Volume 6, Spring 2008 - Saddleback College

Fall 2007 Biology 3A Abstracts
Results
The mean body mass of the Betta fish was
1.55± 0.03g (±SE). Overall there was not a statistically
significant difference in initial aggression response and
ethinyl estradiol acclimated aggression response.
Although the actual approach of the Betta fish to its
image is not specific to the agonistic display, it was
included because it signaled the start of Betta
aggression. The average time it took for the Betta to
notice, then approach its mirrored image was not
affected by exposure to ethinyl estradiol (Table 2).
The average time it took for the initial flaring of the
Betta’s pelvic fin, ventral fin, caudal fin, gill
operculum, and twist its body 90° were longer in the
treated fish, but statistically the averages were not
significantly different (Table 2).
Type of
Fin Flaring
Mean ± SE
pre-exposure
(seconds, N=6)
Mean ± SE
post-exposure
(seconds, N=6)
paire
d t-
test
(two
tailed
)
Approach 39.91 ± 9.34 46.56 ± 54.16 0.657
Pelvic 55.95 ± 17.29 74.135 ± 84.04 0.415
Ventral 92.77 ± 29.00 102.08 ± 89.12 0.484
Caudal 127.00 ± 27.01 125.77 ± 84.71 0.979
Dorsal 92.01 ± 29.47 105.36 ± 56.76 0.503
Gill
Operculum
90°Body
twist
127.52 ± 25.60 148.03 ± 76.83 0.649
117.78 ± 105.8 159.71 ± 91.17 0.517
Table 2. Type of flare, Mean times ± Standard error
pre- and post-ethinyl estradiol exposure, and paired t-
test of the means.
Discussion
Unfortunately ethinyl estradiol did not have a
statistically significant effect on the agonistic
aggressive behavior of male Betta fish. The slight
increases in mean times observed could be attributed to
differences in physiological condition of each Betta
fish (Karino and Someya, 2002). The results of this
experiment were negative, but other experiments have
shown that estrogen affects fish behavior including
aggression. Therefore, future experiments should
increase exposure and/or concentration, or expose
immature fish (Clotfelter and Rodriquez, 2006). If
aggression is not changed, other behaviors like nest
building and mating rituals can be studied.
Possible sources of error can come from the
fact that a pill of Yasmin 28 contains other ingredients
besides ethinyl estradiol. It is possible the observed
changes in behavior are actually caused by those other
ingredients. Also, at times, it was difficult to
differentiate the exact time of the fin flaring. If this
experiment were to be done again, the researchers
suggest that a video recorder be used so that the results
can be reviewed and the exact movements and timing
can be determined.
It should be known that the concentration of
ethinyl estradiol used during this experiment mimics
exceptionally polluted waters and is much higher than
concentrations normally found in natural water systems
(Quintana et al., 2003; Lai et al., 2002). In the future,
it would behoove researchers to repeat the experiment
using varied concentrations of estrogen to determine
exactly where behavior begins to diverge from the
norm. Although even then, the results would not
necessarily be an indication of what actually occurs in
nature, because estrogen degrades and reacts with other
naturally occurring chemicals in ways that are not
simply or easily predicted (Lai et al., 2002).
In conclusion, ethinyl estradiol is a specific
type of estrogen, but as a class, other estrogen derivates
are known to have affected dramatic changes in
population size, reduction in immune responses, have
serious detrimental effects on maturing embryos and
other immature aquatic vertebrates (Clotfelter and
Rodriquez, 2006; Quintana et al., 2004). Although it
may seem that estrogen pollution of water can only
affect aquatic species, it is also able to migrate through
river bed sediments and potentially contaminate the
ground water that humans use (Labadie et al., 2007).
As the human population continues to expand, the
public needs to become aware of the effect that our
agricultural and industry is having on our environment
and our water sources.
Literature Cited
Allen, J.M. and Nicoletto, P.F. (1997). Response of
Betta splendens to Computer Animations of Males with
Fins of Different Length. Copeia, 1997 (1): 195-199.
Clotfelter, E.D. and Rodriquez, A.C. (2006).
Behavioral Changes in Fish Exposed to
Phytoestrogens. Environmental Pollution, 144, 833-
839.
Karino, K. and Someya, C. (2002). The Influence of
Sex, Line, and Fight Experience on Aggressiveness of
the Siamese Fighting Fish in Intrasexual Competition.
Neurotoxicology and Teratology, 24, 29-36.
Kolpin, D.W., Furlong, E.T., Meyer, M.T., Thurman,
E.M., Zaugg, S.D., Barber, L.B., and Buxton, H.T.
(2002). Pharmaceuticals, Hormones, and Other
Organic Wastewater Contaminants in the U.S. Streams,
1999-2000: A National Reconnaissance.
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Saddleback Journal of Biology
Spring 2008