Once upon a time, tropical fish were found only in the world’s tropical waters, those areas between the 23.5° lines of latitude called Capricorn and Cancer, or thereabouts. The reason: there was balance on the reefs, ecosystems unto themselves that thrived in the warm temperatures. Everywhere else, the green depths in the so-called temperate regions, was just too darn cold. Which is to say that prior to the 1970s and 1980s, before massive tracts of coral reef from Australia to Southeast Asia to the Indian Ocean and the Caribbean were bleached to death, unable to support the ecosystems, such fish knew their place.
But recent reports show that angelfish, a colorful, wedge-shaped, formerly-from-the-reef species with exaggerated, almost comical-looking lips, have been prowling the waters off Massachusetts. Like aquatic pioneers who sense a certain danger in the heat – world ocean temperatures have risen 0.9° since 1975 – the angelfish is perhaps attempting to manifest some northern destiny by exploring new possibilities.
A four-scientist team, including two climate scientists, a marine ecologist and a marine biologist, announced this summer that the wandering tropical species is not surprising, given the warming oceans.
“Ocean experts have spotted larvae of butterfly, angelfish and other tropical fish floating in coastal waters as far north as Woods Hole, Mass.,” announced a report by the environmental lobby Environmental Defense, through its campaign for global warming awareness called Oceans Alive. “This evidence points to fish shifting their ranges in response to warming waters.”
“About 15 years ago, some of us in the scientific community were met with a firestorm of criticism from some of our colleagues when we said that the episodes of mass coral bleachings during the 1980s and ’90s were probably due to climate change,” said Environmental Defense marine ecologist Rod Fujita. “Many scientists thought we were crazy, and many thought the oceans could absorb the extra heat pretty well.”
Tropical waters have seen double the heat increase of more temperate waters, according to the report. “[O]cean waters in many tropical regions have risen by almost 2 degrees F (1 degree C) over the past century,” the report reads. “This is 30 times the amount of heat that has been added to the atmosphere, a significant amount even though the ocean has a lot more mass than the atmosphere.” The worst bleaching occurred in 1997 to 1998, when the oceans reached an all-time high average temperature.
“Even five years ago, most people had no inkling of the extent to which global warming was affecting the oceans – but slowly over the years, a consensus has been building,” Fujita said. “Today, we are witnessing impacts that we largely attribute to warming – like the bleaching of corals, changing fish habitat. We’ve gone from denial to talking about how to manage the impacts and reduce the threat of climate change.”
Two articles in the journal Science this past spring and summer describe the unification of the scientific community on the theory of global warming. The most recent article suggested further signs of warming oceans – besides good snorkeling off Cape Cod – will include water shortages due to decreased snowpack in the world’s high peaks.
“The ship is already in motion, and it will take immediate action to turn it away from the danger ahead,” said Environmental Defense climate scientist Dr. James Wang. The full report is viewable at www.oceansalive.org.