Temporal variability of dissolved P speciation in a eutrophic reservoir—implications for predicating algal growth

Weak-anion exchange chromatography was used to explore the temporal variability in the speciation of dissolved P in the surface layer of a eutrophic reservoir. Authentic free ortho-P ion was the most common form of P on three of the five sampling occasions—including during a bloom of the green algae Botryococcus braunii indicating that the bloom was not P limited. Conversely, the absence of authentic ortho-P during a bloom of the dinoflagellate Ceratium hirundinella suggested the bloom was either P limited or co-limited. These observations were confirmed by algal-growth bioassay experiments.