Environmental disaster in the Mar Menor – Seahorses suffocating – Knowledge

The seahorses were once the silent stars in Europe’s largest saltwater lagoon, the Mar Menor in southern Spain. Many older Spaniards today tell of how they dived in the shallow water of the lagoon as children on summer vacation and waited for a seahorse to wrap its tail around their finger. The crystal clear water, the special salinity, a little higher than that of the Mediterranean, from which the lagoon is only separated by a narrow headland: The living conditions were ideal for these small fish with their cute snouts.

Soon, however, the seahorses in the Mar Menor could be completely wiped out. 99 percent of the long-snouted seahorse population, Hippocampus guttulatus, the lagoon has lost in the past eight years, warns the Asociación Hippocampus association. An estimate was made of 200,000 specimens in 2012, and in December 2020 there were only 1,350 animals that, according to extrapolation, live in the lagoon, which covers an area of ​​around 170 square kilometers. And that was before the massive fish deaths that this summer made the Mar Menor a “death zone” according to environmentalists.

15 tons of fish, crustaceans and algae have died in the salt water lagoon in the past few weeks. Hundreds of thousands of seahorses, small fish, clams and crabs suffocated in the water of the lagoon and were washed ashore. According to marine biologists, man is to blame for this: Political failure in conjunction with unscrupulous agricultural production in the Murcia region would have led to the collapse of the former natural beauty.

Environmentalists have been warning of the “green brew” since 2016

The death of the Mar Menor began when the water temperature rose to more than 30 degrees because of the recent heat wave in August. But the heat only acted as an accelerator for processes that caused the oxygen content in the water to drop rapidly. It was a catastrophe with an announcement. For years, not only the seahorse conservationists have been warning that the saltwater biotope is on the verge of collapse. Julia Martínez, biologist and director of the FNCA Water Conservation Foundation, prepared a report in 2019which, on the one hand, points to the unique value of the ecosystem and, on the other hand, to the diverse threats that will lead to its destruction in the foreseeable future if politicians do not act quickly.

But there was no action, Martínez notes bitterly today. The decisive factor, according to the biologist from Murcia, is the intensive agriculture in the region. Murcia and especially the area around the coastal city of Cartagena are nicknamed the “Garden of Europe” because large parts of the tomatoes, cucumbers and citrus fruits that later end up in German supermarkets are grown there. Whereby “garden” is an excessive euphemism for the fact that vegetables and fruit are grown there on bare desert soil with massive use of irrigation and fertilizers.

Precisely those fertilizers prove to be fatal for life in the lagoon: Particularly in heavy rain, they are washed out of the soil, so vast amounts of nitrogen and phosphorus get into the sensitive ecosystem. Stimulated by the excessive supply of nutrients, algae begin to multiply en masse in the water, at some point they are so dense that not enough sunlight can penetrate, they die. A green broth is created. As early as 2016, the environmental organization WWF warned that the green color was a warning sign. Once the algae have died, the process worsens: If bacteria break down their remains, they consume oxygen. In the worst case, the oxygen content decreases so much that fish and crustaceans flee further and further towards the shore and eventually die there.

The Mar Menor was placed under protection several times, which had hardly any consequences

As data from the Murcia region show, as a result of over-fertilization, the nitrate levels in the groundwater and in the soil there are many times higher than the limit value set by the EU. “On the bare ground, nothing holds back the water that is pumped full of nutrients,” explains biologist Julia Martínez. She criticizes the fact that, in addition to the permitted intensive cultivation, there are also large areas that would be used by the agricultural industry without a permit. “Politicians here watched for decades as laws were disregarded,” said Martínez. Agricultural requirements are actually the responsibility of the conservative regional government of Murcia. But it blames the heat wave and the left central government in Madrid for the current fish deaths.

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There seems to be a consensus inside and outside Spain that the Mar Menor deserves special protection. The lagoon bears around ten protection titles: It is among other things a bird sanctuary and a special sanctuary of Mediterranean importance to the United Nations, is subject to the guidelines of the Ramsar Convention for wetlands of international importance and the special protection of the Spanish government. So much protection – and so few consequences. In 1987 there was even a separate law to protect the Mar Menor, but in 2001 the conservative People’s Party overturned the law. Since then, as the environmental protection associations perceive, the agricultural corporations have had a free hand. The fact that a new law to protect the lagoon was passed a year ago could no longer slow down the ongoing destruction.

Environmentalists wanted to embrace the lagoon – but the proximity of humans is fatal

While agriculture does the most damage to the lagoon, other factors also contribute to its destruction. They too are man-made. Biologist Julia Martínez names climate change and tourism that made the problem even worse. On the one hand, climate change results in ever hotter summers, which further fuel the growth of algae. On the other hand, there is also more frequent heavy rain, which causes nutrient-rich water to be washed into the lagoon in large quantities. After such a heavy rain, an oxygen content of zero milligrams per liter of lagoon water was measured in September 2019. Even then, the waves washed several tons of fish carcasses ashore.

The influencing factor tourism brings you back to the seahorses. Because in the 1960s, when those Spaniards who today nostalgically think back to their holidays observed seahorses on the Mar Menor, the tourist infrastructure on the lagoon was only just beginning to grow. In the meantime, practically not a square meter on the narrow headland between the Mediterranean Sea and the lagoon has remained undeveloped. The many motor and sailing boats plowing through the water interfere with the regeneration of the lagoon, and in midsummer the sewage treatment plants are also overwhelmed by the guests in the hotel castles and apartment towers. In the past few years, untreated wastewater has repeatedly entered the Mar Menor.

The protest action by environmentalists, who a few days ago organized a human chain with 70,000 participants around the lagoon, is therefore not without a certain irony: The “hug for the Mar Menor” attracted attention, but it is precisely the closeness of the people that the Lagoon threatens to suffocate.

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