Project description:Marine microbial communities are critical for biogeochemical cycles and the productivity of ocean ecosystems. Primary productivity, at the base of marine food webs, is constrained by nutrient availability in the surface ocean, and nutrient advection from deeper waters can fuel photosynthesis. In this study, we compared the transcriptional responses by surface microbial communities after experimental deep water mixing to the transcriptional patterns of in situ microbial communities collected with high-resolution automated sampling during a bloom in the North Pacific Subtropical Gyre. Transcriptional responses were assayed with the MicroTOOLs (Microbiological Targets for Ocean Observing Laboratories) marine environmental microarray, which targets all three domains of life and viruses. The experiments showed that mixing of deep and surface waters substantially affects the transcription of photosystem and nutrient response genes among photosynthetic taxa within 24 hours, and that there are specific responses associated with the addition of deep water containing particles (organisms and detritus) compared to filtered deep water. In situ gene transcription was most similar to that in surface water experiments with deep water additions, showing that in situ populations were affected by mixing of nutrients at the six sampling sites. Together, these results show the value of targeted metatranscriptomes for assessing the physiological status of complex microbial communities.
Project description:Seamounts, often rising hundreds of metres above the surrounding seafloor, obstruct the flow of deep-ocean water. While the resultant entrainment of deep-water by seamounts is predicted from ocean circulation models, its empirical validation has been hampered by the large scale and slow rate of the interaction. To overcome these limitations we use the growth of planktonic bacteria to assess the interaction rate. The selected study site, Tropic Seamount, in the North-Eastern Atlantic represents the majority of isolated seamounts, which do not affect the surface ocean waters. We prove deep-water is entrained by the seamount by measuring 2.3 times higher bacterial concentrations in the seamount-associated or ‘sheath’ water than in deep-ocean water unaffected by seamounts. Genomic analyses of the dominant sheath-water bacteria confirm their planktonic origin, whilst proteomic analyses indicate their slow growth. According to our radiotracer experiments, the doubling time of sheath-water bacterioplankton is 1.5 years. Therefore, for bacterioplankton concentration to reach 2.3 times higher in the ambient seawater, the seamount would need to retain deep-ocean water for more than 3.5 years. We propose that turbulent mixing of the retained sheath-water could stimulate bacterioplankton growth by increasing the cell encounter rate with the ambient dissolved organic molecules. If some of these molecules chelate hydroxides of iron and manganese, bacterioplankton consumption of the organic chelators would result in precipitation of insoluble hydroxides. Hence precipitated hydroxides would form ferromanganese deposits as a result of the bacterioplankton-mediated deep-water seamount interaction.
2020-05-27 | PXD016702 | Pride
Project description:18srRNA data metagenome data of Southern Indian ocean water sample
Project description:The available energy and carbon sources for prokaryotes in the deep ocean remain still largely enigmatic. Reduced sulfur compounds, such as thiosulfate, are a potential energy source for both auto- and heterotrophic marine prokaryotes. Shipboard experiments performed in the North Atlantic using Labrador Sea Water (~2000 m depth) amended with thiosulfate led to an enhanced prokaryotic dissolved inorganic carbon (DIC) fixation.
Project description:The Antarctic krill provides central ecosystems services to the Southern Ocean grazing on autotroph and heterotoph diet and constituting the dominant food source for higher trophic levels. Moreover, E. superba's extensive equipment with biomacromolecule hydrolysing enzymes represents a largely untapped resource for applied purposes. The proteome compendium of krill provides a valuable basis for future studies on krill biology (e.g., metabolism, development, migration behaviour), for krill's contribution to organic matter turnover in the Southern Ocean, as well as for multilevel biotechnological prospecting.
Project description:The Antarctic krill provides central ecosystems services to the Southern Ocean grazing on autotroph and heterotoph diet and constituting the dominant food source for higher trophic levels. Moreover, E. superba's extensive equipment with biomacromolecule hydrolysing enzymes represents a largely untapped resource for applied purposes. The proteome compendium of krill provides a valuable basis for future studies on krill biology (e.g., metabolism, development, migration behaviour), for krill's contribution to organic matter turnover in the Southern Ocean, as well as for multilevel biotechnological prospecting.
Project description:The Antarctic krill provides central ecosystems services to the Southern Ocean grazing on autotroph and heterotoph diet and constituting the dominant food source for higher trophic levels. Moreover, E. superba's extensive equipment with biomacromolecule hydrolysing enzymes represents a largely untapped resource for applied purposes. The proteome compendium of krill provides a valuable basis for future studies on krill biology (e.g., metabolism, development, migration behaviour), for krill's contribution to organic matter turnover in the Southern Ocean, as well as for multilevel biotechnological prospecting
Project description:The Antarctic krill provides central ecosystems services to the Southern Ocean grazing on autotroph and heterotoph diet and constituting the dominant food source for higher trophic levels. Moreover, E. superba's extensive equipment with biomacromolecule hydrolysing enzymes represents a largely untapped resource for applied purposes. The proteome compendium of krill provides a valuable basis for future studies on krill biology (e.g., metabolism, development, migration behaviour), for krill's contribution to organic matter turnover in the Southern Ocean, as well as for multilevel biotechnological prospecting.
Project description:The Antarctic krill provides central ecosystems services to the Southern Ocean grazing on autotroph and heterotoph diet and constituting the dominant food source for higher trophic levels. Moreover, E. superba's extensive equipment with biomacromolecule hydrolysing enzymes represents a largely untapped resource for applied purposes. The proteome compendium of krill provides a valuable basis for future studies on krill biology (e.g., metabolism, development, migration behaviour), for krill's contribution to organic matter turnover in the Southern Ocean, as well as for multilevel biotechnological prospecting.
Project description:Iron and light are typically recognized as major limiting factors controlling phytoplankton growth in the Southern Ocean. Recent field-based evidence suggests, however, that manganese concentrations in this region can be low enough to impact phytoplankton physiology and primary productivity. Our study examined the interactive influence of combined iron and manganese deprivation on protein expression and photophysiology in Phaeocystis antarctica, a key Antarctic phytoplankter, and provide taxon-specific proteomic evidence that natural Southern Ocean Phaeocystis populations regularly experience stress due to combined low manganese and iron availability. In culture, combined low iron and manganese induced large scale changes in the Phaeocystis proteome and resulted in reorganization of key components of the photosynthetic apparatus; these differences were largely distinct from those arising from changes in irradiance. These results implicate manganese availability as an important driver of Southern Ocean productivity and demonstrate the utility of peptide mass spectrometry as a tool for mapping of manganese contributions to HNLC conditions in this region.