Assimilation and turnover rates of lipid compounds in dominant Antarctic copepods fed with C-enriched diatoms.

The study revealed species- and stage-specific differences in lipid accumulation of the dominant Antarctic copepods, the primarily herbivorous (copepodite stage V (CV), females) and the more omnivorous (females) storing wax esters and triacylglycerols, respectively, which were collected in summer (end of December). Feeding carbon-labelled diatoms to these copepods, C elucidated assimilation and turnover rates of copepod total lipids as well as specific fatty acids and alcohols. The C incorporation was monitored by compound-specific stable isotope analysis (CSIA).

Stoichiometry, polarity, and organometallics in solid-phase extracted dissolved organic matter of the Elbe-Weser estuary.

Dissolved organic matter (DOM) is ubiquitous in natural waters and plays a central role in the biogeochemistry in riverine, estuarine and marine environments. This study quantifies and characterizes solid-phase extractable DOM and trace element complexation at different salinities in the Weser and Elbe River, northern Germany, and the North Sea. Dissolved organic carbon (DOC), total dissolved nitrogen (TDN), Co and Cu concentrations were analyzed in original water samples.

Lipid and fatty acid/alcohol compositions of the subarctic copepods Neocalanus cristatus and Eucalanus bungii from various depths in the Oyashio region, western North Pacific.

Lipids of Neocalanus cristatus and Eucalanus bungii (C3 to adults), collected in March, May, and December from various depths (0-2000m) were studied in the Oyashio region, western North Pacific. Total lipid and wax ester contents of younger N. cristatus stages increased during the development, being higher in May than in March and December.

Seasonal baseline of nutrients and stable isotopes in a saline lake of Argentina: biogeochemical processes and river runoff effects.

The seasonal variability of inorganic and organic nutrients and stable isotopes and their relations with plankton and environmental conditions were monitored in Lake Chasicó. Principal component analysis evidenced the strong influence of the river runoff on several biogeochemical variables. Silicate concentrations were controlled by diatom biomass and river discharge.

Inorganics in organics: quantification of organic phosphorus and sulfur and trace element speciation in natural organic matter using HPLC-ICPMS.

A method is presented for the chemical characterization of natural organic matter (NOM). We combined reversed-phase chromatographic separation of NOM with high resolution inductively coupled plasma mass spectrometry. A desolvation technique was used to remove organic solvent derived from the preceding chromatographic separation.

Vulnerability of pejerrey Odontesthes bonariensis populations to climate change in pampean lakes of Argentina.

The vulnerability of the pejerrey Odontesthes bonariensis population in Lake Chasicó was assessed under different climate change conditions. During the sampling period, the water temperature was adequate for fish reproduction and to sustain an adequate sex ratio. Climate-driven higher temperatures, however, may severely distort population structure and cause drastic reduction or local extinction of stocks.

Microbial production of recalcitrant dissolved organic matter: long-term carbon storage in the global ocean.

The biological pump is a process whereby CO(2) in the upper ocean is fixed by primary producers and transported to the deep ocean as sinking biogenic particles or as dissolved organic matter. The fate of most of this exported material is remineralization to CO(2), which accumulates in deep waters until it is eventually ventilated again at the sea surface. However, a proportion of the fixed carbon is not mineralized but is instead stored for millennia as recalcitrant dissolved organic matter.

Fundamentals of molecular formula assignment to ultrahigh resolution mass data of natural organic matter.

Ultrahigh-resolution mass spectrometry via the Fourier transform ion cyclotron resonance technique (FT-ICR-MS) allows the identification of thousands of different molecular formulas in natural organic matter and petroleum samples. Molecular formula assignment from mass data is most critical and time-consuming for these samples, and in many cases, several formulas can be determined for the same molecular mass. Therefore, automated procedures are required for an efficient exploitation of the extensive data sets.

Fatty acid trophic markers in the pelagic marine environment.

Fatty acids have been used as qualitative markers to trace or confirm predator-prey relationships in the marine environment for more than thirty years. More recently, they have also been used to identify key processes impacting the dynamics of some of the world's major ecosystems. The fatty acid trophic marker (FATM) concept is based on the observation that marine primary producers lay down certain fatty acid patterns that may be transferred conservatively to, and hence can be recognized in, primary consumers.

New evidence of the copepod maternal food effects on reproduction.

Failure of female reproductive capacity in the copepod Calanus helgolandicus was related to number and combination of the phytoplankton species in the diets. The maternal food effects were detectable at different levels: fecundity, oogenesis and hatching. Fecundity and hatching were normal with two single (ca.

High-performance liquid chromatography of lignin-derived phenols in environmental samples with diode array detection.

Lignin-derived and standard phenols were successfully analyzed with reversed-phase high-performance liquid chromatography (HPLC) with diode array detection. The 11 major phenols produced by cupric oxide (CuO) oxidation were clearly and rapidly separated. Determination by diode array detection also allowed detection of interfering impurities within individual HPLC peaks.

Differences in the sterol composition of dominant Antarctic zooplankton.

The composition of free sterols was determined in Antarctic zooplankton species with various feeding behaviors. In the Southern Ocean, the dominant calanoid copepods Calanoides acutus, Calanus propinquus, Metridia gerlachei, and Euchaeta antarctica were investigated during different seasons and compared with the euphausiids Euphausia superba, E. crystallorophias, and Thysanoessa macrura.