Are jelly swarms natural phenomena?
Yes. Jellies have likely swum and swarmed in our seas for over 600 million years. When conditions are right, jelly swarms can form quickly. They appear to do this for sexual reproduction. Since males need to release gametes (sperm) into the water, they need to be very close to females. Therefore, swarming behavior is just a way for them to be close to each other. • Are jelly populations increasing? In some locations, jelly populations are increasing, but such increases are regional in nature. We do not have evidence that there are ‘global’ increases due to global influences, but evidence is mounting that climate change may have an effect. • Are human-caused environmental problems promoting population explosions of jellies? Various types of environmental problems may promote the formation of jelly swarms. These problems include pollution, the over-harvesting of fish, the introduction of non-native jelly species into new habitats, the addition of artificial substrate (like fishing reefs
