The Mar Menor, a year after the collapse: It has a brutal regeneration capacity

 The Mar Menor seems to have recovered a year after suffering the last mass mortality of species, although its health is still far from optimal. In August 2021, it was again covered with a macabre carpet of dead fish and crustaceans, suffocated by lack of oxygen. It was a new chapter in the deterioration accumulated over decades that had reached its turning point five years earlier, in 2016, when this lagoon became a "green soup", a collapse that was repeated later in 2019.

Demonstration by the Mar Menor in Murcia. 

Now, in August 2022, the waters look visibly clearer, and no episode of anoxia or lack of oxygen has occurred again, but what is considered the largest salt lagoon in Europe is still threatened and its future depends on measures that have not been fully implemented, while the regional and central governments blame each other for poor environmental management.

The mass mortality of August 2021 has been, until now, the last cry for help from the Mar Menor. Since then, measures have been intensified to allow their regeneration, such as the removal of algae, and the rapid response of the ecosystem has been surprising. "Removing them before they die and decompose supposes an export of nutrients out of the water, and that has served so that the situation in the lagoon this summer has been better, although this does not mean that the Mar Menor is great or anything for style, since it is still quite threatened", Emilio Cortes, curator of the Murcia University Aquarium, told .

This marine biologist is aware that the lagoon is still admitted to the intensive care unit, but believes that if the appropriate measures are increased, his health will improve markedly in a short period of time. "We are diving practically every week, and since 2016, when the eutrophication events began to occur, we have verified that the Mar Menor has a brutal resilience, a regeneration capacity that we did not think could become so strong," he says. , although he warns that it is necessary to act more quickly because "the continuous crises in short periods of time are reducing that capacity and in the end they can deteriorate it a lot".

Angel Perez Ruzafa, Professor of Ecology at the University of Murcia, highlights the beneficial effect of the algae extraction that has been carried out in recent weeks, which "has prevented the mud from accumulating and being later removed by currents , preventing it from being deposited in deep areas, which is what consumed oxygen and produced anoxia crises".

Perez Ruzafa also trusts the lagoon's capacity to regenerate, something that "already demonstrated in 2018, when it was said that it would take 40 years to recover." As explained to coastal lagoons have "a very important characteristic, and that is that when they have restrictions on communication channels, as is the case of the Mar Menor, they generate a very important self-regulation capacity."

 

Archive image of an episode of fish mortality in the Mar Menor

Excess Nutrients

Experts in this jewel of the Spanish coastline place the origin of the problem in human activity near the riverbank, in the agricultural sector and especially in intensive agriculture, which have contaminated groundwater with nitrates from fertilizers. This excess of nutrients has been what has caused the eutrophication of the lagoon, favoring the proliferation of phytoplankton and, consequently, decreasing oxygen levels.

But livestock and agriculture are not the only sources of discharges. Urban sanitation networks also participate in this contamination, which in summer become saturated with the overload of vacationers. In addition, when there is rain, which in Murcia is usually torrential, a large quantity of nutrients located on the surface enters the lagoon, which are washed away by runoff.

Desalination plants have been another of the main problems that the Mar Menor has faced in recent years. In 1994, the Segura Hydrographic Confederation authorized the use of healthy aquifers to alleviate a drought that was proving devastating for Campo de Cartagena. Desalination plants proliferated and, once the drought was over, they continued to operate, many of them clandestinely, so their discharges continued to reach the waters. In recent years, efforts have been directed at closing these desalination plants, as well as wells, to put an end to the illegal irrigation of thousands of hectares that has done so much damage to the ecosystem.

However, despite the measures adopted, all the sources consulted by agree that the situation has barely changed. "Significant amounts of water continue to enter the aquifer, highly loaded with nutrients, from the water  and from the drainage basin. In that sense, the situation has even gotten worse because, since the water table is so high, it has been affecting the cesspools in homes and even basements, which means that the water that reaches the Mar Menor not only contains nitrates, but now also contains phosphates, and phosphorus activates many nitrogen molecules that quickly enter the food web and they cause algae to proliferate," explains Professor Perez Ruzafa, who criticizes the fact that nothing has yet been done "to lower the water .

For the marine biologist Emilio Cortes, the most important thing at this time is to undertake with greater determination the "control of the discharges and the nutrients that are entering", and considers it essential that "more joint measures be taken by the regional government and the Ministry" so that the situation of the lagoon improves.

"Between 200% and 300% over the limit"

One of the entities that has dedicated the most effort to the recovery of the lagoon is the Association of Naturalists of the Southeast (ANSE). Its director, Pedro Garcia, assures that this year "the Mar Menor presents significantly better conditions compared to last year", although he stresses that "this does not mean that what has been done so far is sufficient, not much less." García denounces that a large amount of water contaminated by nitrates continues to enter, and that "most of the measures planned by the Ministry are not yet being applied." "Apart from the closure of the 5,500 hectares of irrigated land, and a stricter use of fertilizers, which have been significantly reduced, the rest of the measures are still in process," he summarizes.

Thus, the director of ANSE highlights the reduction of the area of ​​illegal irrigation and the control of the use of fertilizers as the two most important measures that have been taken so far, although he expresses his doubts regarding the effect that the removal of algae has had in suspension. "We believe that if the Mar Menor this year has not presented a situation like last year, it may be simply because it has reacted differently," he says, pointing out that the improvement experienced could be mainly due to the "great capacity of the lagoon to recover on its own". "Water loaded with nitrates continues to enter, at levels that exceed the limits dictated by European regulations by 200% or 300%," he stresses.

Human chain formed in August 20122 for the recovery of the Mar Menor, in Los

The best shrimp campaign

 

The critical situation of the Mar Menor has especially affected sectors such as fishing, of great weight within the economy of the area, which has experienced its worst years coinciding with the collapse of these traditionally fertile waters. Although it seems that the fishermen begin to glimpse the light at the end of the tunnel. "This year we are seeing the water quite well, and we believe that we are not going to have any problem of anoxia or anything similar to what happened last year," Jose Blaya, senior patron of the San Francisco Fishermen's Association, told Pedro del Pinata. As he explains, fishing for sea bream is the only one that is being "weak", although he acknowledges that it is still early to make a definitive assessment, since "August is always very bad, and we have to wait for the waters cool down to really know how the situation .

 

However, Blaya reveals that the shrimp campaign started very badly and, without knowing why, has ended up being "extraordinarily good", both in quality and quantity, to the point of qualifying it as "the best in the 45 years that I have in the Mar Menor". Although he laments that "it has cost us fishermen a lot to sell it, and we have had to lower the price." "Consumers have reservations about buying fish from the Mar Menor due to all the circumstances we are going through, and the media that is giving negative publicity that is not true. Our fish is exquisite and passes very rigorous controls," he defends.

 

But if there is something in which this fisherman trusts, it is in the ability of the Mar Menor to recover from his injuries. "We are at sea seven days a week, and if there are 24 hours in a day, we spend at least fifteen of them there, so we know it better than anyone, and we know that its ability to regenerate is spectacular," he says, and gives a recent example: "We have helped to remove algae in an area that was completely deserted, and when we returned after a few days, it was all full of fish".