question archive Pro-Lab Discussion Biologists often have to determine the total number of organisms in a large area
Pro-Lab Discussion Biologists often have to determine the total number of organisms in a large area
Subject:BiologyPrice: Bought3
Pro-Lab Discussion Biologists often have to determine the total number of organisms in a large area. If the organisms in the population being studied do not move around, a quadrant census technique can successfully provide an estimate of population sixe. Another technique must be used with populations such as the fish in a lake. This Technique. is called the “W method. Purpose Estimate population size using the mark :3: recapture technique Materials [per group} Bag of Goldfish crackers 1 medicine measuring cup 1 gallon zip lock bag mrker pen (any color] Procedure: 1. Obtain a population of goldfish in a pond (You my recognize that these are goldfish crackers in a gallon :ip lock bag. at good model of an aquatic ecosystem.) 2, Make sure your population of goldfish is well mixed. 3. Notice. that a Cl is present in Column A of Sample 1 to indicate that there are no marked goldfish present in the population before you start your study. 4. Remove a sample of goldfish from your pond with a medicine measuring cup. Make sure the medicine cup is filled to the top with fish. Record the number of goldfish in your sample in column B, 5. Use a marker pen to make a mark on the body of each of the goldfish in your sample. Now you have 'n'larked"l the first members of you population indicating that they have been captured! a. Record the number of goldfish you marked in Column D and return your marked goldfish to the population. 7. In Column A record the total number of marked goldfish that are now present in your population 8. Julia-t your population of goldfish and withdraw another medicine measuring cup full a. Record the total number of goldfish in this sample [both marked and unmarked) in Column B b. Also record ho'nI many marked goldfish you have 'recaptured' in Column C, and how many goldfish were captured for the first time in Column D. 9. hilark each unmarked goldfish in this sample with the marker. Return all the marked fish to the population. 10. In Column A record the total number of marked goldfish that are now present in your population (the sum of all the goldfish you have marked so for). 11. Repeat this procedure. Fill in the data table. 12. For the last 4 samples use the following equation to calculate the total population size. ii IE'I' :::= I! IlliE'l' I' # total goldfish in sample (3) total number of goldfish in population {I} Remember that the total number of marked goldfish in the population will increase each time you take a sample and return more mrked goldfish to the population.
