As the impacts of climate change escalate, ecosystems will likely undergo events that will disrupt entire populations. In marine ecosystems, anthropogenic warming has subjected organisms to elevated temperatures, oxygen loss, and acidification. The increased frequency and severity of catastrophic events may inhibit a population’s ability to recover and, in turn, may spur collapse.
Mass mortality events can exacerbate the risk of extinction for species that are prone to Allee effects, particularly species harvested commercially. When species experience Allee effects, they exhibit diminished reproductive success at decreased population density. Managed fisheries frequently keep populations at low densities.
In “Catastrophic Mortality, Allee Effects, and Marine Protected Areas,” published in The American Naturalist, Emilius A. Aalto, Fiorenza Micheli, Charles A. Boch, Jose A. Espinoza Montes, C. Broch Woodson, and Giulio A. De Leo focus on one marine species impacted by Allee effects — the green abalone (Haliotis fulgens) near Baja California Sur, Mexico. Using the Isla Natividad fishery as an example, the authors examine whether spatial management strategies are more effective than nonspatial management strategies in alleviating the damage caused by catastrophic events. In particular, the authors seek to ascertain whether designating marine protected areas (MPAs) in fisheries will help combat collapse when a population facing catastrophe is also susceptible to Allee effects. MORE