After the discovery of E.Coli bacteria and feces in the water, nine beaches in Finistère and Morbihan have been banned from swimming until further notice. These bans are not without consequences since after these announcements, many tourists have decided to give up their stay on the Breton coast, according to our colleagues from the Telegram. How do these faeces end up in the waves? How to prevent the E.coli surge on the beaches? And what are the consequences for swimmers who venture to dive into its contaminated waters? Elements of response thanks to the lighting of Laurent Le Berre, departmental delegate of the association Eau et Rivières de Bretagne.
How can E.coli bacteria contaminate bathing water?
In 90% of cases, it comes from the rivers that flow onto the beaches… and which are polluted. Initially, it is the watershed – a basin that collects all the rainwater that comes to feed the watercourse – which, sliding towards the beach, drains its faeces.
In a city in the South-West like Biarritz, one will find in these basins more runoff from urban reservoirs or pavement washouts. Still, Brittany is a very agricultural region with more and more farm-factories developing and expanding on these watersheds. “These factory farms spread their slurry to fertilize the land, including pig slurry, for example, which is spread on bare land. And as soon as it rains a certain amount of water, the earth no longer drinks it and runoff takes place as far as the rivers,” explains Laurent Le Berre. The rivers being relatively small of just a few kilometers, they bring all this to the sea.
It is not to mention that Brittany is also confronted with the presence of green algae, a problem which manifests itself in particular by an excess of nitrates due to these spreadings. These green algae only appear in large closed bays, where the water is not renewed. “In the Iroise to the east of Brest, there are a lot of bathing water problems due to faecal bacteria without there being the presence of green algae. Because this area is located facing the ocean, the water is therefore regularly renewed and very oxygenated. But as soon as it rains, there are a lot of bacteria there, ”says Laurent Le Berre.
How are the beaches controlled?
The law asks the ARS (regional health agency) to apply the European directive on bathing water which requires looking at two bacteria: the famous ereschichia coli (E.coli), therefore, and enterococcus. Samples are regularly taken from the beaches of the European Union in order to determine the level of concentration of these two reliable controls. If the rate is exceeded, this means that there is faecal pollution of the water. “There is then a risk of finding other bacteria in addition to these, such as streptococci, viruses, etc. commented Laurent Le Berre.
How to act as a barrier to bacteria and protect sea water?
To fight against the arrival of these materials on the beaches, Laurent Le Berre and the Eau et Rivières de Bretagne association would like to request a moratorium on the expansion of farms located on the watersheds of green algae on one side, and on the watersheds of beaches known to be problematic in Brittany. “We know very well where the problem beaches are located, and if you trace the map of the density of pigs per square kilometer with the map of the problem beaches linked to bacteriology in Brittany, you will see that it is obvious”, assures Laurent Le Berre.
What are the risks of swimming in contaminated water?
E.coli and enterococci bacteria, the ones found mostly on beaches, are not the most dangerous. However, an excess of these bacteria can cause the panel of diseases in “itis”, such as otitis, conjunctivitis, gastroenteritis, etc. If the latter are certainly not fatal, Laurent Le Berre specifies that where these bacteria are found, there is a significant risk of also finding other viruses and multi-resistant bacteria. Which, he says, is much more worrying.
Remember that a triathlon in particular recently took place in Sunderland in the United Kingdom, and nearly sixty people suffered from diarrhea and vomiting after swimming. The reason ? A presence of E.coli bacteria 39 times higher than the usual rate. “Afterwards, if you want to know the more damaging consequences that an E.coli bacterium can have, you can look at what happened with the Buitoni pizza scandal. With the difference that there, they were ingested. »