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Abstract
The purpose of this experiment was to compare three methods of population estimation: enumeration, mark/recapture, and depletion. We went to Choctafaula Creek in Lee County, Alabama to estimate the population size of the yellow elimia snail (Elimia flava). In this experiment, the enumeration method estimated a population of 847 snails, the mark/recapture method estimated 1,328 snails, and the depletion method gave estimates of 1,918 snails and 680 snails. These three methods each gave an extremely different estimate, and therefore the three methods are not equally valid.

Introduction
Population estimation is important because it gives ecologists an idea of the abundance and distribution of a particular species in an area. Knowing the population of a species in a given area can help ecologists gain knowledge on the various factors that can influence population, and how changes in environmental factors can influence that population. Being able to measure population change over time along with other research can help identify and solve conservation issues before a species becomes extinct (Thomas 1996). As it is often impossible to obtain an exact count of individuals for a population, methods of population estimation are important. Population estimates might be used to give information on the health of a species, for example, to see if a species is increasing or decreasing in numbers in such a way that would cause the species to overrun their habitat or to become extinct. Another possible use for population estimation is to determine possible reasons behind a population increase or decrease.
The purpose of this study is to compare three methods of population estimation: enumeration, mark and recapture, and depletion. Each method has its strengths and weaknesses, and by comparing these three methods, we can determine which method is best, or which combination of methods would be the most accurate. Because we...