Reef fish cope with low oxygen.Despite their seemingly idyllic surroundings, coral reef coral reef
Ridge or hummock formed in shallow ocean areas from the external skeletons of corals. The skeleton consists of calcium carbonate (CaCO3), or limestone. A coral reef may grow into a permanent coral island, or it may take one of four principal forms. fish show unexpected toughness, according to a new analysis offish off·ish
Inclined to be distant and reserved; aloof.
In the first tests of low-oxygen tolerance among reef fish, all 31 species captured off the coast of Australia did surprisingly well, says G6ran E. Nilsson of the University of Oslo The University of Oslo (Norwegian: Universitetet i Oslo, Latin: Universitas Osloensis) was founded in 1811 as Universitas Regia Fredericiana (the Royal Frederick University . The reef fish matched the performance of the epaulette shark, famed for surviving oxygen drops in tide pools cut off from the surf, Nilsson and Sara Ostlund-Nilsson report in an upcoming Proceedings of the Royal Society Proceedings of the Royal Society is a scientific journal published by the Royal Society of London.
Today, the Royal Society publishes two proceeding series:
When respiration physiologists look for adaptation to low oxygen, they poke around in still waters, such as swamps and tide pools, says Nilsson. But coral reefs? "It's not something that most people have bothered about," he says. Plenty of churning there should mix the seawater seawater
Water that makes up the oceans and seas. Seawater is a complex mixture of 96.5% water, 2.5% salts, and small amounts of other substances. Much of the world's magnesium is recovered from seawater, as are large quantities of bromine. well enough to avoid oxygen drops.
Nilsson didn't think to look for low-oxygen tolerance at reefs until he began to observe mouth brooding in cardinalfish around Lizard Island on Australia's Great Barrier Reef Great Barrier Reef, largest complex of coral reef in the world, c.1,250 mi (2,000 km) long, in the Coral Sea, forming a natural breakwater for the coast of Queensland, NE Australia. . A male of these small reef fish takes a female's egg mass, sometimes a quarter of his body weight, into his mouth for a week or two, until the eggs hatch. Since the egg mass might inhibit water flow through the mouth to the gills, Nilsson wondered whether these fish have a special capacity to tolerate low oxygen.
To test the cardinalfish, the researchers sealed them temporarily in containers with seawater and a sensor for oxygen concentration. Many organisms keep consuming the available oxygen at a steady rate until there's so little left that they no longer metabolize me·tab·o·lize
1. To subject to metabolism.
2. To produce by metabolism.
3. To undergo change by metabolism.
to subject to or be transformed by metabolism. normally. The cardinalfish surprised Nilsson by breathing steadily until the oxygen concentration had dropped to 20 percent of its normal concentration.
At first, Nilsson says, he thought he'd found especially low oxygen tolerance in cardinalfish. For comparison, he decided to test reef fish that don't carry broods in their mouths. Surprisingly, he says, all the species he caught showed low-oxygen tolerance.
Data by other researchers show that some freshwater fish such as trout proved only half as tolerant of low oxygen as the reef fish did. The most tolerant of swamp fish require only a little less oxygen than the most tolerant of the reef fish do. Nilsson notes that no one has made comparable measurements on ocean fish away from reefs.
Perhaps reef fish hide in low-oxygen culde-sacs of coral, Nilsson speculates. In lab measurements, he found that those pockets can have oxygen concentrations below 20 percent of saturation.
Physiologist Jeff Graham of the Scripps Institution of Oceanography Scripps Institution of Oceanography: see California, Univ. of. in La Jolla, Calif., says that plenty of questions remain. He'd like to see comparisons between fish that hide in reef nooks and those that don't.