The Effect of the San Onofre Nuclear Power Plant on the Growth of Intertidal
Organisms.
Greg Clarke and Kamen Tagalicod
Department of Biological Sciences
Saddleback College
Mission Viejo, California 92692
This study examined the effects the San Onofre Power Plant had on the
vertical growth of intertidal organisms. It was hypothesized that the vertical growth
of organisms would be significantly smaller closer to San Onofre than in Laguna
Beach. The t-test for two means showed a significant difference between the vertical
growth of organisms at the two different tide pool locations (P=2.26x 10-2±S.E.M).
When the measurements were taken from the two tide pools, a significant difference
in growth was revealed, thus supporting the proposed hypothesis.
Intro
The San Onofre power plant is a nuclear generating plant that is located in northern San Diego
County. The power plant provides about 20% of all electrical power to the residents of Southern
California. But what is it doing to the surrounding aquatic wildlife, and to the intertidal organisms in the
surrounding tide pools. These organisms would consist of Lithothrix (Red Algae), Ulva (Green Algae),
Egregia (Brown Algae), Littorina planaxis (Perriwinkle), Tegula funebralis, (Turban Snail),
Strongylocentrotus franciscanus (Sea Urchin), Anthopleura (Sea Anemone), and the Mytilus (Mussel).
With the San Onofre Nuclear Power Plant the vertical growth of these organisms may be suffer due to
radioactive waste, or other runoff in the water from the power plant. “There are two general approaches to
the treatment of radioactive waste materials… The second approach involves the principles of dilution and
dispersion. Here the purpose is to so dilute the wastes in man’s environment that the radioactivity which
could be returned to man would be negligible compared to the natural background to which he has always
been exposed” (Brown and Richard, 1961). The practice of dumping wastes and CO2 has become a
popular way of disposal for many factories and power plants. Auerbach (1997) found that the point of
dumping of these wastes has a severe impact on the local marine wildlife. Watson (1992) showed that
density of larval Pacific Sardine, (Suvdinops sugux) was 20% less near San Onofre than at Stuart Mesa.
Disposing of waste into the ocean may be safe for man, but not for the wildlife. “…it is quite likely that the
sea will be the safest place to dispose of certain radioactive waste materials…” (Brown, and Prichard
1961). Brown and Prichard (1961) also found that nuclear waste and other hazardous material are
inevitable to reach the ocean. Whether it is through sewers, rivers, or through big factories, the surrounding
wildlife in the tide pools could be effected, and therefore stop their growth.
Materials and Methods
On the third day of November 2009 two students traveled to Laguna Beach, CA to perform a
vertical zonation of organisms living in the intertidal marine environment. The procedure was performed at
approximately 3:30 pm by reason of the tide being at its lowest point. Two 100 meter transect tapes and
two 0.25 m2 quadrats were loaned to the students the day prior. Using the transect tape students started at
the high tide zone (splash zone) and measured out toward the lower intertidal zone. The tapes measured
from 0 to 45 meters. 0.25 m2 quadrats were used every 5 meters along the transect tape for a total of 10
transect points (0, 5, 10, 15, 20, 25, 30, 35, 40, and 45 meters). Green Algae (Ulva), Red Algae
(Lithothrix), Brown Algae (Egregia), Periwinkle snails (Littorina planaxis), Turban snails (Tegula
funebralis), Mussels (Mytilus), Sea Anemones (Anthopleura) and Sea Urchins (Strongylocentrotus) were
the 8 organisms observed. The sum of each organism was calculated in each of the 10 quadrats and
recorded in a lab notebook. This procedure was performed three times on this day at the Laguna Beach
Location.
On November 13th students traveled to San Onofre California to perform the same procedure with
intentions of a significant difference in the distribution of organisms. The tide pool surveyed was
approximately 1 mile from the Nuclear Power Plant itself. At the San Onofre location the following
intertidal organisms did not exist: Periwinkle snails, Mussels, and Sea Urchins. A table was constructed in
the lab notebook to record the organisms that did exist at this location and the Laguna Beach location
(Green Algae, Red Algae, Brown Algae, Turban snails, and Sea Anemones). The quadrats were most often
covered in copious amounts of rocks at this San Onofre location in the middle intertidal and high tide zone.
Students had to move the rocks to uncover the abundant amount of Turban snails on their underside. On
this day of research five transect lines of 45 meters were recorded.
November 18th 2009 students traveled back to the same Laguna Beach location for two more 45
meter transect lines so that it would be an even five in San Onofre and five in Laguna. Data was recorded
in a table for these last two runs during a low tide at 4:30 pm. All data from the three research days was
transferred into Microsoft Excel for number crunching. An equation was used to determine frequency:
Frequency = number of quadrats in which a species occurs ÷ total number of quadrats sampled
Results
There is a significant difference in vertical growth in intertidal organisms between Laguna Beach
and San Onofre tide pools. The measures that were taken started off at 0m, and ended at 45m in 5 m.
increments. As the distance from the splash zone increased, the greater the variety of intertidal species
became. Taken from all five runs, the mean of all specimens came out to 152.8, and when all five runs were
taken from San Onofre the mean of specimens came out to 17.4. When the two means were put through a
one-tailed paired t-test, it was found that there was a significant between the growth of intertidal organisms
(P=2.26x 10-2±S.E.M).
Frequency of Organisms
180
160
140
120
100
80
60
40
20
0
Laguna Beach
San Onofre
Figure 1. Comparing the means of the two beaches the one-tailed unpaired t-test shows a significant
difference in the growth of intertidal organisms (P=2.26 x 10-2±S.E.M). Error bars are set at 95%
intervals.
Discussion
In San Onofre, California the nuclear power plant has an effect on the life of organisms living
nearby. Low or intermediate-level wastes associated with nuclear-power are dispersed into marine
environments as normal operation when deemed by companies as not being a public health risk (Brown et
al, 1961). Although nuclear wastes in the ocean may not be considered a health risk to humans it affects its
direct inhabitance (intertidal organisms) in a significant way being that they exist within a miles distance of
this constant exposure. Laguna Beach contained a more diverse and abundant amount of organisms in its
tide pools when compared to the San Onofre location. Distribution ranged from less frequent to nonexistent when locations were compared. Pacific sardine larvae living immediately above the sea floor
existed less frequently in San Onofre than at Stuart Mesa (Watson 1992). This suggests that there is less
abundance in organisms when being geographically closer to the power plant. Radiation in the water could
be the cause of this phenomenon as it can effect marine life in negative ways.
In the study one possible inconsistency arose with the Turban snail (Tegula funebralis). In
Laguna the Turban snail appeared less frequently than in the San Onofre location suggesting that the power
plant has no negative effect on this organism. The turban snail was the only organism with this occurrence.
Perhaps it has the ability to exist in more extreme conditions unlike the periwinkle snail (Littorina
planaxis) which was non-existent in that location.
In the future students would like to do a bacteriological examination of the water in the two
locations to see how different they are. Testing for temperature and salinity of the water could also tell us
more about how organism growth is affected in the two areas and if it is a result of the power plant
exposure.
Acknowledgements
A special thanks to Professor Teh for the help and support for this project, and to the Department
of Biology at Saddleback College for providing the tools necessary for completion of the project.
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