Lower Cretaceous planktonic foraminifer stratigraphy of sediments from ODP Leg 171B sites

During Ocean Drilling Program Leg 171B, an Aptian to Turonian sedimentary succession yielding exceptionally well-preserved planktonic foraminiferal faunas was recovered at Sites 1049, 1050, and 1052. Most of the standard Tethyan planktonic foraminiferal zones have been recognized within the mid-Cretaceous section, with the exception of two Albian zones not reached by any of the drilled holes. In addition, some emphasis is brought here on the current problems concerning the definition of the Aptian/Albian and Albian/Cenomanian boundaries.

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.

Cretaceous planktonic foraminifera of DSDP Hole 71-511

Lower and Upper Cretaceous sediments of the Maurice Ewing Bank, Site 511 (black shales, mudstones, zeolitic clays, and nannofossil chalk and ooze, 361 m thick) are characterized by an assemblage of planktonic foraminifers of low systematic diversity, including over 50 species. Representatives of Hedbergella, Globigerinelloides, Archaeoglobigerina, Whiteinella, Rugoglobigerina, and Heterohelix are predominant; species of Ticinella, Praeglobotruncana, Globotruncana, Schackoina, and Planoglobulina associated with some interbeds occur in smaller numbers. Planktonic foraminifers enable us to subdivide the Cretaceous sediments into Barremian-Aptian, Albian, upper Cenomanian, Turonian, Coniacian-Santonian, Santonian, Campanian, and upper Campanian-Maestrichtian intervals. The Lower Cretaceous (Albian) and Upper Cretaceous (upper Cenomanian-Turonian) are separated by a distinct hiatus and unconformity. In the Upper Cretaceous section, a hiatus may be present at the top of the Campanian. The upper Cenomanian-Santonian sediments are reduced in thickness, whereas the Campanian-Maestrichtian interval is expanded. In the Barremian-Aptian black shales, planktonic foraminifers are very rare: they were deposited in shallow water under anoxic conditions. In the Albian, when sedimentation conditions became oxidizing and the depth increased to 200-400 meters, they became more common. By the end of the Upper Cretaceous, depths appear to increase to 2000 meters. In the interbeds of calcareous sediments, planktonic foraminifers are common; in interbeds of zeolitic clays they are rare or absent (dissolution facies). Alternation of these types of sediments is especially characteristic of the Coniacian-lower Campanian, testifying to abrupt CCD fluctuations. The planktonic foraminifers of the Falkland Plateau belong to the Austral Province of the Southern Hemisphere. In their systematic composition they are extremely similar to microfauna of the Boreal Province of the Northern Hemisphere.

Tab. 4: Vergesellschaftung von Nitella opaca in Nordwestdeutschland

New facts on the occurrence and distribution of the threatened and rare stoneworts Chara baltica, C. connivens, C. contraria, C. virgata, Nitella hyalina, N. opaca, N. gracilis, N. capillaris, N translucens and N. flexilis and the non-threatened species Chara globularis in the northwestern part of Lower Saxony (Germany) are presented. A description of the stonewort sites is given and the abundance and the degrees of endangering of the species are discussed. Data about the Vegetation of the habitats of Nitella hyalina and N. opaca are reported. Additionally former sites of Chara canescens have been checked again. References to determination problems concerning Nitella opaca and N flexilis are given. Finally the protection of stoneworts, management requirements and the need for future investigations are discussed.

Lipid, carbon and nitrogen content and fatty acid composition of Temora longicornis females and different food species during the experiment

Temora longicornis, a dominant calanoid copepod species in the North Sea, is characterised by low lipid reserves and high biomass turnover rates. To survive and reproduce successfully, this species needs continuous food supply and thus requires a highly flexible digestive system to exploit various food sources. Information on the capacity of digestive enzymes is scarce and therefore the aim of our study was to investigate the enzymatic capability to respond to quickly changing nutritional conditions. We conducted two feeding experiments with female T. longicornis from the southern North Sea off Helgoland. In the first experiment in 2005, we tested how digestive enzyme activities and enzyme patterns as revealed by substrate SDS-PAGE (sodium dodecylsulfate polyacrylamide gel electrophoresis) responded to changes in food composition. Females were incubated for three days fed ad libitum with either the heterotrophic dinoflagellate Oxyrrhis marina or the diatom Thalassiosira weissflogii. At the beginning and at the end of the experiment, copepods were deep-frozen for analyses. The lipolytic enzyme activity did not change over the course of the experiment but the enzyme patterns did, indicating a distinct diet-induced response. In a second experiment in 2008, we therefore focused on the enzyme patterns, testing how fast changes occur and whether feeding on the same algal species leads to similar patterns. In this experiment, we kept the females for 4 days at surplus food while changing the algal food species daily. At day 1, copepods were offered O. marina. On day 2, females received the cryptophycean Rhodomonas baltica followed by T. weissflogii on day 3. On day 4 copepods were again fed with O. marina. Each day, copepods were frozen for analysis by means of substrate SDS-PAGE. This showed that within 24 h new digestive enzymes appeared on the electrophoresis gels while others disappeared with the introduction of a new food species, and that the patterns were similar on day 1 and 4, when females were fed with O. marina. In addition, we monitored the fatty acid compositions of the copepods, and this indicated that specific algal fatty acids were quickly incorporated. With such short time lags between substrate availability and enzyme response, T. longicornis can successfully exploit short-term food sources and is thus well adapted to changes in food availability, as they often occur in its natural environment due seasonal variations in phyto- and microzooplankton distribution.

Phytoplankton parameters in the Large Aral Sea in June 2008

Species composition, abundance, and biomass of phytoplankton in the surface water layer were determined at 10 stations in the central part of the Western Basin (WB) and at one station in the Eastern Basin (EB) of the Large Aral Sea. 42 algal species were found. Diatoms had the highest number of species. Similarity of phytoplankton composition in the WB was high, whereas phytoplankton composition in the WB and EB differed significantly. In WB abundance and biomass of phytoplankton varied from 826x10**3 to 6312x10**3 cells/l (aver. 1877x10**3 cells/l) and from 53 to 241 ?g C/l (aver. 95 ?g C/l). In EB the phytoplankton abundance was 915x10**3 cells/l and 93 ?g C/l. Vertical distribution of phytoplankton in upper 35 m was investigated at one station in WB. Maximum values of phytoplankton abundance and biomass were recorded under the thermocline at 20 m depth. Integrated biomass of phytoplankton was 14 g C/m**2.

Size-related stable isotope changes in Late Cretaceous and Recent planktic foraminifera from the western tropical Atlantic

The paleoecology of Cretaceous planktic foraminifera during the Late Cenomanian to Coniacian period (~95-86 Ma) remains controversial since much of the tropical marine record is preserved as chalk and limestone with uncertain geochemical overprints. Here we present delta13C and delta18O data from sieve size fractions of monospecific samples of exceptionally well preserved planktic foraminifera recovered during Ocean Drilling Program Leg 207 (Demerara Rise, western tropical Atlantic). Our results suggest that all species studied (Hedbergella delrioensis, Heterohelix globulosa, Marginotruncana sinuosa, Whiteinella baltica) grew primarily in surface waters and did not change their depth habitat substantially during their life cycle. Comparison of size-related ontogenetic trends in delta13C in Cretaceous and modern foraminifera further suggests that detection of dinoflagellate photosymbiosis using delta13C is confounded by physiological effects during the early stages of foraminifer growth, raising doubts about previous interpretations of photosymbiosis in small foraminifera species. We propose that obligate photosymbiosis involving dinoflagellates may not have evolved until the Campanian or Maastrichtian since our survey of Cenomanian-Coniacian species does not find the delta18O and delta13C size-related trends observed in modern foraminifer-dinoflagellate symbioses.