Thermally tolerant Kimberley corals are not immune to bleaching

Scientists have conducted the first peer reviewed test to find out if Kimberley coral reefs are resistant to coral bleaching because of their natural ability to adapt to the high temperatures off the northwest coast of Australia, and found they are nonetheless highly susceptible to heat stress and bleaching.

Coral bleaching happens when sea temperatures rise, causing the breakdown of the symbiosis between coral and their zooxanthellae (the microscopic plants which gives coral most of its colour), which can be fatal for the coral.

The study was carried out in partnership with the Western Australian Marine Science Institution’s (WAMSI) Kimberley Marine Research Program and the ARC Centre of Excellence for Coral Reef Studies (Coral CoE) at The University of Western Australia’s Oceans Institute.

Lead author Dr Verena Schoepf said the researchers were surprised to find that corals around the Kimberley region in far north Western Australia are just as sensitive to heat stress and bleaching as their counterparts from less extreme environments elsewhere.

“We found that exceeding the maximum monthly summer temperatures by one degree Centigrade for only a few days is enough to induce coral bleaching,” Dr Schoepf said.

“We were surprised because under normal conditions, Kimberley corals can tolerate short-term temperature extremes and regular exposure to air without obvious signs of stress.”

The Kimberley region has the largest tropical tides in the world reaching up to 10 metres, creating naturally extreme and highly dynamic coastal habitats that corals from more typical reefs could not survive.

“Unfortunately the fact that Kimberley corals are not immune to bleaching suggests that corals living in naturally extreme temperature environments are just as threatened by climate change as corals elsewhere,” Dr Schoepf said.

“We found that both branching and massive corals exposed at low tide coped better with heat stress than corals from deeper water,” co-author Professor Malcolm McCulloch from the Coral CoE said. “However this doesn’t mean that they are immune to bleaching.”

The research also found that massive corals had a better chance of surviving and recovering from bleaching than branching corals.

The current strong El Niño weather pattern in the Pacific puts many coral reefs at risk of severe bleaching, and recent weather predictions show that the Kimberley region might be particularly affected in 2016.

“With the third global bleaching event underway, it has never been more urgent to understand the limits of coral thermal tolerance in corals,” Professor McCulloch said.

Co-authors on the study also included Dr Michael Stat from the Trace and Environmental DNA (TrEnD) Laboratory at Curtin University and Dr James Falter from the Coral CoE at The University of Western Australia.

Paper:
Schoepf, Verena, Michael Stat, James L. Falter, and Malcolm T. McCulloch. 2015. “Limits To The Thermal Tolerance Of Corals Adapted To A Highly Fluctuating, Naturally Extreme Temperature Environment”. Scientific Reports 5 (1). doi:10.1038/srep17639.

Contacts:
Dr Verena Schoepf – (+61 8) 6488 3644 verena.schoepf@uwa.edu.au
Professor Malcolm McCulloch – (+61 8) 6488 1921 malcolm.mcculloch@uwa.edu.au
Aleta Johnston – WAMSI Communications (+618) 6488 4574 / 0431 514 677

Thermally tolerant Kimberley corals are not immune to bleaching

This article was originally published on an archived WAMSI website. Some media or links may appear missing or broken. You can use the search function to look for these, or contact info@wamsi.org.au for a specific request.

Scientists have conducted the first peer reviewed test to find out if Kimberley coral reefs are resistant to coral bleaching because of their natural ability to adapt to the high temperatures off the northwest coast of Australia, and found they are nonetheless highly susceptible to heat stress and bleaching.

Coral bleaching happens when sea temperatures rise, causing the breakdown of the symbiosis between coral and their zooxanthellae (the microscopic plants which gives coral most of its colour), which can be fatal for the coral.

The study was carried out in partnership with the Western Australian Marine Science Institution’s (WAMSI) Kimberley Marine Research Program and the ARC Centre of Excellence for Coral Reef Studies (Coral CoE) at The University of Western Australia’s Oceans Institute.

Lead author Dr Verena Schoepf said the researchers were surprised to find that corals around the Kimberley region in far north Western Australia are just as sensitive to heat stress and bleaching as their counterparts from less extreme environments elsewhere.

“We found that exceeding the maximum monthly summer temperatures by one degree Centigrade for only a few days is enough to induce coral bleaching,” Dr Schoepf said.

“We were surprised because under normal conditions, Kimberley corals can tolerate short-term temperature extremes and regular exposure to air without obvious signs of stress.”

The Kimberley region has the largest tropical tides in the world reaching up to 10 metres, creating naturally extreme and highly dynamic coastal habitats that corals from more typical reefs could not survive.

“Unfortunately the fact that Kimberley corals are not immune to bleaching suggests that corals living in naturally extreme temperature environments are just as threatened by climate change as corals elsewhere,” Dr Schoepf said.

“We found that both branching and massive corals exposed at low tide coped better with heat stress than corals from deeper water,” co-author Professor Malcolm McCulloch from the Coral CoE said. “However this doesn’t mean that they are immune to bleaching.”

coral bleaching hope

Intertidal Acropora corals in the Kimberley are exposed to the air at low tides. (Verena Schoepf)

The research also found that massive corals had a better chance of surviving and recovering from bleaching than branching corals.

The current strong El Niño weather pattern in the Pacific puts many coral reefs at risk of severe bleaching, and recent weather predictions show that the Kimberley region might be particularly affected in 2016.

“With the third global bleaching event underway, it has never been more urgent to understand the limits of coral thermal tolerance in corals,” Professor McCulloch said.

Co-authors on the study also included Dr Michael Stat from the Trace and Environmental DNA (TrEnD) Laboratory at Curtin University and Dr James Falter from the Coral CoE at The University of Western Australia.

Related Links:

Paper:
Limits to the thermal tolerance of corals adapted to a highly fluctuating, naturally extreme temperature environment, by Verena Schoepf, Michael Stat, James L. Falter and Malcolm T. McCulloch is published in the journal Nature Scientific Reports

 

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

Field trip finds turtle and fish food abundant in Bardi Jawi country

A team of CSIRO and UWA researchers has just returned from a 10-day field trip to Bardi Jawi country, where they took the last of their seagrass, seaweed and microalgae measurements for a WAMSI project that will determine the current state of the area’s primary food source for rabbitfish and green sea turtles.

The team worked with the Bardi Jawi Rangers on Tallon Island (Jalarn) and Sunday Island (Iwany) off the Dampier Peninsular in the Kimberley. They measured the growth of seagrass and macroalgae on the reef platforms, and microalgae in the sand that forms the beaches. These are all primary producers that sustain food webs, and the area’s seagrass is a key food source for fish and turtles that are important for the Bardi Jawi.

Preparing for seagrass tethering study (Mat Vanderklift)

Some seagrass was punched with holes to measure growth — researchers measure how far the holes have moved after a week to see how much the grass has grown. Other seagrass was collected, pegged out, measured and returned to the seagrass meadow for a 24 hour period before being measured again to determine how much had been eaten.

CSIRO’s Mat Vanderklift, who is also working on green sea turtle tagging as part of another WAMSI project, said the findings were providing the first comprehensive picture of productivity and seasonality of seaweed, seagrasses and microalgae in the Kimberley.

“Through collaboration with the Bardi Jawi Rangers we have been able to build up detailed seasonal understanding of seagrass productivity through the year,” Dr Vanderklift said. “We also have a better understanding of the importance of this productivity for green turtles and herbivorous fish like rabbitfish.”

Seagrass habitat with a sea cucumber in the Bardi Jawi IPA (Mat Vanderklift)

“The key findings are that the main plants that we have found in the lagoon habitats (the seagrasses Thalassia and Enhalus, and the large brown algae Sargassum) all have high growth rates throughout the year, with growth rates sometimes exceeding a centimetre a day,” Dr Vanderklift said. “We have also found that microscopic algae are very abundant in some places, but not everywhere, and bacteria are particularly abundant in the sediment under mangroves and seagrasses.”

The project has found that herbivores are abundant in the area and that they eat a lot of the seagrass. One of the main herbivores in the area, rabbitfish (Siganus lineatus), is a highly sought after food source by the Bardi Jawi people.

The project is also finding that the seagrasses are living at the limit of their temperature tolerances and further studies of their vulnerability to climate change are needed.

James McLaughlin on Jologo beach talking about microalga with kids from One Arm Point Remote Community School. (Mat Vanderklift)

 

“Collaborations with the Bardi Jawi Rangers have added enormous value to the research,” Dr Vanderklift said. “We have been able to exchange knowledge and learn from each other – for example, the discovery of the importance of seagrass to rabbitfish would not have happened if we had not worked closely together. The success of this project is because of the collaboration we have built together.”

The latest trip also gave the researchers an opportunity to present to children from the local One Arm Point Remote Community School.

James McLaughlin wowed the high school “Bush Rangers” with real-life chemistry on the beach, while Mat Vanderklift talked to dozens of excited children about turtles at their Culture Day. “They all enjoyed the game of guessing where the tagged turtles had travelled,” he said.

The project group is now completing the measurements and analysing the data, and will return to show the community and the rangers the results next year, with the aim of informing the ranger’s activities under their Indigenous Protected Area management plan.

Josh Setting up Benthic chamber module. (Mat Vanderklift)

 

 

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

New research determines dredging effects on seawater quality

WAMSI Dredging Science Node researchers have, for the first time, quantified dredging effects on seawater quality conditions, which is critical to realistic testing in the laboratory.

The literature review along with the examination of some large environmental monitoring datasets from recent dredging projects provided by Chevron Australia, Woodside Energy and Rio Tinto Iron Ore, have been published in PLOS ONE.

Lead author of the paper: Temporal Patterns in Seawater Quality from Dredging in Tropical Environments, Dr Ross Jones from the Australian Institute of Marine Science (AIMS), said bringing the current knowledge together means previous laboratory testing can be appraised on the relevance of the pressure fields used, and that future testing, including the next phase of WAMSI’s dredging science program, now has a peer reviewed reference.

“The reviews of existing monitoring datasets from industry have allowed us to more accurately quantify how dredging affects seawater quality conditions temporally and spatially,” Dr Jones said. “This information is critical to test realistic exposure scenarios.”

The research found that dredging effectively alters the overall probability distributions of fine temporal scale turbidity and light changes, increasing the frequency of extreme values and dampening the probability distribution.

“When averaged across the entire baseline and dredging phases separately for the three Pilbara dredging projects, turbidity values increased by 2–3 fold but when examined by the IDF analysis across baseline and dredging periods, dredging increased the intensity (magnitude) of turbidity peaks by over an order of magnitude, generated peaks that lasted five times longer than the baseline period, and may cause peaks to occur up to three times more frequently,” Dr Jones said.

The second prominent and characteristic feature of the seawater quality conditions during the dredging programs were the low light, or ‘daytime twilight’ periods. Such conditions are well known to be associated with wind and wave events.

“One of the objectives of this analysis was to provide a temporal analysis of seawater quality to allow the design of more realistic experiments examining the effects of sediments on tropical marine organisms (corals, seagrasses, sponges ascidians etc),” Dr Jones said. “The analysis has provided a matrix of empirical data of seawater quality (turbidity and light levels) which effectively captures the entire range of likely seawater quality conditions associated with dredging in a reefal environment.”

“Collectively this information could contribute to the development of seawater quality thresholds for dredging projects and ultimately improve the ability to predict and manage the impact of future projects,” Dr Jones said.

R. Jones, R. Fisher, C. Stark, P. Ridd (October 2015) Temporal Patterns in Seawater Quality from Dredging in Tropical Environments PLOS DOI: 10.1371/journal.pone.0137112

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

Indian Ocean creates its own flow-on effect

New research led by CSIRO has described how heavy rainfall caused the top layer of the southeast Indian Ocean to be less salty, creating a barrier layer which trapped the heat during the deadly marine heatwave – La Niña and the ‘Ningaloo Niño’ of 2010-11. The result was a larger volume of warmer water being driven by a stronger current down the WA coastline.

The finding, which is part of WAMSI’s Kimberley Marine Research Program, provides further scientific knowledge to help predict responses to climate change, and adds another layer to consider when forecasting extreme marine heatwave events.

Surface salinity anomalies (psu) derived from gridded Argo product (relative to 2005–2012 monthly climatology) in February 2011.

According to CSIRO’s physical oceanographer Dr Ming Feng, the change in salinity levels on the top 100 metres of the ocean also raises more questions, such as how it will affect some marine species.

“In the past we have followed the Pacific Ocean climate closer in evaluating WA marine environment. We haven’t focused much attention on the Indian Ocean variables and the effect on the WA environment,” Dr Feng said. “It seems that the more we find out about the Indian Ocean, the more we realise it operates very differently to any other ocean on earth.”

The Leeuwin Current, the eastern boundary current of the southeast Indian Ocean, carries warm fresh tropical water southward along the west coast of Australia. The current is stronger in Australia’s winter and weaker in summer; it also tends to be stronger during La Niña events.

Surface currents in the Indian Ocean during austral summer, adapted from Schott et al. [[1]] and Menezes et al. [[2]]. The background shading shows the sea surface temperature anomalies (°C) in February 2011 derived from the Argo float data. ITF: Indonesian throughflow; LC: Leeuwin Current; SJC: South Java Current; SEC: South Equatorial Current; SECC: South Equatorial Counter Current; SC: Somali Current; NMC: Northern Monsoon Current; NEMC: North East Madagascar Current; SEMC: South East Madagascar Current; SICC: South Indian Countercurrent.

The latest research compared salinity observations at the CSIRO/Integrated Marine Observing System (IMOS) Rottnest National Reference Station collected during the past 60 years. Analysis of these observations revealed the unusual, but significant, freshening of the ocean’s top layer during 2010-2011.

Dr Feng suspects this may not be the first or last time we experience such an event.

“Something similar probably happened in 1999/2000, so it might happen in the future, especially as we experience more frequent warmer conditions,” he said.

It’s thought that the change in salinity can take a few years to return to normal but the El Niño forecast for 2015, which was to result in a weakening in the Leeuwin Current and cooler water temperatures along the coast of WA, has not rung true.

“Typically we should be experiencing cooler temperatures off the west coast this year but the temperatures have still been warmer than normal, so this is an unusual year, and it shows we don’t fully understand the impact of the Indian Ocean,” Dr Feng said.

Ming Feng, Jessica Benthuysen, Ningning Zhang and Dirk Slawinski (October 2015) Freshening anomalies in the Indonesian throughflow and impacts on the Leeuwin Current during 2010–2011 Research Letters DOI: 10.1002/2015GL065848

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

Kimberley reefs based on ancient history

WAMSI’s Kimberley Marine Research Program has provided the first definitive evidence that the region’s fringing coral reefs are long lived features growing over a two-billion-year-old land surface recording changes through post-glacial time and dispelling the theory that the reefs are thin veneers over bedrock.

The findings, published in the Australian Journal of Maritime and Ocean Affairs, make significant inroads into understanding the poorly known coral reefs of the Kimberley in an area that is considered an internationally significant ‘biodiversity hotspot’.

Co-author of the paper, Curtin University’s Mick O’Leary, said the project is working to determine just how unique the Kimberley reef system is.

“We hope to establish whether Kimberley reef morphology conforms to established geomorphic models, like the Great Barrier Reef,” Dr O’Leary said. “It may be that the reefs have developed their own distinctive morphologies driven by extreme environmental conditions, like the massive 11 metre tides that are unique to the Kimberley.”

 The research team used a combination of remote sensing, sub-bottom profiling and associated sedimentological work to produce a regional geodatabase of coral reefs and to determine the internal architecture and growth history of the coral reefs over the last 12,000 years.

More than 860 nearshore reefs were mapped from Cape Londonderry to Cape Leveque with a total of 30 reefs studied in detail and their substrates documented across the Kimberley Bioregion.

The prevalence of rhodolith dominated substrates on high intertidal reefs (both planar and fringing reefs) contrasts with the more coral dominated fringing reefs, with inner to mid-shelf planar reefs having some shared attributes with these contrasting categories.

Satellite images used to map intra-reef geomorphology and associated substrates for the targeted reefs of this study:

 (a) Bathurst and Irvine Islands; (b) Cape Londonderry; (c) Montgomery Reef; (d) Maret Island; (e) Adele Reef; (f) Long Reef; (g) Molema Island; and (h) Tallon Island.

 

Over 294 km of sub-bottom profiling records were aquired from a representative suite of reefs to determine reef growth history.

Two seismic horizons were identified in the inshore reefs (Sunday Islands, Molema Island, Montgomery Reef and the Buccaneer Archipelago, where seismic calibration was available), marking the boundaries between Holocene reef (Marine Isotope Stage 1, MIS 1, last 12 ky) commonly 10 – 15 m thick, and MIS 5 (Last Interglacial, 120 ky; LIG) and Proterozoic rock foundation over which Quaternary reef growth occurred. In the offshore reefs of the Adele Complex, two additional deeper acoustic reflectors were identified (possibly MIS 7 and MIS 9 or 11)

SBP images of the NW channel bank complex associated with North Turtle Reef

 

The transition of reef building organisms was investigated by shallow coring (up to 6 m) providing the first subsurface sedimentary samples for the key types of reef found in the southern Kimberley.

The core study sheds considerable light on the growth history of the reefs and has shown that the inshore reefs are muddy in character, similar to the Cockatoo island fringing reef.

Adele Reef, offshore, is distinctly sandier in character. Radiocarbon dating showed that, like Cockatoo Island, reef growth initiated soon after the inner shelf was flooded (~10,000 years ago).

Early reef buildups are likely to be muddy with branching, plate, and massive corals. This is replaced on many reefs (particularly exemplified by Montgomery and Turtle Reefs) by coralline red algae (rhodoliths), small robust corals and coral rubble as reefs become intertidal at their surface.

Multibeam surveys of reef flats discovered a new reef morphotype, the “High Intertidal Reef” which are uniquely characterised by having reef flats that have a surface elevation that sits above the level mid-tide level. Typically reef flats sit at the level of mean low water spring tide.

Getting ready for coring with help from Bardi Jawi Rangers and Erin McGinty from KMRS.

 

The project’s findings have been integrated into a GIS based database called ‘ReefKIM’ which incorporates a wide range of datasets, including remote sensing images, bathymetric charts, site photos and many geological and biological datasets into one inclusive geodatabase.

The main purpose of ReefKIM is to compile various types and sources of reef and marine environment-related information, fostering data fusion and maximising the accessibility of important information to better understand the Kimberley reefs.

It is intended to provide researchers with an overview of essential information on the Kimberley reefs. It also constitutes a significant decision-support tool, providing managers and stakeholders with practical information for the implementation of their plans and will also help shape the direction of future management policies of the Kimberley region.

Crowdsourcing new information into ReefKIM (also known as the ‘citizen science’ approach) is a promising method for filling knowledge gaps and enhancing understanding of complex reef ecosystems.

 

 

Methodological scheme of data acquisition, processing, integration and storage for the Kimberley reef geodatabase (ReefKIM) (source: Kordi et al., 2016).

 

“Satellite image analysis has revealed that fringing reefs in the Kimberley bioregion grow very well and differ geomorphologically from middle-shelf planar reefs both inshore and offshore,” Dr O’Leary said.

 “The acoustic mid-shelf reef (Adele complex) profiles marked boundaries between Holocene reef (last 12,000 years) and MIS 5 (last 125,000 years) and an ancient Neoproterozoic rock (1,000 to 541 million years ago).

“Correlating the seismic data with the reef chronology determined in Cockatoo and Adele Island, it has been possible to highlight the evolution of multiple stages of reef building, stacked by repeated high sea levels (Adele, 3 stages, at least; Sundays Group, Buccaneer Archipelago and Montgomery Reef, 2 stages; some patch reefs, 1 stage).

“What we’ve found is that the foundation over which reef growth occurred is the two-billion-year-old land surface seen in many Kimberley islands composed of Neoproterozoic rocks. That confirms that Kimberley reefs are not thin growths over bedrock,” Dr O’Leary said.

The findings provides a better understanding of the Kimberley reefs and demonstrate their capacity to succeed in challenging environments while generating complex habitats to support diverse species.

Research Articles:

Collins, L.B., O’Leary, M.J., Stevens, A. M., Bufarale, G., Kordi, M., Solihuddin, T, 2015. Geomorphic Patterns, internal architecture and Reef Growth in a macrotidal, high turbidity setting of coral reefs from the Kimberley Bioregion. Australian Journal of Maritime & Ocean Affairs, Volume 7, Issue 1, pp 12-22. (open access from Nov 2017)

Moataz N. Kordia, Lindsay B. Collins, Michael O’Leary, Alexandra Stevensa (November 2015) ReefKIM: An integrated geodatabase for sustainable management of the Kimberley Reefs, North West Australia Ocean & Coastal Management doi:10.1016/j.ocecoaman.2015.11.004

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

James Price Point data to support Kimberley program

The Browse liquefied natural gas (LNG) Development investigated a major onshore processing facility 52 kilometres north of Broome on the Dampier Peninsula, in Western Australia’s Kimberley region. The Browse Joint Venture (JV) participants commissioned numerous studies and rigorous environmental management planning for the proposed onshore LNG development.

In April 2013, the Browse JV completed its technical and commercial evaluation of the proposed Browse LNG Development near James Price Point and determined that the development concept did not meet the company’s commercial requirements for a positive final investment decision.

Even so, the research and technical work gathered during this time represents a significant and comprehensive collection of unreleased information on the local areas’ marine environment including, habit and species assessments, aerial and vessel megafauna surveys as well as benthic and seagrass habitat surveys.  Woodside, on behalf of the Browse JV, has shared this data with WAMSI for the Kimberley Marine Research Program.

Proposed FLNG location in 2010

“The Browse JV has invested more than A$55 million in environmental research and studies, often in conjunction with leading academic and research organisations, to better understand the offshore marine environment in the vicinity of the three Browse gas fields,” Woodside’s Senior Vice President Projects, Steve Rogers said.

“By sharing our research and collaborating with WAMSI scientists, the valuable data collected over the past two decades can directly improve how the marine environment is managed,” Mr Rogers said.

WAMSI CEO Patrick Seares described the James Price Point data as key to helping the Kimberley Marine Research Program link information developed through its fieldwork focus further to the north, with more studies in the areas of Roebuck Bay and the Browse Basin.

“This enormous marine science program is all being done to improve the understanding and management of the Kimberley marine environment. The Browse JV data will allow us to fill in some of the gaps off the Dampier Peninsula and provide an even more complete picture to marine park and fisheries managers, traditional owners, regulators and future proponents,” Mr Seares said.

“We’ve been working to build both trust and the business case to support broader data sharing with industry on a number of fronts, including the agreements supporting the dredging science node and working with the energy sector on the IGEM system,” Mr Seares said.

“Opening up this data for the Kimberley program is another great step in that process and evidence that leading groups within the energy sector are increasingly working with the science sector to share knowledge. Long may it continue! ”

At this stage the raw data is limited to use for the WAMSI Kimberley Marine Research Program.

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

Groundbreaking tidal study optimises export capacity at the world’s largest bulk export port

By Albina Skender, PPA

A groundbreaking tidal model developed by the Pilbara Ports Authority is receiving industry acclaim for achieving extra depths in shipping channels.

Results from the study, conducted at Port Hedland harbour, when combined with maintenance dredging targeting high spots, achieved an extra depth of 71 centimetres in the shipping channel.

The project has been recognised by industry leaders, and its survey work has been acknowledged as the methodology that should be applied internationally.

The project also won a prestigious Premier’s Award in the Developing the Economy category, which recognises projects that maximise opportunities for the future through stimulating the economy to support employment and growth in Western Australia.

PPA’s Marine Department conducted the tidal study after discovering data inconsistencies with previous hydrographic surveys carried out in the shipping channel. The tidal study was an opportunity to accurately identify existing, deeper channel depths, and resulted in the creation of a Lowest Astronomical Tide (LAT) Model or ‘Hydroid’ unique to Port Hedland.

In short, the study determined the actual levels of LAT measured to ‘the ellipsoid’, a geospatial reference datum. A hydrographic survey conducted to this new LAT model (Hydroid) was consequently fed into the port’s Dynamic Under Keel Clearance (DUKC©) system, allowing for a deeper draft for draft restricted vessels transiting the channel.

The study and the survey, combined with the improved depths of a maintenance dredging campaign in 2013, resulted in an extra 71cms of draft availability in the shipping channel.

Dredging Manager Frans Schlack, who led the project, said the increased draft has provided port customers the opportunity to safely load more product onto vessels, and has potentially extended sailing windows for cape size vessels from six to eight on a tide.

“These developments have enabled PPA to significantly increase its export capacity and allow the port to more safely manage increasing vessel movements in the Port Hedland shipping channel,” he said.

Port Hedland inner harbour (Photo: Pilbara Ports Authority)

The port now regularly facilitates the export of more than a million tonnes on a tide. In February 2015, the port set a new record tonnage of more than 1.5 million tonnes on a single tide that was achieved with eight cape size vessels departing in one convoy. Up to the end of September 2015, the port has achieved one million tonnes on a tide more than 30 times this year.

PPA’s customers are now able to load more product on vessels to a deeper sailing draft, enabling higher volumes of commodities to depart the port in a safe and efficient manner while simultaneously reducing transport costs.

“This not only generates greater export capacity, but it has been achieved without the need to conduct capital dredging (equivalent to three million m³ of material that would otherwise have to be dredged), avoiding significant costs and environmental impacts,” Mr Schlack said.

“The initiative has also given PPA a more precise understanding of the channel, enhancing safety and the port’s ability to manage risk within the uni-directional channel.”

The establishment of the Port Hedland ‘Hydroid’ corrects the long held assumption that LAT is a datum for chart depths and tide readings. LAT is an astronomical event, not a datum.

The establishment of a port’s ‘Hydroid’ creates the correct datum to reference both chart depths and tide heights from which mariners can reliably determine safe navigable depth for their vessels.

“The depths were always there, we just found a better way of measuring them,” Mr Schlack said.

The work has also been acknowledged and commended by the regulator, the Royal Australian Navy Hydrographic Office, which provides leadership, coordination and standards for surveying, mapping and national datasets.

In April 2014, the Permanent Committee on Tides and Mean Sea Level and Ports Australia Hydrographic Surveyors Working Group visited Port Hedland and commended PPA’s work on determining the real tide at the world’s biggest bulk export port.

The Royal Australian Navy Hydrographic Office has also acknowledged the port’s tidal study and survey work as the standard that should be applied internationally, by means of a submission by the office’s Deputy Hydrographer to the Intergovernmental Committee on Surveying and Mapping (ICSM).

Mr Schlack believes other ports can significantly benefit from the model and targeted dredging.

 “A new LAT model will also be created for all other PPA ports, with each port having its own unique Hydroid established through individual tidal studies in combination with PPA’s recognised high standard of hydrographic surveying,” he said.

WAMSI/CSIRO partner with Kimberley Aboriginal groups to manage dugong

CSIRO, with the Western Australian Marine Science Institution (WAMSI), has partnered with four Kimberley Aboriginal organisations to build and deliver a course in aerial survey methodology to Aboriginal Rangers, with a focus on dugongs. The three-day course was hosted by Wunambal Gaambera Aboriginal Corporation’s Uunguu Rangers at their Garmbemirri camp in the north Kimberley.

Representatives from the Balanggarra, Uunguu, Dambimangari and Bardi Jawi ranger groups came together with researchers from CSIRO, training staff from Kimberley TAFE and two specialist consultants to learn best-practice survey techniques for monitoring dugong and other wildlife populations.

Rangers learnt via theory and practice how to conduct aerial surveys, with each participant taking off in a Gippsland G8 Airvan to practice surveying dugongs, dolphins and turtles from the air.

Dugong aerial survey training camp

“We need to know more about where balguja (dugong) live, feed and travel so we can look after them,” Uunguu Head Ranger Neil Waina said. “Learning these survey methods with other Traditional Owner groups will help us keep these animals healthy in our Country and keep our saltwater culture strong.”

Course accreditation on two of the modules (aerial navigation & safety around aircraft) was sought and co-funded by the Aboriginal research partners. The newly trained Rangers then worked closely with CSIRO researchers during September and October to undertake an aerial survey of their sea country and to contribute to critical baseline population surveys of dugongs and other marine wildlife species identified as target species in their Healthy Country Plans such as sea turtles, dolphins and whales.

Rangers conducting aerial surveys

The training course and aerial survey are components of the WAMSI Kimberley Marine Science Program’s Dugong Management project being run through the Coastal Program of the CSIRO Oceans & Atmosphere Flagship.

The dugong project aims to integrate Indigenous knowledge, including that related to seagrass feeding grounds and seasonal effects on distribution and abundance, with existing and new data to better understand dugongs in the Kimberley.

A dugong, photographed at Roebuck Bay (Kimberley). (Photo: Dave Holley www.roebuckbay.org.au)

The dugong is listed internationally as “vulnerable to extinction” and northern Australia is home to the largest remaining populations. They have very high conservation value and are also culturally important to coastal Aboriginal communities.

New distribution and abundance data will be collected using well established aerial survey methodology, and movements of Kimberley dugongs will be studied also using satellite tracking and acoustic tagging technologies in areas important to sea country plans and Indigenous Protected Areas. This new information will be used to work out how best to monitor and manage Kimberley dugongs into the future.

The team.

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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Kimberley Marine Research Program