Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Breath-taking moments in the Black Sea: Periodic hypoxia affects seafloor fauna and carbon turnover

13.02.2017

Periodic oscillations of bottom-water oxygen concentrations can alter benthic communities and carbon storage for decades, reveals a new study published in Science Advances. This is particularly relevant as low oxygen conditions are on the rise in the world’s oceans.

The seafloor plays a key role in the global elemental cycles. Its inhabitants consume and recycle organic matter sinking to the bottom. Usually, only a minor part of that material gets buried in the seafloor. The lion’s share is remineralised by seafloor life – i.e. broken down and fed back to the ecosystem for the production of new biomass. Thus, the fate of this material at the seafloor crucially impacts global carbon and nutrient cycling and, as a consequence, marine productivity and our climate.


Sediment was retrieved with a Multicorer to allow for a detailed analysis of sediment biogeochemistry and its inhabitants along a transect of oxygen concentrations.

R. North, Eawag, Switzerland


Retrieval of cores from the seafloor with the submersible JAGO. Below the black layer that is visible close to the sediment surface the sediment is free of oxygen.

JAGO-Team, GEOMAR Kiel

Temporary shortage, long-term storage

Animals need oxygen to breathe. Hence, declining bottom-water oxygen supply negatively impacts the community composition and activity of marine sediments. To which extent it also determines remineralisation and thus carbon burial rates remained controversial.

Gerdhard Jessen from Max Planck Institute for Marine Microbiology in Bremen, Germany, and an international team of researchers reveal in Science Advances that declining bottom-water oxygen concentrations significantly influence carbon storage in the seafloor for decades. This effect happens earlier then previously thought and over larger areas of seafloor. When oxygen runs short, substantially less organic matter is remineralised and substantially more gets buried. And what gets buried stays buried for a long time.

„The amount of organic matter ending up in the seafloor increases by half when the seafloor is periodically short of oxygen”, says Jessen. „Even tasty and easily available bits, such as freshly deposited algal material, are not consumed.”

The Black Sea as a natural laboratory

Simulating such long-term and complex processes in the lab is hard to do. Therefore, Jessen and his colleagues took research vessel Maria S. Merian to the Black Sea, the largest naturally anoxic water body in the world, within the framework of the EU FP7 project HYPOX.

There, stable stratification results in a natural gradient of bottom-water oxygen concentrations at the outer shelf, ranging from well-oxygenated shallow waters over variable oxygen conditions to anoxic deeper waters below about 160 metres water depth. This provides for close-to-perfect experimental conditions. „We used the Black Sea seafloor as a natural laboratory. It allowed us to investigate what might be coming up to many party of the world’s oceans”, Jessen says.

„Low-oxygen areas in the oceans are on the rise, mainly as a consequence of anthropogenic nutrient inputs and climate change”, explains Antje Boetius, senior author of the study and group leader of the HGF-MPG Research Group for Deep Sea Ecology and Technology. „Thus, it is particularly important to understand and measure what oxygen stress in the oceans means for their inhabitants as well as the global biogeochemical cycles.”

Changing seafloor life

How come that the effects are so drastic if the seafloor runs periodically out of breath? „Oxygen deficiency changes the faunal community of the seafloor “, Boetius elaborates. In particular larger animals, such as worms and mussels, cannot survive without it. These animals rummage through the sediment looking for food and shelter, intermixing oxygen and nutrients for smaller seafloor inhabitants in the process. „The large organisms disappear when oxygen is scarce. Sediment bacteria alone are then responsible for the remineralisation of the organic matter arriving at the seafloor, but they move slowly and take very long to break down complex materials without the help of animals.”

As a result, under hypoxic conditions more organic material is buried and thus removed from the system. Anaerobic microorganisms, gaining their energy without oxygen for example by fermentation or sulphate reduction, take the helm. These also produce toxic sulphide, further slowing down the breakdown of materials.

„The Black Sea can teach us many lessons”, says Boetius, „as it clearly reveals the effects of fluctuating and low oxygen conditions on the ocean ecosystem, causing tremendous changes in the services of the ecosystem to us humans. Investigations as the current one are thus essential in the face of global change, to detect warning signals from the ocean in time.“

Original publication
Gerdhard L. Jessen, Anna Lichtschlag, Alban Ramette, Silvio Pantoja, Pamela E. Rossel, Carsten J. Schubert, Ulrich Struck, Antje Boetius: Hypoxia causes preservation of labile organic matter and changes seafloor microbial community composition (Black Sea). Science Advances 2017. DOI: 10.1126/sciadv.1601897

Participating institutes
Max Planck Institute for Marine Microbiology, Bremen, Germany
Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany

University of Concepción, Concepción, Chile
ICBM-MPI Bridging Group, University of Oldenburg, Oldenburg, Germany
Eawag: Swiss Federal Institute of Aquatic Science and Technology, Kastanienbaum, Switzerland
Museum für Naturkunde, Leibniz-Institut für Evolutions- und Biodiversitätsforschung, Berlin, Germany

Please direct your queries to

Dr. Gerdhard Jessen
E-Mail: gjessen(at)mpi-bremen.de or

Prof. Dr. Antje Boetius
Phone: +49 421 2028 860
E-Mail: aboetius(at)mpi-bremen.de

or the press office

Dr. Fanni Aspetsberger
Dr. Manfred Schlösser
Phone: +49 421 2028 947
E-Mail: presse(at)mpi-bremen.de

Weitere Informationen:

http://www.mpi-bremen.de/en/Breathtaking_moments_in_the_Black_Sea.html

Dr. Fanni Aspetsberger | Max-Planck-Institut für marine Mikrobiologie

More articles from Earth Sciences:

nachricht By saving cost and energy, the lighting revolution may increase light pollution
23.11.2017 | Helmholtz-Zentrum Potsdam - Deutsches GeoForschungsZentrum GFZ

nachricht Frictional Heat Powers Hydrothermal Activity on Enceladus
23.11.2017 | Universität Heidelberg

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Frictional Heat Powers Hydrothermal Activity on Enceladus

Computer simulation shows how the icy moon heats water in a porous rock core

Heat from the friction of rocks caused by tidal forces could be the “engine” for the hydrothermal activity on Saturn's moon Enceladus. This presupposes that...

Im Focus: Nanoparticles help with malaria diagnosis – new rapid test in development

The WHO reports an estimated 429,000 malaria deaths each year. The disease mostly affects tropical and subtropical regions and in particular the African continent. The Fraunhofer Institute for Silicate Research ISC teamed up with the Fraunhofer Institute for Molecular Biology and Applied Ecology IME and the Institute of Tropical Medicine at the University of Tübingen for a new test method to detect malaria parasites in blood. The idea of the research project “NanoFRET” is to develop a highly sensitive and reliable rapid diagnostic test so that patient treatment can begin as early as possible.

Malaria is caused by parasites transmitted by mosquito bite. The most dangerous form of malaria is malaria tropica. Left untreated, it is fatal in most cases....

Im Focus: A “cosmic snake” reveals the structure of remote galaxies

The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.

Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...

Im Focus: Visual intelligence is not the same as IQ

Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.

That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...

Im Focus: Novel Nano-CT device creates high-resolution 3D-X-rays of tiny velvet worm legs

Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.

During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Ecology Across Borders: International conference brings together 1,500 ecologists

15.11.2017 | Event News

Road into laboratory: Users discuss biaxial fatigue-testing for car and truck wheel

15.11.2017 | Event News

#Berlin5GWeek: The right network for Industry 4.0

30.10.2017 | Event News

 
Latest News

Underwater acoustic localization of marine mammals and vehicles

23.11.2017 | Information Technology

Enhancing the quantum sensing capabilities of diamond

23.11.2017 | Physics and Astronomy

Meadows beat out shrubs when it comes to storing carbon

23.11.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>