Abstract
The biomass and production of seagrass populations were reassessed based on the compilation of a large data set comprising estimates for 30 species, derived from the literature. The mean (± SE) above- and below-ground biomass in the data set were very similar, 223.9
±
17.5 and 237.4
±
28
g
DW
m
−2, respectively, indicating a general tendency for a balanced distribution of biomass between leaves and rhizomes
+
roots (mean ratio (± SE)
=
1.11
±
0.08). The biomass development and the ratio of above- to below-ground biomass varied significantly with latitude and was species-specific, with a significant tendency for large-sized seagrass species to develop high below-ground biomass. Maximum daily seagrass production differed significantly among species, but averaged 3.84
±
0.34 and 1.21
±
0.27
g
DW
m
−2 per day for above- and below-ground organs respectively, with an average ratio of above- to below-ground production of 16.4
±
8.5. The biomass turnover rates averaged 2.6
±
0.3 and 0.77
±
0.12% per day for the above- and below-ground material respectively, and tended to be faster for temperate species. The average annual seagrass production found here, 1012
g
DW
m
−2 per year, exceeds previous estimates by 25%, because the average excedent carbon produced by seagrasses must be revised upwards to represent 15% of the total surplus carbon fixed in the global ocean.