Project

4127

Chief Investigator

STARK, Dr Jonathan (Jonny) - Australian Antarctic Division

Title

A Free Ocean CO2 Enrichment Experiment (FOCE) to estimate effects of ocean acidification on benthic habitats

Project aims

Currently, a quarter of the CO2 we emit is absorbed by the ocean. CO2 absorption in seawater changes its chemistry – reducing ocean pH (raising its acidity) – which has significant impacts on biological processes and serious implications for the resilience of marine ecosystems. As CO2 is more soluble in cold water we expect polar ecosystems to bear the heaviest burden of this 'ocean acidification'. We will perform the first in situ polar CO2 enrichment experiment to determine the likely impacts of ocean acidification on Southern Ocean sea-floor communities under increasing CO2 emissions.

Project gallery


Project Summary of the Season 2013/14

The past year has been spent in developing and building the AntFOCE system. This began by modifying the xFOCE concept provided by MBARI to suit Antarctica. Using their accumulated technical expertise and knowledge the Science Technical Support team developed a plan to build the system. This work has progressed to the point where a trial deployment of a single chamber began locally (in the d'entrecasteaux Channel) in late June. Conditions in this chamber have been successfully manipulated to lower pH by 0.4 to approx 7.8
The past year has also been spent in developing the scientific plan. Discussions were held with researchers from Plymouth Marine Laboratories (UK), to complement the existing expertise.
A field team was deployed at Casey for an 8 week period over summer: Glenn Johnstone (Project Manager), Martin Riddle (TNE Program Leader), Bill Kirkwood (MBARI Head Engineer on xFOCE) and Lucy Quayle (UTAS volunteer student). The aim was to find the most suitable site to deploy the FOCE experiment. Requirements included suitable land based access and sufficient area to contain the land based system components. The site had to be as close as possible to the waters edge and adjacent to an area of seabed with characteristic suitable to deploy the experiment for a period of 3 – 4 months: good sea ice over the summer to protect it from icebergs and provide a good working platform to conduct diving operations; suitable benthic habitats; minimal slope; and a depth range to permit workable diving conditions. Two sites in O'Brien Bay, to the south of Casey were determined to be suitable. The final site will be selected in the 2014/15 season by diving. The team deployed artificial substrate units, to enable recruitment and community establishment, which will be deployed into the experiment when it commences. The team took measurements of currents, water samples for accurate determination of pH, and conducted a limited bathymetric survey of the sites.

Project Summary of the Season 2014/15

The antFOCE system was tested locally in Tasmania in June – August and worked well in the trial, which provided feedback on areas which needed modification or tuning. In October/November the field team travelled to Antarctica and spent over 4 months at Casey Station running the first polar FOCE experiment. Arrival at Casey was delayed by several weeks with delays in New Zealand and McMurdo Station. There were many challenges during the season from environmental hazards (from blizzards to meltwater) to technical issues (component failure), to logistical constraints (insufficient transport options to site). The dive team was very successful in deploying and maintaining the underwater components while the technical team installed and tested the onshore infrastructure required to run the system. The diving began in late November and the system was installed and running by late December. Once running the system performed very well and achieved the desired pH offset (approx 0.4 pH) for a period of between 8 and 9 weeks. At the end of this period the experiment was sampled and all the equipment was removed from the site. Samples were processed at Casey and returned to Australia for further processing and analysis.

Project Summary of the Season 2015/16

Following from the successful field season in 2014/15, we conducted extensive laboratory work on samples collected from the antFOCE experiment. This work is ongoing and data is currently being analysed. The carbonate chemistry analysis is complete and demonstrates that the experiment was successful in manipulating pH conditions with a stable offset of 0.4 below background. Some sediment analyses have been completed including metals, nutrients, sediment nitrification and grain size. Microbial and meiofaunal community analysis are incomplete but macrofaunal community analysis has been completed and data is currently being analysed. Excellent progress has been made in the analysis of biofilms including bacteria and diatom components. Bioturbation analysis is proceeding through collaborators at Plymouth Marine Laboratories (UK). Preliminary results indicate significant changes in a range of seabed communities due to ocean acidification. We hosted an international xFOCE workshop at the AAD with participants from the USA, France, the UK, local and interstate. The workshop was a successful forum for discussing different experiences in running FOCE experiments, ranging from engineering aspects to scientific results. A two man field team was sent to Casey to deploy a seapHox water sampling instrument on the seabed in O'Brien Bay, the site of the antFOCE experiment. This will measure conductivity (salinity), temperature, depth, dissolved O2 and pH every 2 hours over a full year, giving a much needed high resolution record of the carbon cycle in Antarctic coastal waters. This will aid in interpretation of results from the antFOCE experiment. Samples of benthic diatom communities were collected for a laboratory experiment being conducted by PhD student James Black, examining benthic diatom community response to ocean acidification under two high CO2 scenarios. This experiment will provide information to help understand changes that occurred in during the field experiment.

Project Summary of the Season 2016/17

In the past year work continued in the laboratory and on data analysis. The majority of the laboratory work has been completed, with some still remaining, and data is currently being analysed. The analysis of sediment biogeochemistry has been completed including metals, nutrients, sediment nitrification and grain size and data is being analysed. Analysis of biofilms, bioturbation, microbial and meiofaunal communities are almost complete and macrofaunal community analysis has been completed. Much of the work is being done through collaborations with external scientists. The carbonate chemistry analysis is complete and a paper is in review with Nature Scientific Reports. The international xFOCE workshop hosted by the AAD in 2016 (with participants from the USA, France, the UK, local and interstate) has resulted in a joint paper on progress in manipulating CO2 levels in-situ in field experiments which is close to submission. A two man field team was sent to Casey to retrieve the seapHox water sampling instrument deployed for a full year on the seabed in O'Brien Bay, the site of the antFOCE experiment. This was successful in obtaining a high resolution record (2 hourly measurements) of salinity, temperature, dissolved oxygen and pH over a full year, providing much needed data on the carbon cycle in Antarctic coastal waters. This will aid in interpretation of results from the antFOCE experiment. Samples of benthic diatom communities were also collected for a second laboratory experiment currently being conducted by PhD student James Black, examining benthic diatom community response to ocean acidification under high CO2 conditions. A similar three month laboratory experiment was successfully run in 2016. These experiments will provide information on the role of benthic diatoms in buffering changes in pH at the sediment-water interface and on effects on benthic diatom photosynthesis and productivity.

Final Summary of Project Achievements

The antFOCE project was a global first, proving that it is possible to conduct community level manipulations of ocean acidification in a real world Antarctic environment. AAD scientists and engineers adapted existing FOCE technology to operate successfully in the harsh environment of Antarctica, with 4 seabed chambers (each 1m sq.) encapsulating existing communities of organisms in 14 m of water underneath sea ice. Such experiments are vital to understanding the future impacts of decreasing ocean pH on marine ecosystems. We demonstrated that even over very short timescales (8 weeks) there are changes in communities of plants and animals living on the seabed. Micro algae at the bottom of the food web showed altered dynamics, with some species increasing and others decreasing in response to acidification, potentially paving the way for widespread changes higher up the food chain. Some examples of this were observed in populations of grazing invertebrates which increased in abundance. We also observed changes to the chemistry of sediments. The changes we observed over this short period were relatively subtle, and demonstrate some potential resilience of Antarctic marine life to future changes in seawater pH, although much longer experiments are required to investigate this further.
In addition we ran a series of innovative laboratory experiments examining the responses of Antarctic micro alage to ocean acidification. Samples of microalgae were collected from Casey station and transported back to a laboratory in Australia where they were exposed to low pH as well as higher temperatures, providing valuable context to inform the field experiment on responses of these key organisms to acidification..
We also collected the first year-long high-resolution (2 hourly measurements) pH data set from coastal Antarctic waters. Such data will be extremely useful in future modelling efforts to refine predictions about changes in Southern Ocean carbonate systems.

Category 1: Peer-reviewed literature

Gattuso J.-P. , Kirkwood W., Barry J.P., Cox E., Gazeau F., Hansson L., Hendriks I., Kline D.I., Mahacek P., Martin S., McElhany P., Peltzer E.T., Reeve J., Roberts D., Saderne V., Tait K., Widdicombe S., Brewer P.G. (2014) Free-ocean CO2 enrichment (FOCE) systems: present status and future developments, Biogeosciences 11. 4057-4075; [Ref: 15372]

Black J.G., Stark J.S., Johnstone G.J., McMinn A., Boyd P., McKinlay J., Wotherspoon S., Runcie J.W. (2019) In-situ behavioural and physiological responses of Antarctic microphytobenthos to ocean acidification, Scientific Reports 9. 1890 (13pp); [Ref: 16015]

Stark J. S., Peltzer E.T., Kline D.I., Queiros A.M., Cox T.E., Headley K., Barry J., Gazeau F., Runcie J.W., Widdicombe S., Milnes M., Roden N.P., Black J., Whiteside S., Johnstone G., Ingels J., Shaw E., Bodrossy L., Gaitan-Espitia J.D., Kirkwood W., Gattuso J.-P. (2019) Free Ocean CO2 Enrichment experiments scientific and technical recommendations for future in situ ocean acidification projects, Progress in Oceanography 172. 89-107; [Ref: 16054]

Stark J.S., Roden N., Johnstone G.J., Milnes M., Black J.G., Whiteside S., Kirkwood W., Newbery K., Stark S., van Ooijen E., Tilbrook B., Peltzer E.T., Berry K., Roberts D. (2018) Carbonate chemistry of an in-situ free-ocean CO2 enrichment experiment (antFOCE) in comparison to short term variation in Antarctic coastal waters, Scientific Reports 8:2816. 16pp; [Ref: 15991]

Figuerola B., Gore D.B., Johnstone G., Stark J.S. (2019) Spatio-temporal variation of skeletal Mg-calcite in Antarctic marine calcifiers, PLoS ONE 1-18; [Ref: 16173]

Figuerola B., Hancock A.M., Bax N., Cummings V.J., Downey R., Griffiths H.J., Smith J., Stark J.S. (2021) A Review and Meta-Analysis of Potential Impacts of Ocean Acidification on Marine Calcifiers From the Southern Ocean, Frontiers in Marine Science 1-22; [Ref: 16370]

Stark J. S., Johnstone G.J., King, C., Raymond T., Rutter A., Stark S.C., Townsend A.T. (2023) Contamination of the marine environment by Antarctic research stations: Monitoring marine pollution at Casey station from 1997 to 2015, PLoS ONE 18(8). e0288485; [Ref: 16896]

Category 3: Article

Stark J.S., Gattuso J.-P. (2016) Third xFOCE Workshop: Present Status and Future Developments of In Situ Ocean Acidification Experiments, Limnology and Oceanography Bulletin 25(3). 94-95; [Ref: 15790]

Category 3: Poster

Roberts D., Stark J., Kirkwood W.J., Peltzer E.T., McMinn A., Davidson A., Riddle M.J., Press A.J., Johnstone G. (2014) Free Ocean CO2 Enrichment of the Antarctic sea floor: antFOCE, 2014 Ocean Sciences Meeting, Honolulu, USA, 23-28 February 2014 .; [Ref: 15668]

Category 3: Verbal presentation

Stark J.S., Black J., Johnstone G., Kirkwood W., Milnes M., Roden N., Whiteside S. (2016) antFOCE (Antarctic Free Ocean CO2 Enrichment) – Ocean acidification under sea ice, 4th International Symposium on the Ocean in a High-CO2 World, Hobart, Australia, 3-6 May 2016 .; [Ref: 15808]

Stark J. S., Black J., Clarke L., Deagle B, Johnstone G., Kirkwood W., Milne M., Powell S., Roden N., Whiteside S. (2016) Antarctic Free Ocean CO2 Enrichment– Ocean acidification under sea ice and its effects on benthic communities, Society of Environmental Toxicology and Chemistry Australasia Conference, Hobart, Australia, October 2016 .; [Ref: 16058]

Stark J. S. (2018) Australian Antarctic ocean acidification research, Reinvigorating Ocean Acidification Research in Australia, Shine Dome, Canberra, Australia, 25 October 2018. .; [Ref: 16096]

Stark J. S. (2018) Ocean acidification in Antarctic coastal ecosystems – experiments and monitoring, South-east Australia Marine Climate Impacts and Adaptation Symposium, CSIRO Marine Laboratories, Hobart, Australia, Feb 20-21, 2018 .; [Ref: 16097]

Stark J.S. (2018) Ocean acidification in Antarctic coastal ecosystems – experiments and monitoring, South-east Australia Marine Climate Impacts and Adaptation Symposium, Hobart, Australia, 20-21 February 2018 .; [Ref: 15992]