MEPS 702:19-38 (2022)  -  DOI: https://doi.org/10.3354/meps14210

ABSTRACT: Polyphosphate-accumulating microbial mats can influence PO₄^3- concentration in the benthic zone. To investigate the role of microbial mats in benthic P cycling, short peat cores including supernatant water from a coastal fen in NE Germany (southern Baltic Sea) were incubated in winter, summer and fall under 3 conditions: in situ, elevated temperature and oxygen-depletion. Bottom water PO₄^3- concentrations decreased in treatments where a microbial mat had formed (summer and winter) but not in the mat-deficient fall treatment. The mats were densely populated with polyphosphate-rich Lyngbya sp. filaments. On the last day of incubation, PO₄^3- concentrations in the oxygen-depleted bottom water were lower in the winter (70×) and summer (44×) than in the fall treatment, demonstrating the significant effect of microbial mats on PO₄^3- fluxes, even under oxygen-depleted conditions. Mean polyphosphate-P content in the upper 1 cm peat layer of 8 freshly collected winter cores was 2.23 µmol g^-1 (5% of total P), comprising a noticeable percentage of the P reservoir. Low sediment Fe:P molar ratios among the cores (5.9-6.3) indicated that P-adsorption sites in Fe-P compounds were fairly saturated and had limited efficiency in precipitating additional bottom water PO₄^3-. Using known temperature-dependent coefficients for biological systems, we estimate that bottom water PO₄^3- concentrations in temperature-elevated cores were reduced by 96% in the presence of a microbial mat. We propose that a microbial mat can take up a large amount of dissolved inorganic P, highlighting its regulatory role in coastal peatland P fluxes under varying environmental conditions.

KEY WORDS: Polyphosphate · Lyngbya spp. · Microbial mat · Benthic · Phosphorus cycling · PolyP-accumulating bacteria · Baltic Sea · Cyanobacteria

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Cite this article as: Choo S, Dellwig O, Wäge-Recchioni J, Schulz-Vogt HN (2022) Microbial-driven impact on aquatic phosphate fluxes in a coastal peatland. Mar Ecol Prog Ser 702:19-38. https://doi.org/10.3354/meps14210 Export citation Share:    Facebook - - Bluesky - linkedIn