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Project details
| Title: | Tracing carbon transfer from coastal vegetated habitats to the deep ocean |
| Id: | 2669 |
| Investigator(s): | Albert Pessarrodona
University of Western Australia [details] |
| Description: | We aim to obtain the first evidence of coastal vegetation carbon export and sequestration in emerging blue carbon sinks in Australia. To do so, we will obtain sediment (and water) samples along the continental shelf and shelf break at locations predicted to have high and low input of kelp-derived particulate organic carbon as predicted by particle tracking models. Export of kelp and other seaweed-derived carbon will be traced from water and sediments using biomarkers (eDNA, stable isotopes). Sequestration will then be determined using particulate organic carbon content along dated sediment cores (aged via 210 Pb dating). Results will feed back into the models to improve estimates of coastal carbon transfer to emerging blue carbon sinks. This research represents a critical step towards quantifying kelp carbon sequestration in the deep ocean and, subsequently, the inclusion of kelp forests in the blue carbon ecosystem Supplementary Proposal policy framework and future carbon dioxide removal projects in Australia. Importantly, the samples collected during the voyage will be made accessible to other researchers and end-users , extending their utility beyond the immediate scope of this project, and helping to improve valuable baseline data from the continental shelf of Australia. |
| Description (full): | To achieve its ambitious climate mitigation targets, Australia has placed substantial focus on and investments in ‘blue carbon’: carbon stored in marine ecosystems. Coastal vegetated ecosystems play a key role in the coastal carbon cycle, with increasing recognition that they act as important donors to several blue carbon sinks. These include continental shelf sediments and the deep sea, which represent promising new avenues for climate action as emerging blue carbon sinks. Yet, accurately measuring the amount of carbon transported from coastal ecosystems to deep carbon sinks remains challenging and relies on ocean current models and expensive in situ verification. Kelp forests represent one of the most extensive coastal ecosystems in the world and are estimated to contribute upwards of 30% of all carbon sequestered by coastal vegetation in Australia. Validating these estimates has proved extremely challenging to date as sampling shelf sediments and offshore waters is logistically challenging and expensive. Here, we aim to obtain the first evidence of coastal vegetation carbon export and sequestration in emerging blue carbon sinks in Australia. To do so, we will obtain sediment (and water) samples along the continental shelf and shelf break at locations predicted to have high and low input of kelp-derived particulate organic carbon as predicted by particle tracking models. Export of kelp and other seaweed-derived carbon will be traced from water and sediments using biomarkers (eDNA, stable isotopes). Sequestration will then be determined using particulate organic carbon content along dated sediment cores (aged via 210 Pb dating). Results will feed back into the models to improve estimates of coastal carbon transfer to emerging blue carbon sinks. This research represents a critical step towards quantifying kelp carbon sequestration in the deep ocean and, subsequently, the inclusion of kelp forests in the blue carbon ecosystem Supplementary Proposal policy framework and future carbon dioxide removal projects in Australia. Importantly, the samples collected during the voyage will be made accessible to other researchers and end-users , extending their utility beyond the immediate scope of this project, and helping to improve valuable baseline data from the continental shelf of Australia. Sediment samples. A multi corer will be used to retrieve up to 1-m deep sediment samples from the sampling stations. Cores will be processed on the ship deck or lab by subsampling ten 1-cm sections. Initially, a subset (n=3) of the slices will be analysed for (a) total organic carbon (TOC) and total carbon (TC) contents, (b) age (210Pb dating), and (c) genetics (kelp DNA abundance via quantitative polymerase chain reaction, qPCR) according to pre-existing standard operating procedures. Following results from these slices, the remaining slices for cores of interest will be analysed. Briefly, sediment TOC and TC contents will be quantified with a CHN elemental analyser after the removal of inorganic carbon with diluted hydrochloric acid; sediments will be aged with an accuracy of up to ~ 120 years by the Pere Masqué Lab (Edith Cowen University); and qPCR assay optimization and sample testing will be conducted using BioRad CFX96 (Frigstad et al. 2021) by the Wernberg Lab members (Indian Ocean Marine Research Centre, UWA). Sediment grain size will also be determined; dry bulk density will be calculated to convert TOC content from %C to C density; and depth layer-specific sedimentation rates will be calculated from 210PB dating results. DNA extraction and further sequencing will be completed at the NSW Department of Primary Industries’ eDNA facility (Narrandera Fisheries Centre- ISO9001 certification) using established methods for brown seaweeds (e.g., Vranken et al. 2021). Water samples. Processing for water samples involves filtering 3-5 L of water through a 0.45 μm sterilized filter using a peristaltic pump. Filters containing the eDNA particle pools sampled from the water will be flash frozen in liquid nitrogen and stored at −80 °C in a Dewar until further processing. Algal DNA will be extracted at the NSW Department of Primary Industri es’ eDNAfacility (Narrandera Fisheries Centre- ISO9001 certification) from the water samples using Qiagen Power Pro kits and amplified using pPCR according to optimised and strict (against contamination) protocols (Frigstad et al. 2021) with 6 technical replicates. Amplification will be done using COI primers for brown seaweeds (e.g., Coleman et al. 2022) as well as species-specific primers for Ecklonia radiata, the main kelp in Australia, based on our Ecklonia mitochondrial genome (Wheeler et al. 2022). Whatman GF/F filters (25 mm diameter; pre-treated with acid to remove inorganic carbon, pre-combusted at 500°C for 24h, and pre-weighed) containing material for POC analysis will be stored in cell culture plates until further processing in land. Filters will then be dried at 60°C for 48h, folded into a tin cup, and analysed with an elemental analyser coupled to an isotope ratio mass spectrometer. |
| Years: | 2026 |
List of surveys that this project was on.
Use [details] link to view survey details (map, reports, metadata etc) including links to download data.
| Survey | Investigator | Description |
|---|---|---|
| IN2026_T03 [details] |
Robin Beaman | The primary objective of this transit voyage is to relocate Investigator from Hobart to Brisbane. In addition, there are three supplementary projects and two piggyback projects included in the voyage. |