Discussion
Our results showed a tremendous decrease of E. coli when
compared to the previous years. This led us to believe that preventative
measures against E. coli were being taken.
In comparison to previous years it is very evident that the local community has
identified the condition of the lake to be an issue and has been working to
improve its quality. For example Kong and Koch sampled 425 MPN E. coli
from the dock in 2006; just one year later our samples along with Lorman’s only
contained 3.1 and 26.2 MPN, a drastic change. It should be considered that
the areas of samples had similar results. Both Kong and Kock’s and our own
had the highest sample readings for E. coli at the dock and exlosure. This
could lead us to believe there is a factor that allows E. coli to reproduce well
there such as poor water current, ample sun, or a mass of animals producing
fecal matter.
An interesting aspect was the amount of E. coli present at the entrance of the
Arboretum spring compared to the amount in the Edgewood Spring itself. The
entrance had 11 MPN/100 ml compared to the actual spring of having zero
positive, which could be due to the amount of water flowing and moving around in
the spring. The movement of water could allow it to clean itself. However, in
the entrance there was no movement in the water which means that the E. coli
could form denser, populated colonies.
There are various factors that may explain why certain areas contain more E.
coli than others. First, we thought that the carp exclosure would be extremely
clean and free of the bacteria due to the lack of carp. However, after seeing
the results, we decided high levels of E. coli could be due to the seagulls that
rest on the outskirts of the area; dumping fecal matter into the exclosure. Also
the lack of a strong current in the exclosure would allow the E. coli bacteria
to form larger colonies.
Next, the Edgewood Spring samples taken by us and Lorman differed. This could
be the result of because the great amount of sediment in our sample. Lorman
managed to get a clean sample, which made the positive cells drop by half of
what we came up with. This led us to believe that the plants and sediments
themselves contained a lot of E. coli as well. Previous studies have shown that
E. coli can reside in the soil. For instance, in lagoon one there is about
3700 MPN/100 of E. coli located in the sediment alone (Dvorak). Now we
didn’t test the lagoon area; however, this bit of data proves that sediment
could’ve increased the amount of E. coli located in an area.
Why the Edgewood Spring contained more E. coli than the Arboretum spring caused
much confusion. We concluded that the sewage system going underneath that
general area could cause more E. coli contamination especially if there is any
kind of leak.
Another important aspect to consider are the possible errors that occurred
during our research. For example, when we counted the amount of yellow cells for
the bacteria, we could have mistakenly included a few that were borderline
(color wise) and didn’t actually contain any bacteria. Also, a consistent,
collecting system should have been employed when gathering the samples For
instance, all samples should have been collected from an equal depth. In
addition, more samples on different days would have allowed us to see if there
were constant changes with the amount of E. coli; thus making our results more
reliable. Comparing how E. coli levels differ throughout the year would allow us
to understand the trend of E. coli even more, and an extension that could be
pursued later.