Seagrass service

Seagrass meadows can often be overlooked, but are in fact vital marine ecosystems, supporting and sheltering myriad life in coastal waters. As well as providing nurseries for young fish, hiding places for vulnerable invertebrates, and grazing for larger marine animals, new research has highlighted a further, previously unknown benefit of these underwater gardens.

“The seagrass appear to combat bacteria,” said lead author Joleah Lamb of Cornell University, “and this is the first research to assess whether that coastal ecosystem can alleviate disease associated with marine organisms.”

While the exact causes of reduction in bacteria in the waters around seagrass remain unclear, tests in Indonesia provided plenty of evidence of the cleansing work of the meadows. Even off beaches where water quality was poor and bacteria of human origin was rife, seagrass meadows nearby demonstrated a distinct drop in the amount of bacteria lingering in their vicinity. Deep in a healthy seagrass meadow lurk all manner of filter-feeders, such as sponges and bi-valves, and these animals may be playing a role in cleaning the surrounding water of bacteria.

These important, beautiful coastal ecosystems are, however, under threat. The discovery of their pathogen-preventing benefits may help raise awareness and aid in their conservation. “Global loss of seagrass meadows is about 7 percent each year since 1990,” said Lamb. “Hopefully this research will provide a clear message about the benefits of seagrasses for human and marine health that will resonate globally.”


Originally published in News in Brief – Biosphere Magazine Issue 24

Lamb, J, van de Water, J, Bourne, D, et al (2017) Seagrass ecosystems reduce exposure to bacterial pathogens of humans, fishes, and invertebrates. Science, DOI: 10.1126/science.aal1956

Photo: Heather Dine / NOAA / by CC


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