Could the coronavirus spread in the marine environment and affect certain species such as oysters and mussels? While the epidemic is still there but that, helping deconfinement, the main beaches of the French coast are now accessible and that traces of the virus have been detected recently in wastewater, the question is quite legitimate. The risk, however, appears particularly low, even nonexistent if one believes the experts of the French Research Institute for the Exploitation of the Sea (Ifremer).
They have just published the first results of analyzes launched a few weeks ago. No less than 21 samples of oysters and mussels collected from various locations on the French coast were analyzed. As well as three samples of seawater also from several French coasts and taken in areas “potentially subject to human discharge”.
No Covid-19 in the samples analyzed by Ifremer
Verdict: the first results obtained are reassuring and no Covid-19 traces were found there . Neither in the water itself, nor in the shells.
“Even if it is not valid for all shellfish and metropolitan marine waters, the absence of traces of SARS-CoV-2 (the scientific name of the new coronavirus, Editor’s note) revealed by our study is good news. “, Underlines Soizick Le Guyader, virologist and head of the Nantes laboratory” Environmental health and microbiology “of Ifremer.
Before stating that Ifremer has decided, as a precaution, to continue taking samples and analyzes on the same sites every two weeks for another several months, “in order to monitor the possible effects of a potentially increased circulation of the virus in the population in the context of the gradual lifting of containment measures ”.
Danger comes from promiscuity, not water
If Covid-19 coronavirus and seawater are clearly not a good mix, what about freshwater from lakes and rivers? A part of the answer was provided by the Higher Council for Spanish Scientific Research (CSIC) , in a study focusing on seawater, swimming pools and lakes and rivers.
This study, published in early May, synthesizes the various research studies that have been carried out, not directly on Covid-19, but on other coronaviruses linked to Covid-19. The six CSIC researchers who are behind this publication are, once again, rather reassuring. For them, the risk is not so much the possible presence of the virus in the water as the promiscuity of bathing places which leads to no longer respecting the rules of social distancing. This facilitates transmission via “respiratory secretions generated by coughing, sneezing and person-to-person contact”.
Pools and Jacuzzi less risky than lakes and rivers
However, on reading this Spanish study, it seems obvious that all these aquatic environments are not equal vis-à-vis the virus. Just as in seawater where salt could reduce the virality of Covid-19, in swimming pools the use of disinfectant such as chlorine could have the same effect. Same thing in jacuzzis where a high temperature can also reduce the lifespan of the virus.
On the other hand, in fresh water, in lakes and rivers, the survival of the virus could prove to be a little longer than in swimming pools and Jacuzzi, explain the researchers. And to mention the risk, which is always possible that wastewater carrying the virus will contaminate bathing water. Precautionary measures must be taken there “in order to avoid crowds” explains the CSIC which drives the point home while affirming that “they are the most advised against aquatic environments”.
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