INVASIVE NON-NATIVE SPECIES

Status and Trends

new introductions continue (status deteriorating), as does their impact

poor spatial and temporal coverage outside the Great Lakes

full impact of coastal marine invasive species just coming to light in some places

Status and Trends legend

KEY FINDING 10. Invasive non-native species are a significant stressor on ecosystem functions, processes, and structure in terrestrial, freshwater, and marine environments. This impact is increasing as numbers of invasive non-native species continue to rise and their distributions continue to expand.

This key finding is divided into five sections:

• Key finding overview (this page)
• Coastal marine ecosystems
• Great Lakes
• Terrestrial plants
• Pathogens and diseases of wildlife

Invasive non-native species also called invasive alien species, are species of plants, animals, and micro-organisms introduced by human action outside their natural past or present distribution, and whose spread threatens the environment, economy or society, including human health. Twelve percent of the 11,950 species assessed in Wild Species 2010: the General Status of Species in Canada¹ are not native. While only a small percentage of them become established and an even smaller number become invasive, the ecological and economic damage of those few species can be enormous.^{2, 3} Invasive non-native species harm biodiversity because they can displace native species and compete with them for resources, degrade habitat, introduce diseases, and/or breed with native species to form hybrids. Numerous factors are responsible for the spread of invasive non- native species, including climate change, unintentional introductions from ship ballast and along roads, intentional introductions, and the increased susceptibility of altered or degraded ecosystems. The control of invasive non-native species is expensive and their eradication is seldom possible. They are considered the second greatest threat to biodiversity worldwide, after habitat destruction, and are an emerging threat to northern Canadian ecosystems as climate warms and species intolerant of current northern climatic conditions expand their ranges.

Global Trends

Invasive non-native species have contributed to nearly 40% of all animal extinctions for which the cause is known.²