Abstract Detail


Thorhaug, Anitra [1], Poulos, Helen [2], Schwarz, Arthur [3], Lopez-Portillo, Jorge [4], Berlyn, Graeme [5].

Restoring Seagrass Meadows as a Tool to Enhance Blue Carbon Capture.

Seagrass meadows are known to have surprisingly high rates of blue carbon sequestration, making them a valuable tool with which to mitigate the rise in global CO2, yet seagrasses are being diminished by 7% y-1 on a global scale. Few studies of organic blue carbon from restored seagrass are available. We assessed sedimentary organic carbon around the Gulf of Mexico (GOM) in restored and natural seagrass meadows. At each of eight sites, collection sediments for carbon analysis included sites with: 1.) restored seagrass; 2.) naturally-occurring seagrass; 3.) sites where sediment have been always barren for 40+ years; and 4.) impacted barren sediment. The analytical methods and procedures of Howard et al. (2014) were used. Cores were 40 cm deep, and were kept cold to prevent microbial carbon degradation. Statistical analysis included: nlme package of R for analyzing differences in % C and Corg content among treatments: disturbance types, sample site regions, and restored seagrass meadow ages. Cores were nested within each site-treatment combination accounting for covariance structure in the nested sampling design. Restored seagrass sites had higher mean Corg stocks (38.7±13.1 Mg ha 1) than natural meadows. The mean Corg in the top 20 cm of the sediment for natural seagrass meadows at the sample sites was 25.7±6.7 Mg Corg ha 1. Restored seagrass meadows had significantly higher Corg than “impacted barren” and “always barren” areas (P<0.05). The baseline (control) of each estuary carbon stock, or “always barren”, varied substantially among sites (from 4.11 to 35.61 Mg Corg ha−1). Organic carbon stocks (Corg) varied significantly among treatments, and across the eight GOM sites (F=3.84, P=0.011), and there was a highly significant relationship between LOI (loss on ignition) and % Corg. We found differences in blue carbon among restored seagrass and natural seagrass samples of our Texas sites (Halodule wrightii) and our Florida sites (Thalassia testudinum or Thalassia with multiple Halodule wrightii sprigs). Vigorous carbon sequestration occurs rapidly after successful seagrass restoration. Blue carbon in restored sites differed significantly with restoration age (young, 15 years since restoration). Background carbon in sediment barren of seagrass varied widely meaning sediment background carbon must be subtracted from total organic seagrass carbon at each site. Variability was substantial in sequestered Corg among sites. These findings are consistent with the idea that rapidly growing restored seagrass meadows have higher metabolic rates, thus capture more CO2, creating more root exudates and trapping more detritus.

Related Links:
Thorhaug et al. (2019) - Gulf of Mexico estuarine blue carbon stock, extent and flux: Mangroves, marshes, and seagrasses: A North American hotspot
Thorhaug et al. (2017) - Seagrass blue carbon dynamics in the Gulf of Mexico: Stocks, losses from anthropogenic disturbance, and gains through seagrass restoration

1 - Greater Caribbean Energy and ENvironment Foundation, 1359 SW 22 Ter Apt 1, Miami, FL, 33145, United States
2 - 158 Prospect St., Plantsville, CT, 06479, United States
3 - Southwestern Adventist University, Biological Sciences, 100 W Hillcrest, Keene, TX, 76059, United States
4 - Instituto De Ecología, A.C., Red De Ecología Funcional, Carretera Antigua A Coatepec 351, El Haya, Xalapa, Veracruz, VER, 91070, Mexico
5 - Yale University, School Of Foresty & Evironmental Studies, Marsh Hall-360 PROSPECT ST, New Haven, CT, 06511, United States

Restored vs natural seagrass blue carbon
seagrass blue carbon vs barren sand carbon
SEAGRASS Blue Carbon.

Presentation Type: Oral Paper
Number: PHYS1003
Abstract ID:348
Candidate for Awards:None

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