Lactate Acid Concentration During Hypoxia in Crabs In and Out of WaterLisa Litwak, Caroline Longerbeam, Kaylee O ’Hora, Nicole Buck

IntroductionThe 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.

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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.

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.

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.

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

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.

Results

Results

Results

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.

Discussion Some reasons for error:

Method of exercising Consistent exercising Proper amount of blood being taken Health of the crab before experiment

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.