Story perspectives

Comb Jelly Blooms as Stickleback Decline Threatens Baltic Fisheries

7/26/2026

Summary

Story summary

Researchers report that the invasive comb jelly Mnemiopsis leidyi is expanding in the Baltic Sea as three-spined stickleback predators decline.
Sticklebacks normally feed on Mnemiopsis leidyi larvae, providing natural control.
Increasing hypoxia limits stickleback activity, reducing predation on the jelly’s larvae.
Warmer water and falling Baltic salinity, which the jelly prefers, further aid its spread.
The jelly now threatens fisheries by eating zooplankton, sprat and sardine eggs.

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Story summary

Researchers report that the invasive comb jelly Mnemiopsis leidyi is expanding in the Baltic Sea as three-spined stickleback predators decline.
Sticklebacks normally feed on Mnemiopsis leidyi larvae, providing natural control.
Increasing hypoxia limits stickleback activity, reducing predation on the jelly’s larvae.
Warmer water and falling Baltic salinity, which the jelly prefers, further aid its spread.
The jelly now threatens fisheries by eating zooplankton, sprat and sardine eggs.