The reporter learned from the Institute of Deep Sea Science and Engineering of the Chinese Academy of Sciences that the "Global Abyss Exploration Project" led by the institute has made major discoveries. The scientific expedition team observed a large number of cetacean fossils and a complete whale fall ecosystem in the Diamantina Abyss in the southeastern Indian Ocean. This has also become the deepest and largest known whale fossil group and whale fall distribution area in the world. The results were published in the international academic journal "Nature" on June 10.
The whale fall ecosystem in the sulfur oxidation stage of the Diamantina Abyss. a-c, Antarctic minke whale whale fall, about 5 meters long, water depth 5610 meters. d, e, beaked whale whale fall, composed of 8 ribs and several thoracic vertebrae, the water depth is 5609 meters. f, whale bone, unknown species. g, the deepest known whale drop, consisting of three slender vertebrae of beaked whales, with a water depth of 6,789 meters. The distance between two red laser spots is 10 cm, and the scale bar is 5 cm.
A whale fall is a special ecosystem formed when a whale dies and sinks to the bottom of the sea. For a long time, most of the whale falls observed by humans have been distributed in waters with a water depth of less than 4,000 meters. The previous deepest record was 4,204 meters. However, there have been no scientific records related to whale falls in abyss areas with water depths exceeding 6,000 meters.
In 2023, the "Global Abyss Exploration Plan" scientific research team boarded the "Discovery 1" scientific research vessel and used the "Struggle" manned deep submersible to complete 32 dive operations at the bottom of the 1,200-kilometer Diamantina Abyss. At a water depth of 4,616 meters to 7,001 meters, a total of 5 whale falls in the chemoautotrophic stage and 476 cetacean fossil accumulations were discovered. The density of cetacean remains in the area reaches 759.5 per square kilometer. It is estimated that the total number of cetacean remains in the entire sea area may exceed 10 million. The study also identified 5 species of beaked whales and 2 species of baleen whales. One whale fall at a depth of 6,789 meters is the deepest whale fall ecosystem known today; the other whale fall at a depth of 5,610 meters was about 5 meters long, the largest whale fall discovered this time. The wreckage was determined to belong to the Antarctic minke whale. The surface of these whale bones is covered with rich microorganisms and animal communities, and the scientific expedition team discovered a total of 35 species of macrobenthic animals.
Fossilized beaked whale skull from the Diamantina Deep. a, b, Angler's beaked whale. c, d, Long-toothed beaked whale. e–g, Diamantina beaked whale. h, Benguela winged whale. i, Roche's Iziko beaked whale. Dashed lines indicate indeterminate sutures. The diagonal lines indicate the main fracture surfaces. Scale bar 20 cm.
The whale bone fossils discovered this time include both living whales and extinct whales, such as the new species of ancient beaked whales published. According to isotope calculations, these fossils can be traced back to 5.3 million years ago, and also prove that whale falls have continued to occur in this abyss for millions of years. The special terrain, extremely low sedimentation rate, and the fact that some beaked whales are prone to death during deep diving may have created this natural whale "graveyard."
This study has raised the water depth record of whale falls from 4,204 meters to nearly 7,000 meters, comprehensively refreshed human understanding of the distribution of whale falls, and provided extremely precious research samples for exploring the early evolutionary history of whales, paleoecology, and the evolution of deep-sea chemical energy ecosystems.