Species biofouling risk assessment

Abstract

Marine biological invasions have increased throughout the world’s oceans to the extent that no region is considered ‘pristine’. At least 1781 species have been identified as introduced in marine or estuarine systems somewhere in the world. Many of these species have been introduced to several regions, inferring an ease of transport by human-mediated mechanisms. A substantial number of these species have either demonstrable or inferred impacts. Marine species have been transported around the world in many ways, both intentionally and accidentally. Concern has typically focused on vessel traffic, specifically the transport of species in ballast water, which is used for trim and stability of commercial vessels. This led to the development of the International Maritime Organization’s International convention for the control and management of ship's ballast water and sediments that was adopted in 2004. More recently, attention has shifted to species that attach to the external surfaces of vessels, including commercial, fishing, and non-trading vessels such as barges, dredges, tugs and recreational yachts. Such species are collectively known as biofouling. Science-based risk assessment is a key element of Australia’s biosecurity system and underpins the nation’s biosecurity policies. However, there are currently no Australian regulatory measures for preventing the introduction of invasive marine species through biofouling. The objective of this project was to conduct a risk assessment to identify and assess the biosecurity risk to Australia associated with the entry, establishment and spread of marine pest species as biofouling. This risk assessment is therefore intended to inform Australian Government policy development for continued management of marine pest risks as biofouling. The risk assessment followed a five-step process: identifying endpoints identifying hazards determining consequences determining likelihood calculating risk. Risk was evaluated across three identified endpoints: inoculation, establishment and spread. International voyages to Australia were assessed for the risk they pose in relation to inoculation and establishment. Likelihood of domestic spread was assessed through analysis of domestic movement of international shipping, other domestic vessel movements/traffic and through natural means. Key hazards for Australia were deemed to be those species with a recognised invasion history, but not currently known to be present in Australian waters. More than 1781 species that have been identified as being introduced to some region of the world were evaluated for their association with biofouling and transport pressure. Species association with biofouling was assessed on the basis of life history characteristics. Transport pressure was calculated as a function of the intersection between a species’ global distribution and the opportunities for transport calculated as a combination of the number of vessels arriving in Australia from regions where a species is present. The consequence (or impact) was assessed for each species on four core values of environment, economic, social/cultural and human health, based on information derived from the literature. The vast majority of species had neither demonstrable nor inferred impacts stated in the published literature, significantly decreasing the ability to assess risk. For those species with available information about their consequence, risk was calculated as the product of likelihood and consequence. The result of this analysis was a restricted suite of 56 species that have a high probability of arrival into Australian waters and the potential to cause moderate to extreme impacts across one or more of the four core values if successfully introduced