An Overview of Risk Assessment in a Marine Biosecurity Context
Our ability to manage the variety of human induced stresses in the marine environment is hampered by limited resources, a lack of fundamental knowledge and the absence of appropriate tools (Lubchenco et al. 1991; Norse 1993). This is particularly true whe
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An Overview of Risk Assessment in a Marine Biosecurity Context Marnie L. Campbell
20.1
Introduction
Our ability to manage the variety of human induced stresses in the marine environment is hampered by limited resources, a lack of fundamental knowledge and the absence of appropriate tools (Lubchenco et al. 1991; Norse 1993). This is particularly true when faced with introduced marine species. Structured and transparent evaluation techniques that both determine and justify management decisions are needed to effectively deal with introduced marine species in both an ecological and socio-political sense (as discussed by Hewitt et al., Chap. 33). Coupling this need with knowledge, resource and data limitations has led decision makers and management to use risk assessment as a means to direct their actions. In simple terms, risk assessment is a method of evaluating the likelihood that an event may occur and the consequences of such an event. In general, ecological risk assessment proceeds by establishing the context (e.g., introduced species in a region; hazard analysis); identifying the risk, hazards and effects (e.g., impacts on core values); assessing those risks (analyse and evaluate the risks); and treating the risk(s) (e.g., incursion response activity, mitigation, Australian Risk Management Guidelines; Standards Australia 2000, 2004). A measure of risk is derived by multiplying likelihood by consequence. Hazard analysis (a technique often confused with risk assessment) determines the actions, events, substances, environmental conditions, or species that could result in an undesired event, but does not identify the likelihood or the level of consequence. Introduced species, vectors or transport pathways are all examples of hazards. Likelihood is the probability that an event may occur. Typically, likelihood will range from rare occurrence to highly likely (or frequent). Consequence, on the other hand, measures the impact an event may have on the values being assessed and can be derived by measuring the change in value from a pre- and post impacted system. Although monetary units are often used to measure change in value (because they are easily understood and facilitate comparison) this does not have to be the unit of measure; semi-quantitative categorical ranking (e.g., low, medium, high value) is also possible.
G. Rilov, J.A. Crooks (eds.) Biological Invasions in Marine Ecosystems. Ecological Studies 204, © Springer-Verlag Berlin Heidelberg 2009
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In general, when management uses risk assessment to evaluate introduced marine species, they ask the question “what is the likelihood that a species will arrive in our region”, or “what impacts (consequences) will that species have on our native biota”.
20.1.1
Defining Endpoints
Before undertaking a risk assessment, the risk endpoint must be identified and agreed. Endpoint selection will determine the null hypothesis that is tested during the analysis. With introduced species risk assessments, the endpoint tends to be either: (a) quaranti
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