Chemical microgradients trigger coral death at Great Barrier ReefMar 28, 4:35 pm
Washington, March 28 (ANI): Researchers have examined corals from the Great Barrier Reef affected by the Black Band Disease and identified the critical parameters that allow this prevalent disease to cause wide mortality of corals around the world.Corals infected with Black Band Disease show a characteristic appearance of healthy tissue displaced by a dark front, the so-called Black Band, which leaves the white limestone skeleton of the coral animal exposed. The dark front is commonly one to two centimetres broad and consists of a complex microbial community among which there are phototrophic cyanobacteria, sulfur oxidizing bacteria and sulfate reducing microorganisms. The corals and their endosymbiotic algae are struck by three stress factors at once: toxic sulfide, anoxia, and a low pH at the boundary of the bacterial mat and the coral tissue.The scientists at the Max Planck Institute for Marine Microbiology along with Australian colleagues investigated the tissue lesions with microsensors for oxygen, sulfide and pH. These microprobes have a tip diameter in the micrometre range and allow the scientists to measure highly resolved depth profiles in the coral tissue. They identified big differences between infected tissue and tissue in the preliminary stage of the disease: "In diseased coral tissue two zones develop: A phototrophic zone at the top in which the cyanobacteria produce oxygen and a lower anoxic zone in which the bacteria degrade the necrotic coral tissue. Sulfide is formed in the degradation process," Martin Glas of the Max Planck Institute in Bremen explained the results."In tissue that is only slightly infected the zonation is not nearly that strong. Usually we could not detect sulfide, and oxygen penetrated deep into the bacterial mat," he said.At the front of the dark zone the conditions are particularly detrimental for the corals. The increased sulfide concentration around the necrosing tissue and the resulting decrease in oxygen leads to the spreading of the lesions to the surrounding, healthy tissue; a positive feedback that causes rapid migration of the Black Band Disease."We assume that the biogeochemical conditions at the surface of the coral tissue are responsible for the fast spreading of the disease. The higher the sulfide concentrations are and the less oxygen there is, the faster the dark front is migrating," Glas describes the causes for the origin and the high virulence of the disease.So far, at least, the scientists have not identified a pathogen that could be responsible for the necrosis of the coral tissue. "Our measurements show that the Black Band Disease can migrate at one centimetre per day in the summer months. At this speed, within a very short time, whole coral colonies can die and the population size of many coral species on the reef can number of species in the reef can drastically decline," said Martin Glas. (ANI)
Dawn of Antarctic ozone hole `healing` Jul 1, 12:28 pm
Washington D.C, Jul 1 (ANI): We are finally seeing a glimmer of good news for environment: ozone damage is on the mend!Full Story »
Turns out, revenge's a 'bittersweet' symphony Jun 30, 7:23 am
Washington D.C, Jun 30 (ANI): To get past it or to get even, that is the question. Now, a recent study has suggested that an eye for an eye can end up making us celebrating and feeling worse at the same time.Full Story »
We evolved 3 times faster post dino extinction Jun 29, 9:03 am
Washington D.C, Jun 29 (ANI): According to a new study, our ancestors evolved three times faster in the 10 million years after the extinction of the dinosaurs than in the previous 80 million years.Full Story »
Global variations in malaria parasites revealed Jun 28, 1:20 pm
Washington D.C, Jun 28 (ANI): A team of scientists has found that the malaria parasite Plasmodium vivax is evolving rapidly to adapt to conditions in different geographical locations.Full Story »
- This is your brain when buying music
- This new technique will help your shampoos' flow freely
- Radioactive fallout of Fukushima accident concentrated in glassy soot'
- LIGO may detect formation of black-hole binary stars: Study
- Driverless cars pose 'safety dilemma'
- Scientists have new theory on how 'climate' affects 'violence'
- Dinosaur-era bugs knew how to camouflage
- Earth's present magnetic field isn't 'same old, same old'
- Global warming forecast: Even warmer days ahead
- For volcanoes, 'calm before the storm' holds true
TOP VIDEO STORIES