Green Crab Affect on Rock Crab Population
by Carissa Fawber
Abstract:
In my research, I wanted to find out if the rise of the green crab population is
correlated to the decline of native crab populations and taking over Maine coastal
habitats. Using GMRI’s vital signs website, I searched whether they did or didn’t find
green crabs and rock crabs along specific sites along coastal Maine. I graphed and
tabled all the data, I found out that their were 271 sites that found green crabs and
16 sites where for green crab was not found, for the rock crab, 30 sites found it and
14 did not find it. Was surprised by the number of sites “not found” and “found”
results for the rock crab because they are closer with the not found 16 to 14. Just
two off. But, the “found” was way off 271to 30 the difference between those two is
241, so my conclusion is that they are taking away the rock crabs.
Introduction:
Green crabs are a species that don’t belong here. They are invasive from
Europe and are taking away many creatures away. I found out that some other crabs
are declining at a fast rate because of the booming green crab populations. I think
that this is important to find if the green crab is taking these crabs away because if
we don’t, we could see these crabs disappear and lose these important animals. The
problem that I’m researching asks if green crabs are growing in population and
causing the rock crab population to decrease at a fast rate. My hypothesis is that
they are since they are taking away other crabs they may be doing the same for this
one as well, if the green crab population is growing then I think that the rock crab is
decreasing.
Methods:
I looked at GMRI’s Vital Signs data on both green and rock crab, and found
who else found them to see the differences. I copied the data into tables to find a
pattern, to see if green crabs are affecting rock crab populations or not. I wrote
down all the data in a table to see the change. To find out if the green crab is
invading. It is important to keep the “found” and “not found” sites apart to see what
you have.
Results:
So as you can see, the difference between the graphs with green graph is the Green
crab and blue is the rock crab the green crab found and not found are vary far apart
and the rock crab found and not found are closer together so you can see that if you
went on a beach you would see around ten times as much Green crabs.
Conclusion:
I had to figure out if Green Crabs are effecting the population of Rock Crabs.
My hypothesis was yes they are because the green crabs are negatively affecting
other crab populations too. The results are 271 green crabs sites found vs. 30 rock
crabs found. sixteen sites where green crabs were not found only 14 sites did no
find rock crabs. You can see green crabs are affecting the rock crabs because
populations the “not found” are really close together you can see how far apart the
“found” was to show the difference and to see how the green crabs are effecting the
rock crabs. In terms of where they live, if you find one rock crab you should be able
to find around ten green crabs. This information is useful to show why the green
crab needs to be eradicated or else our native crabs will be gone.
Some of the issues with the data was that there was so many green crabs that
it took time to sort through and tabulate the data. I think that we should try to take
these crabs away in as many different ways as possible, else our native crabs may
disappear. So I think that we could use them for bait to take them away, even though
it may take some time, it still is a solution that might work like if we used them for
bait or eat more of them then we can slowly take them away.