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:Brda river bacterioplankton meta-community
| PRJNA713972 | ENA
Project description:Bacterioplankton community composition in alpine lakes
Project description:Tadpoles of the anuran species Rana pirica can undergo predator-specific morphological responses. Exposure to a predation threat by larvae of the salamander Hynobius retardatus results in formation of a bulgy body (bulgy morph) with a higher tail. Whereas, dragon fly also induced higher tail tadpole. The tadpoles revert to a normal phenotype upon removal of the larval salamander or dragon fly threat. The objective of the present study was to use Affymetrix Xenopus Genechip to profile gene expression in the tail tissue by different predation threat. Tadpoles of Rana pirica treated with larvae salamander for 8days (S1, S2, S3) or dragon fly for 8days (Y1,Y2, Y3) were analyzed with triplicate. Removal experiments were also treated with predators for 4days and then removed predators from tadpoles (-S1,-S2, -S3) or (-Y1,-Y2,-Y3). Controls were cultured for 8days without predators (C2, C3). Tails from tadpoles after 8days of each treatment were dissected for RNA extraction and gene expression analysis using Affymetrix Xenopus Genechip arrays.