observations 11-8-11

Today I noticed a marked decrease in life in my aquarium, especially in protists.  Near the soil line, I saw one Closterium, a couple Phacus triqueter, and many diatoms.  I also identified Epalxis sp., a ciliate that likes to go in circles (Patterson 1996, p. 141 fig. 311).  I had seen Epalxis during previous observations, but it was less abundant and I was unable to identify it.  Epalxis could be found throughout the aquarium.  Vorticella, Peranema, and Chlamydodon, however, had disappeared completely.  Invertebrates were still quite abundant.  I saw the usual Cyclops and Euchlanis, in addition to a new species, Aeolosoma sp. (Pennak 1953, p. 288 fig. 183)  Aeolosoma, an annelid, was decomposing the top half of my Utricularia plant, which was dead because half of the water had evaporated out of my aquarium.  During this fourth and last observation, the quantity and variety of life had declined, probably due to food becoming scarce.