystems Reduce Exposure to Bacterial Pathogens of Humans, Fishes and Invertebrates. Science, 2017 DOI: 10.1126/science.aal1956

Quotations cited from related articles:

The New York Times: Disappearing Seagrass Protects Against Pathogens, Even Climate Change, Scientists Find

Science Daily: Underwater seagrass beds dial back polluted seawater

Footnotes

Header Photo Credit: Steven Lutz/GRID-Arendal

FootNotes

Header Photo Credit: Steven Lutz/GRID-Arendal

© 2026 Blue Forests Project

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