Sensitivity of invasion speed to dispersal and demography: an application of spreading speed theory to the green crab invasion on the northwest Atlantic coast

• Published in: Marine ecology. Progress series (Halstenbek) 2015-12, Vol.541, p.135-150
• Main Authors: Gharouni, A., Barbeau, M. A., Locke, A., Wang, L., Watmough, J.
• Format: Article
• Language: English
• Subjects: Carcinus maenas; Decapoda; Marine
• ISSN: 0171-8630; 1616-1599
• DOI: 10.3354/meps11508

Spreading speed theory provides a mathematical tool to analyze the demography and dispersal of invasive species. Based on biological records, the secondary spread of the European green crab Carcinus maenas has maintained a relatively consistent rate of advance for over 100 yr, covering a wide range of temperate latitudes and local hydrological environments along the Atlantic coast of North America. We employed a discrete-time model to investigate the green crab’s spreading speed and the relationship between demography and dispersal. The model is an age-structured integro-difference equation that couples a matrix for population growth and a dispersal kernel for spread of individuals within a season. The choice of a Normal or Laplace distribution for the dispersal kernel has only a minimal effect on the spreading speed. Our modeling exercise illustrates that there are many realistic combinations of vital rates (fecundity and survival) and dispersal rates that give rise to a given spreading speed c*. Further, our results indicate that the invasion speed is most sensitive to the standard deviation of larval dispersal, followed by recruitment rate (a demographic parameter that combines fecundity, larval survival, and juvenile survival), and least sensitive to adult survival. We thus enhance understanding of invasion biology, specifically the relative importance of demography versus dispersal distance for marine species with a pelagic larval stage. We also provide insights on and rank possible management strategies.