Coccolithophore abundance and biometry in the South China Sea, 2014

Coccolithophore contributions to the global marine carbon cycle are regulated by the calcite content of their scales (coccoliths), and the relative cellular levels of photosynthesis and calcification. All three of these factors vary between coccolithophore species, and with response to the growth environment. Here, water samples were collected in the northern basin of the South China Sea (SCS) during summer 2014 in order to examine how environmental variability influenced species composition and cellular levels of calcite content. The vertical structure of the coccolithophore community was strongly regulated by mesoscale eddies. All living coccolithophores produced within the euphotic zone (1 % of surface irradiance), and Florisphaera profunda was a substantial coccolithophore and coccolith-calcite producer in the Deep Chlorophyll-a Maximum (DCM), especially in most oligotrophic anti-cyclonic eddy centers. Placolith-bearing coccolithophores, plus F. profunda, and other larger and numerically rare species made almost equal contributions to coccolith-based calcite in the water column. For Emiliania huxleyi biometry measurements, coccolith size positively correlated with nutrients, and it is suggested that coccolith length is influenced by nutrient and light related growth rates. However, larger sized coccoliths were related to low pH and calcite saturation, although it is not a simple cause and effect relationship. Genotypic or ecophenotypic variation may also be linked to coccolith size variation.

Mapping of the Eltanin impact area in the South-East Pacific

Two Polarstern expeditions were conducted in 1995 (ANT-XII/4) and 2001 (ANT-XVIII/5a) to the Bellingshausen Sea and Amundsen Sea and the suspected Eltanin meteorite impact in the SE-Pacific. A survey of the sediment distribution and its acoustic structure along the cruise track was performed. The seafloor topography was sampled using the multibeam sonar system Hydrosweep DS2 which operates on a frequency of 15.5 kHz. The resulting AWI Bathymetric Chart of the Eltanin Meteorite Impact Area is based on a Digital Terrain Model of this area. The mapping was performed using ArcGIS. The Eltanin impact area which covers the 4.100 m high Freden Seamount is visualized by one overview sheet of the scale 1:200,000 and four 1:100,000 subsheets.

Accumulation rates of bulk sediment and opal in surface sediments of the South Atlantic

A set of 114 samples from the sediment surface of the Atlantic, eastern Pacific and western Indian sectors of the Southern Ocean has been analyzed for 230Th and biogenic silica. Maps of opal content, Th-normalized mass flux, and Th-normalized biogenic opal flux into the sediment have been derived. Significant differences in sedimentation patterns between the regions can be detected. The mean bulk vertical fluxes integrated into the sediment in the open Southern Ocean are found in a narrow range from 2.9 g/m**2 yr (Eastern Weddell Gyre) to 15.8 g/m**2 yr (Indian sector), setting upper and lower limits to the vertically received fraction of open ocean sediments. The silica flux to sediments of the Atlantic sector of the Southern Ocean is found to be 4.2 ± 1.4 * 10**11 mol/yr, just one half of the last estimate. This adjustment represents 6% of the output term in the global marine silica budget.