The Great Barrier Reef has a microbial ecosystem far vaster than classical observations suggested. Analysis of DNA present in the water revealed hundreds of unknown bacterial species, as well as hundreds of thousands of viruses.
Researchers studied water samples collected from 48 reefs. Their method allows simultaneous analysis of genetic traces from many organisms. It thus provides access to a part of marine biodiversity that is generally difficult to observe.
Details of the Great Barrier Reef.
Image Wikimedia
The study recorded 5,283 genomes of bacteria and archaea. They correspond to 876 distinct species, of which 584 were not yet represented in public databases. These microscopic organisms form an essential part of the reef's biological functioning.
Scientists also identified 808,585 viral genomes. They correspond to approximately 362,802 distinct virus types. Most are not directly associated with any known disease. In the ocean, viruses infect bacteria and influence nutrient cycling.
This mapping is not just an inventory. Microbial communities could serve as early indicators of reef health. Their composition can change before the appearance of visible signs related to warming, bleaching, or pollution.
Researchers created a database compiling the identified genomes. It should allow other teams to compare microbiomes across reefs and environmental conditions. These comparisons could also help distinguish characteristics of a healthy or degraded reef.
The Great Barrier Reef is an ecosystem under many pressures. This study alone does not yet measure the effect of each threat on microbes. It mainly provides a detailed reference to track their changes over time.