Corals moving north
Some Pacific corals have done the equivalent of moving from sunny
Atlanta to , possibly in response to rising ocean temperatures. Detroit
A new study of reefs around
reveals that a handful of coral species have migrated from the balmy subtropics to temperate climate zones over the last 80 years. The study is the first to track coral reefs for such a long time and over several latitude lines, a Japanese team reports in an upcoming Geophysical Research Letters Japan
Taken with other studies that report animals moving north as temperature rises, it’s a good hypothesis that the corals in this study are moving to fight the heat, says John Pandolfi, a marine biologist at the
University of Queensland in . Researchers will next need to study these species in the lab to test whether temperature is truly the culprit. Brisbane, Australia
But adjusting the marine thermostat isn’t the only way to kill a coral. Too much acidity from high concentrations of carbon dioxide can also weaken coral reefs. So it’s peculiar that the Japanese corals moved north, says Pandolfi, because their new homes are likely more saturated with carbon dioxide. It appears corals are able and willing to make that trade-off, he says.
Importantly the study also showed no changes at the southern end.
"We show the first large-scale evidence of the poleward range expansion of modern corals, based on 80 years of national records from the temperate areas of Japan, where century-long measurements of in situ sea-surface temperatures have shown statistically significant rises. Four major coral species categories, including two key species for reef formation in tropical areas, showed poleward range expansions since the 1930s, whereas no species demonstrated southward range shrinkage or local extinction. The speed of these expansions reached up to 14 km/year, which is far greater than that for other species. Our results, in combination with recent findings suggesting range expansions of tropical coral-reef associated organisms, strongly suggest that rapid, fundamental modifications of temperate coastal ecosystems could be in progress." [Hiroya Yamano, Kaoru Sugihara, Keiichi Nomura 2011: Geophysical Research Letters]