Dataset Information

Short-Term Dynamics of North Sea Bacterioplankton-Dissolved Organic Matter Coherence on Molecular Level.

ABSTRACT: Remineralization and transformation of dissolved organic matter (DOM) by marine microbes shape the DOM composition and thus, have large impact on global carbon and nutrient cycling. However, information on bacterioplankton-DOM interactions on a molecular level is limited. We examined the variation of bacterial community composition (BCC) at Helgoland Roads (North Sea) in relation to variation of molecular DOM composition and various environmental parameters on short-time scales. Surface water samples were taken daily over a period of 20 days. Bacterial community and molecular DOM composition were assessed via 16S rRNA gene tag sequencing and ultrahigh resolution Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR-MS), respectively. Environmental conditions were driven by a coastal water influx during the first half of the sampling period and the onset of a summer phytoplankton bloom toward the end of the sampling period. These phenomena led to a distinct grouping of bacterial communities and DOM composition which was particularly influenced by total dissolved nitrogen (TDN) concentration, temperature, and salinity, as revealed by distance-based linear regression analyses. Bacterioplankton-DOM interaction was demonstrated in strong correlations between specific bacterial taxa and particular DOM molecules, thus, suggesting potential specialization on particular substrates. We propose that a combination of high resolution techniques, as used in this study, may provide substantial information on substrate generalists and specialists and thus, contribute to prediction of BCC variation.

SUBMITTER: Lucas J

PROVIDER: S-EPMC4791370 | biostudies-literature | 2016

REPOSITORIES: biostudies-literature

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Short-Term Dynamics of North Sea Bacterioplankton-Dissolved Organic Matter Coherence on Molecular Level.

Lucas Judith J Koester Irina I Wichels Antje A Niggemann Jutta J Dittmar Thorsten T Callies Ulrich U Wiltshire Karen H KH Gerdts Gunnar G

Frontiers in microbiology 20160315

Remineralization and transformation of dissolved organic matter (DOM) by marine microbes shape the DOM composition and thus, have large impact on global carbon and nutrient cycling. However, information on bacterioplankton-DOM interactions on a molecular level is limited. We examined the variation of bacterial community composition (BCC) at Helgoland Roads (North Sea) in relation to variation of molecular DOM composition and various environmental parameters on short-time scales. Surface water sa ...[more]

PMID: 27014241

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Project description:BackgroundMono-specific aquaculture effluents contain high concentrations of nutrients and organic matter, which affect negatively the water quality of the recipient ecosystems. A fundamental feature of water quality is its transparency. The fraction of dissolved organic matter that absorbs light is named chromophoric dissolved organic matter (CDOM). A sustainable alternative to mono-specific aquaculture is the multitrophic aquaculture that includes species trophically complementary named "extractive" species that uptake the waste byproducts. Sea cucumbers are recognized as efficient extractive species due to the consumption of particulate organic matter (POM). However, the effects of sea cucumbers on CDOM are still unknown.MethodsDuring more than one year, we monitored CDOM in two big-volume tanks with different trophic structure. One of the tanks (-holothurian) only contained around 810 individuals of Anemonia sulcata, whereas the other tank (+holothurian) also included 90 individuals of Holothuria tubulosa and Holothuria forskali. We routinely analyzed CDOM absorption spectra and determined quantitative (absorption coefficients at 325 nm) and qualitative (spectral slopes) optical parameters in the inlet waters, within the tanks, and in their corresponding effluents. To confirm the time-series results, we also performed three experiments. Each experiment consisted of two treatments: +holothurians (+H) and -holothurians (-H). We set up three +H tanks with 80 individuals of A. sulcata and 10 individuals of H. tubulosa in each tank and four -H tanks that contained only 80 individuals of A. sulcata.ResultsIn the time-series, absorption coefficients at 325 nm (a325) and spectral slopes from 275 to 295 nm (S275-295) were significantly lower in the effluent of the +holothurian tank (average: 0.33 m-1 and 16 µm-1, respectively) than in the effluent of the -holothurian tank (average: 0.69 m-1 and 34 µm-1, respectively), the former being similar to those found in the inlet waters (average: 0.32 m-1 and 22 µm-1, respectively). This reduction in the absorption of the dissolved organic matter appears to be mediated by the POM consumption by holothurians. The experiments confirmed the results observed in the time-series. The a325 and S275-295 values were significantly lower in the treatment with holothurians than in the treatment without holothurians indicating a reduction in the concentration of chromophoric organic compounds, particularly of low molecular weight.DiscussionConsequently, sea cucumbers appear to improve water transparency in aquaculture tanks. The underlying mechanism of this improvement might be related to the POM consumption by holothurians, which reduces the concentration of CDOM derived from POM disaggregation or to the direct assimilation of dissolved compounds of low molecular weight as chromophoric amino acids.

Dataset Information

Short-Term Dynamics of North Sea Bacterioplankton-Dissolved Organic Matter Coherence on Molecular Level.

Publications

Short-Term Dynamics of North Sea Bacterioplankton-Dissolved Organic Matter Coherence on Molecular Level.

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