Seagrass biomass and production: a reassessment

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 Pound 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. (C) 1999 Elsevier Science B.V, All rights reserved.