First record of the coloured righteye flounder, Poecilopsetta colorata (Teleostei: Poecilopsettidae) from the Sakalaves seamounts in the Mozambique Channel

Background: The coloured righteye flounder, Poecilopsetta colorata Günther, 1880 was previously known from the eastern Indian Ocean to the South China Sea and Indonesia. Here, a new record from the western Indian Ocean is reported. Results: The new record is based on a specimen collected on the Sakalaves seamounts at 375 m in depth in the Mozambique Channel during a recent oceanographic survey. Four other teleost fish species including an uncommon ophidiid species, Neobythites somaliaensis Nielsen, 1995 were also collected on the same seamounts. Conclusions: The presence of P. colorata in the Mozambique Channel suggests a broad and Indo-West Pacific wide distribution for this relatively rare deep-sea species. The sequence of the cytochrome oxidase subunit-I for the collected specimen is provided as a genetic reference for further DNA barcoding and systematic studies.

Porosity in sediment cores from the central Arctic Ocean during POLARSTERN cruise ARK-XXVII/3 from August-September 2012

During the RV Polarstern cruise ARK-XXVII/3 to the Arctic Ocean in summer 2012, when sea ice declined to a record minimum bottom, sediment cores were collected with a TV-guided multicorer at stations in the Nansen and Amundsen basin. For porosity measurements cores were subsampled and samples were stored at 4°C until analyzes in the home laboratory.

Chlorophyll pigments of the central Arctic Ocean during POLARSTERN cruise ARK-XXVII/3 from August-September 2012

During the RV Polarstern cruise ARK-XXVII/3 to the Arctic Ocean in summer 2012, when sea ice declined to a record minimum bottom, sediments were collected with a TV-guided multicorer at stations in the Nansen and Amundsen basin. Chlorophyll a and phaeopigments were extracted from sediments with acetone using three replicates per station. The concentrations in the acidified supernatants were measured with a Turner Trilogy fluorometer (Boetius and Damm, 1998). The sum of chlorophyll a and phaeopigments is expressed as chloroplast pigment equivalents (CPE) (Thiel, 1982).

Total dissolved organic carbon and total dissolved nitrogen in sediment pore water of the central Arctic Ocean collected during POLARSTERN cruise ARK-XXVII/3 from August-September 2012

During the RV Polarstern cruise ARK-XXVII/3 to the Arctic Ocean in summer 2012, when sea ice declined to a record minimum bottom, water and sediment pore water samples were collected with a TV-guided multicorer at stations in the Nansen and Amundsen basin. 50 ml sediment pore water samples were collected from 0-1, 1-5 and 5-10 cm sediment depths from up to 4 parallel sediment cores at each station. Additionally, overlying bottom waters were carefully collected from undisturbed sediment cores. Acidified pore water samples (pH2) were used for analysis of DOC and TDN concentrations. The measurements were performed by hand injection via catalytic oxidation at high temperature on a TOC-V Shimadzu instrument.

Dissolved organic carbon in sediments of the central Arctic Ocean collected during POLARSTERN cruise ARK-XXVII/3 from August-September 2012

Marine organic matter (OM) sinks from surface waters to the seafloor via the biological pump. Benthic communities, which use this sedimented OM as energy and carbon source, produce dissolved organic matter (DOM) in the process of remineralization, enriching the sediment porewater with fresh DOM compounds. We hypothesized that in the oligotrophic deep Arctic basin the molecular signal of freshly deposited primary produced OM is restricted to the surface sediment pore waters which should differ from bottom water and deeper sediment pore water in DOM composition. This study focused on: 1) the molecular composition of the DOM in sediment pore waters of the deep Eurasian Arctic basins, 2) whether the signal of marine vs. terrigenous DOM is represented by different compounds preserved in the sediment pore waters and 3) whether there is any relation between Arctic Ocean ice cover and DOM composition. Molecular data, obtained via 15 Tesla Fourier transform ion cyclotron resonance mass spectrometer, were correlated with environmental parameters by partial least square analysis. The fresher marine detrital OM signal from surface waters was limited to pore waters from < 5 cm sediment depth. The productive ice margin stations showed higher abundances of peptides, unsaturated aliphatics and saturated fatty acids formulae, indicative of fresh OM/pigments deposition, compared to northernmost stations which had stronger aromatic signals. This study contributes to the understanding of the coupling between the Arctic Ocean productivity and its depositional regime, and how it will be altered in response to sea ice retreat and increasing river runoff.