Are jellyfish increasing globally?
This is the main question that the Global Jellyfish Group is trying to answer but it is a difficult question, because no one has tried to examine jellyfish blooms from all over the world before. When conditions are good (for example, the temperature is just right and there is plenty of food) it is normal for jellyfish to grow fast and reach large numbers. This is part of the natural seasonal cycle of many species of jellyfish.
However, scientists think that we might be seeing more jellyfish blooms than before because ocean conditions are changing, and sometimes those changes are because of humans. A combination of over-fishing, climate change, introduction of species and more nutrients could lead to a surplus of jellies.