New research challenges the assumption that an increase in ocean temperatures associated with climate change will promote future jellyfish outbreaks. A spate of recent blooms has raised concerns that the gelatinous creatures are on the rise and could pose a serious threat to commercial fisheries.
Richard Brodeur at the US National Oceanic and Atmospheric Administration's Northwest Fisheries Science Center in Newport, Oregon, and colleagues analysed the factors influencing jellyfish abundance in the eastern Bering Sea before, after and during one such outbreak in the 1990s, which saw a threefold increase in the number of jellyfish caught. Using a statistical approach known as 'generalized additive modelling', they found that jellyfish abundance was affected regionally by interacting variables — in particular, ice cover, sea surface temperature, currents and wind mixing. Food availability, however, was also key to jellyfish survival, and decreased under warmer ocean conditions.
Outbreaks are the result of a suite of influences, conclude the authors. This suggests that, unlike temperate species, which generally multiply as temperatures rise, jellyfish at high latitudes may not thrive in warming seas. Instead, the authors anticipate that jellyfish populations could move northward into the Arctic Ocean as the ocean warms.
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Newton, A. Northward bound. Nature Clim Change 1, 50 (2008). https://doi.org/10.1038/climate.2008.40