observation session 5

Thursday, November 10, was our last required observation. In these weeks I saw my MicroAquarium follow an expected trend. I watched as it seemed to go from no organisms present, then to a community of organisms grown, then after they were fed, to a huge abundance of organisms. After that I saw the number in organisms decrease but the variety largely increase, and then to what I saw in this last week. When I got my aquarium out, the water level had dropped dramatically, leaving it just around half way full. My plants looked about the same the week before, but then something occurred to me about the plants. The Utricularia gibba, the flowering and carnivorous plant, was the one that did not shrivel up, but possibly even flourished. This made me form a hypothesis because the main observation I made was the large decrease in the number of organisms. It seemed like a massacre as the once dominant rotifers and vortacella were practically nonexistent, and replaced by slightly bigger nematodes and diatoms. Even though this follows the trend of where the observations were heading, it still made me wonder if the carnivorous plant was eating some of these smaller organisms. I did see some skeletons of these organisms, but not nearly as many as I saw alive. However, I did see many dead skeletons down under the soil, including the still abundant diatoms. Over all, for whatever reason, I saw a large number of organisms die off, and the population largely decreased.