Discussion:

 
According to the Chi-tests, H. sanguineus is more likely found in the lower and middle intertidal zones than C. maenas. This differs from the previous study done in 2004 at Clark University where H. sanguineus did not seem to be more dominant over C. maenas. Perhaps H. sanguineus have caused the recruitment of C. maenas to decline. 

Body size was not significantly different between the two groups. Since C. maenas was scarcer than H. sanguineus, the number of measurements done for this species was much less which may have caused unreliable data to test this. Body size is expected to be different if H. sanguineus is out-competing the other species by preying on the same food as C. maenas. If H. sanguineus is able to get to more food, more energy is available for them to grow bigger for protection. H. sanguineus is also expected to have a bigger body size since they naturally do. They are even found to prey on C. maenas which was found through laboratory experiements (Lohrer, et al). 

H. sanguineus may have recently become the dominant crab species in Nahant, MA if data accurately represents the situation at this intertidal. This increases the pressure on the prey in this community like mytillus and algae if this species has a higher density and if the species is more efficient at finding prey. The newly introduced species may have taken this long to become dominant since C. maenas became very well adapted to the coastal shores when it was introduced.

It is possible that C. maenas is still more dominant in the high intertidal since I collected no crabs at this level. This species may be able to handle the environmental pressures that are found higher up the intertidal and they may be able to hide from predators better than H. sanguineus might. Studies have found that H. sanguineus densities are highest in the lower and middle intertidals (Lohrer,et al and Ledesma, et al). C. maenas are known for its tolerance to many conditions which is how it spread across the coast so fast when it was introduced. This may allow C. maenas to become more dominant in the higher elevations so we most likely will not need to worry about a complete take over of H. sanguineus. 

To improve this study, more samples should have been taken, especially in the high intertidal to find which species is more dominant there. A quadrant sampling with a transect may be more ideal than random sampling  since this way the distance to the water and density can be more accurately calculated and evaluated. This would require a better sampling method that would allow one to find crabs in the small sediment more efficiently. It would be interesting to find if Lohrer's findings that H. sanguineus decreases C. maenas recruitment through pressure.

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