A synthesis of modern organic carbon accumulation rates in coastal and aquatic inland ecosystems

Abstract

Organic carbon accumulation in the sediments of inland aquatic and coastal ecosystems is an important process in the global carbon budget that is subject to intense human modification. To date, research has focused on quantifying accumulation rates in individual or groups of aquatic ecosystems to quantify the aquatic carbon sinks. However, there hasn’t been a synthesis of rates across aquatic ecosystem to address the variability in rates within and among ecosystems types. Doing so would identify gaps in our understanding of accumulation rates and potentially reveal carbon sinks vulnerable to change. We synthesized accumulation rates from the literature, compiling 464 rate measurements from 103 studies of carbon accumulated in the modern period (ca. 200 years). Accumulation rates from the literature spanned four orders of magnitude varying substantially within and among ecosystem categories, with mean estimates for ecosystem categories ranging from 15.6 to 73.2 g C m−2 y−1 within ecosystem categories. With the exception of lakes, mean accumulation rates were poorly constrained due to high variability and paucity of data. Despite the high uncertainty, the estimates of modern accumulation rate compiled here are an important step for constructing carbon budgets and predicting future change.

Modeling Organic Carbon Accumulation Rates and Residence Times in Coastal Vegetated Ecosystems

“…Compared to other blue carbon ecosystems, our CAR estimates (from both models) are on the lower end of what has been reported for mangroves (Breithaupt et al, ) and tidal marshes (Ouyang & Lee, ). However, a recent synthesis (Wilkinson et al, ) that restricted the inclusion of studies (excluded surface sedimentation rates) and explicitly considered the uncertainty of estimates using a Bayesian modeling approach, reported lower mean CARs for blue carbon ecosystems, specifically 41, 63, and 73 g OC m −2 yr −1 for seagrasses, tidal marshes, and mangroves, which are quite similar to the rates presented here. Clearly, there is substantial variability in CARs both among and within blue carbon ecosystems.…”

“…Clearly, there is substantial variability in CARs both among and within blue carbon ecosystems. This variability results from a combination of factors ranging from local‐ (Serrano et al, ), regional‐ (Miyajima et al, ), and ecosystem‐level (Wilkinson et al, ) differences, to discrepancies among estimation methodologies (Callaway et al, ; Johannessen & Macdonald, ; Macreadie et al, ). The onefold to threefold difference in CARs produced for the same sites in this study underscores the effect estimation methods can have.…”

“…Reporting 95% confidence intervals, not the range. Corresponding sources: (a) Mazarrasa et al (); (b) Serrano et al () and Serrano, Lavery, et al (); (c) Serrano, Lavery, et al (); (d) Rozaimi et al () and Serrano, Lavery, et al (); (e) Serrano, Lavery, et al (), Serrano et al (), and Serrano, Ricart, et al (); (f) Wilkinson et al (); (g) Ouyang and Lee (); (h) Breithaupt et al ().…”

Carbon Deposition and Burial in Estuarine Sediments of the Contiguous United States

“…If high‐latitude fjords are excluded, the Cui et al () estimate of estuarine OC burial is 60 Tg OC/yr. Another recent global synthesis estimated that lagoons bury 41.4 [18.1–96.9] g OC/m 2 /yr (Wilkinson et al, ). Our typology placed lagoons under the secondary category and were predominantly located within clusters 1, 2, and 5, although only Cluster 6 strongly deviates from the Wilkinson et al () estimate.…”

“…Another recent global synthesis estimated that lagoons bury 41.4 [18.1–96.9] g OC/m 2 /yr (Wilkinson et al, ). Our typology placed lagoons under the secondary category and were predominantly located within clusters 1, 2, and 5, although only Cluster 6 strongly deviates from the Wilkinson et al () estimate. Another global review (Duarte et al, ) estimated that estuaries bury 45.0 g OC/m 2 /yr.…”