Press release

Emiliania huxleyi – an algal dwarf which impacts on the global climate

Mass reproduction of coccolithophores in the Barents Sea , caught by a NASA satellite. When the algae die, the calcified platelets are released into the water and scatter sunlight so that the water appears light blue. Platelets of intact algal cells do not scatter light. Therefore, whether coccolithophores dominate an algal bloom or not can only be seen from space once most individuals have already died and released their calcified platelets. Photo: Jacques Descloitres, NASA/GSFC, MODIS Rapid Response

Algal researchers of the German Society for Plant Sciences have chosen Emiliania huxleyi as alga of the year to highlight its importance as a global key organism.

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"Due to its global importance, Emiliania has been included in the sequencing programme of the Joint Genome Institute in California where its genetic composition will be analysed", explains Professor Dr Peter Kroth, Chairperson of the Phycology Section of the German Society for Plant Sciences. An improved understanding of its genetic make-up will assist in researching the global carbon cycle.

Industry awaits genetic key

Unravelling the mechanism by which the algae can produce little calcified platelets or scales called ‘coccoliths’ (or ‘liths’) and attach these to their surfaces has also potential future applications. Further research in this field may result in new industrial uses in bio- and nanotechnology.

The translocation of lime has created chalk cliffs

Emiliania lives in the well-lit layers of all oceans. It is one of over 300 species of calcified microalgae called coccolithophores which are surrounded by small, distinct calcified platelets which give each species its unique look. Emiliania uses carbon to form these lime-based platelets; carbon is accumulated from the surrounding water in the form of bicarbonate and precipitated as calcite. The liths can only be seen using a scanning electron microscope – they appear as little dots under plain light microscopy. At the end of their lives, coccolithophores sink to the bottom of the oceans and the bound carbon is deposited at great depths forming sediments. In this way lime has been deposited for millions of years on the seafloor: the white cliffs of Dover in England and the chalk cliffs of the Island of Rügen ( Baltic Sea ) are evidence of such ancient sedimentation processes.

Emiliania dominates many algal blooms

Even though Emiliania is only a tiny microalga, it plays a significant role in the global carbon cycle. Its enormous contribution is due to its ability to multiply at an explosive rate: under certain environmental conditions Emiliania reproduces very fast, accumulates in large quantities and forms so-called algal blooms. These can extend over several hundred square kilometres and are even visible from space because they give the surface layers of the oceans a milky appearance. Algal blooms are often almost entirely made up by Emiliania cells which may contribute up to 80 or 90 per cent of the overall phytoplankton community.

Biological carbon pump

Emiliania is very important as it binds, during photosynthesis, a large quantity of the greenhouse gas carbon dioxide which, when the cells die, is transported into the deeper layers of the oceans. Scientists describe this process as the ‘biological pump’. Additionally Emiliania produces calcium carbonate which leads to an acidification of the seawater, which, in turn, results in the increased release of carbon dioxide (the so-called ‘carbonate pump’). Both processes have differential impacts on the oceans’ carbon-binding capacity.

Scientists are fascinated by Emiliania’s success

Anthropogenic increase in carbon dioxide leads to acidification of the oceans in the long-term. Scientists at the Alfred-Wegener-Institute in Bremerhaven currently investigate the ability of Emiliania to bind carbon and deposit this in the deep sea, and whether this will enhance or buffer climate change effects. "We try to answer such open questions by researching how Emiliania can cope with ocean acidification and what consequences this has for the wider marine ecosystem", explains Dr Björn Rost, Leader of the ‘PhytoChange’ research group which focuses on consequences of climate change on marine phytoplankton. "Emiliania is particularly fascinating; we are constantly amazed and try to comprehend how this species can become so dominant in certain regions".