The purpose of this project was to learn more about the research method, to refine my skills using microscopes and to learn how to use new technology that is becoming common biological research.
I found many interesting things in the creek. I never realized that there was so much life in a creek that is subject to non point source, urban pollution and still remains more or less in its natural state for a over an eighth mile as it crosses our campus.
#1 #2 #3#4
Navicula sp. #1 and Cyclotella ? Gonphonema constrictum ? Navicula sp. #2 & #3
Numbers 1, 2, 3, and 4 are all examples of free living diatoms. Diatoms have a cell wall made of silica, they take many different forms. These types glide slowly through the water and seem to become more active as the light from the microscope warmed the slide and they become more photosynthetically active.
I found this chain like algae to be very interesting. I only saw an example of this one time in my random sampling, but it is supposed to be very common.
#6 a, b, c, d These are all unidentified, asymmetric, stalked diatoms (Rhoicosphenia curvate? or Gonphonema ?).
The examples above are of
epiphytic type diatoms. These are the most abundant form of diatoms in
Emigration Creek they are found attached to both rocks and filamentous
In this photo there is a
flat type of epiphytic diatom, it was quite abundant in most of my samples,
there is also a stalked type in the upper left hand corner.
Cocconeis sp. (three cells on lower half of the photo on a cladophora filament)
Here there is a cyanobacteria
(Oscillatoria sp.) and a free living diatom. The cyanobacteria
can be attached to a substrate or it can slowly "swim" through the
water. It is unknown as to how these bacteria move.
This is a Vorticella sp.
is protozoa with a contractile stalk and a bell shaped body. There
are cilia on the anterior end which create feeding currents that draw water
into the mouth. This animal can become free-swimming by shedding
it's stalk and growing cilia on the posterior end. These animals
often occur in dense clusters but are not colonial, each has a separate
#9 Vorticella sp.
The creek is home to many different insect larva, these are most likely some kind of fly larva. Note the sharp jaw like protrusion on the anterior end of # 10, the antenna like projections on #11, and the long tactile hairs on the posterior end of both # 10 and 11.
#12 A Nematode.
This is an example of the
Nematodes (round worms) that are found in the creek. I found these
fairly often in my samples, they were easy to spot with their rapid, wiggling
movement. Note a couple of the classic Nematode characteristics like
a round body, tapered at both ends and no segmentation.
Other Interesting Observations
At the start of the project, I placed a leech and an aquatic worm in the same dish so that I could observe them under the dissecting microscope. After a few minutes in the same dish the leech began to suck blood from the worm. I immediately separated them. I thought that since the leeches were green they probably ate plant material or detritus. A few weeks later I put three leeches and five worms (two large and three small) into a collection dish together and left them for a week. When I returned a leech was attached to the largest worm and its gut was engorged with blood. The other two leeches didn't appear to have had a recent blood meal. I believe that the leeches that exists in the creek could be classified as opportunists. They probably eat whatever they can find.
I found that the abundance of many of the animals and plants that I saw changed over the semester. I expected this and attribute most of the changes in abundance to the changing of the seasons. However, I think that it is worthy to note that it was unseasonable warm during the months of October and the beginning of November. When the temperatures did return to their seasonal averages it felt like a dramatic change. I think that had the temperatures been more near to normal my results would have been different. In general, the abundance of Mayflies indicates a stream returning to health. However, the lack of other insects and their larvae indicate a stream that is in a degraded state of health. It also indicates sever flooding disturbances. This is true in our creek because all of the run off from the streets in this area is dumped into it. Another factor in the flooding is the city's removal of all of the tree debris (limbs) that could slow the flow of the creek, thereby reducing sever flood damage and creating new pools for biota to inhabit. I didn't see any damsel flies, dragon flies or water striders because I didn't study areas where the water was still. I only found one type of algae, Cladophora, but it was abundant on the stream bed. It was especially abundant in areas where sunlight broke through the trees. The algae is very important in this ecosystem. It not only provides food for the various herbivores but it is also a home or at least a place of refuge for all of the animals that I found.
All though this creek is a degraded ecosystem it still has what I consider an abundance of life. I can't imagine how many different kind of things would inhabit the creek if it was in prime condition. After this study, I feel that there is all the more reason to help keep ecosystems in their natural state or help them retain their former glory. Even though a system is degraded there are still animals and plants existing in it that interesting and worth closer examination.
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Jahn, Thoedore Louis, Professor Emeritus, 1949, How to Know the Protozoa, 2nd edition, WCB McGraw-Hill, Dubuque, Iowa.
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