Did you know, mussels can serve many purposes? Apart from being an ingredient for seafood dishes, they can be used as ‘bio-indicators’ of the health of the seas, lakes, and rivers they inhabit, and they possess the incredible potential to aid in the fight against water pollution.
It might be unpleasant to know but the mussel is the “Hoover of the sea”, taking in phytoplankton for nourishment along with microplastics, pesticides and other pollutants in the mix. That is why they make for an excellent gauge and a very efficient natural water filter.
Mussels feed and breathe by pumping and filtering water through their gills. They store almost everything else that passes through—which is why strict health rules apply for those destined for human consumption.
For now, they are just used by scientists to check levels of pollution in water but maybe one day they’ll also be pressed into service to cleanse water. “It’s a super-filter in the marine world, filtering up to 25 liters of water a day,” says marine biologist Leila Meistertzheim who heads a study for France’s Tara Ocean Foundation. “It’s a real model of bioaccumulation of pollutants generally speaking. In some places, mussels are used, as well as oysters, to cleanse the sea of pesticides, for example.”
Meistertzheim uses mussels to gauge the health of the estuaries of the Thames, Elba and Seine rivers. The researchers place the mussels in fish traps and submerge them in the waters for a month. Then they take the mussels out and dissect them to determine what chemical substances lurk in their tissues.
So are the mussels safe to eat? Richard Luthy, an environmental engineer from California’s Stanford University, says that, in most cases, mussels harvested from contaminated waters should not be eaten but if the contaminant is E. coli, mussels can be thanked for the “removal and inactivation” of the fecal material and they are safe for consumption. Luthy calls the service a “public health benefit” and says that the mussels are edible because they “excrete the bacteria as feces or mucus.”
In another seemingly contaminated situation – when waterways are affected by eutrophication as a result of waste dumped into the waterway containing phosphates and nitrites, such as detergents, fertilizers, and sewage – it is also ok to eat the mussels. When a waterway is affected by eutrophication it will be marked by abundant algae. The nutrients in the substances encourage the proliferation of algae, which in turn starves the water of oxygen, disrupting the ecosystem. The mussels will restore the balance to this ecosystem by feeding on the algae and thus “recycling” the nutrients, explains Eve Galimany, a researcher of the US National Oceanic and Atmospheric Administration’s Milford Laboratory who has experimented with mussels in the Bronx River in New York.
“Eutrophication… is the biggest problem of the Baltic Sea, the most urgent one,” says project head Lena Tasse. Mussels “could be part of a solution.” A pilot project titled Baltic Blue Growth in Sweden, Denmark and the Baltic countries, which grows mussels to be fed to animals such as poultry, fish, and pigs, have been using this recycling principle to farm their mussels.
Last but not least, what about the microplastics ingested by mussels? Well, a 2018 study published in the journal Environmental Pollution, based on samples from British coastlines and supermarkets, estimated that every 100 grams (3.5 ounces) of mussels contained 70 tiny pieces of plastic. Should we be worried? For now, there is still no proof of whether consuming microplastics are bad for human health.
Even if you don’t eat mussels you won’t avoid eating microplastics. A recent report by WWF said that humans ingest an average of five grams of microplastics a week which is the weight of a credit card. According to Meistertzheim, it is safe to eat mussels. “I eat them,” she says. “A dish of mussels is not necessarily worse than organic hamburger meat wrapped in plastic.”
