Jellyfish get ahead of summer | The truth

“Jellyfish arrivals are variable, both in time and in their spatial distribution,” explains Diego López Arquillo, scientific diver and researcher at the European University of the Canary Islands. There are multiple factors that impact this and what makes, in turn, “the management and prediction of these situations are complex and dynamic.” In short, you cannot say how many jellyfish will reach each place and when they will do so without question.

However, listening to the experts, it seems inevitable to assume that this year—which has been dry and warm—has created a friendly environment for its presence.

The causes of proliferation

In general, the jellyfish are there and their presence is beyond doubt. Every summer we see them and do it more. This boom—because they were already there, but not so much—is “a recent phenomenon but one that is increasing,” Gili summarizes. “When they appear on beaches, they appear more frequently and in swarms,” ​​he notes.

What are the reasons for this growth? First of all, it impacts the overexploitation of the ocean, explains the expert. “We are removing the organisms that eat them,” he summarizes. Jellyfish eat plankton and currently have no problems accessing their food source. The same does not happen, however, with the species that in turn eat jellyfish, which are in a more precarious situation.

Secondly, its presence is also connected to changes in temperatures. As Gili remembers, their appearance on the beaches is a seasonal phenomenon, connected to sea water temperatures and their life cycles. That was also what explained why we used to only see them during the holiday months.

“They were on the beach in summer because it coincides with their reproduction,” he points out. Now, they arrive earlier—in March they can already be seen—and leave later—September, even October—which gives them time to have more reproduction cycles. As Gili summarizes, there are more progenitors, more eggs, more polyps (one of their life phases), in short, more jellyfish.

Less rain, more specimens

But it is also not only a question of multiplication of reproduction cycles, but also of changes in environmental conditions. The springs were usually rainy, so rivers and other runoff brought fresh water to the coasts. This made coastal waters different from those of the open sea and less receptive to jellyfish.

They became a natural deterrent. “There were years that were dry and there were no barriers,” says Gili. That's why, in the past, every 10 or 12 years there was a kind of jellyfish invasion. Now, however, these conditions occur every year. “Coastal waters are more similar to open ocean waters than before,” he explains.

López Arquillo adds another element: changes in marine currents, “which can transport larvae and adult jellyfish to new areas, increasing their presence on coasts where they were not common before.” “The entry of an invasive species always implies an imbalance for the invaded ecosystem,” he points out. In a new destination they lack predators and this allows them to multiply, even moving native species.

The warning that jellyfish bring

In a way, you could say that jellyfish are a warning from the ocean that something is happening. «Imagine that you go to the beach and find a bottle with a message, it is from the ocean and asks for help. “Jellyfish are that,” says Gili. They are more than just a nuisance to enjoy the beach.

“Proliferations have several negative implications for marine ecosystems and human activities, beyond being a problem for bathers,” says López Arquillo. They may be warning us that we are facing an “unbalanced or declining” ecosystem, that it has been too polluted or that it has been overfished.

And they also warn of economic problems. In fishing, they can anticipate future shortages in fishing grounds. “They don't go anywhere, they're not stupid,” Gili summarizes. They settle in areas with schools of fish where they can eat during spawning, which crushes the population of the school. The problem is not that serious at the moment, but it could be.

Where they are already a question of the present and not of the future is for the tourism industry; something especially dangerous for a country, like Spain, which has one of its great attractions in its beaches. Gili does not fall into alarmism – as foreign media headlines sometimes do – but he does defend the importance of transparency.

“Information is basic to give you peace of mind,” he insists. It should not be 'covered' that the jellyfish have reached a beach so as not to harm the season. “You have to take precautions, like with a storm,” she summarizes. If they appear for a few days, they will eventually leave, something that bathers should learn. Closing the beach may be necessary: ​​two caravels, for example, make it inevitable. Knowing what is happening is also essential to respond if, despite everything, a jellyfish stings.

Some prevention guidelines

When faced with jellyfish, Josep-Maria Gili recommends common sense above all. Not bathing if they are warning us that they are on the coast is, to begin with, the most logical recommendation. Slathering on sunscreen not only protects you from the sun, it can also make your skin less receptive to being bitten. And if they itch, you should not apply ammonia, alcohol, vinegar or pressure bandages, no matter what the -erroneous- popular wisdom says. It is also not advisable to rub the area. Each jellyfish has a different action protocol, but the 'Identification guide for jellyfish and other gelatinous organisms', published by the Institute of Marine Sciences and CSIC, recommends as a general pattern for all of them to eliminate the remains, wash with seawater and apply cold to the affected site. Of course, in the event of complications or even if you are not very clear about what to do, the best solution is to go to health professionals. On beaches that have lifeguard personnel, their professionals already know what to do.