Samples for meiofauna and bacteria were collected using a multiple corer. Like with the box corer, the idea is to recover close to undisturbed samples of seafloor sediments. Thereby, the multicorer basically consists of four units (Barnett et al, 1984): a supporting framework (A), a hydraulic damper (B1 and B2) supporting a sliding framework (C) carrying the assembly of core sampling tubes (E1). When the corer is lowered to the seafloor, the framework rests on the bottom supporting the coring assembly in its upper position through a sliding framework and hydraulic damper.  As the wire from the ship is slackened, the hydraulic damper gently lowers the core assembly so that the cores penetrate the seabed (Barnett et al, 1984). When the multicorer is heaved again a mechanism is triggered, that first closes a valve on top of each sampling tube and at the same time releases a core catcher, which closes the sediment core from the bottom to retain the sample in its original state as it was taken from the seafloor (Barnett et al, 1984).

For the purposes of sampling the seafloor sediments inside the DEA, the design was slightly modified to carry only eight sampling tubes each with a length of 62 centimeters. This was thought to be necessary to increase the chance of coring undisturbed samples in a manganese nodule field. However, the coverage of polymetallic nodules in the DISCOL area only rarely prevented the tubes from entering the sediment, where the penetration depths most of the time were between 35 and 40 centimeters.

Barnett, P. R. O., Watson, J., Conelly, D. (1984): A multiple corer for taking virtually undisturbed samples from shelf, bathyal and abyssal sediments; Oceanologica Acta 7(4); 399-408  

Multicorer used during the DISCOl cruises (Photo: Dr. Gerd Schriever)


Schematic drawing of the multicorer system (source: Cruise report SO061)