Diatom abundance in ODP Leg 178 holes

This paper documents the biostratigraphic distribution and abundance of diatoms from sites drilled during Ocean Drilling Program Leg 178, off the Pacific margin of the Antarctic Peninsula. Drift sediments cored on the continental rise at Sites 1095, 1096, and 1101 have good recovery and a well-defined paleomagnetic record. Well-preserved diatoms are present throughout the upper Miocene to middle Pliocene and in the upper Quaternary section of these sites. The stratigraphic occurrence of diatom species through these intervals defines numerous datum levels. Diatom events are given absolute age estimates through direct correlation to the established paleomagnetic stratigraphy of Sites 1095, 1096, and 1101. Leg 178 diatom biostratigraphic results enable the development of a regional stratigraphic framework for the Pacific sector of the Southern Ocean and record the interaction of open-ocean and shelf-margin diatom floras.

Abundance and biomass of the benthic infauna of the North Sea

In 1986 participants of the Benthos Ecology Working Group of ICES conducted a synoptic mapping of the infauna of the southern and central North Sea. Together with a mapping of the infauna of the northern North Sea by Eleftheriou and Basford (1989, doi:10.1017/S0025315400049158) this provides the database for the description of the benthic infauna of the whole North Sea in this paper. Division of the infauna into assemblages by TWINSPAN analysis separated northern assemblages from southern assemblages along the 70 m depth contour. Assemblages were further separated by the 30, 50 m and 100 m depth contour as well as by the sediment type. In addition to widely distributed species, cold water species do not occur further south than the northern edge of the Dogger Bank, which corresponds to the 50 m depth contour. Warm water species were not found north of the 100 m depth contour. Some species occur on all types of sediment but most are restricted to a special sediment and therefore these species are limited in their distribution. The factors structuring species distributions and assemblages seem to be temperature, the influence of different water masses, e.g. Atlantic water, the type of sediment and the food supply to the benthos.

Calcareous nannofossil assemblages of Ocean Anoxic Event 2 in ODP Sites 207-1258 and 207-1260

The calcareous nannofossils of the Cenomanian/Turonian boundary interval of Sites 1258 and 1260 (Ocean Drilling Program Leg 207) have been studied in order to understand the depositional environment during Oceanic Anoxic Event 2 (OAE2) in the equatorial Atlantic. Nannofossil assemblages show a significant change in relative abundances during the positive d13Corg excursion interval. The strong increase of the high productivity indicator Zeugrhabdotus erectus and the simultaneous decrease of the oligotrophic taxa Watznaueria barnesiae and Watznaueria fossacincta are indicative of enhanced fertility. The decrease of Eprolithus floralis may be attributed to the surface-water temperature increase during OAE2, which is, however, not very significant (~2-3 °C), as suggested by published TEX86 data. It seems more likely that the decrease of E. floralis during OAE2 was evoked by the breakdown of water-column stratification, indicating it as a deep-dwelling species, which prefers stratified waters with a deep nutricline. Prediscosphaera spp. and Retecapsa ficula, which show a significant increase in relative abundances during OAE2, seem to prefer eutrophic environments, while Amphizygus brooksii and Zeugrhabdotus noeliae lower surface-water fertility. Gartnerago segmentatum, Broinsonia spp., Watznaueria biporta, and Seribiscutum gaultensis decrease in abundances during OAE2. It is not clear if they preferred an oligotrophic environment, cooler surface-waters, or if they were inhabitants of the lower photic zone. Published geochemical data suggest that enhanced fertility and higher temperatures during OAE2 may have been caused by submarine volcanic activity through the release of biolimiting micronutrients into the ocean and carbon dioxide into the atmosphere. The breakdown of water-column stratification may have increased further nutrient availability.

Distribution of diatoms in Oligocene to Pleistocene sediments of the tropical Pacific

According to the drilling probes of the Deep Waier Drilling Project, Neogene sediments in a tropical area of the Pacific Ocean are divided into 15 zones based on diatoms. The author shows that a unique zonation may be applied for the entire region. Identification of diatoms zones boundaries was conducted through their direct correlation with nannoplancton, radiolarian and foraminiferal zonal sceals. Their ultra-structure and morphological relationship are being analysed. The mode of siliceous accumulation within the equatorial belt differed through the western central and eastern region since the early Miocene and the difference become more evident from the end of Middle Miocene. The distribution of Neogene diatomaceous silt in the tropical area is controlled by the character of gyre-water circulation and agrees with the modern geographical zonation.

Diatom deposits in the ostpreußischen Haffe

Als man nach dem ersten Weltkrieg im verkleinerten Deutschland nach der Möglichkeit von Neulandgewinnung suchte, dachte man auch an eineTrockenlegung der ostpreußischen Haffe. Aus diesem Anlaß wurden umfangreiche Bohrungen ausgeführt, um ein möglichst genaues Bild vom Untergrunde der Haffe zu bekommen. Auf Veranlassung der Preußischen Geologischen Landesanstalt wurde ich mit der Untersuchung der Diatomeen in den Bohrproben beauftragt. Die Arbeit wurde 1934 begonnen und Ende 1937 wurde der letzte Arbeitsbericht abgeliefert. Die beabsichtigte Veröffentlichung ist bisher unterblieben, weil die Druckvorlagen später verloren gegangen sind. Seitdem sind über die Haffuntersuchungen mehrere Teilergebnisse veröffentlicht worden, von denen hier schon wegen der Terminologie die pollenanalytischen Arbeiten von L. HEIN (1941) und HUGO GROSS (1941) erwähnt seien, auf die im Abschnitt Il 2e näher eingegangen wird. Bei der geologischen Auswertung war Zurückhaltung geboten; denn es wäre gewagt, allein aus der Perspektive der Diatomeenforschung endgültige Aussagen machen zu wollen. Darum habe ich mich bemüht, das Material so weit aufzuschließen, daß es Geologen später auch bei veränderter Fragestellung auswerten können. "Die Theorien wechseln, aber die Tatsachen bleiben." Der Initiative des Herrn Prof. Dr. K. GRIPP und der finanziellen Hilfe der Deutschen Forschungsgemeinschaft ist es zu verdanken, daß die vorliegende Arbeit im Druck erscheinen kann. Zusammenfassung 1. Nur in den alluvialen Schichten des Kurischen Haffs wurden Diatomeen gefunden. 2. Die Diatomeenflora des Kurischen Haffs besteht zur Hauptsache aus Süßwasserformen. 3. Salzwasserformen finden sich in allen Schichten verstreut unter der Süßwasserflora. Wenn sie auch nach Zahl der Arten in manchen Proben einen erheblichen Prozentsatz der Flora ausmachen, so ist doch die Zahl der Individuen stets so gering, daß man nirgends von einer Brackwasserflora sprechen kann. 4. Die Süßwasserflora besteht in den unteren Schichten vorwiegend aus Grundformen; und zwar machen die epiphytischen Bewohner flacher Sumpfgewässer einen großen Teil der Flora aus. 5. In einzelnen Bohrungen kommt in den untersten alluvialen Schichten eine Grundflora mit zahlreichen Mastogloien vor. Dies sind die ältesten diatomeenführenden Schichten, entstanden in isolierten Sumpfgewässern. 6. Die übrigen Schichten mit überwiegender Grundflora sind vermutlich Ablagerungen der Ancyluszeit. 7. Die oberen Schichten, in denen die Planktondiatomeen überwiegen, dürften größtenteils der Litorina-Transgressionszeit angehören, jedoch ist der Transgressions-Kontakt nicht klar zu erkennen. 8. Das Ende der Litorinazeit ist noch weniger erkennbar, da eine grundsätzliche Veränderung der Flora nach oben nicht zu beobachten ist. 9. Die ostbaltischen Charakterformen sind in allen Schichten vertreten.

Abundance of mesozooplankton in the western part of the Black Sea in summer 2002 during the National Monitoring Programme

The dataset is based on samples collected in the summer of 2002 in the Western Black Sea in front of Bulgaria coast. The whole dataset is composed of 47 samples (from 19 stations of National Monitoring Grid) with data of mesozooplankton species composition abundance and biomass. Sampling for zooplankton was performed from bottom up to the surface at depths depending on water column stratification and the thermocline depth. Zooplankton samples were collected with vertical closing Juday net,diameter - 36cm, mesh size 150 µm. Tows were performed from surface down to bottom meters depths in discrete layers. Samples were preserved by a 4% formaldehyde sea water buffered solution. Sampling volume was estimated by multiplying the mouth area with the wire length. Mesozooplankton abundance: The collected material was analysed using the method of Domov (1959). Samples were brought to volume of 25-30 ml depending upon zooplankton density and mixed intensively until all organisms were distributed randomly in the sample volume. After that 5 ml of sample was taken and poured in the counting chamber which is a rectangle form for taxomomic identification and count. Large (> 1 mm body length) and not abundant species were calculated in whole sample. Counting and measuring of organisms were made in the Dimov chamber under the stereomicroscope to the lowest taxon possible. Taxonomic identification was done at the Institute of Oceanology by Lyudmila Kamburska using the relevant taxonomic literature (Mordukhay-Boltovskoy, F.D. (Ed.). 1968, 1969,1972). Taxon-specific abundance: The collected material was analysed using the method of Domov (1959). Samples were brought to volume of 25-30 ml depending upon zooplankton density and mixed intensively until all organisms were distributed randomly in the sample volume. After that 5 ml of sample was taken and poured in the counting chamber which is a rectangle form for taxomomic identification and count. Copepods and Cladoceras were identified and enumerated; the other mesozooplankters were identified and enumerated at higher taxonomic level (commonly named as mesozooplankton groups). Large (> 1 mm body length) and not abundant species were calculated in whole sample. Counting and measuring of organisms were made in the Dimov chamber under the stereomicroscope to the lowest taxon possible. Taxonomic identification was done at the Institute of Oceanology by Lyudmila Kamburska using the relevant taxonomic literature (Mordukhay-Boltovskoy, F.D. (Ed.). 1968, 1969,1972).