Purpose: To understand the recruitment and early life of
H. sanguineus
in the New England rocky intertidal zone. By measuring and taking
census data of the population a better understanding of how long they
stay in the cobble areas, where they go after they grow larger, and why
they are so invasive will all be gained.
Methods: To conduct this study, the area was first assessed to determine the presence of the invasive crab species,
Hemigrapsus sanguineus.
Once these were found to be present a transect was placed
perpendicular to the shore from the water's edge to the high intertidal
zone. Each meter, a small quadrat was
placed at the meter mark and the number of
H. sanguineus
present was recorded. These crabs were measured for carapace width and
returned to the same location. Due to the difficulty of finding a
sufficiently large data set, data was combined with that of Kasia Baca
to increase the sample size. In addition, the difficulty of
finding individuals resulted in changing the methods slightly so that
instead of following a transect, individuals were searched for
throughout the intertidal zone and then the approximate zone for that
individual was determined: 1 for low (1-4 meters), 2 for mid (4-14
meters), and 3 for high (14-20 meters). This assessment was
approximate judging on the zonation that could be seen throughout the
intertidal zone. However, all crabs were found in either the low
or mid zone.
Materials:
- 60 meter transect
- 0.25 square meter quadrat
- Calipers
- Gladware containers for containing found crabs