Particle fluxes at sediment traps AU9701, south of Australia

Sediment trap moorings were deployed from September 21, 1997 through February 21, 1998 at three locations south of Australia along 140°E: at -47°S in the central Subantarctic Zone (SAZ) with traps at 1060, 2050, and 3850 m depth, at -51°S in the Subantarctic Front with one trap at 3080 m, and at -54°S in the Polar Frontal Zone (PFZ) with traps at 830 and 1580 m. Particle fluxes were high at all the sites (18-32 g/m**2/yr total mass and 0.5-1.4 g organic carbon/m**2/yr at -1000 m, assuming minimal flux outside the sampled summer period). These values are similar to other Southern Ocean results and to the median estimated for the global ocean by Lampitt and Antia [1997], and emphasize that the Southern Ocean exports considerable carbon to the deep sea despite its 'high-nutrient, low chlorophyll' characteristics. The SAZ site was dominated by carbonate (>50% of total mass) and the PFZ site by biogenic silica (>50% of total mass). Both sites exhibited high export in spring and late summer, with an intervening low flux period in December. For the 153 day collection period, particulate organic carbon export was somewhat higher in all the traps in the SAZ (range 0.57-0.84 gC/m**2) than in the PFZ (range 0.31-0.53), with an intermediate value observed at the SAF (0.60). The fraction of surface organic carbon export (estimated from seasonal nutrient depletion, Lourey and Trull [2001]) reaching 1000 m was indistinguishable in the SAZ and PFZ, despite different algal communities.

Abundance of mesozooplankton in the Marmara Sea collected during the Bilim 2 cruise in April 2008

The Sesame dataset contains mesozooplankton data collected during April 2008 in the Marmara Sea (between 40°15' - 34°00N latitude and 19°00 - 23°10'E longitude). Sampling was always performed in day hours (07:00-18:00 local time). Samples were taken at 6 stations in the Marmara Sea. Mesozooplankton samples were collected by using a WP-2 closing net with 200 µm mesh size. Sample was immediately fixed and preserved in a formaldehyde-seawater solution (4% final concentration) to be successively analyzed in the laboratory for species composition, abundance and total biomass. The algal organisms materials were then seperated from the mesozooplankton subsample at the dissecting microscope in the laboratory because of the contamination of the net samples with large-sized algae and mucilaginous organic matters. Afterwards, each samples were filtered on GF/C (pre combusted and weighed) for biomass measurements for dry weight. The dataset includes samples analyzed for mesozooplankton species composition, abundance and total mesozooplankton biomass. Sampling volume was estimated by multiplying the mouth area with the wire length. Sampling biomass was measured by weighing filters and then determined according to sampling volume. 1/2 sample or an aliquot was analyzed under the binocular microscope. Copepod species were identified and enumerated; the other mesozooplankters were identified and enumerated at higher taxonomic level (commonly named as mesozooplankton groups). Taxonomic identification was done at the METU-Institute of Marine Sciences by Tuba Terbiyik using the relevant taxonomic literatures.

Planktonic foraminifera, nannofossils and stable isotope record across tghe Paleocene-Eocene thermal maximum of ODP Hole 113-690B

The carbonate saturation profile of the oceans shoaled markedly during a transient global warming event known as the Paleocene-Eocene thermal maximum (PETM) (circa 55 Ma). The rapid release of large quantities of carbon into the ocean-atmosphere system is believed to have triggered this intense episode of dissolution along with a negative carbon isotope excursion (CIE). The brevity (120-220 kyr) of the PETM reflects the rapid enhancement of negative feedback mechanisms within Earth's exogenic carbon cycle that served the dual function of buffering ocean pH and reducing atmospheric greenhouse gas levels. Detailed study of the PETM stratigraphy from Ocean Drilling Program Site 690 (Weddell Sea) reveals that the CIE recovery period, which postdates the CIE onset by ~80 kyr, is represented by an expanded (~2.5 m thick) interval containing a unique planktic foraminiferal assemblage strongly diluted by coccolithophore carbonate. Collectively, the micropaleontological and sedimentological changes preserved within the CIE recovery interval reflect a transient state when ocean-atmosphere chemistry fostered prolific coccolithophore blooms that suppressed the local lysocline to relatively deeper depths. A prominent peak in the abundance of the clay mineral kaolinite is associated with the CIE recovery interval, indicating that continental weathering/runoff intensified at this time as well (Robert and Kennett, 1994). Such parallel stratigraphic changes are generally consonant with the hypothesis that enhanced continental weathering/runoff and carbonate precipitation helped sequester carbon during the PETM recovery period (e.g., Dickens et al., 1997, doi:10.1130/0091-7613(1997)025<0259:ABOGIT>2.3.CO;2 ; Zachos et al., 2005, doi:10.1126/science.1109004).

Abundance of calcareous nannofossils in ODP Hole 122-761C (Table 1)

A biostratigraphically complete (all nannofossil biozones present) Cretaceous/Tertiary boundary was recovered at Site 761 on the Wombat Plateau, northwest Australian margin, during Ocean Drilling Program Leg 122. A quantitative study of calcareous nannofossils on closely spaced samples across the boundary reveals a rapid change in assemblages in a similar fashion to other Cretaceous/Tertiary boundary sites. Nannofossil species were placed into three categories: Tertiary, Cretaceous, and 'survivors'. The rapid sequential turnover in these assemblages is as follows: Cretaceous species are abruptly replaced at the boundary by opportunistic survivor species, which in turn are abruptly replaced by newly evolved Tertiary taxa. The uppermost Maestrichtian assemblage is distinctly mid-latitudinal with few Micula murus and rare to few Nephrolithus frequens. The nannofossil assemblage immediately above the boundary is dominated by an abundance bloom of Cyclagelosphaera spp. No Thoracosphaera or Braarudosphaera abundance blooms are present as at many other localities. The change from a survivor- to Tertiary-dominated assemblage is coincident with the CPla/CPlb nannofossil subzonal boundary, which is marked by the simultaneous first occurrence of several species including Cruciplacolithus tenuis and C. primus. The latter is found to first occur below C. tenuis in the most complete Cretaceous/Tertiary sections. A hiatus between Subzones CPla and CPlb is interpreted to explain this discrepancy.

(Table 2) Concentration of phytoplankton pigments in Adventfjorden in spring and summer of 1997

The study was carried out from April 30 until July 13 of 1997 in Adventfjorden (Spitsbergen). Formation of a less saline and warmer surface water (~1 m thick) caused by melting of the ice was observed in the fjord during the first days of May. In summer the less saline surface layer was about 3 m thick. Euphotic depth measured under the ice sheet reached 12 m, whereas load of mineral matter brought with riverine discharge in summer (content of total particulate matter in the fjord reached 1.66 kg/m**2) dramatically reduced euphotic zone depth to 0.35 m. By pigment measurement three phases of phytoplankton development in Adventfjorden were distinguished: (1) spring bloom that has started under fast ice and reached maximum in the mid of May, (2) stagnation period in June, (3) increase of pigment concentration in July, what could indicate start of the next algae bloom. Analyses of chlorophylls and carotenoids revealed that diatoms (chl c, fucoxanthin), and green algae (chl b, lutein) dominated phytoplankton community in the fjord. Moreover, presence of peridinin indicates presence of Dinophyta and alloxanthin - occurence of Cryptophyta. In May and June 1997 phytoplankton appeared mainly in the surface of water, while in July, as a result of inflow of turbulent riverine waters into Adventfjorden, algae cells were pushed down and the highest numbers were observed at depth ~20 m. Great phaeopigments to chl a ratio (= 0.54) found in fjord seston in June and July probably shows strong impact of zooplankton grazing on phytoplankton development. High contribution of chlorophyllide a in porphyrin a poll in samples collected under fast ice (chlorophyllide a / chl a ratio = 0.18) reflects the final stage of algal communitie succession in ice, just before spring ice melt and release of biota to oceanic water. Chlorophyllide a content during summer was minor or not detectable, demonstrating that diatom cells were in good physiological condition. High chl a allomer / chl a ratio (average = 0.11 for the period investigated) confirms high oxygen concentration in environment of Adventfjorden.