Global patterns and drivers of seagrass biomass, net primary production and meadow structure

We decipher global patterns in seagrass growth and structure to advance seagrass science, facilitate multidisciplinary research, and promote effective management strategies and policy development for seagrass habitats. A global data set on seagrass total biomass, total NPP, shoot density, and percent cover was compiled for 11 genera. Here, we tested how these variables change across seagrass genera, life-history strategy, and geographic location, and then sought to decipher the environmental drivers of the patterns observed. The mean (±SE) total biomass of seagrasses globally was estimated at 340 ± 10 g DW m -2, and total NPP was estimated at 5.4 ± 0.4 g DW m -2 d-1. Mean shoot density across all genera was 1,780 ± 67 shoots m-2, and percent cover was 42 ± 1%. Persistent genera showed the highest total biomass, followed by opportunistic and then colonising genera, whereas shoot density was higher for colonising than for persistent, which had the highest percent cover. Latitudinal and bioregional patterns were identified for some genera, and were mostly driven by genus-specific traits, followed by localised environmental factors. Trends in seagrass meadow ecology were largely influenced by seagrass genera and their life-history strategy, with localised environmental factors, such as temperature and nutrients, also playing a role. Global estimates of seagrass biomass and NPP were 2 times higher than previously reported. Seagrass life-history strategies modulate the trade-offs between NPP and biomass to thrive in specific habitats. This study provides the most updated global synthesis of patterns in seagrass growth and structure.