Outbreak of an undetected invasive species triggered by a climate anomaly
Walsh, J.R., Munoz S.E., & Vander Zanden, M.J. 2016. Outbreak of an undetected invasive species triggered by a climate anomaly. Ecosphere 7(12):e01628. PDF.
Summary
It is possible that climate change will facilitate the transition of naturalized species into invasive status (sleeper species). However, when an invasive species is detected, it can be unclear whether that species has just been introduced, or whether it has existed at low densities prior to detection. Walsh et al. 2016 studied a population outbreak of the invasive predatory zooplankton (Bythotrephes longimanus) in Lake Mendota, Wisconsin. They combine field sampling methods and population modeling to determine whether Bythotrephes existed in Lake Mendota prior to the outbreak, or whether this outbreak was the result of a new introduction. Through field sampling, they determined that the species did indeed occur in the lake roughly 15 years before the outbreak, but was undetected because it existed at low population densities. Their population model suggested that the outbreak was a result of anomalously low summer temperatures that allowed establishment of an egg bank. Further, the population model suggested that more than 3 or 4 years of unfavorable conditions would be needed to return the invasive Bythotrephes population to non-invasive low density levels. This research highlights the potential for anomalous climatic conditions to cause invasive species outbreaks, as well as the utility of combining field and modeling methods to understand invasive species ecology and management options.
Take home points
While it is uncommon for abrupt regime shifts to cause invasive species outbreaks, it will be important to consider the natural history of target invasive species to determine when anomalous climatic events will cause shifts in population equilibria.
Combining population modeling with field methods can provide unique insights into invasive species outbreaks.
Management implications
Rather than directly targeting invasive species, managers can consider manipulating environmental conditions to reduce invasive populations.
Focusing effort toward returning species populations to non-invasive status following anomalous climatic events may be a more realistic goal than species eradication.
Keywords
Shifting Seasons; Model; Invasive Invertebrate; Aquatic Habitat; Bythotrephes longimanus; Spiny Water Flea; Risk Assessment