BDBSA Project Metadata Detail

Survey/Project Number: 1130          Total No. of Sites: 23
Survey/Project Name: Assessing carbon accumulation and loss in mangrove sediments
Abstract: This project aims to assess carbon accumulation and loss in mangrove sediments influenced by various land usage influx of the South Australian coastline. BACKGROUND: Coastal, vegetated ecosystems such as mangrove forests, tidal saltmarshes, and wetlands act as a buffer for marine systems by intercepting pollutants and excessive nutrients. Carbon (C) sequestration in coastal, vegetated ecosystems is dominated by the capture of atmospheric carbon dioxide (CO2) through photosynthesis, and subsequent storage as organic carbon (OC) in above and below ground woody tissues and sediments. Global averages for storage of C, in above-ground and below-ground biomass and associated sediments of mangroves, have been reported as 100, 150 and 750 mg C/hectare, respectively. Consequently, healthy coastal sediments have the potential to store high levels of C over time, and avoid C saturation by growing vertically. However, the quantity of C stored can be impacted by land-use changes occurring in their feeder catchments, and with inflows of water contaminated with nutrients and agrichemicals. OBJECTIVES: This research aims to quantify and characterise the current 0-10 cm OC stock of representative sediments in vegetated, coastal regions of South Australia, with a diverse range of surrounding land uses (e.g. broad acre agriculture, horticulture, industrial/urban). METHODOLOGY: A series of laboratory incubation studies will be undertaken to quantify the potential impact elevated nutrient supply can have on C cycling in coastal sediments. A framework to predict OC turnover under different nutrient loads and identifying C more vulnerable to loss in coastal vegetated ecosystems will be built, with a strong emphasis on the impact of agricultural inputs. OUTCOMES: This information will aid in defining land use management that minimises the risk of degradation and loss of these naturally occurring ecosystems. Overall, increasing the fundamental understanding of the role of vegetated coastal ecosystems in climate change mitigation.
 
Start Date: 01/02/2016      End Date: 30/01/2019
Survey Type: Vegetation Only
   
Study Area Description: General locations: Adelaide & Mt Lofty Ranges (NRM Region) Northern & Yorke (NRM Region) Eyre Peninsula (NRM Region) Reserves: Torrens Island (Conservation Park) St Kilda Mangrove Trail (Reserve) Port Gawler (Conservation Park) Wills creek (Conservation Park) .
Objectives
         Vegetation: Refer to Abstract.
         Fauna: *** No fauna survey objectives recorded
Methodology
         Vegetation: 1.1. FIELD WORK: Soils will be collected from a range of sites that are representative of the range of contexts in which mangroves and salt marshes occur in SA. At each site sampled non-destructive sampling, including: photographs for plant species identification and canopy cover determination; GPRS coordinates of each transect; and sediment pH/EC will be collected for site specific data information. Sediments will be collected using destructive sampling methods along 3x35m transects 10m apart from each other. Manual soil corers (~7.5cm x 12cm) will be used to sample the top 0-10cm depth of sediment at intervals of 5m along each of the 3 transects in each sampled site. Transects will be run 20m inland through salt marsh vegetation and 15m coastward into mangrove forests. The first mangrove in the transitional zone between mangroves and saltmarshes will be used as the reference point for all transects at each site sampled. A total of 4 mangrove sediment cores and 4 salt marsh sediment cores will be collected along each transect, resulting in 24 x 0-10cm sediment cores collected from each individual site. 1.2. EXPERIMENTAL DESIGN: Sediment samples from both salt marsh and mangroves will be used to develop the baseline of preliminary information on the stocks and the chemical nature of carbon in South Australia's coastal sediments impacted by various inland nutrient inputs. Analytical techniques such as including dry combustion will be used to determine total carbon, organic carbon and total nitrogen stocks in freeze dried, <2mm sieved, split and ground subsample of sediment; MIR spectroscopy combined with PLSR analysis will be applied to predict TC, IC and OC stocks in sediments collected along each 35m transect; and NMR spectroscopy to characterise the organic carbon forms present in each sediment type at the time of sampling. Further investigation on the decomposition of SOM in sediments will be explored through particle size fractionation where by the dispersal of <2mm sieved sediments is partitioned into >53m course and <53m fine fractions using an automated fractionation scheme as described in Baldock et al. (2013) in order to characterise the particulate organic matter, humus and resistant organic matter within the SOM of the sediments (Macdonald and Baldock, 2010). 1.3. CARBON CYCLING: [Activity and community structures] Biogeochemical cycling of carbon in salt marsh and mangrove sediments will be investigated through laboratory incubation of sediments in order to assess the simulated impact of external inputs for agriculture on sediment processes (i.e. respiration). Sediments used for incubations will be chosen from study sites found to have comparably different stocks and chemical forms of carbon during the first phase of the study. Sediments will be incubated under aerobic and anaerobic conditions with changes in the concentration of nitrogen over time.
         Fauna: *** No vertebrate methodology recorded

Data Distribution Rules: Sensitive Dataset: Written permission required from Information Authority
Project Basis: Vegetation : Baseline Survey of flora and/or fauna - Standard Biol Survey of SA survey methodology not used.
Vegetation : Unclassified - pending reassessment.
Vegetation : Climate and climate change related investigations
Information Authority: Student
University of Adelaide