Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

A question of light: Ocean acidification slows algae growth in the Southern Ocean

24.02.2015

In a recent study, scientists at the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI), demonstrate for the first time that ocean acidification could have negative impacts on diatoms in the Southern Ocean. In laboratory tests they were able to observe that under changing light conditions, diatoms grow more slowly in acidic water.

In so doing, Dr Clara Hoppe and her team have overturned the widely held assumption that sinking pH values would stimulate the growth of these unicellular algae. Their findings will be published today in the journal New Phytologist.


The single celled algae are exposed to different carbon dioxide concentrations and light intensities. (Photo: Alfred-Wegener-Institut/Clara Hoppe)

“Diatoms fulfil an important role in the Earth’s climate system. They can absorb large quantities of carbon dioxide, which they bind before ultimately transporting part of it to the depths of the ocean. Once there, the greenhouse gas remains naturally sequestered for centuries,” explains Dr Clara Hoppe, a biologist at the AWI and first author of the present study (learn more about the role of diatoms in this interview with Dr Clara Hoppe).

Scientists have so far worked under the assumption that the progressive acidification of the ocean could promote growth in diatoms, primarily because the additional carbon dioxide in the water can have a fertilising effect.

However, previous studies on the topic have overlooked an important aspect: the light environment. The previous experiments used stable unchanging light conditions. But constant light is hard to come by in nature, especially in the Southern Ocean, where storms mix the upper water layers. As Hoppe elaborates, “Several times a day, the wind and currents transport diatoms in the Southern Ocean from the uppermost water layer to the layers below, and then back to the surface – which means that, in the course of a day, the diatoms experience alternating phases with more and with less light.”

Under these conditions, the diatoms suffer most from insufficient light when they are in deeper water layers; this is why they grow more slowly in changing compared to constant light. So here they spend less time under optimal light conditions and have to constantly adjust from more light to less. But these conditions were not taken into account in experiments on ocean acidification so far.

The new study shows: This shifting light intensity significantly affects the reaction to ocean acidification. “Our findings show for the first time that our old assumptions most likely fall short of the mark. We now know that when the light intensity constantly changes, the effect of the ocean acidification reverses. All of a sudden, lower pH values don’t increase growth, like studies using constant light show; instead, they have just the opposite effect,” says Dr Björn Rost from the AWI, co-author of the study.

In experiments conducted at the Alfred Wegener Institute in Bremerhaven, the researchers investigated how the Antarctic diatom species Chaetoceros debilis grows in constant and in shifting light, respectively – and how the effects of the different light conditions change in todays as well as more acidic seawater.

The new study effectively demonstrates that there are surprising interactions between changing light conditions and ocean acidification. As a result, in a future scenario characterised by more acidic water under changing light intensities, diatoms’ biomass production could be drastically reduced.

The results also reveal that under ocean acidification the diatoms are especially sensitive when subjected to phases of higher light levels. As Hoppe relates, “At a certain intensity, the light actually begins to shut down and even destroy part of the photosynthesis chain, a phenomenon referred to as high-light stress. In these phases, the algae cells have to invest a great deal of energy to undo the damage done by the light. This point, at which enough light becomes too much light, is more quickly reached in acidic water.”

For their experiments, Hoppe’s team examined the diatom species Chaetoceros debilis. “Though it’s always difficult to generalise for all species on the basis of just one, Chaetoceros is one of the most important groups of diatoms and is often dominant in algal communities. Further, previous studies have shown that its responses to ocean acidification are fairly typical for other diatom species,” Hoppe explains.

Over the next few years, Clara Hoppe, Björn Rost and their colleagues will continue to explore how different algae species react to changes in their habitat, which species will benefit and which will suffer. The AWI researchers will next turn their attention to investigating plankton communities in the Arctic Ocean.

Notes for Editors:

The original paper was published in nature geoscience under the following title :
“Ocean Acidification decreases the light-use efficiency in an Antarctic diatom under dynamic but not constant light“ in the New Phytologist. DOI: 10.1111/nph.13334.

Photos are available here: http://www.awi.de/index.php?id=7484

To the interview with Dr Clara Hoppe: http://www.awi.de/index.php?id=7485

Your scientific contact persons at the Alfred Wegener Institute is: Dr. Clara Hoppe (phone: +49 471 4831-2096; e-mail: Clara.Hoppe(at)awi.de,).

Your contact person in the Dept. of Communications and Media Relations is Kristina Bär (phone: +49 471 4831-2139; e-mail: medien(at)awi.de).

Follow the Alfred Wegener Institute on Twitter and Facebook. In this way you will receive all current news as well as information on brief everyday stories about life at the institute.

The Alfred Wegener Institute conducts research in the Arctic, Antarctic and oceans of the high and mid-latitudes. It coordinates polar research in Germany and provides major infrastructure to the international scientific community, such as the research icebreaker Polarstern and stations in the Arctic and Antarctica. The Alfred Wegener Institute is one of the 18 research centres of the Helmholtz Association, the largest scientific organisation in Germany.

Ralf Röchert | idw - Informationsdienst Wissenschaft

More articles from Ecology, The Environment and Conservation:

nachricht Conservationists are sounding the alarm: parrots much more threatened than assumed
15.09.2017 | Justus-Liebig-Universität Gießen

nachricht A new indicator for marine ecosystem changes: the diatom/dinoflagellate index
21.08.2017 | Leibniz-Institut für Ostseeforschung Warnemünde

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

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

Im Focus: The fastest light-driven current source

Controlling electronic current is essential to modern electronics, as data and signals are transferred by streams of electrons which are controlled at high speed. Demands on transmission speeds are also increasing as technology develops. Scientists from the Chair of Laser Physics and the Chair of Applied Physics at Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) have succeeded in switching on a current with a desired direction in graphene using a single laser pulse within a femtosecond ¬¬ – a femtosecond corresponds to the millionth part of a billionth of a second. This is more than a thousand times faster compared to the most efficient transistors today.

Graphene is up to the job

Im Focus: LaserTAB: More efficient and precise contacts thanks to human-robot collaboration

At the productronica trade fair in Munich this November, the Fraunhofer Institute for Laser Technology ILT will be presenting Laser-Based Tape-Automated Bonding, LaserTAB for short. The experts from Aachen will be demonstrating how new battery cells and power electronics can be micro-welded more efficiently and precisely than ever before thanks to new optics and robot support.

Fraunhofer ILT from Aachen relies on a clever combination of robotics and a laser scanner with new optics as well as process monitoring, which it has developed...

Im Focus: The pyrenoid is a carbon-fixing liquid droplet

Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.

A warming planet

Im Focus: Highly precise wiring in the Cerebral Cortex

Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.

The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...

Im Focus: Tiny lasers from a gallery of whispers

New technique promises tunable laser devices

Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

“Lasers in Composites Symposium” in Aachen – from Science to Application

19.09.2017 | Event News

I-ESA 2018 – Call for Papers

12.09.2017 | Event News

EMBO at Basel Life, a new conference on current and emerging life science research

06.09.2017 | Event News

 
Latest News

Nerves control the body’s bacterial community

26.09.2017 | Life Sciences

Four elements make 2-D optical platform

26.09.2017 | Physics and Astronomy

Goodbye, login. Hello, heart scan

26.09.2017 | Information Technology

VideoLinks
B2B-VideoLinks
More VideoLinks >>>