Moon jellyfish bloom in Hobart indicates unbalanced marine ecosystem, scientist says

Thousands of jellyfish swarming at Hobart's waterfront dock may seem a natural phenomenon, but a leading scientist has warned its presence indicates something wrong. Marine biologist Lisa-Ann Gershwin said the spectacle was the most amazing bloom of Moon jellyfish (aurelia aurita) she has ever seen. Dr Gershwin, who has been studying jellyfish for 32 years, said these blooms were clear warnings that the marine environment was off-kilter.

"This cascade of species indicates that something's out of balance in the ocean."

She said the jellyfish population explosion was a direct result of an oversupply of nutrients in the water, from runoff, overfishing, and natural upwelling in the ocean. She said huge amounts of nutrients come from salmon hatcheries upriver and fish farms.

"It's too much. The ocean can't take it … the ecosystem is teetering on collapse."

• Read more in ABC News, 23 January 2025
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