Some corals like it hotter.The heat-tolerant algae algae (ăl`jē) [plural of Lat. alga=seaweed], a large and diverse group of primarily aquatic plantlike organisms. These organisms were previously classified as a primitive subkingdom of the plant kingdom, the thallophytes (plants that that live symbiotically sym·bi·o·sis n. pl. sym·bi·o·ses 1. Biology A close, prolonged association between two or more different organisms of different species that may, but does not necessarily, benefit each member. 2. within some corals may enable their hosts to adapt to the warmer water temperatures projected to accompany long-term climate change, field studies suggest. Many coral polyps Polyps A tumor with a small flap that attaches itself to the wall of various vascular organs such as the nose, uterus and rectum. Polyps bleed easily, and if they are suspected to be cancerous they should be surgically removed. that make up shallow reefs draw much of their nourishment from algae that live within the polyps. Those algae, all from the genus Symbiodinium, capture the energy of sunlight and pass along some stored energy to their hosts, says marine biologist Andrew C. Baker of the Wildlife Conservation Society in New York City New York City: see New York, city. New York City City (pop., 2000: 8,008,278), southeastern New York, at the mouth of the Hudson River. The largest city in the U.S. . Many species of the genus die off if the water temperature suddenly spikes by even a few degrees. That happened during an El Nino that began in 1997. Warmer-than-normal water temperatures bathed reefs off the Pacific coast of Panama, and many coral colonies died or temporarily lost their algal algal pertaining to or caused by algae. algal infection is very rare but systemic and udder infections are recorded. See protothecosis. algal mastitis the algae Prototheca trispora and P. symbionts. In 1995, 43 percent of the colonies hosted more heat-tolerant species of Symbiodinium, a grouping known as clade clade Cladus, subtype Genetics A branch of biological taxa or species that share features inherited from a common ancestor; a single phylogenetic group or line. See Inheritance, Species. D. These corals didn't show ill effects of heat when observed in 1997, says Baker. By 2001, 63 percent of the colonies at the Panamanian sites hosted clade D symbionts. Baker and his colleagues present their findings in the Aug. 12 Nature. Results of the Panamanian field surveys, as well as of studies on reefs in the Persian Gulf, Red Sea, and the western Indian Ocean, suggest that heat-tolerant clade D symbionts become more abundant on reefs after heat-induced damage, which is called bleaching. It's not yet clear whether that change stems from higher survival rates among hosts inhabited by clade D algae or from those symbionts' colonization of recently bleached polyps, says Baker. In either case, he notes, these algae may permit some corals to adapt to the increased water temperatures expected to result from global warming. |
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