Dissolved organic matter and metabolic dynamics in dryland lowland rivers.

Autor: Holland A; La Trobe University, School of Life Science, Department of Ecology, Environment and Evolution, Centre for Freshwater Ecosystems, Albury/Wodonga Campus, Vic 3690, Australia. Electronic address: a.holland2@latrobe.edu.au., McInerney PJ; La Trobe University, Centre for Freshwater Ecosystems, Albury/Wodonga Campus, Vic 3690, Australia., Shackleton ME; La Trobe University, Centre for Freshwater Ecosystems, Albury/Wodonga Campus, Vic 3690, Australia., Rees GN; CSIRO Land and Water, Thurgoona, NSW 2640, Australia., Bond NR; La Trobe University, Centre for Freshwater Ecosystems, Albury/Wodonga Campus, Vic 3690, Australia., Silvester E; La Trobe University, School of Life Science, Department of Ecology, Environment and Evolution, Centre for Freshwater Ecosystems, Albury/Wodonga Campus, Vic 3690, Australia.
Jazyk: angličtina
Zdroj: Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy [Spectrochim Acta A Mol Biomol Spectrosc] 2020 Mar 15; Vol. 229, pp. 117871. Date of Electronic Publication: 2019 Dec 02.
DOI: 10.1016/j.saa.2019.117871
Abstrakt: Dissolved organic matter (DOM) within freshwaters is essential for broad ecosystem function. The concentration and type of DOM within rivers depends on the relative contributions of allochthonous sources and the production and consumption of DOM by microbes. In this work we have examined the temporal patterns in DOM quality and productivity in three lowland rivers in dryland Australia using fluorescence excitation emission scans. We assessed the production and consumption of DOM within light and dark bottle assays to quantify the relative contribution of bacteria and algae to the DOM pool and simultaneously assessed whether the systems were autotrophic or heterotrophic. DOM varied temporally within the three river systems over the course of the study period. Characterisation of DOM within light and dark bottles following a 6-hour incubation revealed microbial consumption of a humic-like component and production of protein-like components similar in nature to the amino acids tryptophan and tyrosine. The lack of a significant difference in DOM quality between the light and dark bottles indicated that the protein-like DOM is likely derived from bacterial activity. Respiration was shown to be higher than gross primary production in both whole river and bottle assays, yielding negative net production values and demonstrating that these rivers were predominately heterotrophic. Our work suggests that bacterial metabolism of DOM may be a significant contributor to the production of protein-like components within heterotrophic freshwater systems.
Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
(Copyright © 2019 Elsevier B.V. All rights reserved.)
Databáze: MEDLINE
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