Seagrasses Reduce Bacteria In Polluted Waters – New Study Reveals

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By ERIN BLAKEMORE
FOUND in coastal regions around the world, seagrasses (or sea weed as it is called in Sabah) turn the ocean floor into an underwater meadow. Though mesmerizing to watch, these fields aren’t just for decoration.

Seagrasses have several important environmental roles to play, such as providing essential habitat and sequestering carbon. Now, new research reveals another benefit: making seawater less polluted.

For the study, recently published in the journal Science, a team of scientists tested seawater off the coast of four small islands at Spermonde Archipelago, Indonesia. There, ocean pollution is common due to the lack of septic systems and effective waste disposal systems.

Seagrass grows near a village in the Spermonde Archipelago in Indonesia. Researchers there recently discovered that coastal areas with seagrass have less bacteria than grassless areas. Photo credit Joleah Lamb/Smithsonian

They were on the hunt for Enterococcus, a type of bacteria that indicates that an area has been contaminated by fecal waste.

Though the bacteria don’t always cause serious infections, they often indicate that other, even more harmful, pathogens are present.

They found that water samples from sites near beaches were more than ten times higher than Environmental Protection Agency recommended levels. Samples collected near seagrass meadows, however, had up to three times fewer bacteria.

Similarly, they found that coral reefs located near seagrass meadows had up to two times less disease than those without grasses nearby.

That apparent bacteria-fighting power is just one of seagrasses’ many jobs. They play host to thousands of underwater species, making up vital habitats for animals, and generate oxygen through photosynthesis.

They also serve as a snack for grazing sea animals such as green sea turtles.

Seagrasses sequester carbon, too—it’s thought that they currently store nearly 20 billion tons of the gas. As a result, they’re considered one of Earth’s most valuable ecosystems. Now bacteria reduction can be added to that long list of benefits. – SMITHSONIAN.COM

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