lab report

Fall Microaquarium Project
Kenton Martin
http://funnythingsinthewater.blogspot.com

Introduction

Animal life is dependant upon plants and smaller animals as a source of food. This is known as the food chain. As we observe the chain getting smaller it becomes very fascinating how the relationship between plants and animals progresses. This observation was performed in order to study the organisms which inhabit freshwater resources and determine which microorganisms might be especially important in the food chain.

Materials and Methods

First a microaquarium was filled with water from a local creek. Care was taken to be sure that some of the soil from the creekbed formed a thin layer at the bottom of the microaquarium. A small portion of plant life was then added into the aquarium. The aquarium was then observed under a microscope at least once a week. The observations were recorded in an online blog to serve as a record of what was occuring. This occured over the period of a month at which point the microaquarium observation was complete.

Results and Discussion

The first weeks observation showed several species were present including one midge, one seed shrimp, a few gastrotrichs, several rotifers, and a lot of halteria. One of the more fascinating observations was the rotifer known as a Philodina. It had two spinning flagellates on its anterior called corona. These creatures used the corona to spin water towards it as a source of food gathering (Nograndy 1). The next week showed a huge increase in the diversity of species of life. While the midge passed away, other creatures observed included: Copepods, Diflugia, Paranema, various ameoba with tenderals, a creature known as a Cyclops, more Rotifers including one with shells, the seed shrimp, lots of halteria, a planerium, and the emergence of cyanobacteria and diatoms. The Philodina, while not dwarfing the population of life, did maintain a similar proportion as the week before. This suggested the Philodina have a quick reproductive cycle. Further research showed Philodina have a very quick reproductive cycle (Norgandy 1). The next weeks observation showed an even further increase in biodiversity as none of the previously mentioned organisms were missing, but new organisms were observed. New organisms included: Colpidium, Blepharisma, Nematodes, and rhizomes forming off some of the plants. This was the first week there were dead creatures on the bottom of the aquarium. These were limited to the midge and seed shrimp. Another unique observation was the halteria which had been extremely prevalent in the previous two observations were dropping in number. Research showed that one of the items on a rotifers menu included these cilliates. The fourth week continued this pattern as there were no halteria to be found in the entire microaquarium. Most species were gone. All that was remaining were amoebas, rotifers, microflagellates, and a few seed shrimp. Diatoms and cyanobacteria were still expanding possibly explaining the enormous increase in the ameoba population. The philodina were also in larger quantities. There were around 4 on each wall of the aquarium as well as various ones in the center. One unique thing about the Philodina was that the area of the tank didn't affect whether it would reside there or not. This suggested they were a very hardy species and warrented further research.

The Philodina full listing would be Eukaryota Animalia Lophotrochozoa Rotifera Bdelloidia Bdelloida Philodinidea Philodina ( Myers 2008 ). They are commonly referred to as Bdelloid Rotifers. Philodina play an important part in the the freshwater food chain as they generally serve as the first meal for small fish and as a staple of many predaceous insects (Fernando 26). One of the marvelous things about the Philodina is its lack of sexual reproduction. While males do exist in other families of rotifers, the Bdelloidia do not have males. Reproduction is acheived by parthenogenesis ( Olsen 178). In the case of Philodina the female either lays a female egg or a dormant egg. The dormant eggs are capable of withstanding intense weather enviroments such as cold and dehydration (Olsen 178). Another fascinating fact about the Philodina is that it is capable of surviving dehydration because they are anhydrobiotic. This means they become dormant when dried out, but do not die. When reintroduced to water they are swimming and feeding within an hour (Norgandy 36). These results show the Philodena and Phylum Rotifera are one of the most ecologically hardy and important species existing because they reproduce on their own, are capable of becoming dormant when enviromental conditions are not correct, but also provide an important source of food for many organisms.

Bibliography
Fernando CH. 2002. Tropical Freshwater Zooplanketon. Leiden (Netherlands): Backhuys Publishers. p26.
Myers, P., R. Espinosa, C. S. Parr, T. Jones, G. S. Hammond, and T. A. Dewey. 2008. The Animal Diversity Web (online). Accessed November 26, 2008 at http://animaldiversity.org.
Nogrady T, Wallace R, Snell T. 1993. Rotifera. Volume One, Biology, Ecology, and Systematics. The Hauge (Netherlands). SPB Academic Publishing p. 1-40.
Olsen LH, Pedersen J, Pedersen BV. 2001. Small Freshwater Creatures. New York (NY): Oxford. pg. 137.