When filmmaker James Cameron descended into the Mariana Trench in 2012, he found that there was little movement there: the abyssal depths are not exactly a spectacle of marine biodiversity. Although this is not entirely true, because the director of Titanic only explored what is seen with the naked eye. In reality, life bustles on a microscopic level , as recent research has shown.
In addition, the latest study carried out in the deepest point of the Mariana Trench and, therefore, of the entire planet – the Challenger Abyss, almost 11,000 meters below sea level – has found that a type of peculiar life: heterotrophic bacteria, which, for example, are also abundant in raw sewage. Unable to synthesize their own food, these microbes obtain chemical energy from other organic compounds.
The authors of the research, from the Japanese agency for maritime-terrestrial science and technology (JAMSTEC), report in the journal Proceedings of the National Academy of Sciences that the heterotrophic bacteria of the Challenger Abyss feed on floating particles such as faecal debris dissolved in the water, dust, and possibly organic sediment expelled from earthworks that produce underwater earthquakes . These collapses are relatively frequent on a geological time scale and release “succulent” particles for bacteria for a long time, conjectures Takuro Nunoura, director of the research.
Nunoura’s team has collected genetic samples from the Challenger Abyss with a remote-controlled vehicle. With the results of his exploration, a more precise map of microscopic life in the oceans can be made : phytoplankton abound on the surface, which needs light to carry out photosynthesis; from a depth of 2,000 meters, chemotrophic microorganisms, which transform inorganic compounds such as ammonia or sulfur into food; and from 6,000 meters the heterotrophs that the study reveals reign.
