Small summer swimming dams are real scourges for the biodiversity of our streams, torrents and rivers:
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Playful but dangerous, they stop the vein of water which stagnates and spreads out in the sun during the hottest periods of the year. The water temperature increases by up to 10°C higher than normal. This increase causes a decrease in oxygen tension which promotes eutrophication or even dystrophication. Ecosystem balances are disrupted, which catalyzes the development of brown, black, green algae and, as in the marine environment, toxic algae: Habs which release neurotoxins on the surface. These Habs cause respiratory paralysis, cardiac arrest, digestive disorders and numerous allergies in aquatic animals and humans:

This dystrophication is accentuated with the discharge of nitrates and phosphates from small summer gardens often flowering with invasive exotic plants that consume water or over-agriculture. Watering is supplied by wild pumps which draw water directly from the river and then pump the polluted water back into the watercourse by infiltration via the groundwater table. Fertilizers, pesticides, fungicides, insecticides, medicinal derivatives and gray water from antiquated wastewater treatment plants are found concentrated in summer swimming areas where the water is blocked by small dams for bathers.

Nano-micro-macro-plastics, fibers from cigarette butts / -leau/impact-megots-cigarette-ressources-eau/, cotton buds, clothes, cans, food boxes and all types of macro-pollutants remain blocked by the walls of small dams:

They then have time to release their toxins, especially if the waters are warmer than usual. Finally, sun creams and bathers' cosmetics end up killing the inhabitants of the food chains because they are endocrine disruptors which destroy biodiversity.
Then these small dams are abandoned by bathers at the end of summer and constitute reservoirs at the first floods which accumulate waste and cause increasingly large waves through successive ruptures. Hence more occasional, more violent and more destructive floods, especially if the rivers are no longer maintained or poorly maintained by local residents.

Small dams also prevent the movement of aquatic animals. Some species carry out nocturnal, diurnal and seasonal migrations to search for food or reproduce. These species are blocked by numerous barrier walls and suffer the collateral effects of dystrophication. Their eggs or larvae can no longer develop because the water is increasingly polluted and food is scarce. This results in a great loss of biodiversity.

Plant, animal and also human biodiversity.

The impacts of these pollutants released into water, air and land are increasingly intense on fertility, embryonic development and the functioning of the brain of living beings, including humans. Sun creams, cosmetics, nano-micro-plastic films, fibers, pesticides, hydrocarbons, fungicides, herbicides, insecticides, degraded drugs, etc. which we find concentrated in the waters of our rivers and stored in swimming dams, cause cancer, reduce fertility, sexual difference, destabilize embryonic development, the functioning of the thyroid, disrupt hormonal balances, reduce intelligence quotients of an exposed population etc…. Breast cancer, autism, infertility in both sexes, advanced age of puberty in young girls, hyperactivity in children and adults, concentration disorders, etc. are the results of contact during embryogenesis with all these molecules and especially those emitted by plastics, fibers from cigarette butts, clothing, paints, household products, pesticides, insecticides, fungicides, fertilizers, etc.

The rapid changes in our environment through its contamination and pollution have a direct impact on our health, our intellectual and cognitive balance and increasingly isolate us from the realities of the laws of Nature. Natural selection will be increasingly severe and even deadly for our species according to many scientists. It is not only the currently fashionable carbon dioxide pollution that can affect our future, but also the impacts of cocktails of pollutants which will become more and more intense with climate change.

Planet Earth will regulate biodiversity. We are in the sixth extinction of species. This planet is alive but dead to us. 99.90% of the species present on Earth since the dawn of time have disappeared due to changes in environments. 0.1% of surviving species have repopulated our ecosystems to become, for example, 8 billion ecologically civic-minded human beings. Our planet still has time to rebuild several humanities or others if we disappear.

Aculturism, the environmental incivism of over-tourism are real dangers for fragile ecosystems like those of our rivers, our fresh waters which are so precious in the midst of a period of climate change. We don't go to the river in summer like we do to the beach and especially not in times of drought. Nature suffers from our lack of consideration as we will suffer later from the lack of its consideration.

He who sows the wind reaps the storm according to an old adage. And whoever sows the storm reaps the hurricane...