Galathea Expedition Research Articles

Amphipoda from depths exceeding 6,000 meters revisited 60 years on

Abstract In the 1950s, the Danish Galathea Expedition undertook one of the first and most comprehensive explorations of our ocean’s hadal zone, depths extending from 6,000 to nearly 11,000 m, and presented a rich collection of the diversity of Amphipoda. The subsequent papers, however, concluded that these established ‘nothing essentially new’ to the existing knowledge of amphipod biology. Since Dahl’s foundational paper in 1959, amphipods, primarily from the superfamilies Lysianassoidea and Alicelloidea, emerged as one of the best-sampled hadal fauna, as these mobile invertebrates are readily recovered by different sampling techniques. Importantly, amphipods have become the model taxon, helping us to unlock knowledge about life in the hadal zone. In this review, we collate the knowledge gained since the Galathea Expedition and summarise the current understanding of how amphipods that appear during hadal exploration survive the trench environments. We discuss population structures across depth, inter-trench distribution and connectivity, applications in hadal microbiology, and, critically, how the hadal zone is being impacted by anthropogenic activity.

Holocene climate variability in southern Greenland: results from the Galathea 3 expedition

The third Galathea expedition (Galathea 3) left Copenhagen in August 2006 for a circumnavigation of the globe with the aim of conducting more than 70 scientific programmes en route. The first geological programme took place in South Greenland and included sampling of sediment cores and seismic profiling. The aim of the study is to obtain detailed knowledge about Holocene climate changes and the glacio-marine history.

Foreword*

Humanity has always been fascinated by organisms which survive in the most extreme and hostile environments and one such environment, is the hadal depths of the ocean trenches. Life can exist here in a food deprived habitat at enormous pressure and as far from the sun as possible, and yet it thrives. Which kinds of organisms can are found there and where did they come from? Is it a refuge for old phylogenetic lines elsewhere gone extinct or is it a habitat for highly specialized species? Considering that the trenches constitute only a minor part of the deep sea, the trenches have received the lion’s share of scientific attention. The first ‘Trench’ exploration consisted of depth soundings made during the Challenger expedition in 1872-1876, but biological deep sea sampling started in earnest with the Danish Galathea expedition II 1950-1952 which managed to make collections at the deepest parts of the trenches. Even today the trenches hold many mysteries although the focus has changed somewhat from biology to biochemistry, especially carbon sequestration (Shirayama 1997; Takeuchi et al. 1999; Nakamura & Inagaki 2005).

Welcome by the Dean Henrik Jeppesen at the 8th International Symposium on Tardigrada

Mr. Chairman. Distinguished ladies and gentlemen. As Dean of Science it is a great honour on behalf of the University of Copenhagen and the Faculty of Science to welcome all of you here to the 8th International Symposium on Tardigrada. We are especially happy to have you here at the August Krogh Institute (named after our well-known Nobel Prize winner in Physiology), because on September 1st we celebrate the establishment of the Faculty. So coming here and honouring our 150 year anniversary jubilee help us to promote the importance of science in our society. The University was founded in 1479 as a theological catholic school. It broke down in 1530 and was reestablished in 1537 after the reformation. Right from the start in 1479 there was science thought of at the university. Mathematics and Astronomy. And Zoology became a subject over the centuries together with other subjects which are today regarded as science. But only in 1850 did we become an independent Faculty thanks to the effort and progress done by the Danish Chemist H.C. Ørsted. The animals, which you study, are marvellous in the sense that they can survive under severe conditions for centuries. Under extreme dry conditions in Sahara, in extreme cold conditions (they can survive minus 273 °C, or survive in vacuum). This has practical implications for people who need to excuse their scientific interest, for medicine if we can freeze human tissue, or for space study how to survive under extreme conditions. The study of Tardigrada is an important field here at the Institute of Zoology, at the Zoological Museum, and at the University of Roskilde, 30 km west of Copenhagen. Some of our most distinguished zoologists take part in this research. That might be the reason why you have chosen to have the symposium here in Copenhagen. They are doing research on tardigrades in marine areas, and in Greenland on the ice cap. Especially interesting are the studies done in the Ikka Fjord in Greenland, where the unique Ikkaite Tufa columns made of calcium carbonate hexahydrate originating from alkaline cold springs at the bottom of the fjord create very specific environments with nearly brackish conditions in the center and sea water salinity on the outside. And this creates varied conditions for different species of Tardigrada. We also celebrate this year the 50th anniversary of the 2. Galathea expedition which went round the world and specifically looked for deep sea fauna. There are Tardigrades here. It has been interesting to look through the 54 abstracts in the programme and read the names and work places for the 65 participants listed. In English tardigrades are called water bears, in Danish “bjørnedyr” meaning bear animals. I prefer the Danish version, this sounds more like pet bears. The symposium is followed by a field trip to the faculty's research station on Disko in Greenland. In 1994 I arrived on the new research vessel “Porsild” to Disko to deliver the new boat some of you will sail in during the workshop up there. I stayed there some days, and there was this man Professor Reinhardt Møbjerg Kristensen, looking into his microscope. It was fascinating to see the joy which he expressed explaining his animals. His engagement was so impressive and his talk so marvellous. It was really his pet animals he caressed all day and night. If all of you are looking on the water bears with the same fascination and engagement, then this will be one of the most entertaining symposiums ever held. One can fear that you are so engaged that you will forget everything around you, even to listen to the contributions of the others, and to be careful that maybe a new group will be announced. I wish you some very good days here at the Faculty of Science and some very fruitful days. I should like to thank the sponsors of the meeting, The Danish Science Foundation, The Carlsberg Foundation and Dr. Bøje Benzon Foundation. I would like to express my gratitude to the organizing committee for attracting the conference here and making the programme so wide and interesting. I can promise the committee will do all their best to help you all way through. And for those going to Disko — you will have a most splendid experience. I shall ask my colleagues at my own institute, Geography, to arrange some bad weather except on Thursday where you join the excursion. This to prevent you from sneaking away and enjoy the wonders of Copenhagen. By this once again welcome and a wish for a fruitfulconference.

STYRACOTHORACIDAE (COPEPODA: HARPACTICOIDA), A NEW FAMILY FROM THE PHILIPPINE DEEP SEA

The present work arises from a study of the bathyal and mainly abyssal harpacticoids collected during the second leg of the French ESTASE Expedition in 1984. Copepods were collected on board the RV Jean Charcot during its cruise off the Philippine west coast from Manila to Surabaya in Indonesia. The harpacticoid copepod fauna of Philippine deep waters has received relatively little attention, despite the fact that extensive surveys have been carried out in the Philippine Trench during the Danish Galathea Expedition and the various cruises of the Russian research vessel Vityaz (Belyaev, 1972). Virtually all our knowledge of Philippine deep-sea harpacticoids is contained in Ito's excellent papers (1982, 1983) on Cerviniidae, Thalestridae, and Ameiridae from an abyssal locality southeast of Mindanao. The description by Ito of highly distinctive harpacticoid taxa such as Tonpostratiotes tenuipedalis, Abyssameira reducta, and Parameiropsis magnus, gives an indication that this area might reveal other unsuspected discoveries. The only other deepwater harpacticoid described from the Philippine Sea is Pontostratiotes horrida (Cerviniidae) from 4,300 meters depth in the northeastern sector near the Bonin Islands (Izu-Bonin Trench) (Brotskaya, 1959), but this locality is quite remote from the Philippine waters proper. This paper reports on the first deep-water harpacticoid to be described from off the west coast of the Philippines. The single female collected represents the type of a new family and was found to be infested by an as yet unknown developmental stage oftan

Stomatopod Crustacea collected by the Galathea Expedition, 1950-1952,with a list of Stomatopoda known from depths below 400 meters

Stomatopod Crustacea collected by the Galathea Expedition, 1950-1952,with a list of Stomatopoda known from depths below 400 meters

A Hadal Fish (Bassogigas profundissimus) with a Functional Swimbladder

DURING the Danish Galathea Expedition (1950–52) a specimen of the brotulid fish, Bassogigas profundissimus (Roule, 1913), was caught in the Sunda trench (Station No. 466, depth 7,160 m); it measured 157 mm in standard length. The gear used was a herring otter trawl, which was operated at the bottom for a period of 2 h. The bottom material consisted of bluish mud, and the bottom temperature was 1.5° C. The uphaul of the trawl took 4 h.

Measurements with the carbon-14 technique of the respiration rates in natural populations of phytoplankton

A method for measuring the rate of respiration of a phytoplankton population by means of the carbon-14 technique is described. A curve showing the rate of net photosynthesis as a function of light intensity is obtained. By extrapolation the rate of respiration is deduced. The accuracy of the method is discussed on a theoretical as well as on an experimental basis. From 78 measurements made during the summers of 1956 and 1957 in the North Atlantic and in the Arctic, 90 per cent of all rates measured were 15 per cent or less of light-saturated photosynthesis, 68 per cent were 10 per cent or less. In not a single case did the rate of respiration reach anywhere near the order of magnitude obtained in light-saturated photosynthesis. This was also the case with 12 similar measurements made during the Galathea Expedition, mainly in tropical waters.

Measurements at sea of the vertical gradient of the main geomagnetic field during theGalatheaexpedition

During the Danish Galathea expedition, 1950–52, investigations were made of the vertical gradient of the geomagnetic field, in an attempt to test the probability of the new “fundamental” theory for the main geomagnetic field proposed by P. M. S. Blackett in 1947. Three relative, self-recording magnetometers—one needle instrument measuring the Z-component, one needle and one rotating-coil instrument measuring the H-component—are described. All instruments may be lowered to extreme depths in the sea in non-magnetic containers. In the Pacific Ocean, a series of trial measurements were carried out, and at least one of the H magnetometers proved to be of the desired accuracy of 10γ during a single relative measurement. All trial stations were situated in places with locally disturbed geomagnetic field, which makes the gradient results unreliable, and a breakdown of the technical equipment of the surveying vessel prevented measurements at stations better suited to magnetic work. However, summed up, the trial results indicate a case against the fundamental theory—in accordance with gradient measurements ashore in mines and collieries.

Cosmic Spherules in Deep-Sea Sediments

IN 1876, Sir John Murray1 published observations on magnetic spherules extracted from deep-sea sediments collected by the Challenger Expedition. Together with Renard2, he later described them more fully and gave strong reasons for assuming them to have a cosmic origin. Very few observations have since then been published on these spherules. The two most recent publications are by Bruun, Langer and Pauly3 describing magnetic particles collected from the sediment surface by the Galathea Expedition, and by Laevastu and Mellis4, working in Goteborg, who extracted, counted and measured black spherules from one ordinary long core from the Swedish Deep-Sea Expedition.

Magnetic particles found by raking the deep sea bottom

A collection of strongly magnetic material on the ocean floor was one of the many subjects undertaken by the Danish Deep Sea Expedition - The Galathea Expedition 1950–1952. In the following a description of the instrument, the magnetic rake, is given by its constructor, A. Fr. Bruun, and the way it was handled on the Galathea is mentioned. The description of the material is given by Hans Pauly. His conclusions are further supported by experiments carried out and described by E. Langer. The magnetic rake, an oak-board 100 × 15 × 5 cm, carrying 63 magnets in three rows, was drawn along the ocean bottom and is considered to have covered about 45,000 m 2. Apart from insignificant amoutns of artificial material and varying amounts of magnetite-sand more than 300 particles of a very remarkable character were obtained. Most particles were spheres with a diameter of less than half a millimetre. A lot of them consist wholly of magnetite, but many have a silicate groundmass loaded with magnetite crystallites. In nearly all spherical cavities occur. Seven metallic particles were found in the material. Those examined were seen to contain: NiFe, carbides, phosphides, etc. The structure and composition of these metallic particles seem to require high temperatures and rapid cooling in the formation-process. Discussions of similar material from bottom cores taken by the Swedish Deep Sea Expedition, certain features in crusts of two Danish stony meteorites, the whole picture of the material from the Galathea Expedition 1950–1952 and the Challenger Expedition 1872–1976 seem to favour the ideas of Murray and Renard. The particles are supposed to represent material torn off from meteors due to air-resistance on their passage through the atmosphere; it only seems necessary to add stony meteorites as an important source. It is considered convenient to give these particles a special name in order to distinguish them from meteorites and cosmic dust, and it is therefore suggested to call them caudaites.

Magnetic Measurements in Deep-Sea Investigations: Magnetic Investigations on the Galathea Expedition

Magnetic Measurements in Deep-Sea Investigations: Magnetic Investigations on the Galathea Expedition