Sponges as “water cleaner” raised dissolved oxygen concentrations of seawater, which was necessary for the appearance of animals 550 million years ago
About 550 million years ago, almost all of todays’ living animal phyla appeared on Earth within just a few million years. This expansion of metazoans is also known as the ‘Cambrian explosion’ and marks the beginning of the “Phanerozoic”, the era of ‘visible life’.
The causes of this most dramatic ecosystem change on our planet are still disputed. Geologists know that during this time, the concentration of free oxygen significantly increased in the atmosphere and the oceans. As metazoans (multicellular animals) need oxygen for breathing, this rise in oxygen levels was fundamental to their emergence. But what were the causes of this essential oxygen increase?
Scientists of the German Research Centre for Geosciences GFZ could show for the first time that marine sponges induced changes in the marine carbon and phosphorous cycles that caused a rise in seawater dissolved oxygen levels, providing the basis for the further expansion of metazoans. The study is published in the journal “Nature Communications”.
The GFZ-geochemists provided the evidence by means of a new method using stable silica isotopes – these subgroups of chemical elements that have different atomic masses. Siliceous sponges live on the seafloor and leave behind silicon-rich spicules (see photo) of their skeleton upon their death. However, these spicules are rarely preserved when old seafloor turns into rock.
Michael Tatzel and Friedhelm von Blanckenburg analysed silicon stable isotopes using a modern mass spectrometer to determine the abundance of siliceous sponges in sediments. They did so because silicon from these spicules is retained in shales and cherts (flintstones) and is enriched in “light” silicon-28 relative to silicon-30.
“Our reconstructions reveal an increasing abundance of siliceous sponges in sediments that were deposited between the Precambrian and the Cambrian on the continental slope of todays’ Yangtze Platform in South China”, says lead author Michael Tatzel.
But how does increasing sponge abundance relate to oxygen? Michael Tatzel investigated a multitude of geochemical indicators that react sensitively to the amount of oxygen dissolved in seawater. He found that simultaneously with sponges, the concentration of dissolved oxygen as well as the amount of organic carbon deposited in sediment increased. These fundamental changes resulted from the way sponges live.
Sponges extract organic carbon from seawater for feeding and could thus shift the oxidation of organic carbon to depth or even decreased oxidation. This change to the carbon cycle initiated a chain reaction: the increasing oxygen concentration promoted phosphate deposition and thus reduced phosphorous concentration in seawater and thereby the growth of algae that consume oxygen from seawater upon their death.
“This is, in our view, the first substantial evidence for the hypothesis that sponges functioned as ecosystem engineers and raised oxygen levels in seawater”, says Michael Tatzel. There is a good chance that this sponge-induced increase in oxygen levels exceeded the minimum requirement of multicellular life forms and thus triggered the ‘Cambrian explosion’.
Dr. Michael, Tatzel, email@example.com, 030-81044118
Prof. Friedhelm von Blanckenburg, firstname.lastname@example.org, 0331-2882850
Original study: Tatzel, M., von Blanckenburg, F., Oelze, M., Bouchez, J., Hippler, D., 2017. Late Neoproterozoic seawater oxygenation by siliceous sponges. Nature Communications. DOI: 10.1038/s41467-017-00586-5
Ralf Nestler | Helmholtz-Zentrum Potsdam - Deutsches GeoForschungsZentrum GFZ
Diving robots find Antarctic winter seas exhale surprising amounts of carbon dioxide
15.08.2018 | University of Washington
Algorithm provides early warning system for tracking groundwater contamination
14.08.2018 | DOE/Lawrence Berkeley National Laboratory
Scientists at the University of California, Los Angeles present new research on a curious cosmic phenomenon known as "whistlers" -- very low frequency packets...
Scientists develop first tool to use machine learning methods to compute flow around interactively designable 3D objects. Tool will be presented at this year’s prestigious SIGGRAPH conference.
When engineers or designers want to test the aerodynamic properties of the newly designed shape of a car, airplane, or other object, they would normally model...
Researchers from TU Graz and their industry partners have unveiled a world first: the prototype of a robot-controlled, high-speed combined charging system (CCS) for electric vehicles that enables series charging of cars in various parking positions.
Global demand for electric vehicles is forecast to rise sharply: by 2025, the number of new vehicle registrations is expected to reach 25 million per year....
Proteins must be folded correctly to fulfill their molecular functions in cells. Molecular assistants called chaperones help proteins exploit their inbuilt folding potential and reach the correct three-dimensional structure. Researchers at the Max Planck Institute of Biochemistry (MPIB) have demonstrated that actin, the most abundant protein in higher developed cells, does not have the inbuilt potential to fold and instead requires special assistance to fold into its active state. The chaperone TRiC uses a previously undescribed mechanism to perform actin folding. The study was recently published in the journal Cell.
Actin is the most abundant protein in highly developed cells and has diverse functions in processes like cell stabilization, cell division and muscle...
Scientists have discovered that the electrical resistance of a copper-oxide compound depends on the magnetic field in a very unusual way -- a finding that could help direct the search for materials that can perfectly conduct electricity at room temperatur
What happens when really powerful magnets--capable of producing magnetic fields nearly two million times stronger than Earth's--are applied to materials that...
08.08.2018 | Event News
27.07.2018 | Event News
25.07.2018 | Event News
15.08.2018 | Physics and Astronomy
15.08.2018 | Earth Sciences
15.08.2018 | Physics and Astronomy