Saddleback Journal of Biology - Saddleback College

Fall 2009 Biology 3B Paper
consumers of red and green algae; abnormal algal
growth caused by human-sourced water contamination
may also play a role in the growth tendencies of these
organisms (Watanabe 1984). Variations of factors in
the water can cause fluctuations in population density,
which cause ripple effects throughout the food chain.
Due to the dependence the organisms’ respective food
sources have on good water quality, we hypothesized a
positive correlation between mean size and distance
from our initial location (which had the most
contaminated water, as indicated by temperature and
pH).
Materials and Methods
Locations
Studies were done on limpets and turban
snails at five different locations. On November 8, 2009,
thirteen limpets and thirteen turban snails were
measured near tide pools or rocks at each particular
location. Studies were first conducted at Long Beach
harbor, California and then at the other locations as we
proceeded south in approximately two mile intervals.
Long Beach harbor (latitude 33° 49' N, longitude 118°
9' W) was the initial location and ground zero for this
research due to its hub of shipping activity. The second
location was at the intersection of Appian and Ravenna
(latitude 33° 45' N, longitude 118° 7' W) located in a
residential area. Our third location was at a jetty near a
public beach at the intersection of 1 st Street and Ocean
Avenue (latitude 33° 44' N, longitude 118° 6' W). The
fourth stop was at a pier next to 1580 Seal Way in Seal
Beach, California (latitude 33° 44' N, longitude 118° 6'
W). Our fifth and final stop was at the tide pools of
Crescent Bay in Laguna Beach, California (latitude 33°
32' N, longitude 117° 48' W), which was chosen as our
control group. The magnitude of shipping activity
decreased as we continued to travel south.
Methods and Protocols
The measurement devices favored for this
research were 12-inch rulers, pH strips, and
thermometers. At each location, the thirteen organisms
were carefully extracted and measured, in centimeters,
on their ventral side. Seven readings were collected
each for the pH and temperature of the water at every
location. Observations and data collections were
conducted during low tide to ensure accurate data. An
analysis of variance (ANOVA) test was chosen to
analyze the collected data because we were comparing
the mean lengths of the organisms, pH of the water,
and temperature of the water at several locations.
While studying the results, a significant difference was
taken into account when the probability value (p-value)
was less than or equal to 0.05 (p≤ 0.05) for the mean
combined lengths of the two organisms, temperature of
the ocean, and pH of the water. So, an additional Post-
Hoc analysis test for each data group had to be run to
isolate where the significant differences lied.
Results
Mean combined lengths of both organisms at
all locations differed greatly (Figures 1 and 2). The
mean combined length of turban snails at Long Beach
harbor was 1.77 ± 0.08 cm (±SEM, N= 13). At the tide
pools at the intersection of Appian and Ravenna, which
was approximately 2.4 miles from initial, the mean
combined length of turban snails was 1.22 ± 0.04 cm
(±SEM, N= 13). The mean combined length of turban
snails at the jetty, which was approximately 4.3 miles
away from initial, was 0.90 ± 0.08 cm (±SEM, N= 13).
The mean combined length of turban snails at the
intersection of Ocean Boulevard and Neptune Avenue,
which was approximately 6.3 miles from initial, was
0.64 ± 0.06 cm (±SEM, N= 13). At Crescent Bay,
which was approximately 25.6 miles from initial, the
mean combined length of turban snails was 1.55 ± 0.08
cm (±SEM, N= 13). The mean lengths of the turban
snails significantly decreased (p= 0.0001) as we
traveled south of Long Beach harbor (Figure 1).
2
Length of Ventral Side
(cm)
1.5
1
0.5
0
0 2.4 4.3 Distance
1
6.3 25.6
from Initial (mi)
Figure 1. Bar graph displaying the mean combined
length of turban snails. The size of the snails
significantly decreased as the distance from Long
Beach (initial location) increased. Error bars represent
±SEM for each location (ANOVA, Post-Hoc, p=
0.0001, N=13).
The mean combined length of limpets at Long
Beach harbor was 0.99 ± 0.03 cm (±SEM, N= 13).
From approximately 2.4 miles from initial, the mean
combined length of limpets was 2.10 ± 0.14 cm
(±SEM, N= 13). From approximately 4.3 miles from
initial, the mean combined length of limpets was 2.48 ±
0.11 cm (±SEM, N= 13). At approximately 6.3 miles
away from initial, the mean combined length of limpets
was 3.12 ± 0.28 cm (±SEM, N= 13). At approximately
25.6 miles away from the initial, the mean combined
length of limpets was 2.16 ± 0.12 cm (±SEM, N= 13).
Lengths of the limpets significantly increased
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Saddleback Journal of Biology
Spring 2010