The Scientific Programme of the Meteor Expedition

Through regular soundings, the expedition provided a more detailed picture of the seabed in the South Atlantic than had previously been known. For the first time, a depth profile of the Mid-Atlantic Ridge was created that was accurate by the standards of the time, revealing a greater extent and stronger relief (additional heights and depths, basins and thresholds) than scientists had previously assumed. A total of around 67,000 echo soundings were taken during the expedition and 14 depth profiles of the Atlantic were created.

During the voyage, measurements were usually taken three times per hour at full speed using the echosounding equipment of the Atlas company and the Signal society, resulting in a distance of about 2 to 3 nautical miles between measurements. In areas with uneven relief, soundings were taken more frequently. The more time-consuming, traditional wire soundings with the Lucas sounding machine and thermometric depth measurements could only be carried out at the pre-defined stations.

A corer containing a glass tube and the bottom grab brought sediment samples on board, which were examined for their components and grain sizes. In addition, the salinity of the bottom water above the sediment was determined.

During the expedition, a new undersea threshold was also discovered, surveyed and named – the "Meteor Bank".

Excerpt from Captain Spieß's diary on the "Meteor Bank":
18 October 1925: "In the morning, we find a bank using the echo sounder, we take a sounding at 800 m and station 65. We then name the bank 'Meteor Bank' or 'Meteor Ridge' in a meaningful reference to yesterday's Bouvet Ridge (named Meteor – Bouvet 1870). We sound the bank; it is a perfect cone rising to 590 m."

Excerpt from the expedition report, Work on Profile III on the METEOR Bank:
"At the geographical longitude of Bouvet Island, a threshold rising to 1500 m was identified, the connection of which to the Bouvet Plateau is to be investigated in more detail on Profile V. To the east of this, at 4S0 16'S and 8°14'E, a self-contained bank was found and sounded as planned. This is a bank rising from a depth of 3000 m in a south-west to north-east direction with a minimum depth of 560 m. It does not appear to be of volcanic origin. It has been given the name 'Meteor Bank'."

The survey and description of the Challenger Deep, the Valdivia Bank, the Walvis Ridge, the Bouvet Threshold, the St. Peter and St. Paul Rocks and the Nelson Bank are also mentioned.

Marine biology was less of a focus of the expedition, but is regularly mentioned in the captain's log and carefully summarised in the expedition report. The researchers correlate their observations and plankton count results with oceanographic parameters ("production conditions"), mixing and current conditions. In addition to oxygen, they emphasise the importance of nutrient distribution through vertical mixing for plankton. The expedition claims to have conducted the first plankton counts in "all layers of the ocean" and to have depicted the distribution in longitudinal and cross-sections. The work of zoologist Hans Lohmann (methodology, conclusions) is used as a guide, although he was only able to study plankton at depths of up to 400 metres during his expeditions. Frequent mention is also made of observations of bioluminescence, holothurians and jellyfish caught in the equipment, marine mammals, seabirds and terrestrial animals. The captain highlights the rare finds of deep-sea fish in his diary, sometimes even making sketches. The description of "globerine mud" also takes up a certain amount of space.

The equipment used includes the Apstein Net (to a depth of 200 metres) and the Nansen Closing Net (from 1000 to 700 metres and from 500 to 200 metres) for collecting, identifying and counting larger plankton species, and the Secchi Disc ("white disc") for determining visibility depth. For the quantitative recording of nanoplankton, smaller quantities of water (100 and 540 millilitres), which are obtained from various depths using water samplers, centrifuged and then counted "while still alive" under the microscope. Further information was obtained by sedimentation of water samples and the filtration of seawater from the deck wash pump.

In his expedition report, biologist Ernst Hentschel describes how living conditions along all profiles influence the composition, predominant species and total numbers of plankton. In his description, zones with equal amounts of plankton are delimited by "isoplankton" lines. He highlights a major difference between the plankton in the northern (north of 25°) and southern (south of 30°) Atlantic: At a depth of 200 metres, the plankton abundance (average number of individuals per litre of water) in the south is about twice as high as in the north, while at a depth of 2000 metres the abundance is approximately the same. He explains the observed plankton scarcity on Profile II at 25° to 30°S partly by a disturbance caused by two undersea ridges (Rio Grande Ridge, Walvis Ridge), which divide the water masses, but also suspects other causes that are unclear to him.

Excerpts from the expedition report, Report on Biological Work, by Ernst Hentschel:

"The existence of a climatically determined zonal distribution, the structuring effect of currents and, at the same time, the independence of populations from these complex factors, things that Lehmann had already clearly demonstrated, were clearly evident. There appeared to be signs of periodicity in the life cycle of plankton."

"At the beginning of our expedition, the lightless deep sea was, in the truest sense of the word, mare incognitum for quantitative plankton research. We have now established that in the area of our first three profiles, the water at all depths is still so densely populated with nannoplankton that in little more than half a litre (540 cm³) of water, almost without exception, a few organisms can still be found. This deep-sea plankton is not only an impoverished version of the upper layer plankton, but is also somewhat characteristic..."

Die Deutsche Atlantische Expedition auf dem Vermessungs- und Forschungsschiff METEOR. Festsitzung zur Begrüßung der Expedition am 24. Juni 1927 (1927)

Die Deutsche Atlantische Expedition auf dem Vermessungs- und Forschungsschiff METEOR. Bericht I (Profil I-III), Bericht II (Profil IV-V), Bericht I (Profil VI-XI) (1926-1927)

Die Deutsche Atlantische Expedition auf dem Vermessungs- und Forschungsschiff METEOR (1926)