Dataset: Bioavailability factor of polyphosphate, nucleotides, and methyl phosphonate in bioassay experiments with seawater from R/V Savannah cruise SAV-19-02 in the NW Atlantic Ocean in Spring of 2019

Sampling and analytical procedures:

Bioassay experiments were conducted at station 1 and stations 3. At each station, inorganic and organic phosphate amendments were performed on seawater with and without nitrogen enrichment  (NH₄Cl, NaNO₃). Bioassay Experiments consisted in incubating, over an incubation period of 48h, surface seawater (5m) with inorganic or organic phosphate compounds (20 µM; final concentration of P) including, polyphosphate (polyp), inorganic phosphate (Pi), nucleotides (ATP or AMP) and methylphosphonate (Mepn). In each incubation experiment, a control treatment (surface seawater without amendment) was included.

In bioassay experiments, the bioavailability factor (BF) was determined at T0 for polyphosphate, nucleotides (ATP or AMP) and methylphosphonate (Mepn). BF is calculated as follows: BF=TE-TN/ TP-TN (Björkman and Karl, 1994), where T_E reflects PO₄^3- turnover time in the DOP amended treatment, T_N is the PO₄^3- turnover time in the control (no additions) and T_P is the PO₄^3- turnover time in the treatment amended with Pi. BF ranges from 0 for an unavailable substrate, to a value of 1 for a DOP model substrate having a bioavailability equal to that of +Pi.

Instrument: Radioactivity was assayed on a Packard Tri-Carb liquid scintillation counter. 
Location:  Northwestern Atlantic surface waters. Depth: surface-50 m.