Table 3.

Sequestered CO₂ stocks (negative values), cumulative GHG emissions, and the net GHG benefit from the South Bay meadow in 2013 and in 2016; all values are Mt CO₂ equivalent units. Gross values = observed seagrass meadow-scale stocks; net values = seagrass meadow stock enhancement above the baseline (gross seagrass stocks – equivalent area bare stocks; aboveground biomass - AGB, belowground biomass - BGB); standard errors reflect error propagation.

	2001 Start (Bare)	2013 Gross	2013 Net	2016 Gross	2016 Net
Meadow area (km2)	0.096	5.79	5.79	6.86	6.86
AGB	0	−710 ± 14.8	−710 ± 14.8	−810 ± 17.6	−810 ± 17.6
Live BGB	0	−339 ± 30.0	−339 ± 30.0	−401 ± 33.2	−401 ± 33.2
Dead BGB	0	−857 ± 44.3	−857 ± 44.3	−1020 ± 52.5	−1020 ± 52.5
Sediment Corg	−78 ± 6.29a	−13500 ± 792	−4150 ± 412	−20400 ± 3440	−7360 ± 1790
Total GHG Benefit			−6060		−9590
CH4	0.5 ± 0.20	385 ± 177	335 ± 156	611 ± 275	532 ± 249
N2O	1.5 ± 0.64	420 ± 152	264 ± 84.6	667 ± 243	420 ± 134
CO2 from CaCO3	3.8 ± 1.14	450 ± 137b	0c	623 ± 190c	0c
Total Emissions	5.7	1260	599	1780	952
Net GHG benefit			−5460		−8630

^abackground (i.e. baseline) stock within total seed plot area.

^bThe CO₂ and CaCO₃ gas exchange/reaction ratio may vary; we used 0.6, as discussed in the methods²⁶.

^cNote that we did not observe seagrass-enhanced CaCO₃ burial in this system.