WAMSI congratulates CEO Patrick Seares on new role
Scientists test new sediment sensor that mimics coral reef
Scientists have tested a breakthrough in sensing sediment risks to reefs that uses bundles of fibre optic sensors and hundreds of countersunk holes to mimic coral.
Sedimentation is considered one of the most widespread causes of stress on coral reefs, and researchers are working to understand the patterns of suspension and resuspension caused by wind, wave, catchment run-off and dredging related activity to better inform about the environmental risks.
The newly designed sediment sensor, has 15 separate fibre optic bundles that produce three separate measurements, each an average of five bundles, and the three-millimetre-thick plate is perforated with hundreds of countersunk apertures, the size and spacing designed to mimic coral. The shape allows sediment to be naturally resuspended by wave action in a similar way to that which would occur on a coral.
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| (Whinney J, Jones R, Duckworth A, Ridd P (Dec 2016) Continuous in situ monitoring of sediment deposition in shallow benthic environments Coral Reefs DOI 10.1007/s00338-016-1536-7) |
The sensor was tested as part of a Western Australian Marine Science Institution Dredging Science Node project against different conditions in the Australian Institute of Marine Science (AIMS) National Sea Simulator (SeaSim) laboratory and in the highly turbid inshore reef community of the Great Barrier Reef (GBR).
Researchers from James Cook University and AIMS were able to show previously undescribed patterns of sediment deposits on reef in the turbid coastal central GBR over periods of a few hours rather than averages over days or weeks, giving a greater understanding of the behaviour of one of the key pollutants on coral reefs.
“The in-situ deployment covered a range of physical conditions with peaks in sedimentation occurring after peaks in turbidity and waves when material began to settle out of suspension,” lead researcher, Dr James Whinney said. “The daily average sediment deposition rate was 19 ± 15 mg cm-2 d-1 over the deployment.”
“However, while Sedpods offer a low cost alternative to measure rates of sedimentation, they do not self clean and need to be changed over each day which involves the logistical and financial costs of daily boating and diving to collect and redeploy.
“The next stage is to carry out testing further offshore as well as during dredging campaigns to define the range of sediments rates corals are likely to experience,” ” Dr Whinney said.
Earlier versions of the deposition sensor used in this study have been deployed in Japan, Papua New Guinea and the inshore central GBR (Thomas et al. 2003a; Thomas and Ridd 2005).
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Whinney J, Jones R, Duckworth A, Ridd P (Dec 2016) Continuous in situ monitoring of sediment deposition in shallow benthic environments Coral Reefs DOI 10.1007/s00338-016-1536-7
The WAMSI Dredging Science Node is made possible through $9.5 million invested by Woodside, Chevron and BHP as environmental offsets. A further $9.5 million has been co-invested by the WAMSI Joint Venture partners, adding significantly more value to this initial industry investment. The node is also supported through critical data provided by Chevron, Woodside and Rio Tinto Iron Ore.
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Can Environmental Windows be effective in managing effects of dredging?
An examination of whether dredging operations suspended during generic windows of environmental sensitivity could reduce the impacts on marine life has found the marine invertebrates, seagrasses and macroalgae too diverse to be covered by a one-size-fits-all approach.
An international team of researchers were involved in the review for the Western Australian Marine Science Institutions’ Dredging Science Node. Lead researcher, Dr Matthew Fraser from The University of Western Australia’s (UWA) Oceans Institute, said the results helped to clarify whether there was enough scientific evidence to base the timing of dredging operations outside a set of generic Environmental Windows.
“The project was basically tasked with looking at whether avoiding or reducing dredging during sensitive life history periods may help to minimise dredging impacts, and we used Western Australia as a case study,” Dr Fraser said. “The problem is that we don’t know enough about reproduction, planktonic dispersal and recruitment for many benthic marine organisms in Western Australia.”
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| Western Australia is a hotspot for macroalgal diversity. Slow growing macroalgae are considered as having higher vulnerabilities to dredging impacts. (Matthew Fraser) | Chromodoris westraliensis (Nudibranch) at Cottesloe Reef. (Matthew Fraser) |
“Combine this knowledge gap with species-specific timing of these events suggests a generic environmental window does not protect all species,” co-author UWA’s Professor Gary Kendrick said.
“What this means is that selection and management of Environmental Windows are best considered on a location by location basis with priority given to ecologically and economically important species that we know enough about,” Dr Fraser said.
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| Western Australian seagrasses form important habitat that supports diverse assemblages of marine animals. Slow growing seagrasses such as Posidonia australis (above) are at higher risk from dredging impacts than faster growing seagrasses. (Matthew Fraser) |
Fraser MW, Short J, Kendrick GA, McLean D, Keesing J et al. Effects of dredging on critical ecological processes for marineinvertebrates, seagrasses and macroalgae, and the potential for management with environmental windows using Western Australia as a case study Ecological Indicators http://dx.doi.org/10.1016/j.ecolind.2017.03.026
The WAMSI Dredging Science Node is made possible through $9.5 million invested by Woodside, Chevron and BHP as environmental offsets. A further $9.5 million has been co-invested by the WAMSI Joint Venture partners, adding significantly more value to this initial industry investment. The node is also supported through critical data provided by Chevron, Woodside and Rio Tinto Iron Ore.
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Everything you ever wanted to know about how dredging impacts fish!
Early stages of fish life, such as eggs and larvae, are most likely to suffer lethal impacts from dredging-related stress, while adult fish that migrate from fresh water to the sea to spawn (catadromous fishes) are more likely to change behaviour, according to new research.
A team led by University of Queensland postdoctoral researcher Amelia Wenger examined hundreds of studies to determine how dredging related stressors, including suspended sediment, contaminated sediment, hydraulic entrainment (organisms that get sucked up with the sediment) and underwater noise, directly influence the size of the effect and response in fish across all aquatic ecosystems and all life history stages.
The Western Australian Marine Science Institution Dredging Science Node project, found that across all dredging-related stressors, studies that reported fish mortality had significantly higher effect sizes than those that describe physiological responses, though indicators of dredge impacts should aim to detect effects before excessive mortality occurs.
“Both suspended sediment concentration and duration of exposure greatly influenced the type of fish response we observed, with both higher concentrations and longer exposure associated with fish mortality,” Dr Wenger said.
(Figure 1. A schematic diagram of categories of potential effects of dredging on fish. – Wenger AS, Harvey E, Wilson S, et al. A critical analysis of the direct effects of dredging on fish. Fish Fish. 2017;00:1–19. https://doi.org/10.1111/faf.12218)
“It’s well known that some fish avoid turbid waters but moving to a less ideal environment can affect their chances of survival. Increasing exposure to suspended sediment makes it harder for fish to find their food, elevates their stress levels, and causes damage to fish gills affecting growth, development and swimming ability.
“By analysing several studies, we were able to see clear evidence that fish from all aquatic ecosystems were sensitive to turbidity,” Dr Wenger said.
Studies examining the effects of contaminated sediment also had significantly higher effect sizes than studies on clean sediment alone or noise, suggesting combined dredging stressors produce an effect greater than the sum of their individual effects.
“The review highlights the need for in-situ studies on the effects of dredging on fish which consider the interactive effects of multiple dredge stressors and their impact on sensitive species of ecological and fisheries value,” Dr Wenger said.
The findings are expected to improve the management of dredging projects to ultimately minimise their impacts on fish.
Wenger AS, Harvey E, Wilson S, et al. A critical analysis of the direct effects of dredging on fish. Fish Fish. 2017;00:1–19. https://doi.org/10.1111/faf.12218
The WAMSI Dredging Science Node is made possible through $9.5 million invested by Woodside, Chevron and BHP as environmental offsets. A further $9.5 million has been co-invested by the WAMSI Joint Venture partners, adding significantly more value to this initial industry investment. The node is also supported through critical data provided by Chevron, Woodside and Rio Tinto Iron Ore.
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The underwater world of the Kimberley
Renowned for its extreme tides, the waters of the Kimberley host seagrass and microalgae that thrive against the odds. A three-year study combined science and traditional knowledge to uncover some of the secrets of these fascinating species, and the herbivors that feed on them.
Click here to read the full article by Mat Vanderklift and Gary Kendrick in Landscope
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Results released on seagrass responses to dredging in northwest Australia
Three new reports have been released on the primary producer responses to dredging.
There is almost no knowledge of how seagrass primary producers in the northwest of Australia will respond to the environmental changes produced by dredging. Consequently, it is difficult to predict and then manage the impacts of dredging on these critical habitats with an acceptable level of certainty.
Research within the Western Australian Marine Science Institution (WAMSI) Dredging Science Node focuses on two of the most significant stresses produced by dredging: the reduction in light availability to plants; and the smothering of seagrass and algae as suspended sediments settle.
Project leader Kathryn McMahon from Edith Cowan University and team members from The University Australia, Department of Parks and Wildlife WA and The University of Adelaide have looked at three key areas:
- Seagrasses of the northwest of Western Australia: biogeography and considerations for dredging-related research;
- The current state of knowledge regarding the effects of dredging-related ‘pressure’ on seagrasses using information compiled from unpublished industry data, as well as published reports, articles and books; and
- Genetic variability within seagrass of the northwest of Western Australia
The first project identified five dredging related stressors that are likely to directly impact seagrass habitat and prioritised the top three in the following list that are of most interest for impact prediction and management of dredging events:
- reduced benthic light quantity;
- burial by sediment;
- sediment anoxia and increased hydrogen sulfide production;
- altered benthic light quality (i.e. spectral characteristics); and
- increased suspended sediment
It identified knowledge gaps in three key areas:
- How dredging affects environmental conditions that are likely to impact seagrass.
- Thresholds for dredging-related stressor beyond which seagrasses will be affected; and
- Monitoring during dredging campaigns.
The second project identified the seagrass species Halophila ovalis, Halodule uninervis and Cymodocea serrulata, as the focus of subsequent research into thresholds and indicators of response to dredging-related pressures.
The third study is the first of its kind to examine the patterns of genetic diversity in seagrasses in the Pilbara region which strongly influences their ability to adapt to, resist or recover from these pressures.
This study identified that:
- Most meadows examined had relatively high clonal diversity (i.e. many unique individuals in the meadow), so both sexual reproduction and vegetative growth are important for maintaining these populations; and
- There was a reasonably high level of migration of genes over distances of 2−5km, but lower levels over greater distances. The study also showed that not all seagrass meadows and species in NW Australia have a similar level of genetic diversity. This information should be incorporated into management decisions as the level of genetic diversity has implications for the ability of populations to resist and recover from disturbance.
The WAMSI Dredging Science Node is one of the largest single issue research programs in Australia meeting the needs of the State Government and industry to improve their understanding of how key primary producers are affected by dredging-related pressures.
The full reports can be found on the WAMSI DSN Primary Producer project page
The WAMSI Dredging Science Node is made possible through $9.5 million invested by Woodside, Chevron and BHP as environmental offsets. A further $9.5 million has been co-invested by the WAMSI Joint Venture partners, adding significantly more value to this initial industry investment. The node is also supported through critical data provided by Chevron, Woodside and Rio Tinto Iron Ore.
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Scientists learn more about Kimberley dolphin populations
Australian snubfin dolphins in the Kimberley appear to form at least three genetic populations that require careful management, according to new research.
The snubfin and humpback dolphin are unique to shallow, coastal waters of northern Australia and southern New Guinea. Both species are found off the coast of the Kimberley, though little is known of their numbers, key habitats and movements.
Over the past three years, a Western Australian Marine Science Institution, Kimberley Marine Research Program project has been working to answer some of these questions, by surveying local populations, collecting genetic samples, and developing new tools to help monitor these elusive species.
The research team from Murdoch and Curtin universities found that both snubfin and humpback dolphins occurred at all sites surveyed, although in varying numbers.
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| The team conducted different fieldwork in a number of locations across the Kimberley, and presented data on dolphin relative abundance (R), population genetic structure (G) and/or passive acoustic monitoring (A). |
Humpback dolphins were observed in similarly low numbers at most sites, while snubfin dolphins appeared to occur in greater numbers at a few discrete locations.
Small local populations of snubfins were apparent at Cone Bay and the Prince Regent River; however, previous research showed the Dampier Peninsula sites of Roebuck and Cygnet Bay to support greater numbers, highlighting these sites as key habitats for snubfin dolphins.
Genetic analyses, led by Murdoch University’s Dr. Alex Brown, showed that not all snubfin dolphins in the Kimberley could be considered the same population.
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| Using the biopsy darting system to collect dolphin genetic samples in Cone Bay, with assistance from Dambimangari Ranger Edmund Jungine. Photo: Alex Brown. |
Evidence suggests that there is very limited movement of snubfin dolphins between Roebuck Bay and King Sound, and that animals sampled further north and east may represent a third genetic population.
Analyses of humpback dolphin genetic samples revealed a lack of gene flow between animals sampled in the Kimberley and the Pilbara regions.
“It’s important for decision makers to recognise this genetic structure in order to minimise any threats to small, isolated, local populations,” Dr. Brown said. “For both species, more genetic samples are required in the north/east of the Kimberley to better understand the connectivity of local populations.”
“However, monitoring these species can be tricky, particularly in areas where they are unfamiliar with and shy of boats,” Dr Brown said.
Several scientists in the dolphin project team have been working on this problem by exploring the use of passive acoustic monitoring to detect and monitor dolphin presence and use of particular areas.
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| Acoustic data loggers, developed by Curtin University, were deployed for up to three weeks at Cygnet and Roebuck Bay, recording dolphin vocalisations and allowing the Curtin researchers to characterise the natural soundscape of the two areas. Photo: Alex Brown. |
This new technology was able to pick up the whistles and clicks that dolphins make as they travel, forage and socialise, and the research team uncovered several new whistle types to add the species’ repertoire. However, more work is required before the two species can be efficiently distinguished and the number of animals present can be identified.
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| An audiogram of echolocation clicks, pulsed ‘buzz’ sounds, and tonal whistles recorded in the presence of snubfin dolphins. |
A key part of this research was collaborating with local stakeholders. The research team collected data alongside Yawuru, Bardi-Jawi, Dambimangari and Balanggarra Traditional Owners, as well as regional Parks and Wildlife staff, generating valuable training opportunities.
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| Murdoch University researchers work alongside Balanggarra Rangers Wesley Alberts and Wayne Moore to collect individual identification photos of humpback dolphins in the Cambridge Gulf. Photo: Alex Brown. |
The data collected, along with the improved local collaboration, will help with future research and monitoring in the region.
The full research findings presentation is available on the WAMSI dolphin project webpage.
The $30 million Kimberley Marine Research Program is funded through major investment supported by $12 million from the Western Australian government’s Kimberley Science and Conservation Strategy co-invested by the WAMSI partners and supported by the Traditional Owners of the Kimberley.
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Saltwater crocodile populations continue to grow in Prince Regent River
Population growth rates of estuarine (saltwater) crocodiles in the West Kimberley region of Western Australia do not appear to be slowing, with steady increases in total numbers observed, along with a more gradual increase in the number of large crocodiles (> 3m ~ 10 ft).
There has been a 259% increase in non-hatchling crocodile numbers since the last survey of the Prince Regent system in 1986, some 30 years ago.
The presence of large creek systems adjacent to the main river are allowing sub-adult crocodiles (1.5 – 2m ~ 5-7 ft) to remain near the river of their birth, rather than having to undergo migrations or increased rates of mortality from competition by larger crocodiles. This results in sub-adults making up ~ 20% of the resident crocodile population, compared to 8% in the Adelaide River in the NT, where the crocodile population is considered stable.
Lead researcher for the Western Australian Marine Science Institution’s (WAMSI) saltwater crocodile project, Dr Andy Halford (Parks and Wildlife), when comparing the crocodile recovery in the Kimberley with that in the Northern Territory (NT) said: “Continuous research and surveys in the Northern Territory since the 1980s showed the NT population was considered to have recovered from hunting (outlawed in 1971) by 2000 and we would expect a similar pattern in WA.”
However, comparison of results with established crocodile population patterns in the NT’s Adelaide River indicates that the West Kimberley crocodile populations are still recovering from the large-scale hunting that prevailed pre 1970.
“We counted a total of 5 crocodiles >3m in length in comparison with 63 counted in the Adelaide River and we estimated a biomass density of 91.4 kg/km compared with 274.02 kg/km in the Adelaide River,” Dr Halford said.
“These findings confirm the likelihood of increasing interactions between crocodiles and humans.
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“The interesting difference is that, while a lot of crocodiles between (1.5-2m ~ 5-7 ft) long are usually eaten or killed by larger crocodiles or forced to move into new territory, the percentage of young adults entering the West Kimberley system is up to three times that seen in the NT,” he explained.
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“What this study has told us is that while crocodile populations are healthy and recovering well, because of the unique environment and the considerably smaller amount of appropriate nesting habitats in the West Kimberley, exactly how the future recovery will pan out is unclear.
“What we do know is that there will be increased interactions between crocodiles and humans, and in order to provide advice on managing this, we need to learn more about the amount of available nesting habitat throughout the region, as well as updating our surveys of other river systems,” Dr Halford said.
Dr Halford’s full presentation is available on the WAMSI saltwater crocodile project webpage
The $30 million Kimberley Marine Research Program is funded through major investment supported by $12 million from the Western Australian government’s Kimberley Science and Conservation Strategy co-invested by the WAMSI partners and supported by the Traditional Owners of the Kimberley.
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