According to Adds et al. (1999)[1] the purpose of sampling is to obtain a series of independent estimates of the variables you are measuring. If you want to study Zug Lake and the algae population, you cannot possible measure the whole of Zug Lake. You therefore need to take a sample of the area and the biotic and abiotic conditions in that area. Usually some form of random sampling is the best way to select an unbiased...