Today’s Guardian reports that climate change, over-fishing and land management practices are contributing to a rapid rise in the number of jellyfish in the sea, manifesting themselves as ‘plagues’ in summer waters in the Mediterranean and as far afield as Namibia, Alaska and Australia. A study by scientists at the Spanish Institute of Marine Sciences (ICM) has revealed that, unlike previously thought, jellyfish proliferate throughout the year, not just in summer. They have discovered numerous jellyfish ‘blooms’ along the Catalan coast which are likely to wash inland from deeper waters on the summer tides, plaguing the coastline.
Global warming has created the perfect conditions for jellyfish to breed, with mild temperatures and reduced winter rainstorms. Over-fishing has led to the removal of the jellyfish’s predators, whilst agricultural run-off into coastal waters also contributes to the proliferation of jellyfish populations, through the promotion of algal blooms. The use of beaches in tourism has also contributed to a growth in jellyfish numbers, due to a reduction in the number of nesting sites for leatherback turtles and so a drop in the population of one of the jellyfish’s principle predators.
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