Carcinus maenas

and

Hemigrapsus sanguineus

Experimental Methods


Results


Discussion


 

Glossary

Works Cited

Contact and Copyright Information

Links:
     Bio 201 Homepage
     Clark University
     Northeastern University's Marine Science Center

Special Thanks

Carcinus maenas and Hemigrapsus sanguineus, two crab species which can be found at shorelines across the globe, have recently engaged in a competitive battle over the resources of New England's rocky intertidal.  They are both introduced species on America’s North East Atlantic shore, but C. maenas has been living there for over 200 years and has now become an integral component of the modern day ecosystem.  H. sanguineus, however, was first sighted in 1988 and may still be in the process of expanding its range.

This site documents the project that I carried out at Northeastern University’s Marine Science Center.  Other studies have documented the relationships between crab species in New England (most notably O’Connor 2001 and Cassanova 2001), but these studies took place years ago and put a strong focus on Southern New England (Connecticut, Rhode Island and Southern Massachusetts).  At the time of O’Connor’s study, C. maenas was still the dominant crab species at the two sampled sites north of Cape Cod.  Hemigrapsus sanguineus is still in the process of “settling in” to its role in the ecosystem, and much may have occurred in the past 5 years.  I set out to determine how the competition between these two crab species is playing out.  Specifically, I studied their relationship well north of Cape Cod in Nahant, MA.

I measured the densities of Carcinus maenas and Hemigrapsus sanguineus at four tidal heights in the intertidal at Nahant on 3 dates.  I found that C. maenas is still the dominant competitor and H. sanguineus has not appeared to have made any progress in outcompeting C. maenas in the past five years.  This indicates that H. sanguineus may be at the northern terminus of its range and can only assume a subordinate position to C. maenas north of Cape Cod in an environment so unsuitable to its survival.

This research project and the web page are the result of a semester long course at Clark University taken in the fall of 2004.  Biology 201, The Ecology of Atlantic Shores, was taught by Deborah Robertson, Ph.D. and Todd Livdahl, Ph.D.