Biological Invasions

, Volume 10, Issue 1, pp 117–128 | Cite as

Marine invasive species: validation of citizen science and implications for national monitoring networks

  • David G. Delaney
  • Corinne D. Sperling
  • Christiaan S. Adams
  • Brian Leung
Original Paper


Approximately 1,000 volunteers assessed the presence of invasive (Carcinus maenas and Hemigrapsus sanguineus) and native crabs within the intertidal zone of seven coastal states of the US, from New Jersey to Maine. Identification of crab species and determination of the gender of the observed crabs was documented at all 52 sites across a 725-km coastal transect. Using quantitative measures of accuracy of data collected by citizen scientists, a significant predictor of a volunteer’s ability was determined and eligibility criteria were set. Students in grade three and seven had the ability to differentiate between species of crabs with over 80% and 95% accuracy, respectively. Determination of gender of the crabs was more challenging and accuracy exceeded 80% for seventh grade students, while 95% accuracy was found for students with at least 2 years of university education. We used the data collected by citizen scientists to create a large-scale standardized database of the distribution and abundance of the native and invasive crabs. Hemigrapsus sanguineus dominated the rocky intertidal zone from Sandy Hook, New Jersey to Boston Harbor, Massachusetts while C. maenas dominated the northern extent of the sampled coastline. A citizen scientist of this monitoring network detected a range expansion of H. sanguineus. We identified obstacles to creating a national monitoring network and proposed recommendations that addressed these issues.


Carcinus maenas Citizen science Community-based monitoring Hemigrapsus sanguineus Marine invasive species Quality assurance Validation 



This research was funded by NOAA’s National Sea Grant Aquatic Invasive Species Research and Outreach Program (NA05OAR4171088). We also want to thank Acadia Institute of Oceanography, J. Ainsworth, Bowdoin College, Cornell Cooperative Extension Program of Suffolk County, R. Crossman, Darling Marine Center, M. Delaney, E. Ely, J. Farrell, K. Fellner, R. Foreman, E. Gertzen, Island Alliance, Z. Itzkowitz, S. Myers, National Park Service, New England Aquarium, J. Pederson, M. Raczko, A. Rogers, H. Spence, Capt. D. Weinstein, and especially all the volunteers.


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Copyright information

© Springer Science+Business Media B.V. 2007

Authors and Affiliations

  • David G. Delaney
    • 1
  • Corinne D. Sperling
    • 1
  • Christiaan S. Adams
    • 2
  • Brian Leung
    • 1
  1. 1.Department of Biology & School of EnvironmentMcGill UniversityMontrealCanada
  2. 2.Massachusetts Institute of TechnologyMIT Sea Grant College ProgramCambridgeUSA

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