I have three different shorelines, and three different heights along each shore (high, middle, low). For each of the heights at each of the shores I have quantities of two types of organism. I want to examine the quantities of the two organisms to see a) if they differ in abundance at the three heights on the shore, b) if they differ in abundance across the three shores and c) if there are any interactions between the two species which are affecting their abundance. I have lots of data and would like to know which statistical test is best to use to investigate these things. Thank you very much!
Actually, 2WA would compare them across shores, but it would also investigate, whether there is some aditive influence of organism and shore (like, if you change from high to low AND from 1 to 2), so thats probably not, what you need, right?