Man-Made Structures Responsible for Jellyfish Blooms

Written by on December 10, 2012 in Jellyfish, Marine Life

Jellyfish. Photo credit NOAA.

A recent study suggests that the increase in jellyfish populations is due to the expansion of man-made structures in the water.

Docks, moorings, rigs and other man-made structures provide a good, safe home for jellyfish nurseries. Because jellyfish begin life as a tiny polyp, they need something stable on which they can cement themselves.

This study provides important new insight, as previous research involving the reasons for jellyfish blooms has focused primarily on later life stages.

The research team surveyed polyp infiltration at sites across the globe and then created their own underwater structures to determine which ones best supported the nurseries. They found that polyps appeared to prefer man-made structures over natural ones like rocks and oyster beds.

“Artificial structures provide ideal conditions for settlement by jellyfish polyps. Floating docks and crevices within riprap increase the amount of shaded surfaces of the type that polyps prefer,” they wrote. “Indeed, medusa densities have been shown to decline when artificial substrate is removed.”

They note that jellyfish blooms could be slowed or even prevented if new structures are designed to discourage polyp settlement. Although to be truly successful, these measures would have to be combined with environmental regulations involving nutrient and oxygen concentrations.

Life cycle of scyphozoans.

Life cycle of scyphozoans. Stages 4-11 it remains attached to a solid structure. Photo credit NOAA.

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Copyright © 2012 by Marine Science Today, a publication of Marine Science Today LLC.

About the Author

About the Author: Emily Tripp is the Publisher and Editor of She holds marine science and biology degrees from the University of Miami's Rosenstiel School of Marine and Atmospheric Science and a Master of Advanced Studies degree in Marine Biodiversity and Conservation from Scripps Institution of Oceanography. When she's not writing about marine science, she's probably running around outside or playing with her dog. .


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