Water column

About: Water column is a research topic. Over the lifetime, 13706 publications have been published within this topic receiving 496626 citations.

Tying up Loose Ends of Microplastic Pollution in the Arctic: Distribution from the Sea Surface through the Water Column to Deep-Sea Sediments at the HAUSGARTEN Observatory.

Abstract: Recent studies have shown that despite its remoteness, the Arctic region harbors some of the highest microplastic (MP) concentrations worldwide. Here, we present the results of a sampling campaign ...

Members of a Readily Enriched β-Proteobacterial Clade Are Common in Surface Waters of a Humic Lake

Abstract: Humic lakes are systems often characterized by irregular high input of dissolved organic carbon (DOC) from the catchment. We hypothesized that specific bacterial groups which rapidly respond to changes in DOC availability might form large populations in such habitats. Seasonal changes of microbial community composition were studied in two compartments of an artificially divided bog lake with contrasting DOC inputs. These changes were compared to community shifts induced during short-term enrichment experiments. Inocula from the two compartments were diluted 1:10 into water from the more DOC-rich compartment, and inorganic nutrients were added to avoid microbial N and P limitation. The dilutions were incubated for a period of 2 weeks. The microbial assemblages were analyzed by cloning and sequencing of 16S rRNA genes and by fluorescence in situ hybridization with specific oligonucleotide probes. β-Proteobacteria from a cosmopolitan freshwater lineage related to Polynucleobacter necessarius (beta II) were rapidly enriched in all treatments. In contrast, members of the class Actinobacteria did not respond to the enhanced availability of DOC by an immediate increase in growth rate, and their relative abundances declined during the incubations. In lake water members of the beta II clade seasonally constituted up to 50% of all microbes in the water column. Bacteria from this lineage annually formed a significantly higher fraction of the microbial community in the lake compartment with a higher allochthonous influx than in the other compartment. Actinobacteria represented a second numerically important bacterioplankton group, but without clear differences between the compartments. We suggest that the pelagic microbial community of the studied system harbors two major components with fundamentally different growth strategies.

Physical Transport of Nutrients and the Maintenance of Biological Production

Abstract: The oceanic distributions of nutrients and patterns of biological production are controlled by the interplay of biogeochemical and physical processes, and external sources. Biological and chemical processes lead to the transformation of nutrients between inorganic and organic forms, and also between dissolved and particulate forms. Physical processes redistribute nutrients within the water column through transport and mixing. The combined role of biogeochemical and physical processes is reflected in the observed distributions of nitrate, phosphate and silicate (macro-nutrients). These distributions broadly reflect those of classical water masses, as defined by temperature and salinity, highlighting the important role of physical transport. However, there are also significant differences between the nutrient and water-mass distributions, notably with nutrients showing stronger vertical and basin-to-basin contrasts. Biological production leads to these greater nutrient contrasts with inorganic nutrients consumed and converted to organic matter in the surface, sunlit ocean. A small fraction of the organic matter in this euphotic zone is exported to depth, driven by the gravitational sinking of particles and subduction of dissolved organic matter. This organic fallout is eventually remineralised leading to an accumulation of inorganic nutrients in deeper and older water masses.

Microalgae on the arctic ocean section, 1994: species abundance and biomass

Abstract: Algal species from the ice, the water directly below the ice (the sub-ice area), and the water column from 21 stations in the Arctic Ocean were examined using epifluorescence and inverted light microscopy Biomass of autotrophic dinoflagellates and other miscellaneous autotrophic flagellates was determined for the first time in the central Arctic basins Together these two groups dominated phytoplankton biomass in 74% of samples from the central Arctic, with diatom biomass predominant in the remainder Picophytoplankton at selected stations in the Canada and Makarov Basins contributed 93% to autotroph cell numbers and 36% to autotroph biomass Diatom species achieved high biomass in ice and sub-ice samples The centric diatom Melosira arctica dominated the sub-ice area, while pennate diatoms were major contributors to the ice samples Despite ample silicate concentrations in the water, diatom frustules were often lightly silicified