The activities of particulate and soluble phosphatase were analyzed monthly for 1 year in the coastal ecosystems of the NW Mediterranean Sea. The mean contribution of the particulate activity increased from 56% at an MUF-P concentration of 30 μM to 77% at 0.04 μM. This particulate activity was negatively correlated with the DIP, DOP and TDP concentrations when the activities were related to the seawater volume, chlorophyll a or the protein concentration. The TDP correlations were highly significant (p: 0.001). The DOP correlations were significant (p: 0.04) and became highly significant (p: 0.009) at low DIP concentrations (<0.13 μM). The DIP correlations were significant (p: 0.04) only at low DOP concentrations (<0.18 μM). Thus, the effects of seawater DIP and DOP were found to be linked. The soluble activity exhibited distinct phosphatase fractions with high (0.5-29.5 μM) and low (0.02-2 μM) Km values, but none exhibited significant correlations with phosphorus compounds.
Keywords: Alkaline phosphatase; DIP; DOP; Kinetics; MUF; MUF-P; Mediterranean Sea; Methyl umbelliferyl phosphate; Phosphorus; Plankton; SRP; TDP; dissolved inorganic phosphorus; dissolved organic phosphorus; methylumbelliferone; soluble reactive phosphorus; total dissolved phosphorus.
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