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News Article | December 14, 2015
Site: phys.org

Together CSIRO, the Western Australian Marine Science Institution (WAMSI), and four Kimberley Aboriginal organisations recently took to the skies to conduct aerial surveys of dugongs—a shy marine mammal that is said to have sparked the legend of mermaids. The information gleaned from the surveys will provide will provide a baseline from which they can create management strategies to help conserve dugongs in the future, according to CSIRO oceans and atmosphere researcher Peter Bayliss. The Kimberley dugong population is both environmentally and culturally important, Mr Bayliss says. "They are considered a keystone species ecologically and are also culturally significant to Aboriginal coastal communities, providing a valuable food source," Mr Bayliss says. "There is a deep cultural knowledge of dugongs in the Kimberley and this will be combined with scientific knowledge for their future management. Dugongs are listed globally as 'vulnerable to extinction' and northern Australia and Torres Strait are thought to be home to the largest remaining healthy populations in the world. However, until now the Kimberley was one of the few areas that had not been subject to scientific survey. Aboriginal rangers from the Balanggarra, Wunambal Gaambera, Dambimangari and Bardi Jawi Native Title groups learnt the techniques of aerial surveying as part of a three-day accredited training course. They then put these skills into practice by boarding a Gippsland G8 Airvan to survey dugongs by flying east-west transect lines over about 30,000 square kilometres of coastal waters—an area nearly half the size of Tasmania. The survey plane flew at a constant height and speed to obtain consistent counts—152m above the water and 185 kilometres per hour—with participants counting dugongs sighted within a 200m strip on each side of the aircraft. They flew 14,000 kilometres during the 18-day survey. The aerial surveying course and surveys are part of the WAMSI Kimberley Marine Science Program's Dugong Management project being run through the Coastal Program of the CSIRO Oceans and Atmosphere Flagship. Explore further: New book inspires children to protect dugongs


Yeo S.,Murdoch University | Yeo S.,Western Australian Marine Science Institution | Keesing J.K.,CSIRO | Keesing J.K.,Western Australian Marine Science Institution | And 2 more authors.
Invertebrate Reproduction and Development | Year: 2015

The reproductive biology of the sand dollar Peronella lesueuri was studied between 2009 and 2011 in Cockburn Sound, a large coastal embayment in south-Western Australia. Individuals of P. lesueuri did not display sexual size-dimorphism, and the population was found to have a sex ratio of 1:1. Maturity occurred over the range of 80-115 mm with all sand dollars larger than 115 mm having distinct gonads. Monthly histological analysis of gonads and changes in oocyte proportions over time indicated that P. lesueuri has an annual reproductive cycle; gametogenesis occurs in spring and spawning in summer. Differences in the rate of gametogenesis between 2009/2010 and 2010/2011 may have been influenced by higher temperatures experienced in 2010/2011. P. lesueuri have large ova (mean = 210 μm), which suggests the species has lecithotrophic larval development. © 2015 Taylor & Francis.


Feng M.,CSIRO | Feng M.,Western Australian Marine Science Institution | Hendon H.H.,CAWCR | Xie S.-P.,University of California at San Diego | And 6 more authors.
Geophysical Research Letters | Year: 2015

Ningaloo Niño refers to the episodic occurrence of anomalously warm ocean conditions along the subtropical coast of Western Australia (WA). Ningaloo Niño typically develops in austral spring, peaks in summer, and decays in autumn, and it often occurs in conjunction with La Niña conditions in the Pacific which promote poleward transport of warm tropical waters by the Leeuwin Current. Since the late 1990s, there has been a marked increase in the occurrence of Ningaloo Niño, which is likely related to the recent swing to the negative phase of the Interdecadal Pacific Oscillation (IPO) and enhanced El Niño-Southern Oscillation variance since 1970s. The swing to the negative IPO sustains positive heat content anomalies and initiates more frequent cyclonic wind anomalies off the WA coast so favoring enhanced poleward heat transport by the Leeuwin Current. The anthropogenically forced global warming has made it easier for natural variability to drive extreme ocean temperatures in the region. Key Points There has been an increased frequency of Ningaloo Niño since late 1990s Negative IPO sustains positive heat content anomalies and strong Leeuwin Current Global warming and natural variability together drive extreme ocean temperatures ©2014. American Geophysical Union. All Rights Reserved.


Liu D.,CAS Yantai Institute of Coastal Zone Research | Peng Y.,CAS Yantai Institute of Coastal Zone Research | Peng Y.,University of Chinese Academy of Sciences | Keesing J.K.,CSIRO | And 3 more authors.
Marine Ecology Progress Series | Year: 2016

Small environmental disturbances accumulating over a long period of time may cause a regime shift in marine ecosystems, particularly in sensitive oligotrophic waters. Pearl oyster aquaculture, which has a 50 yr history in Australia, has been regarded as an anthropogenic activity with low environmental risk. To assess the long-term environmental effects of pearl oyster farming, sediment cores taken in Cygnet Bay, Western Australia, were used to reconstruct environmental processes covering an approximately 90 yr period. Biogeochemical parameters in sediment cores from inside and outside a pearl farming area displayed contrasting characteristics over time. Total organic carbon, total nitrogen, biogenic silica (BSi), and fine-grained sediment at the farming site displayed significant increases with the expansion of oyster stocking. In contrast, only small variations in response to climatic signals (rainfall and temperature) occurred over time in the cores outside the farm. The variation in the C:N ratio, δ13C and δ15N ranges over time suggested that increased organic matter was mainly contributed by autochthonous sources rather than terrestrial input. The sequential t-test for a regime shift detected approximately 2-to 3-fold increases in organic matter, 1-to 5-fold increases in silt proportion and 2-to 5-fold increases in BSi concentrations after pearl oyster farming, in contrast to the control site. The rapid development of modern long-line culture since the late 1980s is presumed to have been the dominant driver of environmental changes in sediments. The results provide insight into the magnitude of environmental change which can occur over decades as a result of even minimal anthropogenic activity. © 2016 Inter-Research.


Fisher R.,Australian Institute of Marine Science | Fisher R.,Western Australian Marine Science Institution | Fisher R.,University of Western Australia | Stark C.,Western Australian Marine Science Institution | And 6 more authors.
PLoS ONE | Year: 2015

Dredging poses a potential risk to tropical ecosystems, especially in turbidity-sensitive environments such as coral reefs, filter feeding communities and seagrasses. There is little detailed observational time-series data on the spatial effects of dredging on turbidity and light and defining likely footprints is a fundamental task for impact prediction, the EIA process, and for designing monitoring projects when dredging is underway. It is also important for public perception of risks associated with dredging. Using an extensive collection of in situ water quality data (73 sites) from three recent large scale capital dredging programs in Australia, and which included extensive pre-dredging baseline data, we describe relationships with distance from dredging for a range of water quality metrics. Using a criterion to define a zone of potential impact of where the water quality value exceeds the 80th percentile of the baseline value for turbidity-based metrics or the 20th percentile for the light based metrics, effects were observed predominantly up to three km from dredging, but in one instance up to nearly 20 km. This upper (∼20 km) limit was unusual and caused by a local oceanographic feature of consistent unidirectional flow during the project. Water quality loggers were located along the principal axis of this flow (from 200 m to 30 km) and provided the opportunity to develop a matrix of exposure based on running means calculated across multiple time periods (from hours to one month) and distance from the dredging, and summarized across a broad range of percentile values. This information can be used to more formally develop water quality thresholds for benthic organisms, such as corals, filter-feeders (e.g. sponges) and seagrasses in future laboratory- and field-based studies using environmentally realistic and relevant exposure scenarios, that may be used to further refine distance based analyses of impact, potentially further reducing the size of the dredging footprint. © 2015 Fisher et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.


Jones R.,Australian Institute of Marine Science | Jones R.,Western Australian Marine Science Institution | Bessell-Browne P.,Australian Institute of Marine Science | Bessell-Browne P.,University of Western Australia | And 5 more authors.
Marine Pollution Bulletin | Year: 2016

There is a need to develop water quality thresholds for dredging near coral reefs that can relate physical pressures to biological responses and define exposure conditions above which effects could occur. Water quality characteristics during dredging have, however, not been well described. Using information from several major dredging projects, we describe sediment particle sizes in the water column/seabed, suspended sediment concentrations at different temporal scales during natural and dredging-related turbidity events, and changes in light quantity/quality underneath plumes. These conditions differ considerably from those used in past laboratory studies of the effects of sediments on corals. The review also discusses other problems associated with using information from past studies for developing thresholds such as the existence of multiple different and inter-connected cause-effect pathways (which can confuse/confound interpretations), the use of sediment proxies, and the reliance on information from sediment traps to justify exposure regimes in sedimentation experiments. © 2015.


Jones R.,Australian Institute of Marine Science | Jones R.,Western Australian Marine Science Institution | Jones R.,University of Western Australia | Fisher R.,Australian Institute of Marine Science | And 6 more authors.
PLoS ONE | Year: 2015

Maintenance and capital dredging represents a potential risk to tropical environments, especially in turbidity-sensitive environments such as coral reefs. There is little detailed, published observational time-series data that quantifies how dredging affects seawater quality conditions temporally and spatially. This information is needed to test realistic exposure scenarios to better understand the seawater-quality implications of dredging and ultimately to better predict and manage impacts of future projects. Using data from three recent major capital dredging programs in North Western Australia, the extent and duration of natural (baseline) and dredging-related turbidity events are described over periods ranging from hours to weeks. Very close to dredging i.e. <500 m distance, a characteristic features of these particular case studies was high temporal variability. Over several hours suspended sediment concentrations (SSCs) can range from 100-500 mg L-1. Less turbid conditions (10-80 mg L-1) can persist over several days but over longer periods (weeks to months) averages were <10 mg L-1. During turbidity events all benthic light was sometimes extinguished, even in the shallow reefal environment, however a much more common feature was very low light 'caliginous' or daytime twilight periods. Compared to pre-dredging conditions, dredging increased the intensity, duration and frequency of the turbidity events by 10-, 5- and 3-fold respectively (at sites <500 m from dredging). However, when averaged across the entire dredging period of 80-180 weeks, turbidity values only increased by 2-3 fold above pre-dredging levels. Similarly, the upper percentile values (e.g., P99, P95) of seawater quality parameters can be highly elevated over short periods, but converge to values only marginally above baseline states over longer periods. Dredging in these studies altered the overall probability density distribution, increasing the frequency of extreme values. As such, attempts to understand the potential biological impacts must consider impacts across telescoping-time frames and changes to extreme conditions in addition to comparing central tendency (mean/median). An analysis technique to capture the entire range of likely conditions over time-frames from hours to weeks is described using a running means/percentile approach. © 2015 Jones et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.


Ricardo G.F.,University of Western Australia | Ricardo G.F.,Australian Institute of Marine Science | Ricardo G.F.,Western Australian Marine Science Institution | Jones R.J.,Australian Institute of Marine Science | And 5 more authors.
PLoS ONE | Year: 2016

Suspended sediments produced from dredging activities, or added to the sediment budget via river runoff, are a concern for marine resource managers. Understanding the impact of suspended sediments on critical life history stages of keystone species like corals is fundamental to effective management of coastlines and reefs. Coral embryos (Acropora tenuis and A. millepora) and larvae (A. tenuis, A. millepora and Pocillopora acuta) were subjected to a range of suspended sediment concentrations of different sediment types (siliciclastic and carbonate) to assess concentration-response relationships on ecologically relevant endpoints, including survivorship and ability to metamorphose. Embryos were subjected to short (12 h) suspended sediment exposures from ages of 3-12 hours old or a long (30 h) exposure at 6 hours old. Neither the survivorship nor metamorphosis function of embryos were significantly affected by realistic sediment exposures to ∼1000 mg L-1. However, some embryos exhibited a previously undescribed response to dynamically suspended sediments, which saw 10% of the embryos form negatively buoyant cocoons at siliciclastic suspended sediment concentrations ≥35 mg L-1. Scanning electron and optical microscopy confirmed the presence of a coating on these embryos, possibly mucus with incorporated sediment particles. Cocoon formation was common in embryos but not in larvae, and occurred more often after exposure to siliciclastic rather than carbonate sediments. Once transferred into sediment-free seawater, functional ∼36-h-old embryos began emerging from the cocoons, coinciding with cilia development. Ciliated (>36-h-old) larvae exposed to suspended sediments for 60 h were also observed to secrete mucus and were similarly unaffected by suspended sediment concentrations to ∼800 mg L-1. This study provides evidence that mucous secretion and cilia beating effectively protect coral embryos and larvae from suspended sediment and that these mechanisms may enhance their chances of successful recruitment. © 2016 Ricardo et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.


PubMed | Western Australian Marine Science Institution and Australian Institute of Marine Science
Type: Journal Article | Journal: PloS one | Year: 2015

Dredging poses a potential risk to tropical ecosystems, especially in turbidity-sensitive environments such as coral reefs, filter feeding communities and seagrasses. There is little detailed observational time-series data on the spatial effects of dredging on turbidity and light and defining likely footprints is a fundamental task for impact prediction, the EIA process, and for designing monitoring projects when dredging is underway. It is also important for public perception of risks associated with dredging. Using an extensive collection of in situ water quality data (73 sites) from three recent large scale capital dredging programs in Australia, and which included extensive pre-dredging baseline data, we describe relationships with distance from dredging for a range of water quality metrics. Using a criterion to define a zone of potential impact of where the water quality value exceeds the 80th percentile of the baseline value for turbidity-based metrics or the 20th percentile for the light based metrics, effects were observed predominantly up to three km from dredging, but in one instance up to nearly 20 km. This upper (~20 km) limit was unusual and caused by a local oceanographic feature of consistent unidirectional flow during the project. Water quality loggers were located along the principal axis of this flow (from 200 m to 30 km) and provided the opportunity to develop a matrix of exposure based on running means calculated across multiple time periods (from hours to one month) and distance from the dredging, and summarized across a broad range of percentile values. This information can be used to more formally develop water quality thresholds for benthic organisms, such as corals, filter-feeders (e.g. sponges) and seagrasses in future laboratory- and field-based studies using environmentally realistic and relevant exposure scenarios, that may be used to further refine distance based analyses of impact, potentially further reducing the size of the dredging footprint.


Kordi M.N.,Curtin University Australia | Kordi M.N.,Western Australian Marine Science Institution | O'Leary M.,Curtin University Australia | O'Leary M.,Western Australian Marine Science Institution
Regional Studies in Marine Science | Year: 2016

Coral reefs occur extensively along the northwest Australian continental shelf in the Kimberley Bioregion (KIM), forming major geomorphic features along and just off the coast. These reefs have not been studied in as much detail as the offshore reefs and are poorly known due to the coastal conditions, including extremely high tide regimes, high turbidity and complex coastline morphology. This study aims to establish a regional-scale distribution map of exposed and intertidal reefs of the KIM and to classify the Kimberley reefs into types, adopting widely recognised reef classification and typology schemes. Remote sensing and Geographic Information Systems (GIS) were used in this study to process and produce digital maps as well as to provide some of the first detailed spatial analysis of reef distribution. Outcomes of this study showed that the Kimberley reefs possess strong morphological complexity and clear regional patterns. The study revealed that the number of Kimberley reefs and their area are considerably (60%) greater than previously thought; the total combined reefal area is approximately 1,950 km2. Fringing reefs have been identified as the dominant reef type and are widely distributed throughout the KIM. It was also found that tidal range affected the distribution of reef geomorphologies. The outcomes of this study will contribute to a better understanding of the Kimberley reefs, and provide marine park managers with essential and quality scientific information so that better management decisions can be made in this area. © 2016 Elsevier B.V. All rights reserved.

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