As reported by biologists from the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research in the cover story of the current issue of the scientific journal Current Biology, Antarctic glass sponges have been the prime beneficiaries of the disappearance of the ice shelf.
Glass sponges provide habitat and 3-D structure for other Antarctic benthic organisms like feather and brittle stars. Photo from the study site in the Western Weddell Sea. Photo: Thomas Lundalv.
To the surprise of the scientists, the density of these archaic filter-feeders has increased threefold between 2007 and 2011 despite only low plankton food supply and water temperatures of minus 2 degrees Celsius. The sponges had also grown remarkably quickly and had completely supplanted competitors for food. The results show that communities at the bottom of the western Weddell Sea react considerably more quickly to climate-related changes than previously thought.
Glass sponges (Hexactinellida), an archaic group of animals at the basis of the animal kingdom, dominate the shallow seafloor in the Antarctic. Many biologists believed that glass sponges grew so slowly that two-metre behemoths would have to be around 10,000 years or older. These assumptions have now been challenged in a new study led by scientists from the Alfred Wegener Institute (AWI) and published in the current issue of the scientific journal Current Biology.
During a Polarstern expedition to the poorly accessible region of the former Larsen A ice shelf, AWI biologists Laura Fillinger and Claudio Richter, together with colleagues from the University of Gothenburg and the Senkenberg Research Institute and Natural History Museum; succeeded in demonstrating that glass sponges can grow rapidly within a short period of time. “We were surprised by what we saw on our video screens in 2011 when we lowered our remotely operated vehicle onto the sea bed at a depth of around 140 metres. In an area, which had revealed large numbers of ascidians and only occasional glass sponges during an earlier expedition with the ice-breaking research vessel ‘Polarstern’ in 2007, four years later we found no ascidians at all. These pioneer species had completely disappeared, replaced by three times the number of glass sponges, including several juvenile individuals”, reports Laura Fillinger, lead author of the study.
Until this time scientists had assumed that communities on the Antarctic sea bed only change very slowly because of the very low temperature (minus two degrees Celsius) and patchy supply of food in pack-ice covered waters. “We now know that glass sponges may undergo boom-and-bust cycles, allowing them to quickly colonize new habitats in a short period of time”, says project leader Prof. Dr. Claudio Richter.
“To the organisms living on the sea bed, the disappearance of the hundred-metre-thick Larsen A ice shelf must have been like the heavens opening up above them”, he adds. Where cold, darkness and food shortages had previously reigned, sunlight now allows plankton growth in surface waters and, hence, a rain of food comes down to the sea bed.
Glass sponges feed on the smallest plankton, which they filter from the water. The animals grow to a size of up to two metres, and their vase-like bodies provide perfect hiding, spawning and shelter opportunities for fish, invertebrates and many other sea dwellers. “Like corals, sponges create their own habitats. To an extent they are like cities on the sea bed. There is something going on wherever they grow, and this attracts other sea dwellers to them”, says Claudio Richter.
New spaces are being created for such underwater worlds wherever the ice shelves on the Antarctic Peninsula are retreating or breaking up. However, scientists cannot yet definitively say whether this means that glass sponges will be one of the beneficiaries of climate change. Laura Fillinger: “There are still too many unknowns to make predictions. One example is the question of the influence of competitors: currently we are witnessing a fierce competition for space on the sea bed. Another concerns predators: in our dive in 2011 we hardly saw any of the snails and starfish, which feed on glass sponges. However, it is possible that these voracious predators will follow suit and wreak havoc.”
Marine biologists at the Alfred Wegener Institute will continue to monitor the changes to communities in the western Weddell Sea. In January 2013, the planned dives in the area of the former Larsen A ice shelf had to be called off due to the solid pack ice in the Weddell Sea. However, Claudio Richter and his team hope for better pack-ice conditions during future Polarstern trips to this part of the Antarctic so that they can use new investigative methods to discover more about the life cycle of the glass sponges.Glossary:
metres.Larsen A ice shelf
_2013_11_july/Your scientific contact persons at the Alfred Wegener Institute (AWI) are:
Follow the Alfred Wegener Institute on Twitter (https://twitter.com/AWI_Media) and Facebook (http://www.facebook.com/AlfredWegenerInstitute) for all current news and information on everyday stories from the life of the Institute.
The Alfred Wegener Institute conducts research in the Arctic and Antarctic and in the high and mid-latitude oceans. The Institute coordinates German polar research and provides important infrastructure such as the research icebreaker Polarstern and stations in the Arctic and Antarctic to the international scientific world. The Alfred Wegener Institute is one of the 18 research centres of the Helmholtz Association, the largest scientific organisation in Germany.
Ralf Röchert | idw
Antimicrobial substances identified in Komodo dragon blood
23.02.2017 | American Chemical Society
New Mechanisms of Gene Inactivation may prevent Aging and Cancer
23.02.2017 | Leibniz-Institut für Alternsforschung - Fritz-Lipmann-Institut e.V. (FLI)
In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport
Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...
The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.
The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...
Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...
Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".
Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...
13.02.2017 | Event News
10.02.2017 | Event News
09.02.2017 | Event News
23.02.2017 | Physics and Astronomy
23.02.2017 | Earth Sciences
23.02.2017 | Life Sciences