Pearson's Creek Crayfish Case Study

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Materials and Methods: To gather the needed data on the crayfish, samples were collected at Pearson’s Creek, a little outside Springfield. The spring was right off the road and located directly next to a little over pass. Sampling occurred early morning 0830-0930 on a cloudy day. The weather was a typical mild late summer morning with a rain shower that had passed through the evening before. Two sampling areas that were 10-meters long and the width of the stream were marked off using flags and sticking them in the rocks of the shallow area of the creek. The sample areas were also marked at the 5-meter mark to split each individual trial into two to have a greater chance at collecting a larger population size. The two sampling sites…show more content…
The removal method was done in the 10-meter section that was more upstream and capture-mark-recapture was done more downstream. The purpose of the removal method is to collect a sample of the crayfish and set it aside, away from anymore collections. The next capture should have relatively less than the first. This process is repeated until five trials are finished and each trial having less sample size than the previous one (Zippin 1958). The next method, capture-mark-recapture, is done by catching a sample in a bucket and recording the amount of crayfish and then releasing the samples back into the collection area once marked; in the specific experiment blue and pink nail polish were the marks used (Pradel 1996). In each method, two students stood holding a weighted-down net at the five-meters mark while five other students started at the beginning and shuffled, kicking up rocks to disturb the crayfish underneath. Once the shufflers reached the net, the net was taken out of the water and any crayfish collected were attached to the net. The samples were put into buckets after their length (head to beginning of tail) were measured using a measuring tape and the amount of crayfish were accounted for. The same process was repeated but the net was at the 10-meter mark and the students started shuffling at the five-meter mark. In the capture-mark-recapture method, the crayfish were marked using blue and pink nail polish allowing for the crayfish to be dumped back into the sampling area. The removal method group kept all of the crayfish collected aside to ensure only the new crayfish were collected. The 10-meter portion of the stream was then collected four more times, giving a total of five separate collections for each

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