Amazing stuff! We still know so little about our oceans!
When will autonomous submersibles investigate the flora and fauna at the depth of our oceans? I bet, we will learn a lot more surprising things!
It appears the same Chinese research institute, i.e. Institute of Deep-sea Science and Engineering, Chinese Academy of Sciences, Sanya, China, has previously published a similar study, but more focused on genetic analysis. See Life at depth over 10,000 meters: breakthrough genomic study reveals population dynamics and adaptation to the extreme hadal environments
"The ocean’s mysterious hadal zone, which lies within trenches between 6000 and 11,000 meters down, is one of the least explored habitats on the planet. Recent studies have demonstrated that this abyss is home to a remarkable diversity of life, which manages to thrive despite crushing pressures and frigid temperatures. But many of these organisms, particularly those that are permanently attached to hard, rocky substrates, remain difficult for scientists to sample.
To investigate these deep-sea communities, researchers aboard the Chinese submersible Fendouzhe descended into the darkness of the Kermadec and Mariana trenches. As the team reports in a new study, collected rock samples revealed 32 species, mainly consisting of single-celled organisms called protists, most of them new to science .
The team did find some larger fauna, including two sea anemones, a carnivorous sponge, and a marine worm.
But the vast majority of the observed critters were millimeter-sized and living in a variety of dense formations on rock surfaces, from tubes and chains to large mats. Some organisms were slender and sparsely branched, while others had tiny, bead-like chambers.
One flat, encrusting bryozoan was so transparent that it only became visible once the rocks dried.
Researchers have previously assumed that these organisms get their energy from inorganic chemicals, so the study authors were surprised to find that many of their sampled specimens appear to feed on organic matter. Some have a diet consisting of pine pollen grains, which are transported from the land by wind and ocean currents before settling in trenches."
From the editor's summary and abstract:
"Editor’s summary
Characterizing life at the deepest depths of the ocean is extremely challenging, involving sampling at depths between 9000 and 11,000 meters. Our knowledge of these communities is thus relatively limited. Song et al. report a wide array of species sampled by a manned submersible in the Kermedec and Mariana trenches. They describe a new fauna characterized by mostly filamentous and sedentary protists and forams. Particularly surprising was the presence of heterotrophic, rather than chemolithoautotrophic, organisms feeding on terrestrial pine pollen. The authors argue that similar communities occur across the deepest ecosystems, with implications for understanding carbon hotspots at these depths. ...
Abstract
Deep-sea hard substrates host faunal novelties and distinct evolutionary lineages. However, sessile organisms on rocks are difficult to sample and largely unknown at extreme hadal depths.
Here, we report a deep hard-substrate fauna (9000 to 10,898 meters), comprising 32 species of six protist and metazoan phyla, most millimeter-sized and new to science, from the Kermadec and Mariana trenches, using the manned submersible Fendouzhe.
We show that the filamentous organisms dominating these assemblages are heterotrophic foraminiferans, challenging the earlier chemolithoautotrophic hypothesis.
Large-scale seafloor imaging and sampling suggest that similar protistan-dominated sessile communities thrive in seven hadal regions around Oceania. These faunas open new perspectives on biodiversity at the deepest ocean depths and unveil widespread, but previously unrecognized, carbon hotspots in global hadal trenches."
Project 5921 (Apparently, the project website for this research paper. Contains e.g. lots of images.)
Protist-dominated hard substrate faunas thrive at the deepest ocean depths (no public access)
This protist, which scientists recovered from a deep ocean trench, contained dozens of pine pollen grains in various stages of digestion.
Some of the several hundred photos from the project website
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