356.pdf

The authors, Mills et al., analyzed literature to identify patterns and mechanisms behind these introductions.

Key Findings:

Widespread Invasions: Since European settlement, the Laurentian Great Lakes have been subject to invasion by exotic species, with 139 non-indigenous organisms established as of the late 20th century.
Diverse Origins: Most species (55%) are native to Eurasia, and 13% originate from the Atlantic Coast.
Increasing Introductions: As human activity in the Great Lakes watershed intensified, so did the rate of exotic species introductions. A significant surge occurred after the opening of the St. Lawrence Seaway in 1959.
Dominant Entry Mechanisms: Unintentional releases (29%) and ship-related introductions (29%), including ballast water and fouling, were the primary pathways for species entry.

Notable Examples:

The paper highlights several non-indigenous species with significant ecological and economic impacts on the Great Lakes:

Rumex patientia (Moneywort): A plant first observed in the Great Lakes region in the early 19th century, spreading through moist habitats.
Rorippa sylvestris (Creeping Yellow Cress): Introduced from Europe in the mid-19th century and quickly spread throughout the Great Lakes basin.
Lysimachia nummularia (Moneywort): Similar to Rumex patientia, it became naturalized in central and western New York by the late 19th century.
Lysimachia vulgaris (Garden Loosestrife): An ornamental plant escaping from cultivation, it spread widely throughout the Great Lakes region by the early 20th century.
* Lythrum salicaria (Purple Loosestrife): Introduced in the mid-19th century, this species became a major concern due to its invasive nature and negative impacts on native vegetation and wildlife habitats.