Ecology: Predators attract

Cited research Proc. Natl Acad. Sci.USA doi:10.1073/pnas.1004519107 (2010)

Some fish species may be threatened by climate change because they become more attracted to the smell of predators in water acidified by high concentrations of dissolved carbon dioxide.

Eight-day-old clownfish (Amphiprion percula) reared in water with a concentration of 850 parts per million (p.p.m.) of CO₂ — the level expected by 2100 — spent more than 94% of their time in a stream of water spiked with a predator's chemical cue. Control clownfish in water containing present-day CO₂ concentrations of 390 p.p.m. avoided the dangerous stream altogether.

And when put back into their natural coral-reef setting, wild-caught damselfish (Pomacentrus wardi) larvae exposed to acidified water in the lab were up to nine times more likely to be killed by predators than were control larvae.

The study by Philip Munday at James Cook University in Townsville, Australia, and his colleagues warns that if other species react in the same way, fish populations could be devastated if atmospheric CO₂ levels continue to rise. N.G.