Dynamics of carbon sources supporting burial in seagrass sediments under increasing anthropogenic pressure

Mazarrasa, Inés; Marbà, Núria; García-Orellana, Jordi; Masqué, Pere; Arias‐Ortiz, Ariane; Duarte, Carlos M.

doi:10.1002/lno.10509

Cited by 39 publications

(25 citation statements)

References 61 publications

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“…First, it is important to understand how carbon flows among coastal ecosystems to gain perspective on seascape connectivity and to better inform conservation of nearshore habitats (Hyndes et al, , ). Second, different sources of carbon may vary in their persistence in the sediments, as some sources (e.g., seston, macroalgae) are more labile and can be remineralized at a faster rate than recalcitrant sources such as terrestrial carbon or seagrass tissues (Holmer et al, ; Mazarrasa et al, ; Trevathan‐Tackett, Macreadie, et al, ). Finally, the relative contribution of allochthonous versus autochthonous carbon is an important component of carbon accounting, as projects may not receive credit for allochthonous carbon unless it would have been returned to the atmosphere in the baseline scenario (Emmer et al, ; Needelman et al, ).…”

Section: Discussionmentioning

confidence: 99%

A Synthesis of Blue Carbon Stocks, Sources, and Accumulation Rates in Eelgrass (Zostera marina) Meadows in the Northeast Pacific

Prentice

Poppe

Lutz

et al. 2020

Global Biogeochemical Cycles

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There is increasing urgency to implement climate change mitigation strategies that enhance greenhouse gas removal from the atmosphere and reduce carbon dioxide (CO2) emissions. Recently, coastal “blue carbon” habitats⁠—mangroves, salt marshes, and seagrass meadows—have received attention for their ability to capture CO2 and store organic carbon (OC), primarily in their sediments. Across habitat types and regions, however, information about the sequestration rates and sources of carbon to local sediments remains sparse. Here we compiled recently obtained estimates of sediment OC stocks and sequestration rates from 139 cores collected from temperate seagrass (Zostera marina) meadows in Alaska, British Columbia, Washington, and Oregon. Across all cores sediment OC content averaged 0.75%. Organic carbon stocks in the top 25 cm and 1 m of the sediment averaged 1,846 and 7,168 g OC m−2, respectively. Carbon sequestration rates ranged from 4.6 to 93.0 g OC m−2 yr−1 and averaged 24.8 g OC m−2 yr−1. Isotopic data from this region suggest that OC in the sediments is largely from noneelgrass sources. In general, these values are comparable to those from other temperate Z. marina meadows, but significantly lower than previously reported values for seagrasses globally. These results further highlight the need for local and species‐level quantification of blue carbon parameters. While temperate eelgrass meadows may not sequester and store as much carbon as seagrass meadows elsewhere, climate policy incentives should still be implemented to protect existing sediment carbon stocks and the other critical ecosystem services associated with eelgrass habitats.

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Section: Discussionmentioning

confidence: 99%

A Synthesis of Blue Carbon Stocks, Sources, and Accumulation Rates in Eelgrass (Zostera marina) Meadows in the Northeast Pacific

Prentice

Poppe

Lutz

et al. 2020

Global Biogeochemical Cycles

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“…Future work in the Pacific Northwest and in seagrass meadows more generally should continue to resolve the sources of OC in seagrass meadow sediments. Not only is knowing the relative contributions of different sources important for understanding the long‐term persistence of OC stocks (Mazarrasa et al ) and discerning carbon flow and connectivity in nearshore seascapes (Hyndes et al ), the allochthonous:autochthonous OC ratio is critical for undertaking greenhouse gas benefit accounting in accordance with the Verified Carbon Standard (Needelman et al ). Finally, using environmental DNA has recently been highlighted as a novel method for more precisely determining OC contributions to sediments, and should be further investigated as a tool to resolve sources contributing to seagrass carbon stocks (Reef et al ).…”

Section: Discussionmentioning

confidence: 99%

Reduced water motion enhances organic carbon stocks in temperate eelgrass meadows

Prentice

Hessing‐Lewis

Sanders‐Smith

et al. 2019

Limnology & Oceanography

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Organic carbon (OC) storage in coastal vegetated ecosystems is increasingly being considered in carbon financing and climate change mitigation strategies. However, spatial heterogeneity in these “blue carbon” stocks among and within habitats has only recently been examined, despite its considerable implications. Seagrass meadows have potential to store significant amounts of carbon in their sediments, yet studies comparing sediment OC content at regional and meadow scales remain sparse. Here, we collected sediment cores from six temperate eelgrass (Zostera marina) meadows on the coast of British Columbia, Canada, to quantify sediment OC stocks, accumulation rates, and sources, and to examine local and regional drivers of variability. Sediment OC content was highly variable—across all sites, stocks in the top 0–5 cm ranged from 83 to 1089 g OC m−2, while the 15–20 cm stocks exhibited a 24‐fold difference, from 59 to 1407 g OC m−2. Carbon accumulation rates ranged from 4 to 33 g OC m−2 yr−1. Isotopic mixing models revealed that sediment OC was primarily terrestrial carbon (41.3%) and canopy‐forming kelps (33.3%), with a smaller contribution of eelgrass (25.3%). Here, we show that regional variability in OC content exceeds meadow‐scale variability. This result is likely driven by landscape factors, most notably relative water motion, representing a more dominant control on seagrass OC accumulation than meadow‐scale factors such as canopy complexity. These findings elicit caution when scaling up seagrass meadow OC content and demonstrate that measures of the hydrodynamic environment could improve estimates of carbon storage in temperate soft sediment habitats.

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“…Altogether, these ecosystems cover only 0.2% of the ocean floor but hold a sediment carbon storage equal to over half of the global green carbon storage (carbon stored in terrestrial ecosystems and their soils) and up to 33% of the total oceanic CO 2 uptake (Duarte, 2017;Duarte et al, 2005;Hemminga & Duarte, 2000;McLeod et al, 2011;Nellemann et al, 2009). Furthermore, some marine ecosystems can store carbon up to millennial time scales, while the carbon stored by terrestrial systems is usually sequestered up to decades (Mateo et al, 1997;Mazarrasa et al, 2017a;Samper-Villarreal et al, 2018). However, the longevity of carbon storage varies considerably among species and habitats within both marine and terrestrial systems, most likely due to species-specific traits such as length of the growing season, chemical composition of the plant tissues and plant growth rate, and environmental characteristics like temperature, disturbance, and sediment oxygenation (Mateo et al, 2006;Mazarrasa et al, 2018;Russel et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

Blue Carbon Storage Capacity of Temperate Eelgrass (Zostera marina) Meadows

Röhr

Holmer

Baum

et al. 2018

Global Biogeochemical Cycles

152

148

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Despite the importance of coastal ecosystems for the global carbon budgets, knowledge of their carbon storage capacity and the factors driving variability in storage capacity is still limited. Here we provide an estimate on the magnitude and variability of carbon stocks within a widely distributed marine foundation species throughout its distribution area in temperate Northern Hemisphere. We sampled 54 eelgrass (Zostera marina) meadows, spread across eight ocean margins and 36° of latitude, to determine abiotic and biotic factors influencing organic carbon (Corg) stocks in Zostera marina sediments. The Corg stocks (integrated over 25‐cm depth) showed a large variability and ranged from 318 to 26,523 g C/m2 with an average of 2,721 g C/m2. The projected Corg stocks obtained by extrapolating over the top 1 m of sediment ranged between 23.1 and 351.7 Mg C/ha, which is in line with estimates for other seagrasses and other blue carbon ecosystems. Most of the variation in Corg stocks was explained by five environmental variables (sediment mud content, dry density and degree of sorting, and salinity and water depth), while plant attributes such as biomass and shoot density were less important to Corg stocks. Carbon isotopic signatures indicated that at most sites <50% of the sediment carbon is derived from seagrass, which is lower than reported previously for seagrass meadows. The high spatial carbon storage variability urges caution in extrapolating carbon storage capacity between geographical areas as well as within and between seagrass species.

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Dynamics of carbon sources supporting burial in seagrass sediments under increasing anthropogenic pressure

Cited by 39 publications

References 61 publications

A Synthesis of Blue Carbon Stocks, Sources, and Accumulation Rates in Eelgrass (Zostera marina) Meadows in the Northeast Pacific

A Synthesis of Blue Carbon Stocks, Sources, and Accumulation Rates in Eelgrass (Zostera marina) Meadows in the Northeast Pacific

Reduced water motion enhances organic carbon stocks in temperate eelgrass meadows

Blue Carbon Storage Capacity of Temperate Eelgrass (Zostera marina) Meadows

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