Benthic fauna at station FINO 1, 2005-2007

In der Nordsee wurden auf der Forschungsplattform FINO 1 Felduntersuchungen durchgeführt, um spezielle Fragen zu möglichen Auswirkungen von Offshore-Windenergieparks auf die marine Umwelt zu beantworten. Der Fokus war dabei auf die Konsequenzen für die Lebensgemeinschaft am Meeresboden gerichtet. Es wurden die benthosökologischen Prozesse im Nahbereich der Piles sowie die mittelfristige Entwicklung der Aufwuchsfauna auf der künstlichen Unterwasserstruktur dokumentiert. Die Ansammlung pelagischer Fischen um die Plattform und der Export organischen Materials von der Plattform wurden quantifiziert. Die räumliche Ausdehnung und die Erheblichkeit von Auswirkungen auf die Lebensgemeinschaften des Meeresbodens wurden anhand mathematischer Modellierung abgeschätzt. Zusätzlich wurde die Anwendbarkeit der elektrochemischen Akretionstechnologie zur Schaffung naturnaher Kalksubstrate in der Nordsee getestet und geeignete Parameter für eine erfolgreiche Umsetzung unter Nordseebedingungen ermittelt. Die auch 4,5 Jahre nach Errichtung der Plattform noch ansteigende Artenzahl der Aufwuchsfauna lässt darauf schließen, dass der Sukzessionsprozess noch nicht abgeschlossen ist. Die stark vertikal zonierte Aufwuchsfauna auf der Unterwasserkonstruktion erreicht eine Masse von ca. 5 Tonnen mit ausgeprägten saisonalen Schwankungen. Anhand von echoakustischen Untersuchungen wurden saisonal auftretende Ansammlungen pelagischer Fische um die Plattform dokumentiert. Der Nahbereich der Plattform unterschied sich durch eine Schillauflage und eine räumlich und zeitlich sehr variable Sediment- und Bodenfaunazusammensetzung deutlich von einem Referenzgebiet in 200-400 m Abstand von der Plattform. Eine konzentrische Zonierung mit unterschiedlich stark ausgeprägten Veränderungen der Bodenfauna lässt auf komplexe Veränderung des gesamten lokalen Nahrungsgefüges im Nahbereich der Plattform schließen. Anhand einer Modellierung konnte der Materialexport in die umgebenden Weichbodenbereiche für einzelne Piles und einen hypothetischen Windpark abgeschätzt werden. Die lokale Ausbildung einer hohen Biomasse auf der Unterwasserkonstruktion von WEA sowie der Export mit anschließender Sedimentation lassen zumindest lokal einen erheblichen Einfluss auf Stoff- und Energieflüsse erwarten.

Stable carbon and oxygen isotope record of foraminifera of IODP Site 303-1307

A major tipping point of Earth's history occurred during the mid-Pliocene: the onset of major Northern-Hemisphere Glaciation (NHG) and of pronounced, Quaternary-style cycles of glacial-to-interglacial climates, that contrast with more uniform climates over most of the preceding Cenozoic and continue until today (Zachos et al., 2001, doi:10.1126/science.1059412). The severe deterioration of climate occurred in three steps between 3.2 Ma (warm MIS K3) and 2.7 Ma (glacial MIS G6/4) (Lisiecki and Raymo, 2005, doi:10.1029/2004PA001071). Various models (sensu Driscoll and Haug, 1998, doi:10.1126/science.282.5388.436) and paleoceanographic records (intercalibrated using orbital age control) suggest clear linkages between the onset of NHG and the three steps in the final closure of the Central American Seaways (CAS), deduced from rising salinity differences between Caribbean and the East Pacific. Each closing event led to an enhanced North Atlantic meridional overturning circulation and this strengthened the poleward transport of salt and heat (warmings of +2-3°C) (Bartoli et al., 2005, doi:10.1016/j.epsl.2005.06.020). Also, the closing resulted in a slight rise in the poleward atmospheric moisture transport to northwestern Eurasia (Lunt et al., 2007, doi:10.1007/s00382-007-0265-6), which probably led to an enhanced precipitation and fluvial run-off, lower sea surface salinity (SSS), and an increased sea-ice cover in the Arctic Ocean, hence promoting albedo and the build-up of continental ice sheets. Most important, new evidence shows that the closing of the CAS led to greater steric height of the North Pacific and thus doubled the low-saline Arctic Throughflow from the Bering Strait to the East Greenland Current (EGC). Accordingly, Labrador Sea IODP Site 1307 displays an abrupt but irreversible EGC cooling of 6°C and freshening by ~2 psu from 3.25/3.16-3.00 Ma, right after the first but still reversible attempt of closing the CAS.

Lithology, biostratigraphy, and geochemistry of the Black Sea sediments, DSDP Leg 42 (pt. 2) data

The monograph presents results of deep-sea drilling in the Black Sea carried out in 1975. Detailed lithological, biostratigraphic and geochemical studies of Miocene-Holocene sediments have been carried out by specialists from institutes of the USSR Academy of Sciences, Moscow State University and other organizations. Drilling results are compared with geophysical data. Geological history of the Black Sea basin is considered as well.

Living benthic foraminifera of the western and southern Arabian Sea

Sediments from the western and southern part of the Arabian Sea were collected periodically in the spring intermonsoon between March and May 1997 and additionally at the end of the Northeast Monsoon in February 1998. Assemblages of Rose Bengal stained, living deep-sea benthic foraminifera, their densities, vertical distribution pattern, and diversity were analysed after the Northeast Monsoon and short-time changes were recorded. In the western Arabian Sea, foraminiferal numbers increased steadily between March and the beginning of May, especially in the smaller size classes (30-63 µm, 63-125 µm). At the same time, the deepening of the foraminiferal living horizon, variable diversity and rapid variations between dominant foraminiferal communities were observed. We interpret these observations as the time-dependent response of benthic foraminifera to enhanced organic carbon fluxes during and after the Northeast Monsoon. In the southern Arabian Sea, constant low foraminiferal abundances during time, no distinctive change in the vertical distribution, reduced diversity, and more stable foraminiferal communities were noticed, which indicates no or little influence of the Northeast Monsoon to benthic foraminifera in this region.

Quaternary and Paleogene calcareous nannofossils of ODP Leg 115

The occurrences of ten datum events for the Quaternary and top Pliocene nannofossils are identified at nine Leg 115 sites. A quantitative investigation of Paleogene nannofossils in 470 samples selected from 11 holes at 9 sites yielded 197 taxa, including one new species and 10 unidentified taxa that are likely to be new species. Regional differences in the timing of some biostratigraphically important events are recognized, and a set of datum events useful for biostratigra- phy in the tropical Indian Ocean is presented. Biogeographical differences are minor for Paleogene cores from the tropical sites (Sites 707-716); however, the Quaternary and late early Oligocene floras observed at the two subtropical sites (Sites 705 and 706) differ significantly from the corresponding floras of the tropical sites. Bathymetrically controlled dissolution is recognized by the reduction of species diversity in the Paleogene flora. Selective dissolution of nannofossils is also evidenced by the percentage reduction of three holococcolith taxa, Lanternithus minutus, Zygrhablithus bijugatus, and Holococcolith type A as well as by the increase of Coccolithus pelagicusand Cribrocentrum reticulatumin the deeper sites.

Stable isotope record of Maestrichtian foraminifera

A global compilation of deep-sea isotopic records suggests that Maastrichtian ocean-climate evolution was technically driven. During the early Maastrichtian the Atlantic intermediate-deep ocean was isolated from the Pacific, Indian, and Southern Oceans; deep water formed in the high-latitude North Atlantic and North Pacific. At the early/late Maastrichtian boundary a major reorganization of oceanic circulation patterns occurred, resulting in the development of a thermohaline circulation system similar to that of the modern oceans. A combination of isotopic and plate kinematic data suggests that this event was triggered by the final breaching of tectonic sills in the South Atlantic and the initiation of north-south flow of intermediate and deep water in the Atlantic. The onset of Laramide tectonism during the mid Maastrichtian led to the concurrent draining of major epicontinental seaways. Together, these events caused cooling, increased latitudinal temperature gradients, increased ventilation of the deep ocean, and affected a range of marine biota.

Planktonic foraminifers in DSDP Holes 30-289 and 33-315A

The work is based on samples from Deep-Sea Drilling in the Pacific Ocean and from natural sections in its continental setting. Species composition of planktonic foraminifera from Maastrichtian sediments of the Pacific and South Atlantic oceans, as well as from marginal seas of Australia and New Zealand and epicontinental basins of the northern hemisphere has been analysed. Two main issues: reconstruction of Maastrichtian climatic zonality, and reconstruction of Maastrichtian paleodepths. Four bipolar climatic zones have been distinguished. According to preservation of planktonic foraminifera and composition of their complexes three levels of dissolution have been identified.