Marine Biofouling and Invasive Species: Guidelines for Prevention and Management
MARINE BIOFOULING AND INVASIVE SPECIES: GUIDELINES FOR PREVENTION AND MANAGEMENT 1. INTRODUCTION AND BACKGROUND 1.1 Invasive species in the marine environment An invasive alien species is one which has been introduced by human activity to a new geographic area or ecosystem outside of its natural distribution range, and which has then established and spread threatening ecosystems, habitats and/or other species, and potentially causing economic and/or environmental damage, or harm to human health. It is important to note, however, that native species may also become invasive, usually under altered environmental conditions. Invasive Alien Species in the marine environment are called by a variety of names including Introduced Marine Pests (IMPs) (Australia and New Zealand), Aquatic Nuisance Species (ANS) (United States), and Harmful Aquatic Organisms (IMO Ballast Water Convention). For a number of marine species, the original, natural distribution has been blurred by centuries of transfers via sailing ships, canals, barges, aquaculture, etc., so that it is now difficult to tell whether they are alien or not. In fact, in some regions many historical introductions had been assumed to be part of the native marine community until recent studies raised questions. Examples include several common fouling organisms and wood- borers, such as the infamous bivalve ‘shipworm’ (Teredo navalis), the ship or striped barnacle (Balanus amphitrite), both blue (Mytilus) and brown (Perna) mussel complexes and some oyster species. These widespread and so-called ‘cosmopolitan’ marine species are known as cryptogenic species (Carlton, 1996a). Invasive alien species are now generally recognised as one of the greatest threats to biodiversity globally. In marine and coastal environments, invasive species have been identified as one of the four greatest threats to the world’s oceans along with: • land-based sources of marine pollution, • over-exploitation of living marine resources, and • physical alteration/destruction of marine habitats.
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