Saddleback Journal of Biology - Saddleback College

Fall 2009 Biology 3B Paper
Mean MPN
1600
1400
1200
1000
800
600
400
200
0
North
Mouth
South
Locations
Figure 1: The mean MPN for the north location was 1018 ± 251.457 (x̄ ± SEM). The mean MPN for the middle
location was 1124 ± 241.823 (x̄ ± SEM). Mean MPN of the south location was 591.2 ± 236.789 (x̄ ± SEM). An
ANOVA of the means yields p > 0.05 (0.27812). There is no difference between the means; thus, coliform bacteria
concentration is equivalent in all three locations.
Discussion
The results of the presumptive test were expected to be
different for each location. After incubation, a reaction
was observed in each of the triple strength tubes, and in
one-hundred twenty-seven out of the one-hundred
eighty single strength tubes. The MPN was calculated
by observing and adding up the total amount of tubes
showing a reaction. This is a measure of the
concentration of bacteria per one-hundred milliliters of
water. The mean MPN index for each location suggests
that coliform bacteria, possibly containing enteric
pathogens, are present in the water at Doheny State
Beach. Further testing is necessary to determine what
kind of coliform organisms are present and if they are
harmful. An ANOVA was used to compare the means
of the three different locations. The resulting p-value
showed that there was no difference between the
bacterial concentrations of the three locations. Thus,
the initial hypothesis was not supported. According to
the results, there is an abundance of bacteria spread
equally amongst the three points of location.
A high-traffic area, Doheny is prone to run-off
from deforestation caused by roadwork, development
of residential areas, and other disturbances that
provoke ecological change.(Osborne 2008). Pollution
at this location could easily be controlled by
implementing more trees at the waterway to block
sediment runoff from streams into the ocean, less use
of fertilizers and other nutrients that promote plant
growth, and careful clean-up of road construction.
United States legislation proposed the clean-up of
sewage treatment plants and industries that discharge
pollutants into waterways in 1977 (Clean Water Act);
but other sources of contamination are still present,
such as sulfur dioxide from power plants, garbage in
landfills, and other nonpoint sources (Hart 2008).
These contaminants which accumulate in the air and
reach the ocean through precipitation are harder to
control.
Acknowledgments
Investigators thank Professor Steve Teh for not only
his help but his coordination for all of the materials we
needed. We also thank Vince Fiorentino for helping us
to collect the water samples despite that fact that is was
extremely cold and at night; thanks for getting wet!
134
Saddleback Journal of Biology
Spring 2010