2. Introduction
The green crab, carcinus maenus, is a invasive species
that has spread to North and South America, South
Africa, and Asia ship ballast water. Having a clear
understanding of the physiology of these organisms
can provide useful information in understanding how
they may change the ecosystems they have been
introduced to.
https://ferrebeekeeper.wordpress.com/2013/12/page/2/
3. Introduction
There are periods where a organism may be
unable to supply enough oxygen to cells,
either due to low oxygen levels in the
environment or extended periods of physical
activity. During these periods a alternate
pathway, called anaerobic metabolism is
needed to continue ATP production without
oxygen. This process is necessary for the
survival of all animals, and understanding how
it works within the green crab may help future
researchers predict how successful they may
be in their nonnative environments.
4. Introduction
One form of anaerobic metabolism involves
converting the pyruvate used in glycolysis into lactate
acid in a process called fermentation. Over time this
product will accumulate in the organisms so
measuring it can help measure anaerobic metabolism
over time.
5. Introduction
In this experiment anaerobic metabolism
was examined in animals after periods of
physical activity both in and out of water.
By measuring lactate acid in the
hemolymph.
Hypothesis: Lactate acid concentration
will be the highest during physical activity
out of water, and that over time lactate
acid concentrations would increase both
when exercised in and out of water.
6. Methods
.2 ml of hemolymph was taken from the resting
crab using a 23 gauge needle and 1 cc syringe
then transferred to a micro-centrifuge tube in an
ice bath.
The crab was exercised out of water in two minute
intervals with one minute resting between. .2 ml of
hemolymph was taken at each two intervals for a
total of three samplings
The crab was switched out and the experiment
was repeated by exercising the crab in the
water
7. Methods
The hemolymph taken was treated with R1 and R2.
Standard solution was adding the stock solution (15
mmol/L lactacte) and TRIS buffer in 1ml standards in 5,
10, 15, mmol/L lactate concentrations.
300 μl of R1 was pipetted into a clean square cuvette. 6
μl of 5 mmol/L standard solution was pipetted into the
cuvette with R1 and covered in parafilm.
The comboination was mixed gently and allowed to
stand for at least 2 minutes. 200 μl of R2 was then
pipetted into the cuvette with R1 and the standard
solution and gently mixed again. Cuvette was
placed in a water bath of 37 C for exactly 5 minutes.
11. Discussion
There was a higher rate of lactic acid
accumulation in crab out of water.
This is evidence of how the differences
between air and water create a
difference in anaerobic metabolism.
Overall there wasn’t enough information
to conclude one crab produced more
lactate than the other.
12. Discussion
Some reasons for error:
Method of exercising
Consistent exercising
Proper amount of blood being taken
Health of the crab before experiment
13. Discussion
Crab out of water was harder to exercise
which could explain the results that were
obtained.
There are other things that should be
looked at to see how the green crab
could outcompete native species:
Length of anaerobic metabolism
compared to other crab species
See how environmental stressors effect
anaerobic metabolism like temp, salinity,
ability to resist desiccation, change in diet.
