Like a postcard landscape, the sun sets over the Minor Sea, illuminating with its last rays the volcanic and wild islands of Baron and Perdiguera, a few sailboats rocked by the waves and, further south, the mountains of the Sierra de Cartagena. Even in the middle of October, young children, in swimsuits, still play at nightfall near the calm and temperate waters of this immense salt lagoon of 135 km2, populated by pink flamingos, seahorses and giant nacres, separated from the Mediterranean by an arm of sand 22 km long, the Manga del Mar Menor. This unique ecosystem located in the region of Murcia, in the south-east of Spain, could be idyllic if it had not been massively urbanized from the 1960s and contaminated for decades by the tons of nitrates spilled by the agriculture and animal husbandry.
“I no longer bathe, it disgusts me all this algae and the smell: if it continues, it will look like a pond”, regrets Sagrario Lopez, 54, sitting in a folding chair on the gray sands of San Pedro del Pinatar, alongside her daughter and two grandchildren. “Twenty years ago, it was something else, the water was transparent and we saw tons of fish. Now my friends don’t want to come anymore ”, adds this Madrilenian who came pass here the bridge of the Spanish National Day, October 12th.
Tons of fish, summer visitors have seen a lot this summer, between August 15 and 25: dead. Trapped in pockets of anoxia caused by the eutrophication of the lagoon, nearly five tons of fish came to die near the shore, desperately pushing their mouths out of the water in search of oxygen. While the regional administration pointed out the effects of a possible rise in temperatures, the Spanish Institute of Oceanography (IEO) was clear in its report, delivered on September 13 : the main cause of this mortality episode is “The incessant penetration of fertilizers into the lagoon (…). The excess of phytoplankton limits the entry of light, which affects photosynthesis and the availability of oxygen in the water up to levels close to hypoxia ”.
After the episode of “Green soup” of 2016 – when the entire lagoon turned green under the effect of the proliferation of microalgae, causing the loss of nearly 80% of the underwater vegetation -, then the sudden death of more than 3 tonnes of fish in October 2019 following torrential rains, his conclusion is clear: “The lagoon ecosystem has lost its regulatory capacity. “
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