Ocean Life in Hot Water

Global warming is taking a toll on fish-and helping jellyfish rule the sea

By Bjorn Carey Posted 03.30.2007 at 1:00 am 1 Comment

by Raimundo Valentim/epa/Corbis Fried Fish Warmer oceans could mean fewer fish in the sea--and pricier seafood. Raimundo Valentim/epa/Corbis

Paltry Plankton Using a decade's worth of satellite data, scientists have determined that rising ocean temperatures are killing phytoplankton. Not only do these tiny plants form the base of oceanic food webs, they also process as much carbon dioxide and produce as much oxygen as land plants do. Although the findings may be influenced by El Nio, the researchers say the the study provides a sneak peek at how ocean biology will evolve as the climate continues to change.

Gasping for Air German scientists have found that eelpouts (elongated fish with eel-like heads) require more oxygen to perform basic functions as water temperatures increase-a big problem because warmer waters contain less oxygen. Despite eelpouts' better-than-average tolerance of thermal fluctuations, their population decrease in the North Sea has coincided with rising temperatures. Less-hardy fish such as Atlantic cod are suffering similar effects.

Heat Misers Jellyfish will actually thrive in warmer oceans-bad news for dozens of fish species, says biologist Martin Attrill of the University of Plymouth in England. Attrill has analyzed 50 years' worth of data from the North Sea and found that jellyfish are more prevalent in warm-water years. As seas continue to heat up, this could pose trouble for cod, salmon and other commercial fish: Jellyfish not only outcompete fish larvae for food but eat them too.

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