Konopáčová Eliška, Nedoma Jiří, Čapková Kateřina, Čapek Petr, Znachor Petr, Pouzar Miloslav, Říha Milan, Řeháková Klára
Institute of Environmental and Chemical Engineering, Faculty of Chemical Technology, University of Pardubice, Pardubice, Czechia.
Institute of Hydrobiology, Biology Centre of the Czech Academy of Sciences, České Budějovice, Czechia.
Front Microbiol. 2021 Oct 6;12:735498. doi: 10.3389/fmicb.2021.735498. eCollection 2021.
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 P 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 ( , seasonal range 1.9-129 mg P g OM h) decreased by an order of magnitude from April to October, while half-saturation constant ( , seasonal range 3.9-135 mg P L) did not show any consistent temporal trend. Values of epilithic specific P uptake affinity ( , seasonal range 0.08-3.1 L g OM h) decreased from spring to autumn and were two to four orders of magnitude lower than the corresponding values for seston ( ), 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.
附生藻类对湖泊中的磷（P）循环有重要作用，但其磷吸收特性却鲜有研究。我们于2019年4月、7月和10月，在三个深度处于贫营养至中营养状态的采矿后湖泊中，使用同位素磷测量了附生藻类的化学成分及其无机磷吸收动力学。在采样期间，附生藻类生物量增加了一倍，而生物量中的磷含量降至4月值的60%，且以附生藻类面积计算的磷含量季节性变化很小，在统计学上不显著。较高的附生藻类碳磷摩尔比（平均为677）表明，所有调查湖泊中均存在严重的磷缺乏。关于磷吸收的动力学参数，最大吸收速度（ ，季节性范围为1.9 - 129 mg P g OM h）从4月到10月下降了一个数量级，而半饱和常数（ ，季节性范围为3.9 - 135 mg P L）未表现出任何一致的时间趋势。附生藻类的比磷吸收亲和力值（ ，季节性范围为0.08 - 3.1 L g OM h）从春季到秋季下降，且比悬浮物（ ）的相应值低两到四个数量级，悬浮物呈现相反趋势。基于我们的研究结果，我们提出了浮游微生物和附生微生物稳定共存的一种可能机制，即浮游生物在夏季和秋季大量繁殖，而附生藻类在冬季和春季大量繁殖。此外，还观察到附生藻类上存在可逆的非生物磷吸附现象。
