ZOONEK. Untersuchung der natuerlichen Struktur des Zooplanktons und Nektons im Bereich eines Manganknollenfeldes in der Tiefsee des Suedpazifiks Abschlussbericht

During four cruises of RV SONNE quantitative zooplankton and micronekton investigations were carried out at different locations in the tropical southeastern Pacific. Samples were mainly taken at two depth ranges in the mesotropic Peru Basin. The ranges were characterized by an accumulation of organisms, which are of special interest for the investigations: 1) the deep scattering layer in the mesopelagic zone including the underlying upper bathypelagic zone, 2) the benthic boundary layer at approximately 4000 m depth. Throughout the water column a strong vertical faunal zonation was found. Next to various genera of Euphausiacea, Thaliacea were the most important representatives of diel vertical migrants in terms of individual numbers and biomass. These animals formed a distinct deep scattering layer between 300 and 550 m depth at daytime. Below 1000 m depth, the decline of biomass concentration could be approximated by a power function. In near-bottom samples (<65 m above bottom) in the 4170 m deep DISCOL area in the Peru Basin, Copepoda Calanoida were numerically most abundant. Biomass was dominated by Malacostraca and gelatinous organisms. Near-bottom catches in the nutrient-rich Peru-Trench at depths of about 4000 m yielded twice as much biomass and individual numbers as compared with the DISCOL area. Furthermore, the community structure in the Peru Trench different significantly: the group of Malacostraca dominated both biomass and individual numbers. The regional differences in abundance and structure of the bentopelagic fauna are obviously correlated with differences in the quantity and quality of food particles available in the benthic boundary layer of the deep-see. (orig.)SIGLEAvailable from TIB Hannover: F95B1054+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Forschung und Technologie (BMFT), Bonn (Germany)DEGerman