The influence of mussel restoration on coastal carbon cycling

Abstract

Increasing responsiveness to anthropogenic climate change and the loss of global shellfish ecosystems has heightened interest in the carbon storage and sequestration potential of bivalve‐dominated systems. While coastal ecosystems are dynamic zones of carbon transformation and change, current uncertainties and notable heterogeneity in the benthic environment make it difficult to ascertain the climate change mitigation capacity of ongoing coastal restoration projects aimed at revitalizing benthic bivalve populations. In this study we sought to distinguish between direct and indirect effects of subtidal green‐lipped mussels (Perna canaliculus) on carbon cycling, and combined published literature with in‐situ experiments from restored beds to create a carbon budget for New Zealand's shellfish restoration efforts. A direct summation of biogenic calcification, community respiration, and sediment processes suggests a moderate carbon efflux (+100.1 to 179.6 g C m−2 year−1) occurs as a result of recent restoration efforts, largely reflective of the heterotrophic nature of bivalves. However, an examination of indirect effects of restoration on benthic community metabolism and sediment dynamics suggests that beds achieve greater carbon fixation rates and support enhanced carbon burial compared to nearby sediments devoid of mussels. We discuss limitations to our first‐order approximation and postulate how the significance of mussel restoration to carbon‐related outcomes likely increases over longer timescales. Coastal restoration is often conducted to support the provisioning of many ecosystem services, and we propose here that shellfish restoration not be used as a single measure to offset carbon dioxide emissions, but rather used in tandem with other initiatives to recover a bundle of valued ecosystem services.

Interplay of soil characteristics and arbuscular mycorrhizal fungi diversity in alpine wetland restoration and carbon stabilization

“…Alpine wetland restoration from grazing significantly increased aboveground biomass and influenced soil properties (including content of NH 4 + and WSOC, EC, and pH). This finding supports our first hypothesis and is corroborated by multiple studies indicating that restoration activities contribute to improved soil quality and nutrient availability ( Burden et al, 2019 ; Xu et al, 2019 ; Yang et al, 2019 ; Sea et al, 2022 ; Lovelock et al, 2023 ; Liu J. et al, 2023 ), thereby fostering greater plant growth and productivity as observed in the increased aboveground biomass at restored sites ( Figure 2 ). Contrary to our expectations, however, NO 3 − concentrations and soil moisture did not significantly differ between grazed and restored sites.…”

An Estimate of Carbon Storage Capabilities from Wild and Cultured Shellfish in the Northwest Atlantic and Their Potential Inclusion in a Carbon Economy

“…Note that although not sequestered, that is, not from atmospheric source, bivalve shells do store large amounts of oceanic CO 2 , which could be released to the atmosphere if improperly managed (Alonso et al 2021, Álvarez-Salgado et al 2022). To mitigate this additional CO 2 cost, numerous studies suggest to return shells to coastal aquaculture sites, which would result in increased CO 2 sequestration via the dissolution of CaCO 3 , subsequently canceling out the cost of shell production (Alonso et al 2021, Álvarez-Salgado et al 2022, Sea et al 2022).…”

The Role of a Faunal Engineer, Geukensia demissa, in Modifying Carbon and Nitrogen Regulation Services in Salt Marshes

“…Lower dry bulk density values associated with mussel presence was likely an artifact of higher root and rhizome biomass in sediments underneath their aggregations, however, as belowground cordgrass was removed from sediment samples upon collection. Other bivalve systems have been deemed C sinks, including salt marsh-fringing oyster reefs (Fodrie et al, 2017) and restored, green-lipped mussel beds (Sea et al, 2022). These studies analyzed deeper vertical profiles (10-55 cm) underneath shellfish aggregations-depths that would extend beyond the S. alterniflora root zone in salt marshes.…”