Study uncovers northwest transition zone for Australian reef fish

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Research has shown that a stretch of ocean surrounding the tip of the Dampier Peninsula, 200 kilometres north of Broome, acts as an invisible genetic barrier for a popular harvested tropical fish known as the stripey snapper.

The findings highlight the importance of the transition zone at the border of the Kimberley and Canning marine bioregions as a consideration for fisheries management. 

The barrier spans a 180 kilometre stretch of ocean at the southern border of the Kimberley bioregion that coincides with the mouth of King Sound, which experiences the largest tropical tidal range and fastest tidal currents in the world.

The collaborative project for the Western Australian Marine Science Institution’s Kimberley Marine Research Program, was led by Curtin University researcher Dr Joseph DiBattista and Department of Primary Industries and Regional Development’s Dr Michael Travers together with CSIRO’s Dr Oliver Berry. The results have been published in the international journal Molecular Ecology.

“These results are important for managing harvest of the stripey snapper (Lutjanus carponotatus), because we had assumed that they moved easily between the Pilbara and Kimberley regions, but it appears that they do not,” Dr DiBattista said.

“We know that the fish must rarely move between the Kimberley and Pilbara because they have strong genetic differences between those regions,” Dr Berry said.

 The researchers were surprised at how narrow the barrier was.

“The transition between fish that have the genetic fingerprints of the Pilbara and the genetic fingerprints of the Kimberley occurs over a very narrow region near the mouth of King Sound,” Dr Berry explained. “Fish that are found within this region are a mix, but outside of that region they are distinctive.”

“This study will improve management of this and potentially other reef fish species across northwestern Australia as it highlights the importance of the techniques used in this research to provide outcomes relevant to management, particularly for species with broad ranges such as the recreationally harvested stripey snapper,” Dr Travers said.

 

Map of sampling sites (yellow dots) for Lutjanus carponotatus across the entire sampling range in Northwestern Australia. The Holloway Current is the dominant current affecting coastal waters of the Kimberley, Canning, and Pilbara bioregions and the Leeuwin Current significantly impacts the Ningaloo and Shark Bay bioregions (adapted from Sprintall et al. 2002; Domingues et al. 2007; D’Adamo et al. 2009; Schiller 2011). Illustration of L. carponotatus © R.Swainston/www.anima.net.au.

 

It’s the first time that scientists have examined how far Kimberley marine animals and plants move.

The research also investigated movement in six other marine species including damselfish, corals, seagrasses and trochus shells.

The final results will be presented at the 2017 WAMSI Research Conference by project leader Dr Oliver Berry (CSIRO) in November.  

Links:

The $30 million Kimberley Marine Research Program is funded through major investment supported by $12 million from the Western Australian government co-invested by the WAMSI partners and supported by the Traditional Owners of the Kimberley.

Category: 

Kimberley Marine Research Program

Dredging Science: Understanding how low light levels can affect coral health

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Research has confirmed that some coral and important reef building algae can sustain being exposed to low light conditions for up to 10 consecutive days before their health is critically affected.

The findings have important implications for the environmental impact assessment and management of dredging operations, which cause sediment plumes.

The results of the Western Australian Marine Science Institution’s Dredging Science Node research, conducted in specially developed tank systems at the AIMS National Sea Simulator (SeaSim), have been published in Scientific Reports.

Lead researcher Pia Bessell-Browne from The University of Western Australia Oceans Institute, Centre for Microscopy, Characterisation and Analysis and Australian Institute of Marine Science said corals and important reef building algae are particularly susceptible to light limitation resulting from elevated sediment particles in the water column which can be generated by naturally occurring events, such as cyclones, as well as coastal development activities such as dredging.

 

Experimental tank set up at the AIMS National Sea Simulator used to determine the impacts of 6 light levels on both coral and algal health. (SeaSim)

 

“This study has determined light levels that need to be maintained in order to reduce negative impacts on the health of coral and reef building algae,” Ms Bessell-Browne explained. “When corals do not receive adequate light, the algae that live within their tissues and provide them with up to 90 per cent of their daily energy requirements leave, meaning the corals are without their main food source and can starve if this condition is maintained over extended time frames.”

A range of low light levels were investigated and their impacts on several species of corals, along with juvenile corals and a species of reef building algae were determined.

 

Photographs of representative A. millepora and P. acuta fragments after 30 d of exposure to the six daily light integral (DLI) irradiance treatments of ~0, 0.02, 0.1, 0.4, 1.1 and 4.3 mol photons m−2 d−1 (Bessel-Browne et al., (2007))

 

“The results demonstrate that both corals and algae are sensitive to exposure to low light conditions for more than 10 consecutive days,” Ms Bessell-Browne said. “Juvenile and adult corals have similar low light tolerance, while the reef building algae is more sensitive to the low light conditions than the corals.”

The thresholds determined by these research findings are expected to contribute to the environmental impact assessment and management of dredge programs where these coral and algae species occur in the field.

Bessell-Browne P, Negri A.P., Fisher R, Clode P.L., Jones R (2017) Impacts of light limitation on corals and crustose coralline algae Scientific Reports doi:10.1038/s41598-017-11783-z

 

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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Dredging Science

Branching corals are better at rejecting dredging sediment

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Researchers working to better predict the likely environmental impacts associated with dredging have found that branching corals are highly adept at cleaning their surfaces of depositing sediments compared to other coral structures.

The Western Australian Marine Science Institution Dredging Science Node study assessed the sediment rejection ability of eight common Indo-Pacific coral species from three different morphologies (coral structures) in a series of short-term exposure tests over a range of sedimentation levels and one longer-term exposure test at a high sediment concentration level.

Australian Institute of Marine Science (AIMS) scientists tested: branching corals, that are made up of thick upright and horizontal branches;  foliose coral, that are more flattened and plate-like; and massive corals, that are characteristically ball or boulder-shaped.

The results, published in the Marine Pollution Bulletin, show that sediment accumulation rates on live corals and dead (enamel-covered) skeletons varied between morphologies, with branching species often more adept at self-cleaning.

Lead researcher, Dr Alan Duckworth explained corals have a range of different ways for shifting sediment primarily involving; mucus entrapment, hydrostatic inflation (the ability of corals to expand tissues, resulting in a shape which better sheds sediments), tentacle movement and ciliary action, which is small threadlike appendages producing strong swirls of water that draw nutrients toward the coral, while driving away waste products.

“These ‘active’ (energy-requiring) processes work in combination with ‘passive’ forces associated with gravity,” Dr Duckworth said. “Both the macroscale morphology (growth form, branch thickness and spacing) and microscale morphology (corallite size and shape) affect how sediments settle, collect and are cleared from the surface.

“We found that flow rates (0–17 cm s− 1) significantly affected the coral’s ability to shed sediment as did differences in particle sizes, with coarse silt rejected faster than fine silt, but only at very high (235 mg cm− 2) deposition rates.

“Noncarbonate siliciclastic sediment was rejected faster than carbonate sediments, and smothering for many days by millimetres of low organic content carbonate sediment resulted in bleaching, but no mortality.

“Estimating the sedimentation rate where the self-cleaning ability of corals is exceeded will improve our ability to make scientifically sound predictions of the likely extent, severity, and persistence of environmental impacts associated with dredging and can also be used with water quality monitoring during dredging to inform adaptive management,” Dr Duckworth said.

Duckworth A, Giofre N, Jones R (2017) Coral morphology and sedimentation Marine Pollution Bulletin doi.org/10.1016/j.marpolbul.2017.08.036

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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Dredging Science

SNAPPING BACK: Saltwater crocodiles back from the brink

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For many people, a primeval fear of large carnivores clouds their ability to see how top-order predators struggle to survive on a planet dominated by an ever-intrusive human population. Lions, tigers, wolves, bears, sharks and crocodiles have all suffered extensive population losses due to the proximity of their habitats to cities and towns. Today, Australia has sophisticated nature management capabilities supported by appropriate legislation and enforcement. However these capabilities were not present when the saltwater crocodile was hunted to the brink of extinction between 1950 and 1970. It was only after a national ban on hunting crocodiles was put in place around 1970 that crocodiles were able to begin a slow process of recovery which continues to this day. FULL STORY

This article appears in the Spring 2017 issue of LANDSCOPE, published by the Department of Biodiversity, Conservation and Attractions. For more information, and to order a copy of the magazine or purchase a subscription, visit shop.dpaw.wa.gov.au.

 

Category: 

Kimberley Marine Research Program

Critical sawfish nursery habitats identified in Fitzroy River

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An eight-year study into the movement of critically endangered sawfish in the isolated freshwater reaches of northwestern Australia’s Fitzroy River has identified the habitats that are important to their survival.

A group of Murdoch University researchers has found that deep pools and shallow environments, like glides, are important habitats for the Freshwater (Largetooth) Sawfish (Pristis pristis) and that restriction of flow or altering of river pathways could jeopardise these environments.

Little is known about the movements of these sawfish which rely on the intermittently flowing rivers and estuaries of the Fitzroy River as a globally significant  nursery. Locally they have been recorded up to 400 kilometres from the coast.

With increasing pressure from fishing and the impact to their migration by instream barriers the researchers, supported by the Western Australian Marine Science Institution, Chevron Australia, Western Australian Government’s State Natural Resource Management Program and people of the Kimberley, including the Nyikina-Mangala Rangers, have been working to identify the habitats and conditions that need to be considered in conservation and management decisions for the region.

Lead researchers Jeff Whitty and Associate Professor David Morgan explained the study, published in Endangered Species Research, was conducted over the 2008 to 2015 dry seasons (May or June to November), when the Fitzroy River is transformed into a series of isolated reaches in which the sawfish are trapped.

Two freshwater reaches of the Fitzroy River were monitored that were located between 120 kilometres and 150 kilometres upstream from the river mouth.

The researchers monitored the movements of 32 juveniles sawfish (952 to 2510 mm in length) using acoustic telemetry, with sound-emitting transmitters tracked by a series of loggers over an eight-year period.

 

 

“This study demonstrated for the first time that juvenile Freshwater Sawfish are least active by day, when they occupy deeper runs and pools near large woody debris,” Mr Whitty said. “They are most active during night-time and twilight hours in shallow water such as glides, pool edges, and shallow runs, when their prey are also more abundant in shallow waters.

“More observations need to be done, however, on why the juvenile sawfish move to the deeper pools in the day,” Mr Whitty said. “It appears unlikely that they are moving to deeper water only to conserve energy in cooler water because, at least during the early dry season, there’s little difference between surface and bottom water temperatures.”

Some of these questions are being addressed by PhD researcher, Karissa Lear, a Forrest Foundation Research Scholar, who is using accelerometers (the same technology that is in FitBits, smart phones, and other smart devices) to study sawfish behaviour.

 

PhD student Karissa Lear with a sawfish pup temporarily held at Kimberley Training Institute in Broome to examine metabolic rate. (David Morgan, Murdoch University)

 

Ms Lear is also examining the metabolic rate of sawfish while they are wearing their accelerometers, which tells how much energy each specific behaviour costs.

“These studies will allow us to put accelerometers on wild sawfish in the Fitzroy, look at what they are doing in their natural environment, estimate how much energy they are using based on their behaviour, and importantly, see how their behavioural patterns, feeding effort, and energy use change throughout the dry season as temperatures increase,” she said.

Links:

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Sawfish Project

Kimberley Marine Research Program final reports

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More than nine final reports for the Western Australian Marine Science Institution Kimberley Marine Research Program will be available online this month delivering the marine research needed to support the management of the marine environments of the Kimberley region.

The $30 million program, which began in 2012, has had up to 160 scientists from 10 partner agencies working across four themes along the 13,500km Kimberley coastline.

Information and updates on the 24 projects is available at www.wamsi.org.au/kmrp/kimberley-marine-research-node-projects.

The final reports that will be available in September include:

Habitats, Biodiversity Assessments and Baselines

1.1.3 ECOLOGICAL CONNECTIVITY: Ecological Connectivity of Kimberley Marine Communities www.wamsi.org.au/ecological-connectivity

Marine Fauna

1.2.4 DOLPHINS: Relative abundance, population genetic structure and acoustic monitoring of Australian snubfin and humpback dolphins in regions within the Kimberley www.wamsi.org.au/ dolphins

Reef Growth and Maintenance

Understanding ecological processes in the Kimberley and their influence on marine biodiversity conservation

 

The $30 million Kimberley Marine Research Program is funded through major investment supported by $12 million from the Western Australian government co-invested by the WAMSI partners and supported by the Traditional Owners of the Kimberley.

Category: 

Kimberley Marine Research Program

WAMSI Kimberley Marine Research Program seminar series available online

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The Kimberley Marine Research Program is presenting its latest research results with two open sessions scheduled for September and seven presentations held at the Department of Biodiversity, Conservation and Attractions (DBCA) in Kensington over the past month. The Lunch and Learn sessions are part of the knowledge transfer process to Kimberley marine managers and stakeholders.

Presentations in September will include:

  • 15 Sep – Marine Turtles (Scott Whiting, Tony Tucker, DBCA) www.wamsi.org.au/marine-turtles (more details to follow on the WAMSI events calendar)
  • 21 Sep – Using models to predict future scenarios in the Kimberley region (Fabio Boschetti, CSIRO) www.wamsi.org.au/modelling-future-kimberley-region    (click here to see event listing)
    As part of the WAMSI Kimberley Marine Research Program, supported by the Kimberley Science and Conservation Strategy, scientists from CSIRO and ALCES (based in Canada) have been building a modelling tool to condense data collected from the KMRP projects to help inform future management decisions that may be required for the marine environment. Researchers have employed the use of two models (Ecopath with Ecosim [EwE] and ALCES) to help improve our understanding of the likely impact of increases in different pressures, and how effective different management strategies might be. Its hoped that such a tool and the outputs will improve capacity to plan and manage the Kimberley’s network of marine reserves. Dr. Fabio Boschetti from CSIRO will give an overview of the initial results from the EwE simulations of impact on the marine environment under different scenarios.  

Links to the presentation abstracts, audio and slides now online are listed below:

  1. Predicting biophysical response to climate change (Dr Ming Feng, CSIRO)
  2. The spatial distribution of humback whales in the Kimberley (Dr MIchelle Thums, AIMS)
  3. Monitoring of Humpback Whales at Pender Bay, southern Kimberley region (Chandra Salgado Kent, Curtin)
  4. Understanding the ‘impact’ of the Ningaloo Research Program (Chris Cvitanovic, UTAS)
  5. The long-term drivers of Environmental Change in King Sound, Kimberley: the Coral record
  6. Impact of the 2015/16 Marine Heatwave and unprecedented Coral Mass Bleaching in the Kimberley Corals
  7. Historical reconstructions from sediment records of water quality as an influence on coral reefs (John Keesing, CSIRO)
     

  8. Predicting biophysical response to climate change (Ming Feng, CSIRO) (29 August)

    www.wamsi.org.au/climate-change#Presentations

As part of the WAMSI Kimberley Marine Research Program, scientists from CSIRO have been using historical data and numerical modelling to investigate how sensitive the coastal marine waters off the Kimberley are to changes in ocean temperature, sea level, and shelf circulations that may be caused by human activity and natural climate drivers in the Indo-Pacific Ocean.

Dr. Ming Feng from CSIRO gives an overview of the sensitivity of coastal sea levels, ocean temperature and precipitation to climate variability such as the Pacific ENSO, with focus on climate drivers of the marine heatwaves off the coast. He also discusses potential impacts of climate change on the physical environment off the Kimberley coast and recent regional downscaling model results that are relevant to the future management of the Kimberley environment.

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  1. The spatial distribution of humback whales in the Kimberley (Michele Thums, AIMS) (8 August)

    www.wamsi.org.au/humpback-whale-monitoring#Presentations

As part of the WAMSI Kimberley Marine Research Program, supported by State Government investment,  scientists from AIMS, Centre for Whale Research, Curtin and the Department have been investigating how humpback whale use of the Kimberley has changed over time and the best methods to continue to monitor the population and its use of Kimberley coastal waters. 

There is a great deal of information on the presence of whales and the recovery of the humpback whale population, much of it recorded by industry. Dr Michele Thums and Dr Mark Meekan from AIMS have worked with Curt Jenner from the Centre for Whale Research to compile existing information on whale presence and distribution across the Kimberley from a variety of sources to produce heat maps of core areas and important habitat. Dr Thums also discusses new cutting edge science looking at the potential for counting whales from space, using satellite imagery to understand how whale numbers and distribution across the Kimberley may change as an alternative to vessel and aerial survey techniques that can be very expensive in the remote Kimberley environment.

  1. Monitoring of Humpback Whales at Pender Bay, southern Kimberley region (Chandra Salgado Kent, Curtin) (8 August)

    Monitoring of Humpback Whales at Pender Bay, southern Kimberley region (Chandra Salgado Kent, Curtin) (8 August) www.wamsi.org.au/humpback-whale-monitoring#Presentations

Another alternative means of monitoring is the use of a land based site manned by volunteers. Dr Chandra Salgado Kent describes a project that has evaluated the data collection methods and five years of data from a community monitoring program at Two Moons Whale and Marine Research Base at Pender Bay on the Dampier Peninsula. She discusses the type of information that can be gained from such a monitoring tool and its applicability in the Kimberley.

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  1. Understanding the ‘impact’ of the Ningaloo Research Program (Chris Cvitanovic, UTAS) (4 August)

    www.wamsi.org.au/news/understanding-%E2%80%98impact%E2%80%99-ningaloo-research-program#presentation

Dr Chris Cvitanovic is an Interdisciplinary Research Fellow in the Centre for Marine Socio-ecology at The University of Tasmania. His research is focused on maximising the real world impacts of scientific research by enhancing knowledge exchange among scientists and decision-makers and improving public engagement in science.

In this presentaiton Chris shares his research evaluating the impact of the Ningaloo Research Program, an extensive program of marine research conducted through WAMSI and the CSIRO Wealth From Oceans program between 2006 and 2011:

The Ningaloo Reef is Australia’s largest fringing coral reef, extending across 300 kilometres of coastline between Exmouth and Carnarvon in Western Australia.  This area is a global biodiversity hotspot and in 2011 was inscribed on the World Heritage List in recognition of the ‘outstanding universal value of the area’. It is also a premier tourist destination, a key service point for oil and gas development and exploration, and supports two permanent communities in Exmouth and Coral Bay.  Given the multiple and competing uses of the region, in 2004 the Western Australian Government allocated $5 million for research to support the management of the Ningaloo Marine Park. This program was then incorporated into the broader WAMSI research program in 2006 and grew in value to $36 million of research funding over ten years.  In this talk, Dr Cvitanovic will present two of the key impacts that have resulted from the Ningaloo Research Program.  First, he provides an overview of the new scientific knowledge that has emerged from the program that can support the ongoing management of the region.  He then presents the results of his current research that explores how the Ningaloo Research Program has enhanced trust between the local Ningaloo communities and WA Department of Biodiversity, Conservaiton and Attractions, and how this can be leveraged to further engage local communities in the management of the region. 

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  1. The long-term drivers of Environmental Change in King Sound, Kimberley: the Coral record (Faye Chen and Malcolm McCulloch, UWA) (27 July)

  2. Impact of the 2015/16 Marine Heatwave and unprecedented Coral Mass Bleaching in the Kimberley Corals (Verena Schoepf, Christoper Cornwall, Steeve Comeau, Morane Le Nohaïc and Malcolm  McCulloch, UWA) (27 July)

     www.wamsi.org.au/calcification#Presentations

The Kimberley region in northwest Australia is a naturally extreme environment that features abundant and highly diverse coral reefs. However, it is currently unknown how Kimberley corals can cope with these extreme conditions and whether this affects their calcification rates and resistance to climate and environmental change. Professor McCulloch from UWA has undertaken research to understand how corals, the key ecosystem engineers on tropical reefs, have adapted and will respond in the future to the extreme variations in physical (e.g., light, temperature, water motion) and chemical (e.g., pCO2, oxygen, and nutrients) conditions characteristic of the Kimberley coastal region.

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  1. Historical reconstructions from sediment records of water quality as an influence on coral reefs (John Keesing, CSIRO) (27 July)

    www.wamsi.org.au/sediment-record#Presentations

Dr John Keesing from CSIRO has been working with a team of researchers to obtain baseline and historical water quality information on the Kimberley so that future impacts and risks can be forecast, better managed and understood in the context of coastal development and global climate change. Dr Keesing describes how this research has used a palaeoecological approach to reconstruct a timeline of change in water quality over the last 100 years using a series of biogeochemical proxies for phytoplankton composition and biomass, temperature and terrestrial influences. Where possible these were matched to historical land/water use, meteorological or hydrological observational records.

The project examined sediment cores from three coastal locations, Koolama Bay (King George River), Cygnet Bay and Roebuck Bay. Each sampling location provided a contrast with which to evaluate changes over either a spatial or temporal gradient of human or natural influence. The presentation gives an overview of the results available to date for all sites but will focus in detail primarily on the analysis of Cygnet Bay samples which gave an indication of the subtle, but long-term effects of pearl oyster farming over the last 60 years and the more abrupt effects of climate change on phytoplankton biomass over the last 20 years and how temperature increases rather than rainfall increases have influenced this. ​

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The $30 million Kimberley Marine Research Program is funded through major investment supported by $12 million from the Western Australian government co-invested by the WAMSI partners and supported by the Traditional Owners of the Kimberley.

 

Category: 

Kimberley Marine Research Program

Study finds early warning triggers for corals during dredging operations

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Effective management of dredging operations requires understanding the effect of the activities on the surrounding environment including important habitats like coral. New research conducted by researchers from the Australian Institute of Marine Science (AIMS) and The University of Western Australia (UWA) has supported decision-making in this field by defining a series of thresholds that can be used to reliably predict the impact of water quality levels on coral health.

The study, conducted as part of the Western Australia Marine Science Institution Dredging Science Node, used a comprehensive water quality and coral monitoring dataset collected by industry during a past dredging project that occurred off Western Australia.

“Essentially, we’ve used this data to understand how turbid the water can get before coral health begins to be affected,” AIMS Ecological Risk Assessment Modeller and lead author Dr Rebecca Fisher said.

The researchers examined water quality measurements, such as light levels, turbidity and sedimentation, and compared them to observed changes in the health of hundreds of individually marked corals that were surveyed each fortnight. This led to an improved understanding of how corals in shallow, reef environments respond to changing water quality which then allowed the team to develop water quality ’trigger-points‘– or thresholds – at which the corals were negatively affected. Cutting-edge modelling techniques were applied to account for uncertainty in the assessment of coral health in order to increase the reliability of the water quality thresholds.

Figure 3 from Fisher et al –  Example coral mortality and water quality data used for analyses, showing time series of proportional live coral cover measurements for representative colonies of each taxa (black circles) and mean daily turbidity (NTU; red lines). Solid black lines represent GAM smooths (see Appendix S2 for details) with grey bands indicating 95% confidence bounds, fitted using a beta distribution to the proportion of live coral cover. Right hand panels show images of each colony at the start of dredging and immediately preceding the start of bleaching (day 203, used as the end point in the present analysis, Figure 2)

 

“The dataset used was particularly valuable because it contained measurements of water quality and coral health close to the dredging, in areas where it was expected and approved by the regulators that corals would be impacted through to areas further away where there was no effect,” Dr Fisher explained. “It’s important to understand how corals respond when exposed to a full range of conditions, including those that are more extreme. This provided the information needed to build a pressure:response curve: without observing those upper limits, you just have no way of finding thresholds.

“This work will be useful to industry to improve confidence in managing dredging operations to protect the environment. It will assist managers and regulators assessing future proposals to provide confidence about the potential impacts to coral reef environments, based on the predicted water quality conditions,” Dr Fisher said.

Links:

 

The WAMSI Dredging Science Node is made possible through $9.5 million invested by Woodside Energy, Chevron Australia and BHP Billiton 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 Australia, Woodside Energy and Rio Tinto Iron Ore. The commercial entities had no role in data analysis, decision to publish, or preparation of the manuscript.

 

Category:

Dredging Science

A thin layer of sediment impacts coral settlement behaviour

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Further research into dredging pressures on coral has revealed that even a very fine layer of sediment can prevent coral larvae from settling on a surface and building on the coral community.

Successful recruitment, where coral larvae attach and establish themselves as part of the adult community, is important for sustaining and recovery of coral reefs.

The research published in the Science of The Total Environment for the Western Australian Marine Science Institution’s Dredging Science Node found that coral larvae avoid sediment-covered surfaces, but will settle nearby on clean substrates including grooves and downward facing surfaces.

 

A conceptual diagram showing possible coral settlement behaviour and cause–effect pathways in response to sediment stressors, such as suspended sediments, deposited sediment and reduced light. (Ricardo et al)

 

The study also looked at how sediment affects coral behaviour with regard to calcareous red algae (CRA), which are rock-hard calcareous algae that contribute significantly to reef calcification and cementation, and induce larval settlement of many benthic organisms including corals.

Study author, Gerard Ricardo, from the Australian Institute of Marine Science, looked at coral settlement on sediment-covered and sediment-free surfaces under controlled conditions at the National Sea Simulator facility in Townsville.

 

VIDEO: A time-lapse of Acropora millepora larvae settling on calcareous red algae (CRA) recorded over 2.5 hours.

 

VIDEO: A time-lapse of Acropora millepora larvae settling on sediment-covered and sediment free calcareous red algae (CRA).

 

“We found a very fine layer of sediment prevents larvae from settling in two ways,” Gerard Ricardo said. “First by creating a physical barrier over the CRA, and second by deteriorating the quality of the CRA. This means that sediment deposited during dredging, and even following some natural deposition events, may influence where larvae settle on a reef.”

“These results have implications for reef recovery and resilience because of the overall reduction in optimal-substrate space, and the flow-on effects for newly-metamorphosed corals that settle in sub-optimal locations,” Mr Ricardo said

 

Ricardo G.F., Jones R.J., Nordborg M, Negri A.P. (2017) Settlement patterns of the coral Acropora millepora on sediment-laden surfaces. Science of the Total Environment doi.org/10.1016/j.scitotenv.2017.07.153

The WAMSI Dredging Science Node is made possible through $9.5 million invested by Woodside Energy, Chevron Australia and BHP Billiton 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 Australia, Woodside Energy and Rio Tinto Iron Ore. The commercial entities had no role in data analysis, decision to publish, or preparation of the manuscript.

Category:

Dredging Science

Award goes to WAMSI sea sponge responses to dredging project

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Three researchers from Western Australian Marine Science Institution’s Dredging Science Node recently presented their findings at the World Sponge Conference in Ireland, with PhD candidate Brian Strehlow winning a prize for best student presentation.

Mr Strehlow, from The University of Western Australia, won the prize for best student presentation in the category of organismal biology, for his full-length presentation (12 minutes with 3 minutes for questions) which elaborated on the mechanisms of resilience to sediment-related stress that some sponge species possess.

“Identifying relative impacts by different types of pressures in combination with thresholds and guidelines will assist managers to reduce the risks and severity of impacts from dredging developments,” Mr Brian Strehlow said.

As part of the presentation, short videos showed that sediments that enter a sponge (Video 1) can be expelled after a return to controlled conditions (Video 2).

 

VIDEO 1: 3D X-ray of Ianthella basta after 48 hours of acute sediment exposure to siliciclastic sediments (shown in white) in the high sediment (135 ± 30 mg L-1) treatment

 

VIDEO 2: 3D X-ray of Ianthella basta after 3 weeks of recovery in control conditions (0 mg L-1) after 48 hours of acute sediment exposure to siliciclastic sediments in the high sediment (135 ± 30 mg L-1) treatment.

 

“Describing these mechanisms was an important part of determining the pressure-response relationships of sponges to sediment-related stress,” Mr Strehlow said.

Dr Mari Carmen Pineda and Team leader Dr Muhammad Abdul Wahab, both from the Australian Institute of Marine Science, also presented talks on their dredging science results.

Whereas Brian Strehlow’s presentation focused on the mechanisms underpinning the resilience of some species, Dr Pineda’s talk (12 min) elaborated on the dose:response relationships and cause:effect pathways for multiple sponge species exposed to sediment stress.

Dr Abdul Wahab presented a talk entitled, “Effects of dredging on benthic filter feeding”. This talk also presented results of the WAMSI research, including field surveys of filter feeding communities before and after dredging.

 

WAMSI project sponge group
Top: Brian Strehlow (PhD candidate; winner best student talk)
Bottom left to right: Cecilia Pascelli (PhD candidate; winner best student talk), Heidi Luter (Post-doc), Blake Ramsby (PhD candidate), Muhammad Abdul Wahab (Post-doc), Mari-Carmen Pineda (Post-doc)

 

Presentations

Pineda MC, Strehlow B, Duckworth A, Jones R (2017) Pressure-response relationships of sponges to dredge pressures – a laboratory approach. 10th World Sponge Conference. Sponges & their Environment ABSTRACT

Strehlow B, Pineda MC,  Duckworth A, Clode P, Webster N (2017) Sub-lethal stress responses of sponges to dredging pressures. 10th World Sponge Conference. Sponges & their Environment. ABSTRACT

Wahab MAA, Fromont J, Gomez O, Fisher R, Jones R (2017) Effects of dredging on benthic filter feeding communities. 10th World Sponge Conference. Ecosystems & Environment. ABSTRACT

Posters

Fromont J, Wahab MAA, Gomez O, Ekins Merrick, Goverdina Geerruida Grol M, Hooper J.N.A. (2017) North-western Australia: a sponge biodiversity hotspot. 10th World Sponge Conference ABSTRACT

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The WAMSI Dredging Science Node is made possible through $9.5 million invested by Woodside Energy, Chevron Australia and BHP Billiton 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 Australia, Woodside Energy and Rio Tinto Iron Ore. The commercial entities had no role in data analysis, decision to publish, or preparation of the manuscripts.

Category:

Dredging Science