Western Australian Marine Science Institution
Western Australian Marine Science Institution
Bessell-Browne P.,Australian Institute of Marine Science |
Bessell-Browne P.,University of Western Australia |
Bessell-Browne P.,Western Australian Marine Science Institution |
Fisher R.,Australian Institute of Marine Science |
And 5 more authors.
Ecological Indicators | Year: 2017
Some coral species of the genus Porites can produce thick mucous sheets that partially or completely envelope the colony's surface. This phenomenon has been reported many times, but the cause and ecological significance remains unclear. In this study, sheet production was examined in response to elevated suspended sediment concentrations associated with a large-scale, extended dredging project on a coral reef. Approximately 400 corals at 16 locations situated from 0.2–33 km from the excavation area were examined at fortnightly intervals over the 1.5 year dredging campaign. Mucous sheets were observed on 447 occasions (from 10,600 observations), with average mucous prevalence ranging from 0–10%. Overall 74 ± 5% of the colonies <1.5 km from the dredging produced one or more sheets. High levels of mucous coverage (≥95% of the colony surface) was observed on 68 occasions, and 82% of these occurred at sites close to the dredging. Approximately 50% of colonies produced ≥3 sheets over the monitoring period, and 90% of these were located close to the dredging. In contrast, at distantly located reference sites (>20 km away), mean mucous sheet prevalence was very low (0.2% ± 0.1), no colonies produced more than 1 sheet, and only 1 colony was observed with high mucous coverage. In a laboratory-based experiment, explants of Porites spp. exposed to fine silt also produced mucous sheets (105 sheets recorded in 1100 observations), with nearly 30% of the fragments exposed to repeated sediment deposition events of 10 and 20 mg cm−2 d−1 producing 2 new sheets over the 28 day exposure period. These multiple lines of evidence suggest a close association between mucous sheet formation and sediment load, and that sheet formation and sloughing are an additional mechanism used by massive Porites spp. to clear their surfaces when sediment loads become too high. These results suggest that mucous sheet formation is an effective bioindicator of sediment exposure. © 2017 The Author(s)
Duckworth A.,Australian Institute of Marine Science |
Giofre N.,Australian Institute of Marine Science |
Jones R.,Western Australian Marine Science Institution
Marine Pollution Bulletin | Year: 2017
The sediment rejection ability of 8 coral species of 5 families and 3 morphologies were assessed in a series of short term exposure tests over a sedimentation range of 0.5-40mgcm-2 d-1 and one longer term exposure test of 235mgcm-2. Sediment accumulation rates on live corals and dead (enamel-covered) skeletons varied between morphologies, with branching species often more adept at self-cleaning. Flow rates (0-17cms-1) significantly affected sediment-shedding ability as did differences in particle sizes, with coarse silt rejected faster than fine silt, but only at very high (235mgcm-2) deposition rates. Siliciclastic sediment was rejected faster than carbonate sediments and smothering for many days by mms of low organic content carbonate sediment resulted in bleaching, but no mortality. The findings are discussed with respect to turbidity generated in natural and dredging-related resuspension events and in the context for impact prediction for dredging projects. © 2017.
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 4 more authors.
Science of the Total Environment | Year: 2017
Successful recruitment in corals is important for the sustenance of coral reefs, and is considered a demographic bottleneck in the recovery of reef populations following disturbance events. Yet several factors influence larval settlement behaviour, and here we quantified thresholds associated with light attenuation and accumulated sediments on settlement substrates. Sediments deposited on calcareous red algae (CRA) directly and indirectly impacted coral settlement patterns. Although not avoiding direct contact, Acropora millepora larvae were very reluctant to settle on surfaces layered with sediments, progressively shifting their settlement preference from upward to downward facing (sediment-free) surfaces under increasing levels of deposited sediment. When only upward-facing surfaces were presented, 10% of settlement was inhibited at thresholds from 0.9 to 16 mg cm− 2 (EC10), regardless of sediment type (carbonate and siliciclastic) or particle size (fine and coarse silt). These levels equate to a very thin (< 150 μm) veneer of sediment that occurs within background levels on reefs. Grooves within settlement surfaces slightly improved options for settlement on sediment-coated surfaces (EC10: 29 mg cm− 2), but were quickly infilled at higher deposited sediment levels. CRA that was temporarily smothered by sediment for 6 d became bleached (53% surface area), and inhibited settlement at ~ 7 mg cm− 2 (EC10). A minor decrease in settlement was observed at high and very low light intensities when using suboptimal concentrations of a settlement inducer (CRA extract); however, no inhibition was observed when natural CRA surfaces along with more realistic diel-light patterns were applied. The low deposited sediment thresholds indicate that even a thin veneer of sediment can have consequences for larval settlement due to a reduction of optimal substrate. And while grooves and overhangs provide more settlement options in high deposition areas, recruits settling at these locations may be subject to ongoing stress from shading, competition, and sediment infilling. © 2017
News Article | December 14, 2015
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
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 |
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.
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.