As
the
findings
of
Depledge
and
Billinghurst

(1999)

stated,
 increased
 estrogen
 levels
 in
 aquatic
 environments
 have
 caused
morphological
changes
and
endocrine
disruption
in
 several
 species
 of
 fish.
 Pintor
 et.
 al.
 (2008)
 noted
 that
 behavioral
 aggression
 changes
 of
 male
 crayfish
 were
 evaluated
 due
 to
 their
 extremely
 aggressive
 nature.
 By
 exposing
 a
 group
 of
 male
 crayfish
 to
 estradiol,
 the
 main
 component
 of
 the
 female
 hormone
 estrogen,
 increased
 levels
of
aggression
were
observed
in
this
reserch.
Previous
studies
using
estradiol
on
fish
populations
showed
 morphological
 and
 behavioral
 changes
 (Clotfelter
 and
Rodriguez,
 2006).
 The
 goal
 of
 this
 research
 is
 to
 test
 the
 aggression
levels
of
male
crawfish
after
the
introduction
of
17
 B-estradiol
 into
 their
 environment.
 The
 prediction
 was
 that
the
introduction
of
17
B-estradiol
into
the
water
supply
 would
 increase
 the
 crawfish
 aggression.
 The
 results
 may
 assist
 the
 understanding
 of
 estrogenic
 products
 on
 the
 environment,
 specifically
 male
 crawfish
 in
 the
 Waco
Wetlands
of
Texas.
Twelve
 male
 crawfish
 were
 collected
 from
 the
 Lake
Waco
 Wetlands.
 Because
 17
 B-estradiol
 is
 insoluble
 in
 water,
ethanol
was
used
to
dissolve
the
estradiol
into
a
 concentrated
solution.
Then
the
solution
was
diluted
to
a
 concentration
 of
 300
 µg
 17
 B-estradiol/L
 tap
 water
 in
 each
test
container.
Each
crawfish
was
acclimated
for
at
least
24
hours
in
a
 holding
container.
Pairs
of
crawfish
were
transferred
to
a
 testing
container
where
their
behavior
was
videoed
for
5
 minute
 intervals
 and
 were
 returned
 to
 the
 holding
 containers.
 Next,
 17
 B-estradiol
 was
 introduced
 to
 the
 water
 supply
 at
 a
 concentration
 of
 300
 µg/L
 tap
 water.
The
crawfish
were
exposed
to
this
estradiol
solution
for
2
hours.
The
behavioral
effects
of
the
estradiol
solution
 were
 monitored.
 After
 all
 testing
 the
 aggression
 was
 assessed
 using
 the
 aggression
 scale
 developed
 by
Karavanich
and
Atema
(1998).
In
assessing
the
crawfish
 aggression
levels,
the
 distributions
was
normal.
There
was
sufficient
 statistical
evidence
to
 support
that
the
mean
 aggression
levels
is
higher
 post
estradiol
exposure.
This
conclusion
can
be
 drawn
because
the
pvalue
0.0034
is
statistically
small.
The
 experiment
 conducted
 showed
 a
 positive
 correlation
 between
 aggression
 levels
 in
 male
 crawfish
 with
 the
 introduction
 of
 estradiol.
 Previous
 studies
 revealed
 morphological
 and
 behavioral
 changes
 in
 aquatic
 organisms
 exposed
 to
 estradiol
 (Clotfelter
 and
Rodriguez,
2006).
This
experiment
was
designed
to
test
 the
 aggression
 levels
 of
 male
 crawfish
 pre
 and
 post
 estradiol
exposure.

The
significance
of
this
study
shows
 that
 there
 was
 a
 positive
 correlation
 with
 estradiol
 and
 increased
 aggression
 in
 male
 crawfish
 of
 the
 Waco
Wetlands.
 
This
study
indicated
that
there
could
be
an
 affect
 of
 estrogen
 pollution
 on
 aquatic
 organisms
 such
 as
crawfish.
Test
Statistic
 -2.9758
Prob>
|t|
 0.0068*
Prob
>
t
 0.9966
Prob
<
t
 0.0034*
Clotfelter,
E.
and
A.
Rodriguez.
2006.
Behavioral
changes
in
fish
 exposed
to
phytoestrogens.
Environmental
Pollution
144:833-839.
Depledge,
M.H.
and
Z.
Billinghurst.
1999.
Ecoloical
significance
of
 endocrine;
disruption
in
marine
invertebrates.
Marine
Pollution
Bulletin
39:32-38
Karavanich,
C.
and
J.
Atema.
1998.
Individual
recognition
and
 memory
in
lobster
dominance.
Animal
Behavior
56:1553-1560.
Pintor,
L.
M.,
A.
Sih,
and
M.L.
Bauer.
2008.
Differences
in
 aggresssion,
activity
and
boldness
between
native
and
intoduced
 populations
of
an
invasive
crayfish.
Oikos
117
(11):
1629-1636.
A
 special
 thanks
 to
 Dr.
 Marty
 Harvill,
 Dr.
 Shannon
 Hill,
Kristen
 Rose,
 Nora
 Schell,
 Lake
 Waco
 Wetlands,
 Baylor
Department
of
Biology,
and
URSA.