ARC Grant Success (October 2015)
The Centre for Coastal Biogeochemistry was successful again in the latest ARC round with another Discovery and another DECRA.
Professor Bradley Eyre, director of the University's Centre for Coastal Biogeochemistry Research, has received $305,000 for a three-year study investigating the rates of denitrification in seagrasses and how effectively they work as 'cleansers' of nitrogen. The project is being undertaken jointly with Professor Ronnie Guld, from the University of Southern Denmark.
The Discovery Project is titled 'Resolving the amount of nitrogen lost from seagrass communities via denitrification: importance for global nitrogen budgets'.
"We will be looking at seagrasses in estuaries on the east coast of Australia and in parts of Denmark. Seagrasses are an important part of the benthic habitat in these systems and our preliminary work has shown high rates of nitrogen removal via denitrification in the seagrass, which converts fixed nitrogen into a gas which is lost from the system," Professor Eyre said.
"It's essentially a cleansing process, taking nitrogen out of the water. It's a really important process to understand. If it turns out that the high rates we have measured to-date are found in all seagrasses, they may play an important role in the global nitrogen budget.
Dr Christian Sanders, also in the centre but based at the University's National Marine Science Centre at Coffs Harbour, received a Discovery Early Career Research Award (DECRA), worth $393,434, for his project 'Mangroves as nutrient filters: Resolving the balance between groundwater exports versus soil burial'.
Dr Sanders said mangrove wetlands naturally filter and bury large quantities of carbon and nutrients through soil accretion. This process of sequestering carbon in marine ecosystems is also referred to as 'blue carbon'.
"This project will determine site specific mangrove carbon and nutrient sequestration along the Australian coast, permitting these wetlands to be included in national policy frameworks, including the CO2 emissions reduction schemes," Dr Sanders said.
"Such information will allow adaptation strategies to use coastal wetland habitats that sequester greenhouse gases, providing strong support for mangrove forest protection and restoration."
Science and coal seam gas - a case of the tortoise and the hare? (December 2014)
One of the key questions about the coal seam gas (CSG) industry, which is now being developed at breakneck speed across Australia, is how much methane is released as "fugitive" emissions.
Three weeks ago we published a paper containing the first detailed maps of atmospheric greenhouse gases in Queensland's CSG heartland. Our study clearly exposes the lack of knowledge in this area, leaving open the question of whether CSG really is greener than coal.
This research has seen us caught in the middle of a scientific, economic and political tug of war. While the industry keeps expanding at a rapid rate, is CSG science moving too slowly?
Our story started in 2012, when we won an Australian Research Council grant to purchase cutting-edge greenhouse gas monitoring equipment, which we initially planned to use to investigate coastal waters, rather than CSG fields.
At about the same time, our local community in northern New South Wales was fired up over concerns about future CSG development. Campaigns such as Lock the Gate began to gain traction, and the issue prompted large rallies.
One of the community's main concerns was about the lack of scientific information. While no experimental Australian data other than our recent papers has been published in the peer-reviewed literature on fugitive emissions, the NSW government has released a broad review of CSG, and CSIRO has recently released initial experimental results on fugitive emissions from some CSG wells.
Fugitive emissions were often viewed as a minor issue, with much of the concern focused on CSG impacts on groundwater. In 2012, we had at our disposal cutting-edge instruments not only to measure the concentrations of greenhouse gases with extremely high precision, but we could also detect their "chemical fingerprint" to pinpoint sources.
We drove to the gas fields of Queensland's Darling Downs region, where CSG production has been proceeding at full steam for a decade or more. That night we stayed in a hotel filled with mining workers in hi-vis clothing and a carpark full of utes with flashing yellow lights. Our plan was to survey the local area, both inside and outside the gas fields. We detected increased methane levels across wide areas of the Darling Downs (compared with our local area of Casino, NSW).
A day's drive had produced more data than was available from the CSG industry or the Queensland government after more than a decade of mining.
To share or not to share?
Our results pointed to something unusual in the gas fields. We felt compelled enough to share our findings in a submission to the Department of Climate Change and Energy Efficiency. We also held a seminar in Lismore, NSW, in November 2012 that triggered a rollercoaster ride of media, political and community interest in our research.
Then came the backlash, with criticism that our data had not yet been peer-reviewed and was therefore worthless (despite it being common practice for scientists to present research at conferences and seminars before peer-review). We were attacked by the industry and even by the then federal resources minister, Martin Ferguson.
This was no longer just a matter of science. With billions of dollars invested, thousands of jobs promised, and growing community interest in the topic, we were in the middle of a political and social firestorm. If fugitive emissions turned out to be significant, the industry may not be economically viable in the face of a price on carbon, and the major assumption that natural gas was a clean source of energy could be dismissed.
We spent weeks fielding calls and emails from the media, the community, colleagues and even investment companies seeking advice on divestment (we had none).
The initial media frenzy died down, and last year our first study was peer-reviewed and published. A few weeks ago, we followed this up with our second paper. Each paper produced its own extra flurry of media attention, criticism and counter-criticism.
It has been said that procrastination is the grave in which opportunity is buried. CSG wells have a typical lifetime of 10-20 years. Government reviews have taken 19 months to complete. Our initial experimental results have taken from 6 to 24 months to be peer-reviewed. Will the wells run dry before peer-reviewed science can explain what is coming out from them?
Only time will tell.
ARC Grant Success ( November 2014)
The Centre did well in the 2015 Round of ARC grants with the lead on two Discovery Grants and a DECRA and as Co-CI on an SCU lead LIEF. In addition, centre staff were Co-CI's on two ARC Discovery Grant lead by other institutions
Damien Maher- ARC DECRA
(DE150100581) Resolving the role of aquatic ecosystems in processing and degassing terrestrially fixed carbon $360,000
Bradley Eyre, Kai Schulz – ARC Discovery
Eyre, Schulz, (DP15010209) Dissolution of CaCO3 in sediments in an acidifying ocean, 2015-2017, $350,000.
Christian Sanders, Isaac Santos- ARC Discovery
Sanders, Santos, Will soil carbon burial increase in mangrove wetlands?,$277,187
Bradley Eyre, Christian Sanders – ARC LIEF
Reichelt-Brushett, Burton, Eyre, Johnstone, Sanders, (LE150100007) Metal speciation for complex studies in changing environments, 2015, $170,000
Brendan Kelaher – ARC Discovery
Kelaher, Sulfur cycling in toxic oozes, microbialites and petroleum
Symon Dworjanyn – ARC Discovery
Dworjanyn, Adaptive capacity of marine invertebrates in a climate change ocean
Review in Nature Climate Change (November 2014)
Professor Bradley Eyre is lead author of a review just published in Nature Climate Change. He and his co-authors Andreas Anderson and Tyler Cyronak argue that changes to carbonate dissolution in an acidifying ocean, which have been relatively overlooked, are potentially more important than calcification for the future accretion and survival of coral reef ecosystems.
Falling ocean pH levels means rising threats for coral reefs ( August 2014)
The rate of acidification in coral reef ecosystems is more than three times faster than in the open ocean, say a team of Southern Cross University biogeochemists. Led by recent graduate Dr Tyler Cyronak, the results highlight how coral reefs may be acidifying faster than expected. The University's Centre for Coastal Biogeochemistry Research has published its results, 'Enhanced coral reef acidification driven by regional biogeochemical feedbacks' by Dr Tyler Cyronak, Associate Professor Isaac Santos, Associate Professor Kai Schulz, and Professor Bradley Eyre, in the latest edition of the Geophysical Research Letters journal. Ocean acidification, or the lowering of the ocean pH due to anthropogenic inputs of carbon dioxide, has been well documented in the open ocean. However, this research looked back at studies done in coral reefs since the 1960s and found that the rate of acidification in coral reef ecosystems was more than three faster than in the open ocean.
The researchers developed a model based on previous work at Heron Island in the Great Barrier Reef to determine what the potential causes of this rapid increase in carbon dioxide were. "Our model demonstrated that small changes in the biogeochemistry, or the way coral reefs breathe carbon dioxide, could be to blame," said Dr Cyronak. "During the day coral reefs take up carbon dioxide because photosynthesis is dominant and at night they release carbon dioxide through respiration. Small changes to this natural daily cycle can have a big impact on the average acidity of coral reef waters."
Professor Bradley Eyre, director of the Centre for Coastal Biogeochemistry Research, said the study was significant. "The findings from this study are globally important because coral reefs are under a lot of pressure from climate change," said Professor Eyre. "Ocean acidification in particular is expected to result in reef loss, which may now be worse than previously expected." The biogeochemists argue that increased inputs of organic material and nutrients could be responsible. "More organic material can change the ratio of respiration to photosynthesis," said Associate Professor Kai Schulz. "Coral reefs are generally balanced, but if respiration increases it can have a big effect on the average carbon dioxide levels of a reef." The news is not all bad for coral reefs, with the scientists offering some hope. "I think there are some positives to these findings," said Dr Cyronak. "Generally ocean acidification is thought of as a global problem. However, if the pH of a coral reef can be controlled by reducing runoff and terrestrial inputs there may be solutions to help offset the global problem of ocean acidification, or at least the increased threat, on a regional level."
The work was funded by the Australian Research Council Discovery program.
The 7th International Symposium on Isotopomers (July 2014)
Prof. Bradley Eyre attended The 7th International Symposium on Isotopomers at Tokyo Tech Front, July 2014. He presented a paper titled "First use of cavity ring-down spectrometry for N2O cycling studies in aquatic ecosystems". The presentation generated lots of discussion about the use of laser based spectrometry in aquatic systems and the requirements for verification with traditional IRMS. This presentation should lead to ongoing international collaboration between researchers at the Centre for Coastal Biogeochemistry and Toyko Tech Front. While in Japan Prof. Eyre also visited the University of Toyko and gave a presentation titled "Carbon and nitrogen cycling in permeable carbonate sediments". He also toured the facilities of the Atmosphere and Ocean Research Institute.
Great Barrier Reef Dredging Workshop (May 2014)
Professor Bradley Eyre from the Centre for Coastal Biogeochemistry Research was invited to participate in an expert panel convened in Townsville to develop a synthesis statement on the effects of dredging and offshore spoil disposal on the Great Barrier Reef (GBR). This is a joint initiative between the Great Barrier Reef Marine Park Authority (GBRMPA) and the Australian Institute of Marine Science (AIMS). Dredging and offshore spoil disposal is a highly topical subject area which is receiving attention in the media and public arenas, but with considerable confusion and debate around the scientific evidence and interpretation. The Great Barrier Reef is a national treasure and World Heritage Area, but the recently released draft GBR region strategic assessment report shows that the Reef is in decline, especially in the inshore areas of the southern two thirds of the region. In this context, it is critical that we understand and reduce the cumulative impacts of all pressures on this iconic ecosystem.
AMSA's Third Annual Postgraduate Symposium (May 2014)
PhD students Jackie Gatland, Melissa Gibbes, Philip Riekenberg, and Hanieh Tohidi Farid and honours student Ben Stewart recently presented current and planned research in the SEQ Australian Marine Science Association's Third Annual Postgraduate Symposium, held on Stradbroke Island from 16th – 18th May 2014. Presentations were well received and each participant got valuable feedback in regards to improving their oratory skills. The forum also provided an opportunity for postgraduate students to meet others working in similar fields of research. The workshop also provided a friendly environment for participants to receive a range of advice on topics including presentation styles, effective communication in science, and how to efficiently utilise limited writing time from senior and early career scientists, science journalists, policy scientists, and even a wildlife documentary film-maker.
ARC Discovery Research makes the "2013 Prime Minister's Prizes for Science" presentation (October 2013)
A photo from Prof. Bradley Eyre ARC Discovery research "DP110103638-Unravelling the synergistic effect of ocean acidification and pore water advection on carbonate sediment dissolution: a global sink for CO2?" was used in the "2013 Prime Minister's Prizes for Science" presentation.
"The Australian Research Council (ARC) would like to express its appreciation for your recent contribution of imagery towards the 2013 Prime Minister's Prizes for Science presentation. This year's awards night featured an opening presentation which showcased the variety of research activity occurring with the assistance of ARC funding. We received over one thousand photos, computer modelling graphics and videos after our call out for contributions towards the presentation. Questacon put together the montage, drawing from amongst the diverse imagery received to illustrate a cross-section of discipline areas across universities."
The final presentation displayed on the evening can be viewed on YouTube 2013 Prime Minister's Prizes for Science presentation (Prof. Bradley Eyre features at 1:45)
Ocean Acidification Grant Success (October 2013)
Prof. Bradley Eyre, and his team Dr. Isaac Santos and Dr. Damien Maher, in collaboration with the Australian Institute of Marine Science (AIMS), secured $700,000 of funding from the Great Barrier Reef Foundation's (GBRF) 2013 funding round. The GBRF engages its network to identify, shape, fund and oversee research that will underpin protection and preservation of coral reefs. The funding is for two ocean acidification projects titled " A carbon budget for the Great Barrier Reef" and "Increasing carbonate chemistry data for the Great Barrier Reef".
Ocean acidification is often referred to as the "evil twin" of climate change. Inputs of anthropogenic carbon dioxide to the atmosphere are not only raising the earth's temperature, but uptake of this carbon dioxide is lowering the pH of the oceans. It is generally predicted that ocean acidification will have a devastating impact on marine life that secrete calcium carbonate, including coral in the Great Barrier Reef. As such, ocean acidification is an important focus for the GBRF.
$220,000 of the funding will directly to CCBR researchers who will undertake carbon biogeochemistry measurements in north Queensland rivers, estuaries and mangroves during the wet and dry seasons to identify the role of terrestrial inputs in the carbon biogeochemistry of the GBR lagoon. The research team will also participate in a 21 day cruise aboard the AIMS research vessel the RV Cape Ferguson that will undertake three inner to outer reef transects, including 24 hour sampling at a number of coral reefs. During this cruise CCBR researchers will measure water column CO2 concentrations and stable isotopes, radium isotopes and rates benthic calcium carbonate dissolution. This data will be used to establish a carbon budget for the Great Barrier Reef. CCBR PhD students Tyler Cyronak, Rachel Murray and Judith Rosentreter will also work on the projects and the funding will also support some of Dirk Erler's research.
AMSA 2013 (July 2013)
The Centre had a strong showing at the national Australian Marine Science Association (AMSA) conference in July with nine centre staff, 2 PhD students and 2 honours students attending. Prof. Bradley Eyre, Dr. Kai Schultz, Dr. Joanne Oakes, Dr. Damien Maher, Dr. Sergio Ruiz Halpern and Dr. Perrine Mangion chaired and/or convened three special sessions at the conference that ran over 2 of the 4 days of the conference. The highlight of the conference was CCBR PhD student Tyler Cyronak winning the Peter Holloway Oceanography Award for best oral presentation in the field of oceanography. Tyler received a certificate and $500 for his presentation on "Drivers of pCO2 variability in two contrasting coral reef lagoons". Dr. Sergio Ruiz Halpern also won an iPad in a lucky draw for attendees that used the conference program app instead of the hard copy booklet. So overall a very successful conference for the Centre.
New study finds correlation between CSG wells and radon concentrations in the atmosphere (April 2013)
New research has found a significant link between concentrations of radon gas in coal seam gas (CSG) fields and the number of CSG wells nearby.The work by researchers at Southern Cross University and published recently in the international scientific journal Environmental Science and Technology is the first peer reviewed study in Australia reporting a field experiment specifically designed to look into potential influences of CSG on the chemistry of the atmosphere.
"The study measured radon concentrations at monitoring stations both inside and outside the Kenya/Talinga gas fields north of Tara in southern Queensland," said lead author Douglas Tait, a PhD student with the University's Centre for Coastal Biogeochemistry Research in the School of Environment, Science and Engineering.The study found a significant correlation between the number of CSG wells and the concentration of atmospheric radon measured over a 24 hour period in the surrounding area.
"Radon is an excellent tracer of other gases because it is unreactive and its short half-life prevents any significant build-up in the atmosphere over long time scales. Therefore, the presence of radon in the atmosphere requires a nearby source," said Mr Tait.Radon exists naturally in soils but when the soil structure is changed more radon can be released to the atmosphere.
"Any air in contact with the soil has a higher concentration of radon, making it an excellent tracer for gases released from processes that alter soil structure associated with CSG mining," said co-author Associate Professor Isaac Santos.The research team found radon concentrations approximately three times higher in areas with high densities of CSG wells than those areas with low densities.
"It has been known for years that radon anomalies can be observed during earthquakes. As the soil structure expands or contracts and cracks before and during an earthquake, it creates conduits for the release of soil radon into groundwater and the atmosphere," Professor Santos said."We hypothesise that an analogous process is happening when the soil structure is altered during CSG mining through processes such a drilling, hydraulic fracturing and alteration of the water table."
Dr Damien Maher, another of the study's co-authors, said the findings suggested leakage from not only infrastructure but alternative gas pathways though diffuse soil emissions that had yet to be accounted for."Fixing the infrastructure is relatively easy. Fixing up the changes in the soil structure is much more difficult.""Methane, for instance, is 100 times more powerful than carbon dioxide as a greenhouse gas, and if there are unidentified pathways for methane release this can have significant ramifications for greenhouse gas budgets.
"Natural seeps coincidently occurring near CSG wells in the area could cause similar patterns therefore it is essential to conduct baseline studies before the development of CSG fields."Mr Tait said using radon as a natural tracer offered a novel way for scientific studies to assess the impact of CSG mining on atmospheric chemistry.
The study was described during a public seminar at Southern Cross University in November 2012 and can be downloaded from the School of Environmental Science and Technology website.
The paper, 'Enrichment of radon and carbon dioxide in the open atmosphere of an Australian coal seam gas field' by PhD candidate Douglas Tait, Associate Professor Isaac Santos, Dr Damien Maher, PhD candidate Tyler Cyronak and undergraduate student Rachael Davis, is available at Environmental Science and Technology.
SCU releases first independent methane observations in Australian CSG fields (November 2012)
Preliminary research conducted by Southern Cross University shows methane concentrations collected around the Tara gas fields in Southern Queensland are significantly higher than surrounding areas where there is no coal seam gas infrastructure.
Dr Isaac Santos and Dr Damien Maher from the University's Centre for Coastal Biogeochemistry Research in the School of Environment, Science and Engineering presented their research at a public lecture in Lismore last night (November 14).
Southern Cross University today rejected claims the research was premature or lacking in scientific rigour as claimed by industry group, Australian Petroleum Production & Exploration Association Ltd.The University has world leading expertise in the field of geochemistry, achieving the highest rating of 5 'well above world standard' in this field in the Excellence in Research for Australia 2010 report.Dr Santos said their scientific results were currently being peer reviewed by an international scientific journal."Despite commercial production starting in the mid-1990s, this is the first publicly available data on concentrations of methane in the atmosphere of Australian CSG production areas."We used cutting edge technology to make the measurements. Our work highlights the need for further research to adequately quantify the emissions and their source," Dr Santos said.
Dr Santos and Dr Maher produced the first independent maps of atmospheric methane concentrations in CSG production fields in Australia in an effort to determine whether gases may be leaking from CSG infrastructure.
Methane is the dominant gas in CSG.The scientists surveyed methane concentrations in air and water samples in two areas: the CSG mining fields around Tara in Southern Queensland, and CSG exploration activity in the Richmond River catchment around Lismore in Northern New South Wales.
Typically background concentrations of methane in the atmosphere are approximately 1.8 parts per million But Dr Maher said concentrations of methane were much higher in the atmosphere and waterways around Tara than in the Lismore area.
"In Tara the concentrations are consistently higher than two parts per million and approach seven parts per million in a few locations. This is about three and a half times higher than expected if there was no change in the atmosphere.
"These results are higher than values reported for conventional gas production fields in Siberia, one of the world's largest natural gas production areas," said Dr Maher.
Dr Santos said there were two explanations for the increases: fugitive emissions caused by methane escaping from CSG activities or natural seepage."Any geological area that has gas deposits is going to have natural seeps. At this stage we are unable to separate the contribution of CSG activities from natural seeps because no sampling was done in Tara prior to mining.
"Our research highlights the need for sampling and baseline studies to be established before changing the environment. These baseline studies are the best and perhaps the only way to fully assess change potentially brought about by any industry," said Dr Santos.
Dr Maher said while CSG may have been promoted as a clean energy source, no independent studies had quantified the whole gas field methane output from Australian CSG fields.
"This is clearly the next step. Methane is a powerful greenhouse gas, at least 25 times more powerful than carbon dioxide. Given fugitive emissions are not directly measured at this stage, follow-up quantitative research could potentially change carbon tax estimates for the CSG industry."
Currently CSG fugitive emissions estimates have not been assessed by independent organisations.
"Typically in Australia we assume a figure of 0.12 per cent leakage at the wellhead of total gas production but we don't have any data backing up that assumption. Some studies overseas indicate that lifecycle fugitive emissions may be up to eight per cent," Dr Maher said.
"While the figure of eight per cent has come under fire by some academics and the CSG industry, the lack of baseline data makes it extremely difficult to put an exact number on mining-specific emissions after mining has commenced. We don't know what fugitive emissions are coming from Australian CSG mining.
"We need to do site specific experiments to quantify those emissions for every gas field."
Dr Santos said industry currently had a 'fire detector' approach to methane.
"A 'fire detector' approach to methane regulation means methane is treated as an explosive hazard only. Concentrations have to reach explosive levels to be considered a problem.
"Our results indicate that we should adopt more of a 'smoke detector' approach in which methane is treated as a powerful greenhouse gas. By using this approach minor leaks over a large area should be accounted for."
SCU's Centre for Coastal Biogeochemistry ResearchThe research by Dr Santos and Dr Maher builds on Southern Cross University's strengths in the field of geochemistry. In 2010, SCU was given the highest rank of 5 'well above world standard' in the Excellence in Research for Australia (ERA) 2010 report. SCU's ERA rank in the field of geochemistry is matched by only other two universities in Australia.
ARC Future Fellowship (October 2012)
Dr Kai Schulz, a research scientist at the Leibniz Institute of Marine Sciences at the University of Kiel in Germany, received a highly prestigious ARC Future Fellowship. The Future Fellowships, announced by the Minister for Science and Research, Senator Chris Evans, provide research opportunities for some of the world's best mid-career researchers. Dr Schulz received $714,528 which is the largest ARC Grant ever awarded to the University. His project, titled 'Future carbon cycling - predicting and understanding coccolithophorid calcification in a changing ocean', will investigate the impact of increased carbon dioxide levels in the ocean and the subsequent impact on coccolithophores - one-celled marine plants that live in large numbers throughout the upper layers of the ocean. Less than 4% of Future Fellowship applications submitted in the last round were awarded to Foreign Nationals. The outstanding quality of researchers that the Centre is able to attract to Southern Cross University from overseas highlights its international standing. Kia's Future Fellowship is part of the Centre's continued success, with ARC Fellowships awarded in 2008, 2010 and 2011, including an ARC DECRA last year.
ASLO 2012 (July 2012)
The CCBR had a strong showing at the 2012 Association for Limnology and Oceanography (ASLO) Aquatic Sciences Meeting in Otsu, Japan. Overall there were five presentations in three separate sessions given by CCBR researchers, post-docs, and students, with two sessions co-chaired by CCBR. Dr Isaac Santos co-chaired a session on the interaction between groundwater and surface water in coastal ecosystems and also gave a talk on a newly developed method that concomitantly measures CO2 and radon concentrations, a technique that will allow researchers to trace the influence of groundwater on CO2 concentrations in coastal ecosystems. PhD candidate Tyler Cyronak gave a talk in the same session on pore water advection and the release of alkalinity to coral reef ecosystems, a potentially important buffer against rising pCO2 in the ocean.
Dr Joanne Oakes co-chaired a session that addressed the use of stable isotopes in aquatic ecosystems and presented her work on the fate of carbon using stable isotope tracers in the sediments of an Australian estuary. Dr Sergio Ruiz-Halpern and honours candidate Lindsay Golsby-Smith gave presentations in a session that focused on the transport of organic matter from terrestrial ecosystems to the ocean. Dr Ruiz-Halpern gave a poster presentation on locally collected data from the Richmond River, linking flood events and enhanced carbon export from estuaries. Lindsay gave her talk on another local estuary, the Caboolture River, and showed how different carbon sources influence the deoxygenation of the water column during rainy and dry periods. The meeting was a big success for CCBR, which allowed the centre to interact on an international level. However, it wasn't all work in Japan as there were many interesting places to explore and much sushi and sake to be tasted!
More information about the conference can be found at this website: aslo.org/meetings/japan2012
Estuaries play key role in carbon capture (March 2012)
Australian estuaries may be more important than previously thought in capturing and storing carbon from the atmosphere, according to new research from Southern Cross University's Centre for Coastal Biogeochemistry Research.Dr Damien Maher and Centre director Professor Bradley Eyre published a paper in Global Biogeochemical Cycles that measured carbon flows and CO2 fluxes in three temperate Australian estuaries."Knowing carbon fluxes from these ecosystems is important in understanding what will happen in the future as far as atmospheric CO2 concentrations are concerned," Dr Maher said."Global warming and other climate change issues like ocean acidification make carbon cycling an important topic to study."In order to get a range of different conditions, the study examined carbon fluxes in three estuaries along the mid New South Wales coast. Hastings River near Port Macquarie was the northern most estuary, followed by Camden Haven south of Port Macquarie. The third estuary was Wallis Lake, 156km north of Newcastle. "These estuaries were selected because they represent a natural gradient in estuarine types in terms of geomorphology, river flow, and habitat coverage," Dr Maher said. "This enabled us to determine how these factors control the carbon cycle at the estuary scale."The results from the study point to these estuaries being different in how they process carbon when compared to similar estuaries found throughout the world. "In terms of carbon cycling estuaries are normally heterotrophic, which means that they release CO2 to the atmosphere," Dr Maher said."These three estuaries are unique in that they are autotrophic, meaning they absorb CO2 from the atmosphere. We believe this is driven by the high primary production associated with the extensive seagrass beds found in these ecosystems."Dr Maher said the study showed that coastal Australian ecosystems may be helping to absorb CO2 put into the atmosphere through human activities. The study also showed seasonal differences in CO2 absorption, with more CO2 being absorbed in the summer then during other seasons."These estuaries act naturally to absorb CO2 from the atmosphere on a yearly basis," he said.Dr Maher said the study also looked at whether the carbon was released back into the oceans or buried, keeping it out of the atmosphere."The estuaries showed differences in their ability to bury the carbon, with the Wallis Lake and Camden Haven burying a larger percentage of the carbon as compared to Hastings River," Dr Maher said. "This is probably because of the different residence times of water in the estuaries. Basically, the longer the water spends in the estuary the more of a chance it has to be buried."Professor Eyre said the study demonstrated the important role of coastal estuaries."This paper illustrates the need to study more of these ecosystems which will help to gain an understanding of how these ecosystems affect global carbon cycling," Professor Eyre said
Updated: 02 November 2015