Lämpö ja kuivuus aiheuttavat ennenaikaista ja vaikeasti ennustettavaa saapumista
En April’s second week, the residents of the municipalities surrounding the Roses Bay, in the heart of the Costa Brava, encountered an unusual phenomenon for this time of year when, attracted by the high temperatures, they decided to put on their swimsuits, take out the umbrella from the storage room, and head out to enjoy a pleasant day at the beach. The reddish-yellow color of the sand had been replaced by the purplish hue of a layer formed by thousands of jellyfish that stretched along its shores. The most affected area was Cala Montjoi, known for having hosted the famous ElBulli restaurant. Earlier, in February, on the Galician coast, especially in A Coruña, dozens of specimens also appeared on its Atlantic beaches. In both cases, it is the same species, the Pelagia noctiluca, ”very stinging and dangerous depending on the sensitivity of the person,” although not as aggressive as the famous Portuguese man o’ war, as stated by Diego López Arquillo, a scientific diver and researcher at the European University of the Canary Islands, to 20minutos. At this point, it is necessary to clarify that, although for example, the Portuguese man o’ war is socially conceived as a jellyfish, it is not. The Portuguese man o’ war, like in this case the Pelagia noctiluca, is ”colonies of organisms,” as López points out. However, the important thing is that their properties are equally stinging and represent, in addition to a nuisance, a danger to swimmers. You have surely seen them on the beaches of the municipality these days, they are the famous Sant Pere boats (Velella Velella). They are not jellyfish, they are colonies of polyps about 7cm long that float on the surface of our coasts. They are stinging species, but harmless to humans. pic.twitter.com/dLz1tBg373— Ajuntament de Begur (@AjBegur) April 9, 2024 In any case, the early arrival of jellyfish on the Spanish coast is a very uncommon phenomenon that, however, we will have to get used to it being more recurrent due to the advance of the high temperatures season and the severe drought that plagues Spain, among other factors. The difficulty of predicting arrivals As López explains, it is very important that there is ”more research” on the subject, since it is difficult to predict these massive arrivals outside the periods in which they are more normal. ”These concentrations can vary each year depending on multiple climatic and ecological factors, which makes the management and prediction of these situations complex and dynamic, even the measurement of the total number of specimens. They are influenced by slight modifications in the marine currents due to temperature changes, to storms, like the recent Nelson, which can suddenly change their distribution compared to the supposed arrival pattern in summer.” In this way, it is adventurous to affirm that the early appearance of jellyfish anticipates a complicated summer in terms of the influx of these invertebrates. However, it is undeniable that if the unusual high temperatures allow us to take a dip earlier than we are used to, we will have to get used to the fact that the same heat will cause jellyfish to be our beach companions. Other factors that influence their appearance Although López insists that ”we must continue to investigate the cause-effect relationship between the destabilization of environmental factors and the pace of jellyfish appearance,” he does point to other possible factors, in addition to heat and changes in marine currents, that favor their advent. Among them, overfishing, ”which affects the jellyfish’s predator species,” such as tuna, swordfish, or bonitos, as well as other migratory fish. ”Another aspect to consider is the increase in nutrients in the oceans due to agricultural runoff and untreated wastewater. This promotes the growth of plankton, the main food source for jellyfish,” says the researcher from the European University of the Canary Islands. Finally, the drought makes it more attractive for jellyfish to approach the shore due to the presence of a greater amount of saltwater. The scarcity of rainfall is undermining river flow, with the consequent decrease in freshwater —key to keeping jellyfish away from the coasts— that reaches the sea. With all this, it is expected that the areas most affected by the arrival of these invertebrates this summer will be ”the coastal areas of the Costa Brava, the Alboran Sea, the Balearic Islands, the Canary Islands, and Galicia,” which, in any case, are the most accustomed to living with them.