In a new study, scientists from the ZMT have noted significant changes in the calcareous skeleton of the alga Halimeda as a result of a more acidic water environment. These may have an impact on the formation of tropical beaches and islands, as the calcareous structures of Halimeda are an important component of their sediments.
The acidification of the oceans is increasing inexorably. In particular, marine organisms with calcareous skeletons such as sea shells, corals or calcareous algae can suffer. In a new study, scientists from the Leibniz Center for Tropical Marine Ecology (ZMT) in Bremen have noted significant changes in the calcareous skeleton of the green alga Halimeda as a result of a more acidic water environment.
These changes are an indication of the processes that occur at a lower pH level – that is, in more acidic water – in the skeleton of the calcareous alga. Since sandy beaches in many tropical regions largely consist of skeletal fragments of these algae, these changes may have an impact on the composition and formation of tropical beaches and islands.
In the seawater facility of the ZMT, the researchers exposed the Halimeda algae to water with a lower pH level, as may be found in many regions of the oceans 40 to 50 years from now. For the first time, the research group focused on the structure of the algal skeleton.
“While many studies on calcareous algae or corals have thus far only compared the quantity of calcareous skeleton produced at different pH values, we concentrated on the microstructure of the skeleton. For this purpose, we used our scanning electron microscope which can magnify the structures of animals and plants up to 100,000 times“, said biologist Andre Wizemann, one of the authors of the study.
As the researchers observed, the Halimeda alga forms a skeleton of fine calcareous needles, which are formed during the day at the cellular surface. At night these needles recrystallise – they partially dissolve and fuse to a dense, compact skeleton armor. Thus, the alga protects itself from predators and gains stability, so that it can survive at higher water flow, for example at the edges of coral reefs.
However, such a massive skeleton can only form if the calcium saturation in the surrounding water is high. At a lower pH level the content of calcium carbonate in the sea decreases. “In the algae from the more acidic water we mainly found just the fine needles which were formed by the algal cells. While the calcium production of the alga was not hindered, it lacked the solid support structure because the process of recrystallisation was disturbed,” said Wizemann.
The small Halimeda algae may not seem very spectacular at first glance. “In warmer coastal regions, however, the calcareous structures of the dead Halimeda algae are an important component of sediments,” Wizemann added. “On the Caribbean islands their skeletal parts can comprise up to 50% of the beach sand.” If their calcareous skeleton is weak and brittle, this can have far-reaching consequences. The fine calcareous needles dissolve more easily in water than a compact skeleton does. Therefore, not much remains of the algae after their death. This in turn could have a negative effect on the formation of tropical beaches and coral reef islands, which consist largely of calcareous sediments.
Wizemann, A., Meyer, F.W., Hofmann, L.C., Wild, C., Westphal, H. (2015). Ocean acidification alters the calcareous microstructure of the green macro-alga Halimeda opuntia. Coral Reefs 34(3), pp. 941-954. DOI: 10.1007/s00338-015-1288-9.
Dr. Susanne Eickhoff | idw - Informationsdienst Wissenschaft
How does the loss of species alter ecosystems?
18.05.2017 | Deutsches Zentrum für integrative Biodiversitätsforschung (iDiv) Halle-Jena-Leipzig
Excess diesel emissions bring global health & environmental impacts
16.05.2017 | International Institute for Applied Systems Analysis (IIASA)
Two-dimensional magnetic structures are regarded as a promising material for new types of data storage, since the magnetic properties of individual molecular building blocks can be investigated and modified. For the first time, researchers have now produced a wafer-thin ferrimagnet, in which molecules with different magnetic centers arrange themselves on a gold surface to form a checkerboard pattern. Scientists at the Swiss Nanoscience Institute at the University of Basel and the Paul Scherrer Institute published their findings in the journal Nature Communications.
Ferrimagnets are composed of two centers which are magnetized at different strengths and point in opposing directions. Two-dimensional, quasi-flat ferrimagnets...
An Australian-Chinese research team has created the world's thinnest hologram, paving the way towards the integration of 3D holography into everyday...
In the race to produce a quantum computer, a number of projects are seeking a way to create quantum bits -- or qubits -- that are stable, meaning they are not much affected by changes in their environment. This normally needs highly nonlinear non-dissipative elements capable of functioning at very low temperatures.
In pursuit of this goal, researchers at EPFL's Laboratory of Photonics and Quantum Measurements LPQM (STI/SB), have investigated a nonlinear graphene-based...
Dental plaque and the viscous brown slime in drainpipes are two familiar examples of bacterial biofilms. Removing such bacterial depositions from surfaces is...
For the first time, scientists have succeeded in studying the strength of hydrogen bonds in a single molecule using an atomic force microscope. Researchers from the University of Basel’s Swiss Nanoscience Institute network have reported the results in the journal Science Advances.
Hydrogen is the most common element in the universe and is an integral part of almost all organic compounds. Molecules and sections of macromolecules are...
22.05.2017 | Event News
17.05.2017 | Event News
16.05.2017 | Event News
22.05.2017 | Materials Sciences
22.05.2017 | Life Sciences
22.05.2017 | Physics and Astronomy