In Scotland, local nuclear engineers were forced to seek help from their Japanese counterparts after two offshore nuclear power plants were on the verge of shutting down due to a jellyfish attack. Huge masses of invertebrates fill the water bodies of the stations and disable hydraulic structures. In Japan itself, this phenomenon is already called the second most dangerous for nuclear power plants - only earthquakes are more terrible.
From a regional problem, jellyfish invasions have turned into an evil on a planetary scale, and incidents like the Japanese and Scottish ones can now be repeated on any coast. The only exceptions are the polar regions, since these creatures are quite thermophilic. And also jellyfish have become an excellent indicator of the degree of pollution of the aquasphere - the more runoff in coastal waters, the higher the number of jellyfish.
In fact, jellyfish also do not like toxins and plastic, as waste of human activity. However, they require much less oxygen than the same fish, so they can survive in dirty water, where other marine inhabitants die en masse. This has already led to disruptions in the natural mechanisms of regulation of the number of living species in nature, and multiplying jellyfish is just a natural result. But for humans, as land dwellers, the sight of hordes of transparent monsters seems apocalyptic.
Worst of all, neither the clever Scots nor the experienced Japanese have figured out how to solve the problem. Most of these jellyfish are inedible, unsuitable for processing into any useful raw materials, and their catch and disposal require colossal efforts. And the only indirect benefit from them is that they serve as an indicator of the state of the region's ecology.