Tadpoles Lab Report

Introduction: The overall population of a species would be best determined by a total count of organisms. Since this is impractical for most species, different methods have been developed to help determine population size. The most popular type of population estimation is by conducting a mark-recapture census. This method was used to find the population of tadpoles in three local ponds. This experiment was used to test a class hypothesis that a specific pond would contain a higher density of tadpoles based on its location, availability of cover, sunlight availability and other factors. We hypothesized that Pond 4 would be highest in density due to the characteristics listed above.
Materials and Methods: The Mark-Recapture method was used to gather data for each pond. Groups of five – six students collected tadpoles from each pond. Three students collected tadpoles using a kick-net. A second group of students then measured and marked each tadpole. Marking was done by cutting a
Pond 1 had the highest population density of tadpoles, followed by Pond 4. A 95% confidence interval data from each pond overlapped, indicating that there was no significant statistical difference in population from pond to pond. Dispersion of the tadpoles was calculated, resulting in a value >1, placing the tadpole populations into a clumped dispersion pattern. The Chi-Square test was used to test the ratio of dispersion against a pre-determined critical value. The Chi-Square test showed a value > 5.99 (critical value), confirming that the conclusion about dispersion holds true that the tadpoles are of clumped dispersion. Pond 1 was determined to be the most densely populated pond, showing the hypothesis to be incorrect. Pond 2 showed to have the largest average body length, but also the lowest population density (Table