AZORES ISLANDS (8 Jan 2003) -- Numerous microscopic creatures, many never before seen or identified, have been found living in and around hydrothermal vents deep in the Atlantic Ocean, indicating that the Atlantic supports its own unique ecosystem. The creatures, several single-celled microbes, were found in samples taken from the Lucky Strike and Rainbow sites at the Mid Atlantic Ridge, located just over a mile down into the Atlantic near the Portuguese Azores Islands. Findings are published in the current Proceedings of the National Academy of Sciences. Laboratory sequencing determined that the microbes consisted of known and unknown forms of eukaryotes, organisms composed of one or more cells that contain a nucleus. "Many of the microbial eukaryotes that we have found are not closely related to the species that (have already been) recognized but, on the contrary, they are new species and, in certain cases, they may even constitute new eukaryotic kingdoms," said David Moreira, a member of the French Research Council whose laboratory is located at the University Paris-Sud, and one of the paper's authors. Of the known species, Moreira and his team were surprised to find some thought to exist only in the Pacific Ocean's Guaymas Basin. They also found species that appear to be unique to the Atlantic. Most seem to fall into the alveolate group, which includes already known species like ciliates and dinoflagellates. Conditions are harsh near the vents, where water seeps through cracks in the seafloor and is heated to as high as 400 degrees Celsius (752 Fahrenheit) by molten rock deep below the ocean crust. Any life there must take advantage of all the food sources it can. | | "We think that many of them probably feed by predating or grazing on the very rich populations of bacteria and archaea that also live in hydrothermal regions," Moreira told Discovery News. "In addition we suspect that some other of these microbial eukaryotes are probably parasites." Bivalves, such as clams, thrive near the vents, and could be hosts for the parasitic microbes. W. Ford Doolittle, professor of Biochemistry and Molecular Biology at Dalhousie University in Canada, and an expert on eukaryotic origins, believes that Moreira and his team are engaged in "very important work." Since hydrothermal systems have existed since perhaps the beginning of Earth's history, it is possible that ancient forms of eukaryotes without mitochondria - small, granular bodies within cells - may be present at the vents. "We do not know if they exist," said Moreira, "but their discovery would be amazing since they would be the missing link that would tell us extremely important information about the early evolution of our own distant ancestors." SOURCE - Discovery News |
