Warmer seawater could be the reason for the death of thousands of small crustaceans in the Balearic seas. This is the main hypothesis being considered by researchers after unsuccessfully searching for the presence of pathogens associated with the organisms that appeared lifeless on the beaches of Pollensa and Alcudia in February 2024.
Amalia Grau, one of the researchers, says they found "no infectious-contagious explanation" for the appearance of the krill. "They probably arrived dragged by an upwelling of the water mass, and since the Mediterranean is so warm and these crustaceans are so sensitive to temperature, they died.
"We analysed the krill using molecular biology and histology, two techniques that guide us in searching for the causes. That's why we can confidently say there was nothing pathological, although using molecular biology in other cases has seen pathogens linked to mass mortality in the Balearics."
The dynamics of Mediterranean water masses are changing. Proof of this is the high mortality rate this summer of stranded and dead manta rays. "Spanish and Italian researchers say that the movements of manta rays have changed in the Mediterranean. They've been observing this for some time, and it seems to be related to changes in current movements. As it's warmer, the currents are changing, as is happening in the Atlantic with the Labrador Current that comes from Greenland."
There was no repeat of the phenomenon this winter. Nevertheless, Grau points out that it was something never seen before. "I've been working here for 33 years, and this was the first case."