Tadpole Population – Mark and Recapture

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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 small notch out of the dorsal fin of the tail. The total length (mm) of each tadpole was measured from the tip of the snout to the base of the tail; this data was recorded using a field portable computer system. The first census consisted of two separate collections and combination of data from each collection was used. The second census was conducted using the same methods as the first census, however the number of marked tadpoles was simply recorded, no further marking occurred. Results: From the data of each census I was able to calculate population size (N, individuals per area), Dispersion, and Density of tadpoles for each pond( Table 1). 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...
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