The Mar Menor is the largest salt lake in Europe and is in a critical situation. In mid-August, more than 5 tons of fish and mollusks were found dead on the shores of the Murcian lagoon. It is not the first time that it has happened, during the last years several episodes of this type have accumulated. What is happening in the Mar Menor and why is it in danger?
Ten days of anoxia in the Mar Menor: “You can’t bathe in the rotten smell of dead fish”
The appearance of tons of dead fish is a consequence of what experts call eutrophication, that is, the contamination of the waters by nitrates and phosphates from the fertilization of the surrounding crops. These nutrients reach the lagoon through boulevards or channels that flow there or, to a lesser extent, through aquifers. Up to 5 tons are dumped every day. Fertilizers produce the increase in phytoplankton that consume oxygen from the water. The massive presence of microalgae also clouds the lagoon and prevents light from reaching the seabed. In this way, the flora dies due to lack of sunlight, stops photosynthesis and, therefore, stops providing oxygen to the ecosystem.
All this leads to anoxia, that is, the total absence of oxygen that aquatic life allows. This phenomenon is the cause of the images we have seen these days.
Environmental crises in the Mar Menor, environmental organizations denounce, are the leitmotif of the area in recent years, among other reasons, due to the lack of control over agricultural holdings and urban and tourist overcrowding.
In 2016 the lagoon became a big “green soup” due to excess phytoplankton. Three years later, in 2019, sediment was poured from surrounding fields massively by DANA’s torrential rains. A month later, the first anoxia occurred, causing the death of around 3 tons of fish.
Since then, different initiatives have been carried out in search of a solution for the recurring environmental crises in the area. Among them a regional law to protect the Mar Menor that, among other measures, shields the first 500 meters of crops without chemical fertilizers, although in practice the application of the norm is non-existent.
Environmental organizations denounce the inaction of the regional government, which is responsible for agriculture and the environment. But they also do not exempt the central government from responsibility, which they ask to intervene in this environmental crisis. The two administrations have set out to find effective solutions to tackle the destruction of this unique ecosystem in Europe that, years ago, had crystal clear waters.