Saddleback Journal of Biology - Saddleback College

Fall 2009 Biology 3B Paper
ones. With this in mind, we set out to determine the
density of common tide pool organisms for two
locations. The locations where our research was
conducted were at Doheny State Beach, California and
Treasure Island, California in November of 2009.
Locations were chosen due to contamination
differences between both locations, this may
potentially have an effect on the density of the
organisms. These variations in density, with time may
have a much greater impact on the organism’s ability to
survive and since they are a basic food source for fish,
and fish are a basic food source for people, an
extinction of fish will be catastrophic. According to
Natural Resources Defense Council, recent reports
released on July of 2009, Testing the Waters 2009 A
Guide to Water Quality at Vacation Beaches, have
determined that “Doheny State Beach violated the
state’s bacterial standards as much as 49 percent of the
time in 2008. Doheny remains among the most
contaminated according to bacterial measurements.
The average percentage that showed unsafe bacteria
levels for Doheny in 2008 was 36%, compared to
Laguna Beach at 0%, indicating very low levels of
unsafe bacteria.” Chronic contamination has been a
problem for years at Doheny, and scientists are still
investigating likely causes. Such causes may include,
but not directly related, is “an abundance of Carbon
Dioxide changes the chemistry of the sea causing the
life for most marine organisms to be in danger
(Caldeira 2003).” Water temperature, rising pH levels,
directly related to water temperature, depth, tidal
amplitude, and turbidity are important factors of
increased water contamination (Cha 2004). These
factors may potentially cause a change in density for
the tide pools.
Among the organisms discovered in the tide
pools, were the Sea anemone (Amthopleura
xanthogrammica), California mussel (Mytilus
californianus), Blue Banded hermit crab (Pagurus
samuelis), and the Black Turban snail (Tegula
funebralis). These organisms were chosen for our study
due to its availability and allow for accurate data. All
organisms were present at both locations. Efforts in
reducing water contamination in our local beaches will
benefit marine organisms by increasing their means of
survival in intertidal ecosystems and ultimately, benefit
the human race.
Materials and Methods
The observation of marine organisms in the
tide pools at Doheny State Beach and Treasure Island
was done on November 14, 2009 at low tide. Six tide
pools at each location were selected to be observed
based on their area which was measured with a tape
measure and by measuring the length and width of each
tide pool. The Anthopleura xanthogrammica (green
sea anemone), Mytilus californianus (California
mussel), Pagurus samuelis (blue banded hermit crab),
and Tegula funebralis (black turban snail) were all
tallied at each tide pool and recorded in our lab
notebook. These organisms were selected because they
were present at both locations and we were looking to
compare if pollution was beginning to affect the
abundance of these marine organisms. The data was
then transferred to Microsoft Excel. The density of
each organism in each tide pool was calculated by the
ratio of the number of individuals of a species to the
total area it inhabited. Using the density calculations
the relative density was calculated by the ratio of the
density of a species to the total densities of all species
multiplied by one hundred. The relative densities of
each organism at each location were graphed on a bar
graph using Microsoft Excel. An unpaired two-tailed t-
test was ran on the data and showed that there was no
significant difference between the relative densities of
all the organisms at both locations (p=0.99±S.E.M.).
Results
The mean relative densities of each organism
at both locations were graphed using a bar graph on
Microsoft Excel (figure 1). An unpaired two-tailed t-
test was ran on the data and results showed that there is
no significant difference between the mean relative
densities of the green sea anemones, California
mussels, black turban snails, or blue banded hermit
crabs. A statistical analysis was also run on the data in
order to calculate the standard error means.
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Saddleback Journal of Biology
Spring 2010