title: The Origin of Invasive Microorganisms Matters for Science, Policy, and Management: The Case ofDidymosphenia geminata.
abstract: The value of distinguishing native from nonnative invasive species has recently been questioned. However, this dichotomy is important for understanding whether a species' successful dominance is caused by introductions, changing environmental conditions that facilitate an existing population, or both processes. We highlight the importance of knowing the origin of hard-to-detect invasive microorganisms for scientific research, management, and policy using a case study of recent algal blooms of the stalk-producing diatom Didymosphenia geminata. Nuisance blooms have been reported in rivers worldwide and have been hastily attributed to introductions. However, evidence indicates that blooms are probably not caused by introductions but, rather, by environmental conditions that promote excessive stalk production by this historically rare species. Effective responses to invasive microorganisms depend on knowing whether their proliferation is caused by being nonnative or is the result of changing environmental conditions that promote invasive characteristics of native species.
authors.affiliation: Brad W. Taylor ( brad.taylor@dartmouth.edu ) is affiliated with the Department of Biological Sciences at Dartmouth College, in Hanover, New Hampshire, and with the Rocky Mountain Biological Laboratory, in Crested Butte, Colorado. Max L. Bothwell is affiliated with Environment Canada, at the Pacific Biological Station, in Nanaimo, British Columbia, Canada.
authors.forename: Brad W
authors.initials: BW
authors.lastname: Taylor
authors.affiliation: Brad W. Taylor ( brad.taylor@dartmouth.edu ) is affiliated with the Department of Biological Sciences at Dartmouth College, in Hanover, New Hampshire, and with the Rocky Mountain Biological Laboratory, in Crested Butte, Colorado. Max L. Bothwell is affiliated with Environment Canada, at the Pacific Biological Station, in Nanaimo, British Columbia, Canada.
authors.forename: Max L
authors.initials: ML
authors.lastname: Bothwell
keywords: algal blooms; diatom; environmental change; exopolymers; phosphorus