Low Specific Phosphorus Uptake Affinity of Epilithon in Three Oligo- to Mesotrophic Post-mining Lakes

Eliška Konopáčová; Jiří Nedoma; Kateřina Čapková; Petr Čapek; Petr Znachor; Miloslav Pouzar; Milan Říha; Klára Řeháková

doi:10.3389/fmicb.2021.735498

Low Specific Phosphorus Uptake Affinity of Epilithon in Three Oligo- to Mesotrophic Post-mining Lakes

Front Microbiol. 2021 Oct 6:12:735498. doi: 10.3389/fmicb.2021.735498. eCollection 2021.

Authors

Eliška Konopáčová^{1

2}, Jiří Nedoma², Kateřina Čapková², Petr Čapek³, Petr Znachor^{2

3}, Miloslav Pouzar^{1

4}, Milan Říha², Klára Řeháková²

Affiliations

¹ Institute of Environmental and Chemical Engineering, Faculty of Chemical Technology, University of Pardubice, Pardubice, Czechia.
² Institute of Hydrobiology, Biology Centre of the Czech Academy of Sciences, České Budějovice, Czechia.
³ Faculty of Sciences, University of South Bohemia, České Budějovice, Czechia.
⁴ Center of Materials and Nanotechnologies, University of Pardubice, Pardubice, Czechia.

Abstract

Epilithon contributes to phosphorus (P) cycling in lakes, but its P uptake traits have been rarely studied. We measured the chemical composition of epilithon and its inorganic P uptake kinetics using isotope ³³P in three deep oligo- to mesotrophic post-mining lakes in April, July, and October 2019. Over the sampling period, epilithon biomass doubled, while the P content in biomass dropped to 60% of the April values, and the seasonal changes in P content expressed per epilithon area were only marginal and statistically not significant. High epilithic C:P molar ratios (677 on average) suggested strong P deficiency in all investigated lakes. Regarding the kinetic parameters of phosphorus uptake, maximum uptake velocity (V _max , seasonal range 1.9-129 mg P g OM^-1 h^-1) decreased by an order of magnitude from April to October, while half-saturation constant (K _S , seasonal range 3.9-135 mg P L^-1) did not show any consistent temporal trend. Values of epilithic specific P uptake affinity (SPUA _E , seasonal range 0.08-3.1 L g OM^-1 h^-1) decreased from spring to autumn and were two to four orders of magnitude lower than the corresponding values for seston (SPUA _sest ), which showed an opposite trend. Considering our results, we suggest a possible mechanism underlying a stable coexistence of planktonic and epilithic microorganisms, with plankton prospering mostly in summer and autumn and epilithon in winter and spring season. Additionally, a phenomenon of reversible abiotic P adsorption on epilithon was observed.

Keywords: epilithon; hydric recultivation; oligotrophic lakes; periphyton; phosphorus uptake; specific P affinity.