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Saturday, 27 January 2007 02:21
Larsen ice shelf left few scars
Everyone knows that the bulk of an iceberg is underwater, so what happens when they hit the sea floor? Icebergs that scrape over the sea floor or get stuck on underwater elevations cause enormous disturbance events. Entire faunal assemblages are wiped out during such events. Scraping icebergs leave behind a diverse landscape, usually marked by “bulldozed” areas as well as ploughed sediments or piles of rock. This new, unoccupied habitat is quickly seized by mobile pioneer species. Often, patchworks of different recolonization stages form and thus enhance species diversity.
Initially, scientists assumed that the seafloor fauna of the Larsen A and B area would have been strongly affected by iceberg scouring. When an ice shelf collapses, many smaller icebergs form in a shor...
Thursday, 25 January 2007 15:43
Deep-sea fauna abundant under Antarctic ice shelf
Under the former Larsen ice shelf east of the Antarctic Peninsula, deep-sea sea cucumbers and stalked feather stars were ubiquitously found in shallow waters. These animals usually inhabit far greater water depths.
The main aim of the current Polarstern expedition to Antarctica is the investigation of marine ecosystems under the former Larsen ice shelf. This "white spot" with regard to biodiversity research gave rise to the following questions: What kind of life actually existed under the former floating ice shelf which was up to several hundred meters thick? What are the prospects for the future after the collapse of the ice shelf?
Obviously, prosperous life did not exist in the area where the Larsen B ice shelf broke off three years ago. This is surprisin...
Thursday, 25 January 2007 01:57
Southern Ocean bird observations now online
Because they are so many birds and so few observers around Antarctica, every observation matters. The recently launched marine biodiversity internet portal SCAR-MarBIN allows birdwatchers to directly upload their data, making them available to scientists as well as the general public.
As top predators, birds are an important component of the Southern Ocean‘s ecosystem. They are part of the comprehensive effort of the Census of Antarctic Marine Life (CAML) to study the distribution and abundance of the Antarctic biodiversity. CAML is now using the SCAR MarBIN portal, developed at the Royal Belgian Institute for Natural Sciences by Claude De Broyer and Bruno Danis, to concentrate biogeographical data on bi...
Wednesday, 24 January 2007 03:49
The scavenging hordes
Thousands of amphipods can reduce fish carcasses to bones, but these carrion experts are unexpectedly scarce in the area of the recently collapsed Larsen B ice shelf, where the Polarstern Expedition is currently conducting research
Baited traps consistently used to provide good numbers of amphipods throughout the expedition, whether designed to catch them or targeting fish. “Traps are secured on a metal frame, equipped with a weight and buoys designed to cope with the high pressure at the sea floor, and then dropped to the bottom. After 48 hours, the vessel returns, triggering the traps' release from the weights via an acoustic signal sent from a transmitter. Within 15 to 30 minutes, depending on the water depth, the traps float to the surface and are recovered,” explai...
Tuesday, 16 January 2007 07:11
March of the sea cucumbers
Remotely Operated Vehicles (ROVs) remain an efficient technology to uncover the secrets of Antarctic sea floor fauna. A video sequence at the foot of the Larsen B ice-shelf remnant reveals deep-sea sea cucumbers as abundant inhabitants.
ROVs have become standard non-invasive imaging tools for the Alfred Wegener Institute’s biological expeditions. For our expedition, devoted to the study of continental shelf sea floor communities (which were once under the now collapsed Larsen B ice-shelf), the ROV model Cherokee was selected (shown in the photo).
“Inspection ROVs like the Cherokee are fast to deploy and easy to recover” explains the marine ecologist Julian Gutt, who has 15 years ROV experience in Antarctic sea floor fauna investigation. Already used on a...
Thursday, 11 January 2007 18:32
Acidification of the oceans - what's the impact on fish?
Climate change-induced increase of carbon dioxide, according to modelling approaches, is going to cause the acidification of the world’s oceans. By the year 2100 the current pH might drop by 0.5. Our research is focusing on the question ‘how do fish respond to such changes?’
At the department "Marine Animal Physiology" of the Alfred Wegener Institute, researchers developed a device that enables onboard measurements of the impact of decreased pH values on the gill functioning of freshly caught fish (see overview photograph). In order to simulate blood circulation, specially prepared gill tissue is constantly flushed with a saline solution. Special devices allow measurements to be taken of gill performance in plain and acidified seawater for more than 6 hours (see det...
Tuesday, 09 January 2007 00:13
Art meets science – octopus and biologist create art onboard “Polarstern”
Education and Outreach is playing an ever increasing role in the world of science. This is also true for our expedition especially with regard to the upcoming International Polar Year. Scientists, which rely on funding from the government, fulfil their obligation towards the general public and funding bodies by communicating their results in an easy and comprehensible manner. More and more scientific organisations such as the "Census of Marine Life" encourage liaisons between art and science. Unfortunately due to great scientific interest it was not possible to give an artist the opportunity to join the expedition. But an unexpected awakening of creativity, imagination, and artistic talent occurred onboard the “Polarstern”. Indeed these are skills that are also of high relevance to a...
Monday, 08 January 2007 18:00
Paradigm shift in octopus habitat use – what do they do without rocks and crevices
“The Octopods are for the most part benthic or bentho-pelagic, living in holes or crevices, beneath large rocks or in caves… ” This has been the dogma of octopus habitat use for decades because observations have been limited to areas of the oceans where octopuses could be easily found: shallow, near-shore and typically rocky, habitats. But what of the majority of the ocean floor, where the bottom is characterized by muddy and sandy sediments, is there a place for octopuses here? The answer is "yes". Today’s technology enables us to see the ocean floor almost everywhere with high-resolution still photography and ROV-mounted video cameras. Images from the Polarstern’s first deployment of the photosled show octopuses burrowed in fine sediment, as seen in the attached image. Waters...
Friday, 05 January 2007 18:13
Likely new parasite found in stomachs of Emperor penguin chicks
Penguins are the uncontested cutest birds worldwide. In the great colonies of the Emperor penguins (Aptenodytes forsteri) in the high Antarctic it happens often that young chicks die a natural death. This provided a unique opportunity for us (Sven Klimpel and Markus W. Busch) to analyse the parasitic fauna and stomach contents of these fascinating birds. Such investigations are important because they provide information on the life of the parasites and also on the habitats and general trophic status of the penguin hosts within the Antarctic ecosystem.
The Emperor penguin colony close to the German Neumayer Station is one of approximately 35 known colonies in Antarctica. We collected 12 dead chicks for parasitological and feeding ecology examinations on board. It was found th...
Wednesday, 03 January 2007 18:22
By their eggs you shall know them!
So far, spawning grounds of most Antarctic fish species are not known. Nevertheless, there is a great deal of interest to locate these places and to protect them by international law. Rüdiger Riehl from the Institute of Zoomorpholgy, Cell Biology and Parasitology of the University of Duesseldorf might have found a way to do exactly that.
During his research on fish eggs, which spans over 30 years, he has found that most of these eggs possess microstructures that allow the identification of specimens to the family level, genus level and even species level. The tool of choice is a scanning electron microscope (SEM), which is used to capture minute differences on photographs. He is using differences in the microstructure of the egg surface, for example the presence or absence...