The Pond, by Mariam and Stanley

September 15^th, 2010:

            Dr. Pike and Ms. Wilson’s biology 20 class went to Nosehill Park from Sir Winston Churchill high school to learn about ecology and make connections about different ideas, questions and concerns about the ecosystems there. The ecosystem that we looked at was the pond.

Figure 1.  the pond at Nose Hill.

First Impressions

Human interference didn’t seem too bad. From the exterior, the pond seemed perfectly healthy, filled with organisms thriving and interacting with one another. A hawk circled the sky, perhaps looking for its prey, something like a mouse. This would be an example of predation, an interaction in which one species kills and consumes another species to gain energy. Walking forwards, we found a variety of organisms around the pond, such as a black salamander (figure 2). We hypothesized that, because of the approaching cold weather of September, it was looking for a place to stay to keep warm, perhaps a hole dug by another organism; if the other organism was unaffected, this would be a commensalistic relationship, whereas if the other organism was negatively affected, it would be parasitism. We were surrounded by interactions.

Figure 2.  A tiger Salamander found under
some wood at the pond.

A Closer Look

The pond, in all its interactions, looked healthy, but we decided to take a closer look. Strapping on his chest wader, Stanley braved it out and walked into the pond to collect a water sample as well as organisms with a net (figure 4). There were a great number of organisms with a wide variation, but we also noticed that we did not see any fish. We decided to look further into the chemicals in the pond. Researching, we found that the pond was acidic. It had a pH of 6.

Some Explaining To Do

           Why was the pH acidic? A variety of reasons. Firstly, pH, the measurement of free hydrogen ions in a substance, determines the acidity of a substance. Natural functions can contribute to this process. These may include:

·         Biological filtration

o       When releasing ammonia (NH₃), nitrogen and hydrogen ions are released. Bacteria break this ammonia down into nitrite (NO₂), causing the three hydrogen ions to release. H+ ions cause a drop in pH. _{(Roocroft, 2010)}

Figure 3.  An interaction between a spider
and a thistle plant; commensalism.

·         Photosynthesis

o       Plants, fish and bacteria constantly undergo photosynthesis, a process where carbon dioxide (CO₂), energy and water (H₂O) are used to create oxygen (O₂) and glucose (C₆H₁₂O₆). _{(Roocroft, 2010)}

Figure 4.  Stanley collecting a pond sample.

Unfortunately, living in such an urbanized area, with roads right at the top of the hill beside the pond, humans must have interfered with the acidity of the pond in some way or another. Another reason for the acidity being unnaturally high is chemicals from humans washing into the pond. Since there are homes at the top of the hill parallel to the road, chemicals may have washed in from things like soaps, fertilizers, and other interfering factors. Litter does not prove to be an enormous problem at the pond; however it was present in small amounts. The chemicals may have also seeped through to the pond water because of rain, as water levels rise significantly and much washes into the pond. For more information on this pond, including what YOU can do to help keep it healthy, check out Mariam R. and Stanley C’s podcast or vodcast!

Bibliography

Roocroft, Tony. (2010.) pH levels. Retrieved from the internet:

http://www.pond-doctor.co.uk/longpHlevels.html