Muddying the waters: The science of protecting the environment during dredging

Styan, Craig; Hanley, Jessica

doi:10.1080/18366503.2013.10815746

Cited by 5 publications

(5 citation statements)

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“…In this analysis, we use novel statistical approaches and mathematical tools to derive in situ dose – response relationships and critical thresholds for the management of dredging using information collected during a capital dredging project that occurred near the reefs around Barrow Island (Western Australia). The monitoring associated with this project went beyond that required by the regulatory framework and involved continuous water quality monitoring concurrent with health measurements of hundreds of corals examined at two weekly intervals across 26 sites (Styan & Hanley, ) located along a gradient from 200 m to up to 30 km away from the dredging.…”

Section: Introductionmentioning

confidence: 99%

Accounting for environmental uncertainty in the management of dredging impacts using probabilistic dose–response relationships and thresholds

Fisher

Walshe

Bessell-Browne

et al. 2017

Journal of Applied Ecology

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Dredging and related activities are common across nearshore marine environments, potentially threatening nearby ecosystems. Regulatory frameworks are essential for minimizing environmental impacts, yet rely heavily on a sound understanding of how ecosystems will respond to environmental stressors, and the thresholds that delineate benign and harmful conditions. Here, we use novel statistical approaches and mathematical tools to account for uncertainty in deriving in situ dose–response relationships and thresholds for the environmental management of dredging, based on estimates of the probability of non‐zero mortality of corals during a dredging campaign at Barrow Island, Western Australia. Using modified receiver operating characteristic curves, we derive thresholds with explicit Type I and Type II errors rates, across the full range of primary stress pathways and exposure dimensions (intensity, frequency and duration). Monitoring coral health and mortality can be expensive and water quality indicators are often used to supplement direct receptor monitoring during dredging management. We found strong relationships between coral mortality and a range of water quality exposure metrics, lending support to the use of water quality metrics as management tools for protecting corals during dredging. Metrics based on sediment deposition were more statistically powerful than those based on either light or turbidity, but may be more difficult to implement in practice. Thresholds reflecting aversion to a false sense of security in environmental protection or aversion to the costs of false alarms varied substantially for all exposure metrics examined. Synthesis and applications. Strategies for managing environmental harm under uncertainty are critical to achieving an informed risk‐weighted balance between environmental protection outcomes and development costs. Our study demonstrates the complexities of how communities respond to variable environmental exposure across a range of pressures in time and space, and the value of integrating probabilistic approaches in environmental management to account for that complexity and its associated uncertainty. Coral mortality was strongly related to a range of water quality exposure metrics associated with dredging activities, and regulatory thresholds based on water quality can provide a solid and cost‐effective foundation for protecting corals during dredging. The probabilistic dose–response relationships and thresholds presented here are the first to be derived from in situ data using dredging related coral mortality and represent a step forward in integrating formal decision science approaches into environmental management.

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Section: Introductionmentioning

confidence: 99%

Accounting for environmental uncertainty in the management of dredging impacts using probabilistic dose–response relationships and thresholds

Fisher

Walshe

Bessell-Browne

et al. 2017

Journal of Applied Ecology

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show abstract

“…Whilst there is a wealth of existing information, derived from the suite of scientific and collaborative programs associated with offshore developments in the past few decades, and from a large number of commercially funded studies, value for money will be maximised when the long-term benefits of the accumulated work are combined with all the appropriate science, some of which has yet to be performed. Here, success to date is not necessarily clear (Hanley, 2011;Falkenberg & Styan 2014) despite costs having been significant, such as on the Gorgon project (Styan & Hanley, 2013).…”

Section: The Northwest Shelfmentioning

confidence: 99%

“…As a result, the critical factor becomes the significance of the magnitude of the measurement uncertainties to the intended purpose of the measurements. Associated with the location of coastal and offshore developments, a large number of measurement campaigns have been made in association with EIA and monitoring on the continental shelves of northern Australia, such as the NWS (Styan & Hanley, 2013) and the GBR shelf (Benson et al 1994;MacDonald et al 2013;Fabricius et al, 2013). Here, the OBS has been the instrument of choice for regulators and biologists alike, in trying to assess the natural and anthropogenic influences upon the biology, associated with changes in 'water quality' and 'sedimentation'.…”

Section: Case Study 1 -Turbidity Measurementmentioning

confidence: 99%

“…Taken together, the above list constitutes a strong argument for new regulatory-focussed work to develop the understanding of the relevant physical systems, so that context is firmly established and individual developments do not themselves become expensive experiments (e.g. Styan & Hanley, 2013).…”

Section: What Contribution Can Turbidity Data Make?mentioning

confidence: 99%

“…Whitlam, 2013). These activities have caused considerable direct impact on the physical environment, especially in relation to dredging works (Styan and Hanley, 2013). Our concern is that the consequences of these environmental changes are not fully understood, owing to a deficiency in the application of the physical sciences in environmental impact assessment (EIA) decision-making processes.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Managing marine environments and decision-making requires better application of the physical sedimentary sciences

Larcombe

Morrison‐Saunders

2017

Australasian Journal of Environmental Management

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Effective management of marine environments requires a sound understanding of the relevant physical sedimentary sciences. Environmental impact assessment (EIA) is a key management and decision-making tool employed in Australia for coastal and marine developments. This article examines the veracity of the application of the marine physical sciences within the EIA process, using turbidity measurement and sediment transport pathways as examples. A review of EIA guidance reveals deficiencies in regulation. Turbidity measurement is poorly understood and performed in current practice, while a focus on protecting marine habitats largely ignores those physical sedimentary processes, such as long-term bed-sediment transport pathways, that create and maintain these habitats. Thus evaluations of impacts of offshore activities such as channel dredging and spoil emplacement at sea are fundamentally flawed. An extensive body of scientific knowledge is already available on marine physical processes, and equivalent information for assessments of terrestrial development is routinely taken into consideration. Perhaps practice for the marine environment lags behind that for terrestrial settings or is it a case of 'out of sight-out of mind'? We call on environmental management professionals to increase engagement with the physical processes that determine the quality of marine environments.

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Patterns of fish use in urban estuaries: Engineering maintenance schedules to protect broader seascape habitat

Waltham

McCann²,

Power³

et al. 2020

Estuarine, Coastal and Shelf Science

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Muddying the waters: The science of protecting the environment during dredging

Cited by 5 publications

References 0 publications

Accounting for environmental uncertainty in the management of dredging impacts using probabilistic dose–response relationships and thresholds

Accounting for environmental uncertainty in the management of dredging impacts using probabilistic dose–response relationships and thresholds

Managing marine environments and decision-making requires better application of the physical sedimentary sciences

Patterns of fish use in urban estuaries: Engineering maintenance schedules to protect broader seascape habitat

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