High alkaline phosphatase activity in phosphate replete waters: The case of two macrotidal estuaries
Tóm tắt
The occurrence of alkaline phosphatase activity (APA) that hydrolyses organic phosphorus into phosphate (PO4) is commonly related to PO4 deficiency of oceanic, coastal and fresh waters. APA is almost never investigated in PO4‐rich estuaries, since very low activities are expected to occur. As a consequence, microbial mineralization of organic phosphorus into PO4 has often been ignored in estuaries. In this study, we examined the importance of potential APA and the associated microbial dynamics in two estuaries, the Aulne and the Elorn (Northwestern France), presenting two different levels of PO4 concentrations. Unexpected high potential APA was observed in both estuaries. Values ranged from 50 to 506 nmol L−1 h−1, which range is usually found in very phosphorus‐limited environments. High potential APA values were observed in the oligohaline zone (salinity 5–15) in spring and summer, corresponding to a PO4 peak and a maximum bacterial production of particle‐attached bacteria. In all cases, high potential APA was associated with high suspended particulate matter and total particulate phosphorus. The low contribution of the 0.2–1 μm fraction to total APA, the strong correlation between particulate APA and bacterial biomass, and the close relationship between the production of particle‐attached bacteria and APA, suggested that high potential APA is mainly due to particle‐attached bacteria. These results suggest that the microbial mineralization of organic phosphorus may contribute to an estuarine PO4 production in spring and summer besides physicochemical processes.
Từ khóa
Tài liệu tham khảo
Aminot A., 2009, Practical guidelines for the analysis of seawater, 143
Ammerman J. W., 1993, Handbook of methods in aquatic microbial ecology, 649
Chrost R. J., 1990, Aquatic microbial ecology: biochemical and molecular approaches, 47, 10.1007/978-1-4612-3382-4_3
Chrost R. J., 1986, Fluorescence correction for measurements of enzyme activity in natural waters using methylumbelliferyl‐substrates, Arch. Hydrobiol., 106, 79, 10.1127/archiv-hydrobiol/106/1986/79
Siuda W., 1987, The relationship between alkaline phosphatase (APA) activity and phosphate availability for phytoplankton and bacteria in Eutrophic lakes, Acta Microb. Pol., 36, 247