No abstract

Context. The Australian Government has developed a methodology for payment for carbon services provided by blue carbon ecosystems that focuses on avoided emissions and carbon additionality resulting from tidal restoration of coastal wetlands. Aims. This study is a firstpass prioritisation for tidal restoration of coastal wetlands in New South Wales (NSW). Methods. A pixel-based approach was applied using readily available datasets, with particular focus on watersheds above in-stream tidal barriers. Key results. Many sites were identified, to investigate in detail, opportunities to restore tidal flows to coastal wetlands. More were associated with the broad coastal floodplains of northern NSW than narrower floodplains of southern NSW. Conclusions. Information is needed about the location, ownership, land tenure, structure, condition and height of in-stream and over-land flow barriers, particularly in the context of rising sea levels. Decisions about managing in-stream drainage and flood mitigation infrastructure should be made cognisant of opportunities to increase blue carbon, and provide associated co-benefits, including mitigating other deleterious impacts from coastal wetland drainage. Implications. Decision support tools for evaluating economic and environmental costs and benefits of tidal barriers will assist decision-makers assessing future proposals to repair or remove aging barriers, or create new tidal barriers.

For the first time, a sediment core spanning the entire Holocene has been analysed from Fiji. The 6 m core was obtained from the floor of an ancient coastal lagoon (palaeolagoon) adjacent to Bourewa, the site of the earliest known human settlement in this island group. The basal sediments, just above bedrock, date from 11 470 cal BP. A major transition occurs around 8000 cal BP where marine influences on palaeolagoon sedimentation increase sharply. Full shallow-water marine conditions are attained around 4630 cal BP and last until 3480 cal BP after which there is a regressive phase. The results agree with the area-specific predictions of sea level in the ICE-4G model, particularly in the timing of the highstand. In addition, the results support the ideas (a) that early human colonisation of Fiji occurred during the late Holocene regression, (b) that the first inhabitants of Bourewa utilised both nearshore marine (reefal) and brackish lagoon food sources, and (c) that the abrupt human abandonment of the area around 2500 cal BP could have been prompted by a reduction in these resources driven largely by sea-level fall.

No abstract