The rise and fall of seagrasses in the Pilbara

By Jo Myers & Mat Vanderklift (CSIRO)

Dredging associated with large port developments can reduce the light required for seagrass photosynthesis and smother their growth. This can be caused by large plumes of sediment which some seagrasses are very sensitive to (along with natural disturbances such as cyclones), while others have the capacity to cope, or to recover quickly.

Relatively little is known about normal patterns in seagrass composition, abundance and distribution in north-western Australia, including whether they have natural cycles in abundance across seasons. Knowing more about seagrass ecosystems is important for designing or interpreting studies that aim to detect potential dredging-related impacts on seagrass, and when making predictions about whether they can recover from disturbances, and if so, how quickly.

Results from research on seagrasses in the Pilbara, funded by the Western Australian Marine Science Institution (WAMSI) Dredging Science Node, has found that the most common species of seagrass in the region have similar life histories (they tend to be relatively good at colonising new space) but tend to have different patterns of spatial and temporal variation in abundance and reproduction. This creates challenges for people who assess environmental approvals, because it means that the temporal dynamics of seagrasses in the Pilbara might be less predictable than those of seagrasses in adjacent regions (the Kimberley and the Gascoyne). Monitoring programs that are established to detect potential changes in abundance will need to ensure that their design accommodates this variability.

WAMSI Scientist monitoring recovery of seagrass from cleared experimental plots
(Photo: Paul Lavery, ECU)

Another key finding from the research, led by CSIRO and Edith Cowan University, was the main mechanisms by which seagrasses recover after disturbance. In tropical regions, such as northwest Australia, small-leaved species of seagrasses are often characterised by natural patterns of loss and recovery that can span months or years. Vegetative growth (extension of rhizomes by remaining plants) accounts for most recovery, though recovery from seeds has also been recorded. Understanding which of these mechanisms dominates at a particular location is important for predicting the potential for seagrasses to recover after loss or reduction in abundance.

A field experiment undertaken at Thevenard Island during 2014 and 2015 involved clearing areas of seagrass and the placement of partial and full barriers around the cleared areas — these barriers were designed to disentangle vegetative growth from regeneration from seeds. The experiment showed that the primary mechanism for recovery of cleared areas was vegetative growth.

Halophila ovalis seagrass. Tropical seagrasses are important habitats for marine turtles including the loggerhead turtle that feeds on fauna associated with seagrass beds such as ascidians, clams, mussels and other invertebrates (Photo: Mat Vanderklift, CSIRO)

The main seagrass species at the study site was Halophila ovalis, which is also the most widespread species in the Pilbara. One key implication of this finding is that recovery from disturbances that remove seagrass from relatively small areas should occur within months, provided that sufficient meadow remains for rhizomes to colonise from. When seagrass loss occurs over a larger area, recovery might rely more heavily on immigration of plant fragments or seeds from distant sites, which will take much longer.

LINKS:

For further information about WAMSI and the Dredge Science Node, including access to the final reports (Theme 5.3 and Theme 5.4) see wamsi.org.au/dredging-science-node

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.

Category:

Dredging Science

Kimberley dolphin project covers new ground

By Dr Alex Brown

WAMSI-supported researchers have been in the Cambridge Gulf and Prince Regent River working with local rangers to find out more about the distribution, abundance and population structure of the Australian snubfin (Orcaella heinsohni) and humpback (Sousa sahulensis) dolphins.

The Australian snubfin and humpback dolphins are found in coastal and estuarine waters across northern Australia and the aim of the Kimberley Marine Research Program’s dolphin project is to contribute data towards assessment of their conservation status.

The first trip saw researchers Dr. Alex Brown (Murdoch University Cetacean Research Unit) and Dr. Simon Allen collaborate with the Balanggarra Rangers to perform a two-week survey in the Cambridge Gulf and adjacent coastal waters.

The aims were to:

  1. collect data on the relative abundance and genetic connectivity of coastal dolphins; and
  2. provide rangers with camera equipment and training in dolphin survey techniques – part of a project funded by the Commonwealth Government and WWF-Australia to support the capacity of Indigenous rangers across northern Australia to conduct dolphin research and monitoring.

Following a day of training presentations and exercises, the research team established a base camp at Lacrosse Island, 85 km north of Wyndham, providing good access to the remote waters at the top of the Cambridge Gulf. The support of Department of Parks and Wildlife’s utility vessel Joowinyin was essential to move food, fuel and equipment to the island.

A view of Turtle Bay and our camp from ‘Telstra Hill’. (Photo Alex Brown)

 

Using the ranger boat, the team covered a 476 km area, focusing on the northwest of the Gulf between the Lynne and Helby Rivers but also covering the open coast west to the Berkeley River, north along King Shoal and Medusa Bank, and east around Cape Domett.

Balanggarra Rangers, Wesley (left) and Wayne (centre left), assist with photo-identification alongside researcher Simon Allen (right) and skipper Andy Yardley (centre right). (Photo: Alex Brown)

 

Both species were encountered throughout the area surveyed, including the river mouth habitats, which they are known to often frequent, but also along less sheltered sections of open coast and where shallow waters extended further offshore.

Snubfin dolphins were sighted 22 times, while 18 schools of humpback dolphins were observed – providing ample opportunities for the Balanggarra Rangers to develop their data collection skills.

The survey team attempted to quantify the number of dolphins in the area by taking photographs of unique markings on their dorsal fins. However, many of the animals were too shy to be approached close enough for high-quality photos (< 50 m), and only one quarter of all dolphins approached could be properly recorded.

The boat-shy behaviour, which is not uncommon in these species, also limited the team’s success in using a darting system to obtaining tissue samples for genetic analyses – a single humpback dolphin sample being the total from the trip.

Snubfin dolphins (Photo: Pete O’Connor, Dambimangari Rangers)

 

On the second trip, Dr. Brown joined Parks and Wildlife and Dambimangari Rangers on PV Worndoom for an eight-day survey in Lalang-garram / Camden Sound Marine Park, focussing on the popular Prince Regent River.

Regular sightings of snubfin and humpback dolphins suggest this to be an important habit for these species – both of which are key indicators of marine park health under the management plan.

Photo-identification techniques were more successful in this area, and biopsy darting provided an additional two snubfin dolphin genetic samples.

With this initial survey complete, an ongoing monitoring program will be developed to allow park managers to monitor the status of tropical dolphin species in key parts of the park.

Overall, these data add to our understanding of the distribution and relative abundance of tropical inshore dolphins off northwest Australia, and provide comparisons to encounter rates at other studied sites in the western Kimberley.

The genetic samples will be analysed alongside others from the region, providing a starting point for further data collection and investigations of population connectivity in the Kimberley.

 

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.

Category:

Kimberley Marine Research Program

Changes needed to sawfish barriers in Fitzroy River

At least two access ways through freshwater barriers need to be established for endangered freshwater sawfish (Pristis pristis) populations living in the north of Western Australia and other areas need to be monitored according to a new report by Murdoch University researchers.

The report1, funded by the Chevron Wheatstone project through the Western Australian Marine Science Institution (WAMSI) recommended fishways need to be constructed on the Camballin Barrage and the Myroodah Crossing on the Fitzroy River.

Camballin Barrage, Fitzroy River (Photo: David Morgan)

 

Sawfishes are a family of rays with a long, narrow, flattened rostrum, or nose extension, lined with sharp teeth. Some can grow up to seven metres in length. All of Australia’s species of sawfishes are listed as Critically Endangered by the International Union for the Conservation of Nature (IUCN). Research has found their ranges have decreased by 30-80 per cent depending on the species as a result of habitat loss and overfishing2.

David Morgan holding a tagged Green Sawfish (Photo: Jeff Whitty)

 

In northern Western Australia, the Fitzroy river is arguably the most important nursery for freshwater sawfish and the Ashburton River estuary is currently the only identified pupping site and nursery for green sawfish (Pristis zijsron) in the world.

Freshwater Sawfish are born in estuaries before migrating upstream to spend their first four-five years of life in river systems. Locally they have been recorded up to 400 kilometres from the coast in the Fitzroy River. Upon nearing maturity they move back to coastal and marine waters.

Freshwater sawfish (Photo: David Morgan)

 

Dr David Morgan led the research to examine what prevents sawfish in northern Western Australia from being able to migrate. 

“The Barrage, on average (2002-2015), reduces the time that Freshwater Sawfish can move upstream by 184 days,” Dr Morgan said.

”Northern Australia represents one of the only remaining population strongholds for this sawfish and although recruitment is linked to river flood, there have been a number of years recently where recruitment has failed.

“The relatively pristine nature of large northern Australian rivers is essential for juvenile freshwater sawfish. We have some understanding of the importance of rivers such as the Fitzroy River in the Kimberley and the Daly River in the Top End. However, we know little about the adult population.

“There is considerable pressure to develop the freshwater resources of northern Australia, but proposals will firmly need to consider impacts on freshwater sawfish.

“Structures such as dams and barrages in rivers are barriers to sawfish migration, while dry season water extraction could reduce available river habitat. Connectivity from estuaries through to upstream reaches of rivers is essential for allowing the species to complete its lifecycle,” Dr Morgan said.

 

1Wheatstone Environmental Offsets: Barriers to sawfish migrations report

2.Dulvy, N. K., Davidson, L. N. K., Kyne, P. M., Simpfendorfer, C. A., Harrison, L. R., Carlson, J.K., and S. V. Fordham. 2016. Ghosts of the coast: global extinction risk and conservation of sawfishes. Aquatic Conservation: Marine and Freshwater Ecosystems 26:134-153.

Category: 

Sawfish Project

Survey indicates strong support for Kimberley coast protection

By Murdoch University News

Research indicates strong public support for protecting and conserving much of the Kimberley coastline according to a report for WAMSI’s Kimberley Marine Science Program.

Murdoch University scientist Dr Jennifer Strickland-Munro and her research team conducted an online survey of more than 370 people to find the majority placed a high value on conservation and protection across the coast, including sites not covered by Marine Protected Areas (MPAs). Increased Aboriginal management was also highly valued.

 

“The survey results should be considered in the future planning strategies and management of the Kimberley coast and marine environment,” Dr Strickland-Munro said.

Two marine parks have been established along the coast; at Eighty Mile Beach and Lalang-garram/Camden Sound with proposals for three more at Roebuck Bay, Horizontal Falls and North Kimberley.

The Kimberley MPAs are managed for multiple uses including biodiversity conservation, Aboriginal culture and heritage, nature-based tourism, commercial fishing and aquaculture, science/education, recreation and recreational fishing.

The survey asked respondents to place markers on a map to show the coastal and marine areas they valued along with their management preferences for the region. The results showed there were no unvalued places along the entire Kimberley coast.

Figure 2: Responses across the different value categories. Subsistence included food, collection

 

“We also found that pro-conservation preferences dominated, but significant differences in responses suggest the potential for conflict over future management,” Dr Strickland-Munro said.

Fifteen per cent of the preferences mapped in the survey were pro-development, with resource related preferences supporting commercial fishing, new port and oil and gas developments.

Many value and preference hotspots were located outside the existing and proposed MPAs, including the northern tip of the Dampier Peninsula, the Buccaneer Archipelago and King Sound near Derby.

Figure 3: Hotspot map for values relating to the ‘physical landscape’.  Numbers are the frequency for ‘physical landscape’ values. The location of hot spots varied according to value type. However, Roebuck Bay, the western and northern coastal fringes and marine environments of Dampier Peninsula, the Buccaneer Archipelago, Horizontal Falls and Talbot Bay, and Montgomery Reef appeared as hot spots for a number of values. Sites northward of this also appeared as hotspots, although of less intensity than other area.

 

“Our findings reinforce the importance of taking a broader, comprehensive and regional view to marine conservation,” Dr Strickland-Munro said.

“In Australia, as elsewhere in the world, marine and coastal management have struggled to include diverse values, knowledge systems and cultural contexts,” she explained. “These social elements of planning are much more challenging to include compared with the biological and physical attributes of MPAs.

“MPAs can be politically-driven in their boundaries and zoning or these processes may not provide the time or resources for significant stakeholder involvement during planning phases to ensure lasting public support.

“The participatory mapping we used in our survey can be a powerful tool to help address this issue, connecting resource users, planners and managers.

“Our research contributes to marine spatial planning, which helps to identify potential conflicts among users and is particularly useful for large areas like the Kimberley that contain both State and Commonwealth jurisdictions,” Dr Strickland-Munro said.

Links:

Social values and aspirations for coastal waters of the Western Kimberley project page

Social values and aspirations for coastal waters of the Western Kimberley Report

Research Articles:

Strickland-Munro J, Kobryn H, Brown G, Moore S (2016) Valuing The Wild, Remote And Beautiful: Using Public Participation Gis To Inform Tourism Planning In The Kimberley, Western Australia International Journal of Sustainable Development and Planning DOI: 10.2495/SDP-V11-N3-355-364

Strickland-Munro J, Kobryn H, Brown G, Moore S (July 2016) Marine spatial planning for the future: Using Public Participation GIS (PPGIS) to inform the human dimension for large marine parks Marine Policy DOI: 10.1016/j.marpol.2016.07.011

Pearce J, Strickland-Munro J, Moore S (June 2016) What fosters awe-inspiring experiences in nature-based tourism destinations?, Journal of Sustainable Tourism, DOI: 10.1080/09669582.2016.1213270

Brown G, Strickland-Munro J, Kobryn H, Moore S (Dec 2015) Stakeholder analysis for marine conservation planning using public participation GIS Applied Geography DOI:10.1016/j.apgeog.2015.12.004

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.

 

Category:

Kimberley Marine Research Program

Tide turning for Kimberley crocodiles

By Kandy Curran, Roebuck Bay Working Group

An audience of more than 100 people at the latest Science on the Broome Coast series were surprised to hear the tide is turning in different directions for the two species of crocodiles in the Kimberley region.

CSIRO freshwater crocodile biologist Dr Ruchira Somaweera, and Parks and Wildlife estuarine crocodile scientist Dr Andrew Halford, presented their research findings at the University of Notre Dame campus on September 20, 2016.

Whilst Dr Somaweera predicts a likely severe decline in freshwater crocodile numbers in some parts of the Kimberley with the invasion of cane toads, Dr Andrew Halford’s research shows estuarine crocodile numbers increasing steadily since full protection in 1997.

Freshie hatching (Photo: Ruchira Somaweera)

Dr Somaweera said that although cane toads are the biggest threat to freshies, other threats include invasive weeds such as exotic passionfruit vine that can choke river bank nesting habitats, bycatch in fishing, and predation by their saltwater relatives.

Two studies in the Northern Territory along the Daly and Victoria River systems showed significant  population declines (77% and 60% respectively), highlighting the concern for the Kimberley freshie.

Dr Somaweera said there is hope however for Crocodylus johnstoni. Recent studies show freshwater crocodile hatchlings are intelligent and can develop a taste aversion for toxic toads if they experience a non-fatal experience from eating a juvenile that has made them ill.

Dr Ruchira Somaweera presenting at Science on the Broome Coast

“I think we will see a phase of severe decline, and then those that have adapted will form a stronger population,” Dr Somaweera said.

Dr Halford is finding a steady increase in numbers of larger saltwater crocodiles as the population matures over time. Surveys conducted along the Roe and Prince Regent Rivers show a significant increase in the population of ‘salties’.

“Numbers (of saltwater crocodiles) are up in the range of a 100 to 300 per cent increase since 1997 – when their numbers were estimated to be as low as 2,500,” Dr Halford said. “It’s been 30 years, so it’s a very clear example of what happens when you take human predators out of the equation.”

Dr Halford said that increased population density is forcing younger males to move south, hence the increase in sightings around Broome in recent years. It’s not clear if these animals will establish breeding populations around Broome and further south as this will depend on the availability of suitable nesting habitat.

Freshie taking off (Photo: Ruchira Somaweera)

 

The Science on the Broome Coast series is hosted by the Roebuck Bay Working Group and Yawuru Land and Sea Unit in Broome, and sponsored by Inspiring Australia, Rangelands NRM through the Federal Government Landcare program, State NRM through Royalties for Regions, Western Australian Marine Science Institution, Department of Parks and Wildlife and University of Notre Dame Broome.

 

Category:

Kimberley Marine Research Program

Life in the mud attracts global travellers

By Kandy Curran, Roebuck Bay Working Group

Professor Theunis Piersma’s footprint on the mudflats of Roebuck Bay and Eighty Mile Beach will go down in scientific history, for 20 years of continuous research of the wetland’s remarkable migratory shorebirds and rich invertebrate life. 

Recognising the critical importance of the benthic fauna from his base at the NIOZ Royal Netherlands Institute of Sea Research, Professor Piersma made the long journey to the remote town of Broome in 1996, to see the Ramsar listed wetlands for the first time. 

Speaking at the Science on the Broome Coast series on October 6, 2016, Professor Piersma presented findings from this research, including disturbing news of the alarming population decline in migratory shorebirds using the East-Asian Australasian Flyway.

Pebble crab (family Leucosiidea) © Kandy Curran

As Professor Piersma explained, ‘a benthic invertebrate dataset is being amassed from the results of monthly mud sampling Roebuck Bay since 1996 (in collaboration with Broome Bird Observatory and Parks and Wildlife Yawuru joint management team), and from major benthic mapping expeditions in 1997, 2002, 2006 and 2016, where volunteers and scientists sieved mud from 2,000 locations, turning up a staggering 50,000 invertebrates.

Incredibly, colourful topshells, tiny mudwhelks and snails can reach an abundance of 3,000 per square metre in Roebuck Bay’s intertidal mudflats. Bivalves are plentiful too, with more than 30 different species. Surprisingly though, the most abundant and diverse animals are worms. Some of these remarkable benthic invertebrates are superfoods for migratory shorebirds, replenishing fat stores for their annual life cycle along the flyway.

 

The benthic expedition underway on Roebuck Bay’s remarkable intertidal mudflats. © Kandy Curran

 

Australia however, is only one of nine flyways of the world under growing pressure. In 2006, Professor Piersma procured international funding to establish the non-profit Global Flyway Network to better understand and help conserve migratory shorebirds in a rapidly changing world. Through the Global Flyway Network, Broome ornithologists are employed to conduct shorebird research on Roebuck Bay, Eighty Mile Beach and at the migratory shorebird’s staging grounds on China’s Yellow Sea.

Sadly, these studies are showing a significant decline in populations of migratory knots and godwits. Professor Piersma says, ‘My hypothesis from a large data set, is that habitat loss and environmental degradation of the Yellow Sea mudflats is the key factor in this downward spiral.’

 A world leader in wetland and waterbird ecology, with a long list of prestigious scientific awards, publications and books, Professor Piersma’s  take home message is, ‘Don’t take Roebuck Bay for granted, since this remarkable embayment has the richest intertidal mudflats in the world’.

The Science on the Broome Coast series is hosted by the Roebuck Bay Working Group and Yawuru Land and Sea Unit in Broome, and sponsored by Inspiring Australia, Rangelands NRM through the Federal Government Landcare program, State NRM through Royalties for Regions, Western Australian Marine Science Institution, Department of Parks and Wildlife and University of Notre Dame Broome.

Read more about the Roebuck Bay benthic survey here.

Grant Pearson, Randal Tabrizian, Kandy Curran, Professor Theunis Piersma © Kandy Curran

Category: 

Kimberley Marine Research Program

New survey allays fears about coral reef health in the inshore Kimberley

Only six months after one of the worst summers in history for coral bleaching, a new coral reef biodiversity and health survey suggests some of Australia’s most biologically important fringing reef communities in the central Kimberley remain intact.

READ MORE

 

Category: 

Kimberley Marine Research Program

What do flatback turtles in NW Australia eat?

Surprisingly, little is known about what flatback turtles eat and what we do know comes from examining the stomach contents of dead flatback turtles. 

The Department of Parks and Wildlife has joined forces with WAMSI to try to answer this question through a 17 day field campaign to flatback turtle foraging grounds in the little known and relatively pristine tropical waters of north-west Australia’s remote Kimberly region.

Read More at: http://northwestatlas.org/node/1665

Category: 

Kimberley Marine Research Program

Blueprint for Marine Science Report – September 2016

Western Australia’s marine science, government, industry, conservation and community sectors met at the inaugural Blueprint for Marine Science Forum in Perth to begin building an Australian-first collaboration around marine science.

For more information, click the following link: http://www.marinescienceblueprint.org.au/latest-progress/wa-marine-science-strategy-achieves-unprecedented-collaboration

DSN Report 4.3: Corals of the northwest of Western Australia: biogeography and considerations for dredging-related research

WAMSI dredging science research has delivered the first guide to the choice of coral species for laboratory experiments to determine the effects of dredging activities on adult and juvenile corals in Western Australia.

Identifying scientifically appropriate coral species that will help to determine the overall ecosystem response to dredging-related pressures is one of three key research areas under the WAMSI Dredging Science Node, along with studies into primary producers such as seagrass and algae, and filter feeders such as sponges.

In Australia, and especially in sub-tropical and tropical north-western Australia, there are many examples of current and planned major dredging projects where millions of cubic metres of sediments require removal. These volumes are significant by global standards and since the released sediments can reduce or block light, clog filtering and feeding apparatus and smother benthic organisms they carry a significant environmental risk.

At the Australian Institute for Marine Science’s National Sea Simulator (SeaSim) laboratory in Townsville, Queensland, researchers are able to ‘pressure test’ for ecological responses. And so the criteria for identifying the best type of coral from the WA coast to test not only had to prove to work well under laboratory conditions but also be readily available for collection from the SeaSims lab doorstep, the Great Barrier Reef (GBR).

In order to identify which corals best fitted the criteria to achieve the most useful results the biogeographic distribution of hard corals was examined over ~2,500 km from Ashmore Reef (12°S) in the Timor Sea to the Recherche Archipelago near Esperance (34°S).

Using data mainly from studies conducted in association with the Western Australia Museum, together with digital records from the east coast held by the Museum of Tropical Queensland ~3,500 records were grouped to 19 locations and then sorted according to family, genus and species.

Of the WA records, the total hard coral species count was 361 species from 17 Families and 83 genera. The highest species count (253 species) was recorded at Scott Reef (North and South Scott Reef and Seringapatam Reef).

Another important criterion was that the corals were reasonably abundant, not just for collecting/permitting purposes but because they are an important part of the species in that habitat.

(Source: Jones R,  Corals of the north west of Western Australia: biogeography and considerations for dredging-related research)

Nine coral species were selected for study Each of these species is found in the central GBR and at each of the sites from Shark Bay to Ashmore Reef and Cartier Islet (i.e. the tropical/reef building territories).

The species represent five families including Poritidae and Acroporidae which are abundant in the Pilbara and commonly used in tagged-coral monitoring program in the Pilbara (Hanley 2011) and in the central GBR (Jones 2008).

The selected species have a range of forms and structures (morphologies):

  • Acropora millepora which “broadcast spawn” by releasing gametes—eggs and sperm—into the water to spread offspring. Broadcasters represent the majority of all reef-building corals.
  • Pocillopora damicornis is a brooder, which are most often not reef-building. Brooders release only sperm, which is negatively buoyant, sinking on to the waiting egg carriers.
  • Acropora tenuis is also a broadcast spawning species but it spawns just after sunset a few hours earlier than A. millepora allowing for more experiments to be performed on the night of spawning. It is a very common species with a similar widespread distribution pattern as Acropora millepora.

Both Pocillopora damicornis and Acropora tenuis will also be used in DSN studies (Theme 7) to help manage the risk of dredging projects around coral reefs where many (though not all) coral species spawn at predictable times of the year.

Links:

Background:

The Western Australian Marine Science Institution is delivering one of the largest single-issue marine research programs in Australia. It will vastly improve the planning and regulation of major dredging operations in our precious marine environment.

This world-class marine research is enhancing capacity within government and the private sector to predict and manage the environmental impacts of dredging in Western Australia. The outcomes will increase the confidence, timeliness and efficiency of the assessment, approval and regulatory processes associated with dredging projects.

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.

Category:

Dredging Science