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Project details

Title: Natural iron fertilisation of oceans around Australia: Linking terrestrial dust and bushfires to marine biogeochemistry
Id: 2451
Investigator(s): Andrew Bowie
University of Tasmania - Institute of Marine and Antarctic Studies [details]

Description: The main aim for this supplementary project is to sample aerosols to study natural iron fertilisation of oceans around Australia: linking terrestrial dust and bushfires to marine biogeochemistry See main project in2016_v04_doblin for more details.
Years: 2016 to 2022
Hierachy: University of Tasmania » Institute of Marine and Antarctic Studies


Conference abstract


Journal Article

List of surveys that this project was on. Click on column header to sort.

Use [details] link to view survey details (map, reports, metadata etc) including links to download data.

Survey InvestigatorDescription

Alix Post (GA) This study has two main scientific objectives: i) to understand past changes in Antarctic Bottom Water (AABW) production using long sediment cores from the continental slope over multiple warm periods during the Pleistocene; ii) develop an improved bathymetry model to support oceanographic modelling of AABW pathways. Sediment core records of previous warmer interglacials will provide an analogue for understanding the impact of any future changes in bottom water production associated with a warming climate. This project will recover long sediment cores from the shelf and slope off Cape Darnley to provide palaeoceanographic records over multiple glacial-interglacial cycles, including previous interglacials when Antarctic air temperatures were 2 to 4.5°C warmer than today. A multi-proxy approach, combining sedimentological, geochemical and biological proxies, will provide evidence of the nature and timing of past changes in AABW formation, and associated variations in meltwater input, and the extent of the Cape Darnley polynya. AABW has previously been associated with unique and diverse benthic ecosystems, including hydrocorals. We will investigate the presence and distribution of hydrocorals, and, if present, analyse their carbonate skeletons to understand past water mass variability over recent centuries, complementing the sediment core records.

Dr Jutzeler (UTAS) The aim of this project is to link the behaviour of deep submarine eruptions with the morphology of their deposits. Modelling calculations of sediment mass fluxes will permit the first-ever hazard mapping scheme for submarine volcanoes globally (tsunami and sediment flows), and provide new ore vectoring strategies for exploration in Australia. For operational reasons the publication of the voyage plan has been postponed.

John Keesing (CSIRO) RV Investigator research voyage in2017_v05, titled "Long-term recovery of trawled marine communities 25 years after the world's largest adaptive management experiment." The North West Shelf has seen massive reductions in trawling area and effort over past decades from the previous high levels of foreign trawling up until 1990. There remains debate about whether slow growing benthic organisms such as coral and sponges have recovered from this disturbance and whether the current management zoning which has been in place for 20 years and which includes areas closed to fishing, specific areas for trawling and trap is sustainable and effective. The outcomes of the study will have relevance to how trawl fishing is managed in Australia and internationally.

Andrew Bowie (UTAS) The application will support research to quantify the importance of iron-rich aerosols from Australia for marine biogeochemistry and ocean ecosystem health. The project will sample and conduct experiments on atmospheric particles containing terrestrial dust and bushfire smoke that are transported from Australia to its surrounding oceans. The application supports the training and research of two postgraduate students from IMAS-UTAS. The outcomes will provide a scientific basis for managing the complex role of iron in sustaining marine ecosystem biodiversity and for informing government policy on ocean fertilisation as a carbon mitigation strategy.

Martina Doblin RV Investigator research voyage in2016_v04, titled "Influence of temperature and nutrient supply on the biogeochemical function and diversity of ocean microbes." Scientific Objectives: 1. Characterise the diversity and function of microbial communities in the relatively warm EAC, against the relatively cool water of the Tasman Sea and adjacent shelf waters. 2. Conduct perturbation experiments to experimentally test the role of temperature and nutrients (particularly N and Fe) in microbially mediated biogeochemical transformations. 3. Assess the links between microbial biomass, size structure and carbon production with higher trophic levels zooplankton, micronekton and cetaceansseabirds) in a frontal eddy(ies) relative to adjacent shelf and EAC waters. 4. Sample sediments to examine water-sediment geochemical processes and historical record of plankton. Previous sampling opportunities have not allowed us to revisit water masses (Aim 1) or conduct replicate experiments in the same water mass (Aim 2). Our objectives are therefore to more comprehensively sample the distribution and diversity of microbes across multiple oceanographic features. This includes cross-shelf transects, but also includes cross-eddy transects by extending shelf transects offshore (Aim 3). To achieve Aim 3, we will require real-time satellite information to identify our target area, as well as access to the IMOS ocean colour, SST, SSH data archive while on board. We will also conduct in situ 'mapping' of the target frontal eddy area using the Triaxus towed underwater body before we determine the exact location of transects and daytime CTD stations. Aim 3 activities will also involve bioacoustic monitoring in the western Tasman Front off Port Stephens, and within and outside of a frontal eddy. This will involve recording data from the EK60 of all 5 frequencies (if possible), which need to be appropriately coordinated with both ADCP. We suggest the two instruments should be programmed to ping and listen together, and to ignore any EK60 deeper than 750 to 1,000 m (to be confirmed with MNF and CSIRO bioacoustics group). Aims 1 and 2 relate to our original application for ship time and are hence the top priority. The Aim 3 activities occur mostly at night, which can be integrated into the day-time focussed sampling of Aims 1 and 2. Our intent is therefore to address these aims in waters north of Bass Strait (depending on the oceanographic features present). Activities to address Aim 4 have the lowest priority and are left to later in the voyage, but PIs have indicated that sediment cores from Port Hacking (NSW) will have strong scientific value for examining sediment fluxes and looking at the historic presence of microbial taxa.

A. Bowie (ACE CRC UTAS) Voyage objectives The main objective of this transit voyage is to move the vessel from Hobart to Sydney prior to IN2016_V04. The objectives listed below are complementary with the transit. 1. Natural iron fertilisation of the oceans around Australia: linking terrestrial dust and bushfires to marine biogeochemistry Oceans play a vital role in Earth's climate through the control of atmospheric CO2. An important component of this system is the iron cycle, in which iron-rich aerosols are transported from land via atmosphere to ocean. Iron is a key micronutrient for marine phytoplankton, the scarcity of which controls essential biogeochemical processes. This project will facilitate an integrated ship-based atmospheric observational program for trace elements in oceans around Australia. During the voyages, we will sample and conduct experiments on atmospheric particles containing terrestrial dust, bushfire smoke and anthropogenic emissions that are transported from Australia to its surrounding oceans. This will provide the critical information on atmospheric iron supply for ocean fertility and health, providing the science for predicting a key factor in the future impact of the oceans on climate. The project supports the training and research of two postgraduate PhD students from IMAS-UTAS. 2. We will also opportunistically collect event-based clean rainwater samples using either a polyethylene funnel and collection bottle (when conditions allow) or a Dual Chimney Precipitation Sampler (N-Con Systems model 00-127; currently on order), to quantify the trace metal deposition in the 'bulk' and 'precipitate-only' fractions. Ideally samples would be collected on upper and forward decks, either above the bridge or at the bow when heading into the wind.

M. Coffin (IMAS, UTAS) HEOBI Heard Earth-Ocean-Biosphere Interactions RV Investigator voyage IN2016_v01. Voyage objectives: [1] Seafloor and subseafloor mapping/geophysical characterisation. Continuous mapping will be carried out using the multibeam systems, multi-frequency split-beam echosounders, sub-bottom profiler, gravimeter, and (on long transits between ports and the study area) magnetometer to characterise bathymetric features and identify those most likely to include volcanic or hydrothermal activity. XBT or CTD data will be acquired at standard intervals for sound velocity corrections to the multibeam data. The data will be initially processed at sea to inform site selection for volcanic and hydrothermal sampling. [2] Nature of submarine volcanoes and hydrothermal systems. We will characterise the spatial distribution, morphology, and geology of active submarine volcanoes and hydrothermal systems. [Extract only] [3] Detecting hydrothermal inputs to the ocean, and vertical water movements that deliver them to surface waters. full-depth CTD/LADCP/TMR transects will be performed to capture cross-shore gradients in water. [Extract only] [4] Detecting impacts on surface phytoplankton production. During the underway mapping we will continuously operate sensors to measure biological activity (fluorescence for phytoplankton abundance, fast-repetition-rate fluorescence for phytoplankton photosynthetic competence, transmission for total carbon biomass, and O2/Ar ratio mass spectrometry for net community production). The sensors will be augmented by underway sampling for phytoplankton pigments, particulate organic and inorganic carbon, biogenic silica, heterotrophic bacterial responses, and microscopic phytoplankton identification to characterise community structures, and 15N measurements to identify the extent of nitrate versus ammonium metabolism - a key indicator of ecosystem Fe stimulation capable of additional carbon sequestration. Above and downstream of active hydrothermal systems, we will obtain samples for further analyses ashore. We also intend to carry out deckboard micro-nutrient enrichment incubation experiments to ascertain the biological response of hydrothermal iron to surface phytoplankton communities. Deployment of a bio-optical sensor package after each CTD deployment will provide measurements to link these communities to satellite images. [5] Ocean circulation around Heard Island and across the eastern Indian Ocean sector of the Southern Ocean. The shipboard ADCP and all available underway systems (thermosalinograph, meteorology, and biogeochemical systems) will be run at all times. We will seek contributions of autonomous instruments to deploy on the voyage to provide more detailed sampling of the circulation. We have contacted the Global Surface Drifter Program run by NOAA, and the Australian office of the International Argo Program. The lowered ADCP will be used at every CTD station to measure full water column velocity. New processing methods also allow the detection of internal waves and mixing using a shear-strain parameterisation, even in shallow waters. [Extract only] [6] Microbial response and bacterial processes What is the response of the microbial community to iron and organic carbon availability in different zones of the Southern Ocean, with focus on the possible impact of hydrothermal activity. More specific question: How does iron and carbon limitation affect heterotrophic bacterial respiration and growth efficiency, and its diversity? This text is an extract ONLY from the voyage plan. Please see in2016_v01 plan for full details.
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