A global dataset of seaweed net primary productivity

Abstract

Net primary productivity (NPP) plays a pivotal role in the global carbon balance but estimating the NPP of underwater habitats remains a challenging task. Seaweeds (marine macroalgae) form the largest and most productive underwater vegetated habitat on Earth. Yet, little is known about the distribution of their NPP at large spatial scales, despite more than 70 years of local-scale studies being scattered throughout the literature. We present a global dataset containing NPP records for 246 seaweed taxa at 429 individual sites distributed on all continents from the intertidal to 55 m depth. All records are standardized to annual aerial carbon production (g C m^-2 yr^-1) and are accompanied by detailed taxonomic and methodological information. The dataset presented here provides a basis for local, regional and global comparative studies of the NPP of underwater vegetation and is pivotal for achieving a better understanding of the role seaweeds play in the global coastal carbon cycle.

Fig. 1

Temporal coverage of seaweed NPP measurements conducted at different habitat types and by tidal level (intertidal or subtidal), which are indicated in different colours. (a) Number of database records (i.e. a measurement of NPP per taxa, depth, site, year and method) depending on when the measurements were conducted. (b) Number of studies by date of publication (note not all data came from published studies).

Fig. 2

Taxonomic coverage of the database. Multiple denotes taxonomic groupings that involve species from different phyla (e.g. algal turfs).

Fig. 3

Location (A) and depth (B) of the study sites included in the database. Measurements conducted in the intertidal (i.e. above sea level are indicated in grey).

Fig. 4

Latitudinal patterns of observed NPP depending on measuring methods. Dots indicate the average NPP of a study conducted within a given location.

Fig. 5

Distribution of observations depending on the methodology applied to measure NPP. (a) Biomass-accumulation-based and (b) Photorespirometry-based methods.

Fig. 6

Number of studies measuring seaweed NPP per decade grouped by broad methodology.