Effect of some factor on some aspect of sampling

1. Effect of some factor on some aspect of sampling

2. 2 options • Do the actual technique • Do a simulation to see factors that effect the technique

3. Further Thoughts • Use CMR or Quadrat Method to test a question • Test some factor that effects the accuracy of CMR or Quadrat Method • Use Quadrats to test change along an environmental gradient. • Use quadrats to assess impact – before and after or effected and uneffected areas

4. CMR • Actual • (I) pond size (D) fish population • Simulation • (I) mixing time, # in the capture, size of the habitat, size of the organism, population size, capture technique (tool), • All can be done as t-test or linear regression • (D) accuracy of the method (%error)

5. CMR • Actual • Simulation • (I) mixing time, # of recaptures, method of marking, size of the initial capture, capturing technique, # marked, • Either t test or linear regression • (D) accuracy of the method (%error)

6. CMR Options • Actually Done • (I) Pond size, (D) Fish Population • (I) (D) population of freshmen • Simulation (beans) • IV – Mixing time / method, Size of the beans, Amount in population, weight, Method of marking, sample size, habitat size, # of recaptures, • Remember T-test or Linear reg is possible for each • DV – accuracy of the method (% error)

7. CMR N = (# marked in first catch) (Total # in second catch) # of Recaptures in second catch • Traps placed within boundaries of study area • Captured animals are marked with tags, collars, bands or spots of dye & then immediately released • After a few days or weeks, enough time for the marked animals to mix randomly with the others in the population, traps are set again • The proportion of marked (recaptured) animals in the second trapping is assumed equal to the proportion of marked animals in the whole population • Repeat the recapture as many times as possible to ensure accuracy of results • Marking method should not affect the survival or fitness of the organism

8. Quadrat Method • Actually use it • (I) environmental variable (D) population of a plant species, (I) size of quadrat, • Gradient • (I) distance from ocean (D) ghost crab burrow density • (I) high vs low tide (D) ghost crab burrow density • Simulation • (I) size of quadrat, size of habitat, (I) dispersion of quadrats – distribution method, • (D) accuracy of the method (% error)

9. Quadrat Method • Actually use it • (I) N vs S facing slopes (D) population of a species of plant • (I) Insolation, (I) Moisture, • (I) fire or flood effects, • Gradient • (I) depth in a pond (D) population • Simulation • (I) • (D) accuracy of the method (% error)

10. Quadrat Method • Actually Done • (I) sun vs shade (D) clover population • (D) ant hills in an area • Gradient • (I) distance from ocean (D) ghost crab burrow density • (I) distance from low tide line (D) Mangrove populations (Red & Black), (D) mudcrabs in mangroves • (I)Distance from the bridge (D) population on the beach, (D) litter on the beach • (I) distance from pond (D) • Simulation • (I) size of quadrat , (I) number of quadrats, • (D) accuracy of the method (% error)

11. N = (Mean # per quadrat) (total area) Area of each quadrat • Mark out a gridline along two edges of an area • Use a calculator or tables to generate two random numbers to use as coordinates and place a quadrat on the ground with its corner at these coordinates • Count how many individuals of your study population are inside the quadrat • Repeat steps 2 & 3 as many times as possible • Measure the total size of the area occupied by the population in square meters • Calculate the mean number of plants per quadrat. Then calculate the population size with the following equation

12. Other • Point Counts of animals • (I) time of day (D) seagull population