One Third of Reef-Building Corals Face Extinction Risk
In terms of promoting and supporting the greatest variety of life, reef corals are the “rain forests” of the oceans.
The corals themselves also have commercial value (for jewelry, aquarium decoration, etc.). Corals–symbiotic colonies of plant-like and animal-like creatures–have existed on this planet for tens of millions of years. However, some 45% of all coral species went extinct around the same time as the dinosaurs did. Hardest hit were a group of photosynthesizing, algae-harboring corals known as zooxanthellates. The symbiotic , red-brown algae that co-exist with these corals (and provide their energy source) are known as zooxanthellae.
Marine scientists have noted for several years now the spread of a coral disease known as Yellow Band Disease (YBD)–so named for the yellowish bands that spread across coral polyps–but had attributed its spread to thermal stress caused by global warming. Thermal stress is known to weaken much marine life, including corals, shellfish, and some species of zooplankton. But in November of 2008, researchers at Woodshole Oceanographic Institute (WHOI), on Cape Cod, Massachusetts, isolated the bacteria that caused YBD–actually four species of Vibrio bacteria that combine with the indigenous Vibrio bacteria to attack zooxanthellae (see the paper in the Journal of Applied Microbiology).
