1. ACIDIFICATION
OF
INLAND
LAKES
AND
ITS
EFFECT
ON
ZOOPLANKTON
COMMUNITIES
1
Running
Head:
ACIDIFICATION
OF
INLAND
LAKES
AND
ITS
EFFECT
ON
ZOOPLANKTON
COMMUNITIES
Acidification
of
Inland
Lakes
and
its
effect
on
Zooplankton
Communities.
Jorge
Jamie
Gomez
University
of
North
Florida
Biology
Department

2. ACIDIFICATION
OF
INLAND
LAKES
AND
ITS
EFFECT
ON
ZOOPLANKTON
COMMUNITIES
2
Abstract
This
paper
details
and
explores
some
of
the
negative
effects
of
inland
lake
acidification
on
zooplankton
populations.
Many
studies
have
been
done
to
emphasize
the
importance
of
reducing
sulfur
dioxide
emission
in
the
United
States
and
in
Europe
to
attempt
to
curtail
the
effects
of
acidification.
One
of
the
most
pressing
issues
regarding
acidification
is
its
effect
on
zooplankton
communities.
Some
zooplankton
communities
show
compensatory
effects
within
functional
groups.
Others
show
a
historical
resistance
to
acidified
waters
whereas
others
have
no
history
and
are
highly
disturbed
by
acidification.
Global
warming,
which
is
changing
drought
patterns
and
forest
fire
occurrence,
is
adding
a
new
obstacle
to
the
recovery
of
acidified
lakes
to
previous
and
tolerable
levels.
New
drought
patterns
are
causing
a
re-­‐acidification
of
lakes
well
before
a
recovery
is
complete
and
setting
the
recovery
process
back
years.
Another
problem
with
droughts
and
the
resulting
re-­‐acidification
is
the
emergence
of
resting
zooplankton
eggs.
This
in
itself
is
not
of
much
concern
but
when
this
occurs
before
a
lake
has
reached
pre
acidification
pH
levels
it
reduces
or
eliminates
the
survival
of
zooplankton
and
depletes
the
amount
of
resting
viable
eggs.
Although
lakes
are
chemically
recovering,
biological
recovery
lags
for
1-­‐6
years,
therefore
strong
efforts
must
be
implemented
to
prevent
future
re-­‐acidification
events.
Keywords:
acidification,
zooplankton,
recovery,
pH,
lakes,
anthropogenic

3. ACIDIFICATION
OF
INLAND
LAKES
AND
ITS
EFFECT
ON
ZOOPLANKTON
COMMUNITIES
3
Acidification
of
Inland
Lakes
and
its
effect
on
Zooplankton
Communities.
Sulfur
Dioxide
emissions
have
greatly
affected
a
large
amount
of
inland
lakes
by
acidification,
which
is
a
form
of
environmental
contamination
that
affects
the
biota
of
a
lake
ecosystem
by
lowering
the
pH
(Gonzalez
&
Frost,
1994);
therefore
much
was
done
in
the
1980s
and
1990s
to
reduce
its
emission.
A
big
concern
from
acidification
is
its
effect
on
geochemistry
and
the
bioavailability
of
heavy
metals.
Fish
become
much
more
susceptible
to
mercury
with
lowered
alkalinity
(Burger,
1997).
Another
concern
is
the
effect
of
acidification
on
primary
producers
and
zooplankton,
which
will
be
the
focus
of
this
paper.
Although
there
are
reports
of
recovery
in
acidified
lakes
in
North
America,
Scandinavia
and
Eastern
Europe,
there
are
still
areas
that
have
not
shown
any
recovery
such
as
Germany,
the
United
Kingdom,
southeastern
Canada
and
the
Adirondacks
of
North
America
(Frost,
Fischer,
Klug,
Arnott
&
Montz
et
al,
2006).
Causes
of
acidification
are
numerous
and
include
natural
sources
such
as
the
gradual
changing
of
a
forest
from
deciduous
to
coniferous
(Korsman
&
Segeström,
1998).
A
large
part
of
acidification
events
are
due
to
anthropogenic
sources
such
as
sulfur
dioxide
emissions
from
diesel
fuels
(Frost
et
al.,
2006),
and
industrial
waste
(Cairns,
Heath
&
Parker,
1975).
Acidification
of
lakes
has
detrimental
effects
on
zooplankton
populations
and
overall
food
web
ecology
(Locke
&
Sprules,
1994).
Some
of
the
effects
of
acidification
may
be
offset
by
compensatory
dynamics
of
functional
groups
(Fischer,
Frost
&
Ives,
2001)
and
some
may
be
exacerbated
by
re-­‐acidification
events
that
can
be
the
results
of
drought,
forest
fires
and
global
warming
(Arnott
&
Yan,
2006).
The
historical
acidic
profile
of
a
lake
may
also
help
to
determine
the
possible
effects
on

4. ACIDIFICATION
OF
INLAND
LAKES
AND
ITS
EFFECT
ON
ZOOPLANKTON
COMMUNITIES
4
zooplankton
and
food
webs
(Fischer,
Klug,
Ives
&
Frost,
2001).
There
are
many
causes
of
acidification
including
natural
and
anthropogenic
and
the
effects
on
zooplankton
vary
from
severe
to
moderate
and
recovery
is
a
process
that
can
take
up
to
ten
years
if
there
are
no
re-­‐acidification
events.
The
stability
of
zooplankton
populations
is
dependent
upon
a
variety
of
factors.
Some
of
the
factors
include
the
taxa’s
resistance
stability
or/and
a
systems
ability
to
stay
at
equilibrium
after
the
onset
of
a
perturbation
such
as
acidification.
The
majority
of
zooplankton
taxa
typically
begin
to
experience
the
negative
effects
and
the
stress
of
acidification
when
the
pH
of
a
system
becomes
<6
and
become
completely
overwhelmed
at
pH
levels
<5.
(Locke
&
Sprules,
1994).
The
ecological
history
of
a
freshwater
lake
is
also
a
factor
in
a
zooplankton
taxa’s
ability
to
respond
to
a
perturbation.
Zooplankton
in
lakes
with
a
history
of
natural
acidification
events
or
yearly
fluctuations
in
pH
levels
tend
to
respond
better
and
absorb
much
of
the
impact
of
anthropogenic
stressors
in
comparison
to
zooplankton
that
experience
a
novel
perturbation
in
pH
levels
(Fisher
et
al.,
2001).
Some
of
the
effects
that
can
increase
the
rate
of
population
decline
and
loss
of
zooplankton
taxa
are
not
always
directly
related
to
the
actual
pH
drop
in
a
lake.
Many
times
the
effect
can
be
a
byproduct
such
as
the
elimination
of
prey
items
or
the
elimination
of
higher
trophic
level
organisms
that
would
reduce
the
amount
of
zooplankton
predators.
Another
factor
that
affects
zooplankton
survival
is
the
reproductive
rate
of
prey
species
in
acidified
conditions,
which
is
directly
related
to
food
availability.
Many
species
of
zooplankton
respond
differently
to
acidification,
one
example
is
Keratella
chochlearis,
whose
response
to
acidification
depends
on
the

5. ACIDIFICATION
OF
INLAND
LAKES
AND
ITS
EFFECT
ON
ZOOPLANKTON
COMMUNITIES
5
availability
of
food.
K.
cochlearis
is
adversely
affected
by
pH
level
drop
only
if
food
is
scarce
and
is
not
affected
by
pH
fluctuations
if
food
is
highly
available
(Gonzáles
&
Frost,
1994).
Declining
population
in
different
zooplankton
taxa
has
detrimental
effects
on
the
well
being
of
freshwater
lake
ecosystems.
Compensatory
effects
of
functional
groups
may
offset
some
of
the
negative
consequences
of
lake
acidification.
When
taxa
of
a
functional
group,
such
as
herbivorous
cladocerans
or
herbivorous
copepods,
were
diminished
or
completely
eliminated
by
an
acidification
event,
other
taxa
that
performed
similar
functions
often
experienced
population
growth
during
the
same
event.
This
compensatory
effect
helps
to
offset
some
of
the
food
web
disruptions
that
would
other
wise
take
place
(Fischer,
Frost
&
Ives,
2001).
Other
perturbations
that
increase
acidification
in
lakes
are
forest
fires,
and
with
the
onslaught
of
global
warming,
temperature
increases
and
uncharacteristic
droughts
also
play
a
role
(Kormans
&
Segerström,
1998,
Arnott
&
Yan,
2002
and
Cairns
et
al.,
1975).
With
global
warming
predicted
to
change
global
rainfall
patterns,
temperatures
and
increase
the
occurrence
of
large
forest
fires,
the
acidification
of
lakes
may
drastically
increase
in
frequency
and
severity
(Angeler
&
Moreno,
2007)
while
the
recovery
process
may
be
severely
impeded
due
to
re-­‐
acidification
events
(Arnott
&
Yan,
2002).
A
common
misconception
about
lake
acidification
is
that
all
events
are
due
to
anthropogenic
causes
when
in
reality
there
are
many
natural
factors
that
cause
or
contribute
to
acidification
events.
Although
forest
fires
usually
cause
a
decrease
in
pH
by
the
burning
of
the
humus
layer
on
the
watershed,
they
may
actually
help
to

6. ACIDIFICATION
OF
INLAND
LAKES
AND
ITS
EFFECT
ON
ZOOPLANKTON
COMMUNITIES
6
reduce
adverse
zooplankton
responses
to
anthropogenic
lake
acidification
by
natural
selection
(Koorsman
&
Segerström,
1998).
Lakes
with
regular
pH
fluctuations
caused
by
forest
fires
develop,
through
evolution,
zooplankton
species
that
are
less
susceptible
to
anthropogenic
acidification
events
(Fischer
et
al.,
2001).
Although
forest
fires
seem
to
help
zooplankton
responses
through
selective
pressures,
lakes
that
are
in
chemical
and
biological
recovery
from
acidification
and
experience
a
re-­‐acidification
event
due
to
fire
will
experience
set
backs
in
the
overall
recovery
(Korsman
&
Segerström,
1998).
Droughts
that
are
a
result
of
El
Niño
meteorological
events
are
having
a
compounding
effect
on
zooplankton
populations
in
acidified
lakes.
The
problem
being
that
reduced
sulfur
compounds
that
have
been
safely
trapped
in
the
catchment
become
oxidized
when
they
come
into
contact
with
the
atmosphere
due
to
dropping
water
levels.
When
the
rains
return
and
the
water
levels
rise,
the
oxidized
sulfur
compounds
are
then
added
back
into
the
water
column
and
the
lake
experiences
a
re-­‐acidification
event
(Arnott
&
Yan,
2002).
Although
González
and
Frost
(1994)
state
that
rotifer
diversity,
in
acidified
lakes,
is
sometimes
higher
for
certain
taxa,
Arnott
and
Yan
(2002)
argue
that
this
is
due
to
the
drought
re-­‐
acidification
phenomena
and
may
eventually
cause
populations
of
taxa
to
disappear.
According
to
Frost
et
al.
(2006),
zooplankton
recovery
in
acidified
lakes
may
take
up
to
ten
years.
The
problem
is
that
after
a
drought,
zooplankton
are
cued
to
come
out
of
diapause
and
viable
eggs
hatch
when
the
rains
return.
This
presents
an
issue
because
the
limited
quantity
of
viable
eggs
have
been
deposited
and
stored
in
the
sediments
prior
to
acidification.
During
re-­‐acidification
events,
the
newly
hatched

7. ACIDIFICATION
OF
INLAND
LAKES
AND
ITS
EFFECT
ON
ZOOPLANKTON
COMMUNITIES
7
eggs
and
zooplankton
that
come
out
of
diapause
are
in
an
inhospitable
environment
and
do
not
survive.
If
the
zooplankton
do
not
survive
to
reproduce,
the
eggs
stored
in
the
sediment
will
eventually
run
out
causing
a
disappearance
of
the
taxa
(Arnott
&
Yan,
2002).
Global
warming
and
related
temperature
increases
can
have
several
negative
effects
in
freshwater
lakes
including
the
intensification
of
acidification
events.
Potassium
cyanide
is
a
salt
that
is
present
in
large
quantities
in
lakes
that
receive
wastes
from
industrial
plants.
In
high
temperatures
and
low
pH,
potassium
salts
hydrolyze
into
Hydrogen
Cyanide
(HCN),
which
is
highly
toxic
to
aquatic
organisms
(Cairns
et
al.,
1975).
Temperature
increases
play
a
significant
role
in
hatching
cues
for
zooplankton
(Angeler
&
Moreno,
2007),
which
as
mentioned
before
could
significantly
decrease
zooplankton
diversity
and
decrease
the
rate
of
lake
recovery
(Arnott
&
Yan,
2002).
Acidification
of
lakes
is
highly
detrimental
to
zooplankton
communities
in
fresh
water
lakes.
There
are
many
factors
that
affect
the
severity
of
the
acidification
event.
Sulfur
emission
is
one
of
the
most
prevalent
causes
of
acidification.
Once
a
freshwater
lake
reaches
a
pH
<6
adverse
affects
begin
to
take
place
for
most
zooplankton
taxa
except
acidophilic
species.
At
pH<5
most
of
the
zooplankton
are
in
unable
to
survive
the
acidity
of
the
water.
Once
a
recovery
takes
place
there
is
a
three
to
ten
year
lag
in
biological
recovery
compared
to
chemical
(pH)
recovery.
Certain
condition
such
as
global
warming,
drought,
forest
fires
and
changing
climate
patterns
exaggerate
the
effect
of
acidification
and
can
cause
a
recovering
system
to
re-­‐acidify.
Future
studies
can
be
done
and
focused
on
ways
in
which
lakes
can
be

8. ACIDIFICATION
OF
INLAND
LAKES
AND
ITS
EFFECT
ON
ZOOPLANKTON
COMMUNITIES
8
safely
alkalinized
as
well
as
methods
to
reestablish
zooplankton
populations
in
order
to
restore
lake
chemistry
and
food
web
stability.

9. ACIDIFICATION
OF
INLAND
LAKES
AND
ITS
EFFECT
ON
ZOOPLANKTON
COMMUNITIES
9
Bibliography
Angeler,
D.
G.
and
Moreno,
J.
M.
(2007).
Zooplankton
Community
Resilience
after
Press-­‐Type
Anthropogenic
Stress
in
Temporary
Ponds.
Ecological
Applications.
17(4),
1105-­‐1115.
Arnott,
S.
E.
and
Yan,
N.
D.
(2002)
The
Influence
of
Drought
and
Re-­‐Acidification
on
Zooplankton
Emergence
from
Resting
Stages.
Ecological
Applications.
12(1),
138-­‐153.
Burger,
J.
(1997).
Methods
for
and
Approaches
to
Evaluating
Susceptibility
of
Ecological
Systems
to
Hazardous
Chemicals.
Environmental
Heath
Perspectives.
105(44),
843-­‐848.
Cairns
Jr.,
J.,
Heath,
A.
G.
and
Parker,
B.
C.
(1975).
Temperature
Influence
on
Chemical
Toxicity
to
Aquatic
Organisms.
Journal
(Water
Pollution
Control
Federation).
47(2),
267-­‐280.
Fischer,
J.
M.,
Frost,
T.
M.
and
Ives,
A.
R.
(2001).
Compensatory
Dynamics
in
Zooplankton
Community
Responses
to
Acidification:
Measurement
and
Mechanisms.
Ecological
Applications.
11(4),
1060-­‐1072.
Fischer,
j.
M.,
Klug,
J.
L.,
Ives,
A.
R.
and
Frost,
T.
M.
(2001)
Ecological
History
Affects
Zooplankton
Community
Responses
to
Acidification.
Ecology.
82(11),
2983-­‐
3000.

10. ACIDIFICATION
OF
INLAND
LAKES
AND
ITS
EFFECT
ON
ZOOPLANKTON
COMMUNITIES
10
Frost,
T.
M.,
Fishcer,
J.
L.,
Arnott,
S.
E.
and
Montz,
P.
K.
(2006).
Trajectories
of
Zooplankton
Recovery
in
the
Little
Rock
Lake
Whole-­‐Lake
Acidification
Experiment.
Ecological
Applications.
16(1),
353-­‐367.
Gonzales,
M.
J.
and
Frost,
T.
M.
(1994).
Comparisons
of
Laboratory
Bioassays
and
a
Whole-­‐Lake
Experiment:
Rotifer
Responses
to
Experimental
Acidification.
Ecological
Applications.
4(1),
69-­‐80.
Korsman,
T.
and
Segerström,
U.
(1998).
Forest
Fire
and
Lake-­‐Water
Acidity
in
a
Northern
Swedish
Boreal
Area:
Holocene
Changes
in
Lake-­‐Water
Quality
at
Makkassjon.
Journal
of
Ecology.
86(1),
113-­‐124.
Locke,
A.
and
Sprules,
W.
G.
(1994).
Effects
of
Lake
Acidification
and
Recovery
on
the
Stability
of
Zooplankton
Food
Webs.
Ecology.
75(2),
498-­‐506.