Estimating the Potential Blue Carbon Gains From Tidal Marsh Rehabilitation: A Case Study From South Eastern Australia

Gulliver, Anne; Carnell, Paul E.; Trevathan-Tackett, Stacey M.; Costa, Micheli Duarte de Paula; Masqué, Pere; Macreadie, Peter I.

doi:10.3389/fmars.2020.00403

Cited by 22 publications

(13 citation statements)

References 36 publications

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“…In the Bay of Fundy, which like the Severn Estuary is hypertidal, carbon accumulation is lower but within the same order of magnitude at 13.29 t C ha -1 yr -1 [25], but rates at other sites are an order of magnitude lower than at Steart Marshes. For example, saltmarshes in eastern England were reported to accumulate carbon at a rate of 1.04 t C ha -1 yr -1 for the first 20 years following creation [24], while a recovering saltmarsh in Australia accumulates at a rate of 0.5 t C ha -1 yr -1 [40].…”

Section: Discussionmentioning

confidence: 99%

Rapid carbon accumulation at a saltmarsh restored by managed realignment far exceeds carbon emitted in site construction

Mossman

Pontee

Born

et al. 2021

Preprint

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Increasing attention is being paid to the carbon sequestration and storage services provided by coastal blue carbon ecosystems such as saltmarshes. Sites restored by managed realignment, where existing sea walls are breached to reinstate tidal inundation to the land behind, have considerable potential to accumulate carbon through deposition of sediment brought in by the tide and burial of vegetation in the site. While this potential has been recognised, it is not yet a common motivating factor for saltmarsh restoration, partly due to uncertainties about the rate of carbon accumulation and how this balances against the greenhouse gases emitted during site construction. We use a combination of field measurements over four years and remote sensing to quantify carbon accumulation at a large managed realignment site, Steart Marshes, UK. Sediment accumulated rapidly at Steart Marshes (mean of 75 mm yr-1) and had a high carbon content (4.4% total carbon, 2.2% total organic carbon), resulting in carbon accumulation of 36.6 t ha-1 yr-1 total carbon (19.4 t ha-1 yr-1 total organic carbon). This rate of carbon accumulation is an order of magnitude higher than reported in many other restored saltmarshes, and is higher although more similar to values previously reported from another hypertidal system (Bay of Fundy, Canada). The estimated carbon emissions associated with the construction of the site were ~2-4% of the observed carbon accumulation during the study period, supporting the view that managed realignment projects in such settings are likely to have significant carbon accumulation benefits. We outline further considerations that are needed to move towards a full carbon budget for saltmarsh restoration.

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Section: Discussionmentioning

confidence: 99%

Rapid carbon accumulation at a saltmarsh restored by managed realignment far exceeds carbon emitted in site construction

Mossman

Pontee

Born

et al. 2021

Preprint

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“…For example, sites that have been modified for salt works that are no longer operational could be restored to salt marsh habitat by removing tidal barriers and re-establishing tidal flows. This has been successful at impounded areas [23,73]. The potential to establish tidal connectivity to the salt pan area at Swartkops Estuary was considered as a restoration approach [70].…”

Section: Opportunities For Restoration Following Land-use Changementioning

confidence: 99%

“…With high intrinsic ecological and economic value, ecological restoration has become recognized as critical for ecosystems like salt marshes that can provide multiple services (Figure 2; [20,21]). Restored salt marshes are valuable "blue carbon" ecosystems, as they can sequester and store carbon at efficient rates for centuries [22,23], thereby presenting important opportunities for climate change mitigation. Additionally, salt marshes provide nursery habitats and support fisheries which are crucial to food security and livelihoods around the world [24].…”

Section: Introductionmentioning

confidence: 99%

Salt Marsh Restoration for the Provision of Multiple Ecosystem Services

2021

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Restoration of salt marsh is urgent, as these ecosystems provide natural coastal protection from sea-level rise impacts, contribute towards climate change mitigation, and provide multiple ecosystem services including supporting livelihoods. This study identified potential restoration sites for intervention where agricultural and degraded land could be returned to salt marsh at a national scale in South African estuaries. Overall, successful restoration of salt marsh in some estuaries will require addressing additional pressures such as freshwater inflow reduction and deterioration of water quality. Here, we present, a socio-ecological systems framework for salt marsh restoration that links salt marsh state and the well-being of people to guide meaningful and implementable management and restoration interventions. The framework is applied to a case study at the Swartkops Estuary where the primary restoration intervention intends to route stormwater run-off to abandoned salt works to re-create aquatic habitat for waterbirds, enhance carbon storage, and provide nutrient filtration. As the framework is generalized, while still allowing for site-specific pressures to be captured, there is potential for it to be applied at the national scale, with the largest degraded salt marsh areas set as priorities for such an initiative. It is estimated that ~1970 ha of salt marsh can be restored in this way, and this represents a 14% increase in the habitat cover for the country. Innovative approaches to restoring and improving condition are necessary for conserving salt marshes and the benefits they provide to society.

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“…Other hotspots of saltmarsh expansion include small embayments around the western coast of Port Phillip Bay (Central Bays, VIC; Figure S1a), which have experienced similar droughts that have permitted the advancement of saltmarsh to cover previously known water sources (Figure S1c in supplementary). Moreover, we managed to capture the performance of several restoration projects in the north-western coast of Port Phillip Bay [17,83,84], with over 60 ha (according to our maps) of area reconverted from salt ponds or water management facilities to saltmarsh ecosystems (Figure S1b). However, there are some limitations with our models, as some of that increase has been associated with rapid expansion of Phragmites reed (especially in interior lakes of the western coast of Port Phillip Bay in Victoria, see Reedy Lake in Figure S1d and [85]), a rapidly growing freshwater grass that can live in brackish waters and which is spectrally similar to other, often adjacent, saltmarsh graminoids [77].…”

Section: Mangrove and Saltmarsh Distributionmentioning

confidence: 99%

“…In temperate regions of south-eastern Australia, around 20 percent of Australia's mangroves and saltmarshes have been lost since colonisation [16], with some estuaries losing up to 80 percent [15]. As a consequence, coastal wetland ecosystems have been a focus of many conservation and restoration projects in temperate and sub-tropical regions of Australia [17][18][19]. The success of such projects requires a good understanding of spatial and temporal ecosystem distribution to inform better management strategies and to ensure effort is directed towards appropriate areas [20][21][22].…”

Section: Introductionmentioning

confidence: 99%

Mangrove and Saltmarsh Distribution Mapping and Land Cover Change Assessment for South-Eastern Australia from 1991 to 2015

et al. 2021

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Coastal wetland ecosystems, such as saltmarsh and mangroves, provide a wide range of important ecological and socio-economic services. A good understanding of the spatial and temporal distribution of these ecosystems is critical to maximising the benefits from restoration and conservation projects. We mapped mangrove and saltmarsh ecosystem transitions from 1991 to 2015 in south-eastern Australia, using remotely sensed Landsat data and a Random Forest classification. Our classification results were improved by the addition of two physical variables (Shuttle Radar Topographic Mission (SRTM), and Distance to Water). We also provide evidence that the addition of post-classification, spatial and temporal, filters improve overall accuracy of coastal wetlands detection by up to 16%. Mangrove and saltmarsh maps produced in this study had an overall User Accuracy of 0.82–0.95 and 0.81–0.87 and an overall Producer Accuracy of 0.71–0.88 and 0.24–0.87 for mangrove and saltmarsh, respectively. We found that mangrove ecosystems in south-eastern Australia have lost an area of 1148 ha (7.6%), whilst saltmarsh experienced an overall increase in coverage of 4157 ha (20.3%) over this 24-year period. The maps developed in this study allow local managers to quantify persistence, gains, and losses of coastal wetlands in south-eastern Australia.

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Estimating the Potential Blue Carbon Gains From Tidal Marsh Rehabilitation: A Case Study From South Eastern Australia

Cited by 22 publications

References 36 publications

Rapid carbon accumulation at a saltmarsh restored by managed realignment far exceeds carbon emitted in site construction

Rapid carbon accumulation at a saltmarsh restored by managed realignment far exceeds carbon emitted in site construction

Salt Marsh Restoration for the Provision of Multiple Ecosystem Services

Mangrove and Saltmarsh Distribution Mapping and Land Cover Change Assessment for South-Eastern Australia from 1991 to 2015

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