A dataset of global ocean alkaline phosphatase activity

Abstract

Utilisation of dissolved organic phosphorus (DOP) by marine microbes as an alternative phosphorus (P) source when phosphate is scarce can help sustain non-Redfieldian carbon:nitrogen:phosphorus ratios and efficient ocean carbon export. However, global spatial patterns and rates of microbial DOP utilisation are poorly investigated. Alkaline phosphatase (AP) is an important enzyme group that facilitates the remineralisation of DOP to phosphate and thus its activity is a good proxy for DOP-utilisation, particularly in P-stressed regions. We present a Global Alkaline Phosphatase Activity Dataset (GAPAD) with 4083 measurements collected from 79 published manuscripts and one database. Measurements are organised into four groups based on substrate and further subdivided into seven size fractions based on filtration pore size. The dataset is globally distributed and covers major oceanic regions, with most measurements collected in the upper 20 m of low-latitude oceanic regions during summer since 1997. This dataset can help support future studies assessing global ocean P supply from DOP utilisation and provide a useful data reference for both field investigations and modelling activities.

Fig. 1

Work-flow of GAPAD compilation, standardization and quality-control.

Fig. 2

APA measurement distributions in the ocean. (a) Latitudinal, (b) Vertical, (c) Yearly, and (d) Monthly distributions of APA measurements with each substrate colored. Blue, orange, yellow and purple bars represent measurements with the substrates MUF-P, DiFMUP, MFP and pNPP, respectively.

Fig. 3

Global distribution of APA measurements in GAPAD for the different four substrates. (a) MUF-P, (b) DiFMUP, (c) MFP and (d) pNPP. Each marker represents a fraction, with red plus, green pentagram, blue cross, yellow square, magenta diamond, cyan upward-pointing triangle and black right-pointing triangle representing bulk APA, dissolved APA, particulate APA, bacterial APA, phytoplankton APA, Trichodesmium APA, and zooplankton APA respectively. Definitions of the different fractions of APA in this figure are described in the Methods section.

Fig. 4

Global distribution of Log10-transformed full-depth-averaged bulk APA measurements in GAPAD for the four different substrates. (a) MUF-P, (b) DiFMUP, (c) MFP and (d) pNPP.

Fig. 5

Global distribution of Log10-transformed full-depth-averaged APA measurement of MUF-P in GAPAD for the five different fractions. (a) dissolved APA, (b) particulate APA, (c) bacterial APA, (d) phytoplankton APA and (e) Trichodesmium APA.