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Thirsty mangroves caused unprecedented dieback

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Dr Norm Duke inspecting the affected area
A James Cook University scientist has discovered why there was an unprecedented dieback of mangroves in the Gulf of Carpentaria in early 2016 – the plants died of thirst.

Dr Norman Duke, leader of JCU’s Mangrove Research hub, headed an investigation into the massive mangrove dieback. The findings were published in the Journal of Marine and Freshwater Research today (Tuesday 14 March)

The scientists used aerial observations and satellite mapping data of the area dating back to 1972, combined with weather and climate records.

Dr Duke said they found three factors came together to produce the unprecedented dieback of 7400 hectares of mangroves, which stretched for 1000 kilometres along the Gulf coast.

“From 2011 the coastline had experienced below-average rainfalls, and the 2015/16 drought was particularly severe. Secondly the temperatures in the area were at record levels and thirdly some mangroves were left high and dry as the sea level dropped about 20cm during a particularly strong El Nino.”

Dr Duke says this was enough to produce what scientists regard as the largest recorded incident of its kind, and the worst instance of likely climate-related dieback of mangroves ever reported.

“Essentially, they died of thirst,” he said.

Dr Duke said scientists now know that mangroves, like coral reefs, are vulnerable to changes in climate and extreme weather events.

He said the mangroves of Australia’s Gulf region have experienced relatively little anthropogenic impact and are considered the least altered mangrove ecosystems in the world.

“So the relative dominance of climate influences in this region is of critical interest to world observers of environmental responses to climate change.”

Dr Duke said the area is sparsely populated, with passing fisherman and scientists conducting unrelated work the first to notice the dieback.

“It took 4-5 months to come to the attention of mangrove tidal wetland specialists and managers. Our response to this event further involves training and equipping Indigenous rangers and local community volunteers to build local partnerships for rigorous and repeated shoreline assessments.”

“We cannot afford to be caught out like this again!” said Dr Duke. “The Gulf dieback has been a wakeup call for action on shoreline monitoring. We urgently need a national shoreline monitoring program commensurate with our global standing. We have the specialists, we have the resources, and we know there is interest and concern amongst the Australian public.”

To progress this further, Australia’s top specialists and managers will review the situation at a dedicated workshop during next week’s Australian Mangrove and Saltmarsh Network annual conference in Hobart (http://www.utas.edu.au/land-food/geography-and-spatial-sciences/amsn-conference-2017), hosted by the University of Tasmania and CSIRO.

“The aim of Australia’s specialist network is to apply intelligent, innovative and considered responses, as fully expected by the public, to improve and disseminate informed understandings of the changes taking place in high value natural resources such as Australia’s coastal tidal wetland habitats,” Dr Duke said. 

Contact:

Dr Norm Duke

E: Norman.duke@jcu.edu.au

M: 0419 673 366

Link to pics and video: http://bit.ly/29xN67a

(Copy and paste into your browser address bar).

The Journal of Marine and Freshwater Research paper is available on request from Dr Duke.

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Guide to Stream Invertebrates

TropWATER has recently produced a guide to stream invertebrates that is freely available for download from the web. It is based on a study of Wet Tropics streams, but should be usable with all perennial coastal streams in tropical Queensland. It will be useful for community groups, schools and environmental consultants. It is available at:

https://research.jcu.edu.au/tropwater/publications/1709Guidetotheriffleinvertebrates.pdf

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Animals in Motion 2017 at JCU

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Mark Hamman presenting some resent movement research
About 40 people gathered at JCU in mid-February to participate in ‘Animals in Motion’, a 2-day symposium about wildlife telemetry research and collaboration, supported jointly by TropWATER, CTBCC and CSTFA.

Presenters outlined their work with diverse terrestrial and marine species, including crocodiles, cassowaries, sharks, racoons, northern bettongs, flying foxes, reef fish, geckos, tube-nosed bats, mantas and marine turtles. Their purposes in studying animal movement were also very diverse, from reducing human-wildlife conflict to understanding the risks of epidemic disease transmission.

New perspectives on different tracking methods were introduced, illustrated by hard-won experience in challenging research situations, and elaborated during a comprehensive panel discussion. A hands-on workshop on analysing and visualising movement data was a highlight for R-users.

Speakers also addressed the need for collaboration in tracking studies and shared successful strategies for starting collaborative projects with diverse stakeholders. Members of the audience contributed additional insights during a wide-ranging discussion about collaboration challenges.

For additional pictures from the symposium see: https://twitter.com/JCU_AniMotion

To join the ‘Animals in Motion’ mailing list for notification about proposed follow-up workshops please email: julia.hazel@jcu.edu.au

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Expanding the information base for coastal management

Graphic abstract by Claudia Trave
Graphic abstract by Claudia Trave
An invited feature article in the journal Wetlands Ecology and Management illustrates the lack of quantitative information on the ecological function of Australia's saltmarsh communities in different locations, scales and contexts. Decision makers may therefore have insufficient evidence to compare the relative costs and benefits of coastal development or ecosystem protection. The synopsis of Australian saltmarsh information was prepared by TropWATER scientists with funding from and in collaboration with the Marine Biodiversity Hub as part of the project 'Underpinning the repair and conservation of Australia's threatened coastal-marine habitats'. It identifies knowledge gaps and principles to guide research, and a need to gather evidence aligned to policy priorities and markets for ecosystem service payments, such as blue carbon or nutrient trading schemes. Ongoing work in this project is looking at how saltmarsh supports fisheries productivity in Queensland, NSW and Tasmania. This will help to support coastal management decisions and raise awareness of the value of Australia's coastal seascapes. See more about saltmarsh protection and repair.

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Measuring the impact of feral pigs on tropical wetland floodplains

Wetland with pig and cattle exclusion fencing, Archer River catchment
Wetland with pig and cattle exclusion fencing, Archer River catchment
Feral livestock, particularly pigs, as well as cattle, contribute widespread damage to the landscape, displace native species and threaten agricultural production in northern Australia. Millions of dollars have been and continue to be invested in feral animal management programs. However, these programs are rarely linked to quantified long term outcomes for environmental and cultural asset protection. The damage caused by feral animals is most obvious in wetlands, which hold incredible biodiversity and cultural values. In just a few days, feral pigs can destroy large areas of aquatic vegetation, and in doing so, dramatically impact on water quality and local aquatic species (e.g. freshwater turtles). The solution is to fence entire wetlands, however, explicit data supporting this management intervention is not available.

In November 2016, TropWATER’s Dr Nathan Waltham and Jason Schaffer, joined a research team from CSIRO (Project Lead), and Queensland Government, to examine the extent of damage created by feral animals to aquatic ecosystems, and methods to best control them. This project is funded through National Environmental Science Program (NESP) Northern Australia Environmental Resources Hub.   

Adjacent unfenced wetland where pig have access, Archer River catchment
Adjacent unfenced wetland where pig have access, Archer River catchment

Dr Waltham said that “Our project study area is the Archer River catchment, Cape York, though the consequences of feral animal impact on tropical wetlands is a problem across northern Australia.”  “Already the first two rounds of field work have been completed, and we are currently analysing the data”. 

The project team also includes Indigenous land and sea rangers, and the local community. “Working with the community and rangers, we have been able to transfer knowledge about the landscape”.

“Understanding more about the indigenous history of the region, has allowed me to more fully appreciate the value of wetlands in the area, but also how pigs and other feral animals have interfered in these values”, said Dr Waltham.

For more information, contact Dr Nathan Waltham (Nathan.waltham@jcu.edu.au)

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Tour of US inspires Australian coastal restoration

TropWATER’s Dr Ian McLeod joined restoration experts from The Nature Conservancy on a tour of US coastal restoration sites in December 2016. The team visited restoration projects in Texas, Louisiana, New Jersey and Virginia and met with scientists, Government workers and practitioners to share knowledge and discuss collaborative opportunities.  

Ian (second from left) with TNC staff from China, the US and Australia. They are standing on a recently-deployed 'oyster castle' structure. Oysters will grow on this structure and help protect the shoreline from erosion

Highlights included learning about the logistics of a US$100,000,000 oyster restoration project in Harris Creek (Chesapeake Bay), seeing the effectiveness of oyster reef restoration for shoreline protection and attending the Restore America’s Estuaries (RAE) Summit in New Orleans. Dr McLeod and the team also met with the President and Board of Restore America’s Estuaries to discuss greater collaboration between the US and Australia.

“It was really inspirational to see that large-scale restoration of important coastal habitats such as saltmarshes, seagrasses and shellfish is possible. Coastal restoration is a multi-billion dollar industry in the US and much of the inspiration for this restoration is coastal protection and job creation for coastal communities", said Dr McLeod. 

 "I've come back with my mind buzzing with new ideas about how to answer important research questions to empower the scaling-up of coastal restoration in Australia", said Dr McLeod.

Funding for the trip was provided through a James Cook University Rising Stars Award. Dr McLeod is the Principal Investigator of a National Environmental Science Programme-funded coastal restoration project led in Partnership with The Nature Conservancy, Australia. Read more about the project here.

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Oysters growth a year after 'oyster castle' deployment in Virginia
 

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