Proposal: Tahoe Research Supported by SNPLMA 2010
I.
Title
Page
Title
Subtheme
Principal
Investigator
and
Receiving
Institution
Co‐Principal
Investigator
Agency
Collaborator
Grants
Contact
Person
Funding
requested:
Total
cost
share
contributions):
The
ecology
of
curly
leaf
pondweed
(Potamogeton
crispus)
and
the
potential
for
control
using
bottom
barriers
in
Lake
Tahoe
2a:
Understanding
the
impacts
of
aquatic
invasive
species
Marion
Wittmann,
Ph.D.
University
of
California
Davis
Tahoe
Environmental
Research
Center
291
Country
Club
Drive,
Incline
Village,
NV
89451
Phone:
775
881
7560
x7402
Fax:
775
832‐1673
Email:
mwittmann@ucdavis.edu
Sudeep
Chandra,
Ph.D.
Department
of
Natural
Resources
and
Environmental
Science
Mail
Stop
186
University
of
Nevada
Reno,
NV
89557
Phone:
775‐784‐6221
Fax:
775‐784‐4583
Email:
sudeep@cabnr.unr.edu
Lars
W
J
Anderson
USDA
Agricultural
Research
Service
Department
of
Plant
Science,
Mail
Stop
4
Weed
Science
Program,
UC
Davis
One
Shields
Avenue
Davis,
CA
95616
Phone:
(530)
752‐7870
Fax:
(530)
752‐4604
lars.anderson@ars.usda.gov
Kim
Boyd
Tahoe
Resource
Conservation
District
870
Emerald
Bay
Road,
Ste.
108
South
Lake
Tahoe,
CA
96150
Phone:
530
543
1501
x109
Fax:
530.543.1660
Email:
kboyd@tahoercd.org
Ted
Thayer
and
Rita
Whitney
Tahoe
Regional
Planning
Agency
p.o.
box
5310
Stateline,
Nevada
Phone:
775
589
5301
Fax:
775
588
4527
Email:
tthayer@trpa.org
George
Malyj
UC
Davis
John
Muir
Institute
of
the
Environment
(JMIE)
Watershed
Sci
Bldg,
RM
1105G,
Davis,
CA
95616
Phone:
530
752
3938,
FAX:
530
754
9364
gjmalyj@ucdavis.edu
$
184,040
$
1
Proposal: Tahoe Research Supported by SNPLMA 2010
II.
Proposal
Narrative
a.
Project
abstract
Aquatic
invasive
species
introductions
to
Lake
Tahoe
have
increased
in
recent
decades
and
are
rapidly
dispersing
and
impacting
the
nearshore
of
Lake
Tahoe.
Curly
leaf
pondweed
(Potamogeton
crispus)
was
recently
discovered
in
the
southern
portion
of
Lake
Tahoe
and
is
rapidly
expanding
along
the
littoral
zone.
Because
of
curly
leaf
pondweed’s
recent
introduction
and
restricted
range,
it
is
a
viable
candidate
for
control
or
eradication
in
Lake
Tahoe.
The
understanding
of
the
interaction
between
the
ecology
and
management
of
an
invasive
species
is
key
toward
a
successful
control
program.
The
major
objectives
of
this
proposal
are
to:
(1)
identify
the
role
the
“turion
bank”
of
curly
leaf
pondweed
plays
in
Lake
Tahoe
waters
and
the
potential
for
this
bank
to
contribute
to
the
spread
of
the
invasive
species,
(2)
the
susceptibility
of
this
bank
to
the
treatment
of
three
kinds
of
bottom
barriers,
and
(3)
recommend
and
outline
the
method
which
should
be
employed
at
the
lake
to
prevent
further
expansion
of
the
plant.
This
proposal
directly
addresses
the
need
for
control
and
management
of
this
new
and
aggressive
invasive
plant
species.
b.
Justification
statement:
explain
the
relationship
between
the
proposal
and
the
subtheme(s)
In
order
to
control
or
eradicate
Lake
Tahoe’s
established
aquatic
invasive
species,
it
is
necessary
to
understand
the
species‐specific
ecology
combined
with
novel
applications
of
effective
low
cost
non‐
chemical
treatments
to
prevent
population
growth.
Curly
leaf
pondweed
(Potamogeton
crispus),
is
one
of
Lake
Tahoe’s
most
recent
nearshore
aquatic
invaders,
and
because
of
its
unique
life
history
traits
(turion
production
and
seasonal
growth
patterns),
this
species
has
competitive
advantages
over
native
aquatic
plants
and
has
been
called
one
of
the
most
widely
distributed,
nuisance
forming
taxon
in
North
America
(Crowell
2003,
Johnson
2007).
Due
to
its
recent
introduction,
and
restricted
range
in
the
southern
portion
of
Lake
Tahoe
(Figure
1),
curly
leaf
pondweed
is
in
an
early
invasion
stage
(Figure
2)
and
thus
is
a
candidate
for
eradication
or
control.
The
goal
of
this
research
is
to
study
a
life
history
trait
of
curly
leaf
pondweed,
specifically,
vegetative
turion
production,
its
relationship
to
plant
biomass,
and
the
role
that
it
plays
in
(1)
population
expansion
in
the
nearshore
of
Lake
Tahoe,
(2)
its
susceptibility
to
non‐chemical
treatment
using
gas
permeable
and
impermeable
bottom
barriers,
and
(3)
recommend
the
method(s)
that
should
be
employed
to
control
this
early
invader
that
accounts
for
the
potential
rate
of
population
growth
in
certain
conditions
in
the
lake.
Through
this
research,
we
will
provide
information
related
to
the
invasion
pressure
of
variable
density
populations
of
curly
leaf
pondweed
in
the
lake
and
the
contributions
they
have
to
range
expansion
in
the
nearshore.
This
will
inform
the
potential
for
rapid
propagation,
and
provide
managers
with
a
mechanism
to
identify
the
magnitude
of
an
infestation
as
an
invasion
source
and
target
specific
densities
of
this
species
for
control.
In
addition,
we
will
determine
the
effectiveness
of
a
currently
utilized
control
mechanism
(bottom
barriers)
on
the
reduction
of
curly
leaf
pondweed
plant
biomass
as
well
as
on
turion
germination.
We
will
return
to
the
experimental
treatment
sites
one
half
year
and
one
year
after
application
and
measure
recolonization
rates.
Through
this
research,
we
can
make
recommendations
regarding
the
use
of
a
feasible
technology
for
non‐chemical
treatment
of
a
new
invasive
species,
recolonization
rates
associated
with
this
treatment,
and
a
life‐history
based
predictive
model
to
assess
the
rate
of
population
growth,
areas
to
target
for
treatment
based
on
differential
population
growth
rates,
and
potential
reductions
to
estimated
growth
rates
based
on
management
efforts.
c.
Concise
background
and
problem
statement
Invasive
species
introductions
and
impacts
in
Lake
Tahoe
and
the
need
for
effective
management.
Aquatic
invasive
species
have
been
identified
in
recent
years
as
a
major
threat
to
Lake
Tahoe
and
there
have
been
a
number
of
rapid
responses
by
basin
management
agencies
to
monitor
and
control
various
non‐native
invertebrate,
macrophyte
and
warmwater
fish
populations.
In
particular,
three
recent
2
Proposal: Tahoe Research Supported by SNPLMA 2010
invaders,
Asian
clam
(C.
fluminea)
(discovered
2002),
Eurasian
watermilfoil
(Myriophyllum
spicatum)
(identified
1995,
Anderson
and
Spencer
1996)
and
curly
leaf
pondweed
(Potamogeton
crispus)
(discovered
2003)
are
aggressively
spreading
within
Lake
Tahoe
and
are
establishing
or
threatening
surrounding
water
bodies
in
the
region.
In
Lake
Tahoe,
Asian
clam
has
been
shown
to
alter
nutrient
cycling
and
water
quality
by
creating
localized
increases
in
nitrogen,
phosphorus
and
calcium,
and
are
also
associated
with
filamentous
algal
blooms
and
decreases
to
nearshore
aesthetic
through
shell
matter
deposition
(Wittmann
et
al.
2008).
In
the
Tahoe
Keys,
Eurasian
watermilfoil
provides
habitat
for
warmwater
invasive
fishes
(Kamerath
et.
al.
2008),
pumps
phosphorus
into
the
water
column
potentially
leading
to
increased
algae
production
(Walter
2000),
and
is
a
navigation
nuisance
to
homeowners,
who
incur
an
annual
harvesting
cost
of
$260,000
for
this
species
(Dotson
2007).
Similarly,
curly
leaf
pondweed
has
spread
across
a
majority
of
the
south
shore
of
Lake
Tahoe
since
its
discovery
(Figure
1),
and
has
been
called
the
most
widely
dispersed,
nuisance
forming
invasive
aquatic
macrophytes
in
North
American
lakes
where
it
can
inhibit
recreation,
increase
water
column
phosphorus
concentrations
and
impair
water
quality
(Bolduan
et
al.
1994,
Woolf
and
Madsen
2003).
Bottom
barriers
as
a
non‐chemical
management
strategy
for
aquatic
invasive
species
The
use
of
benthic
barriers
to
inhibit
vital
physiological
or
metabolic
requirements
such
as
photosynthesis
or
respiration
is
well
known
as
a
non‐chemical
management
strategy
for
aquatic
nuisance
species
(Engel
1984,
Ussery
et
al.
1997,
Gunnison
and
Barko
1992,
Eichler
et
al.
1995,
Wittmann
et
al.
submitted).
In
Lake
Tahoe,
the
use
of
polyethylene
fabric
bottom
barriers
to
control
Eurasian
watermilfoil
has
been
implemented
since
the
2007
(Rita
Whitney,
TRPA
pers.
comm.)
with
localized
population
reductions
after
treatment.
In
2009,
UCD
and
UNR
researchers,
in
cooperation
with
Tahoe
basin
agencies,
field
experimented
with
EPDM
rubber
benthic
barriers
on
Asian
clam
populations
and
achieved
100%
mortality
in
28
days
due
to
the
reduction
of
dissolved
oxygen
concentrations
under
the
barriers
(Wittmann
et
al.
submitted).
In
2010,
one
acre
of
EPDM
benthic
barrier
was
applied
to
Asian
clam
populations
in
Lake
Tahoe
as
part
of
a
120
day
experiment
using
this
method.
Specific
life
history
characteristics
of
Eurasian
watermilfoil
and
Asian
clam
make
these
species
ideal
candidates
for
treatment
with
benthic
barriers.
Eurasian
watermilfoil,
as
all
submersed
aquatic
macrophytes,
require
light
for
growth
and
the
use
of
benthic
barriers
manipulates
the
habitat
by
blocking
light,
resulting
in
both
immediate
and
long
term
population
reduction
(USACE
2005).
While
Asian
clam
is
tolerant
to
a
number
of
toxicants,
turbid
conditions
and
wide
temperature
ranges,
this
species
is
hypoxia
intolerant
(Matthews
and
McMahon
1999)
and
thus
populations
can
be
reduced
by
eliminating
dissolved
oxygen
with
gas
impermeable
barriers.
Traditional
aquatic
macrophyte
(i.e.,
gas
permeable)
benthic
barriers
have
been
used
on
curly
leaf
pondweed
in
other
systems
with
variable
results.
Mayhew
and
Runkel
(1962)
and
Mayer
(1978)
reported
that
covering
curly
leaf
pondweed
populations
with
benthic
barriers
(polyethylene
and
Aquascreen™
(fiber
glass
coated
sheeting))
was
effective
at
reducing
biomass,
but
did
not
report
on
subsequent
recolonization.
Madsen
and
Crowell
(2002)
suggest
that
bottom
barriers
are
effective
to
prevent
the
growth
of
rooted
curly
leaf
pondweed,
however,
long‐term
management
requires
the
elimination
of
vegetative
buds
called
turions
to
interrupt
the
life
cycle
of
curly
leaf
pondweed.
The
unique
life
history
of
curly
leaf
pondweed:
Turion
production,
population
propagation
and
the
impacts
of
light
and
oxygen
reduction
Curly
leaf
pondweed
sprouts
from
dormant
shoot
segments
called
turions.
In
the
American
northeast,
turions
are
observed
to
germinate
in
late
summer
or
fall,
and
the
plants
overwinter
as
small
plants
and
resumes
growth
in
spring
when
water
temperatures
rise
(Figure
3).
Individual
stems
may
spread
locally
by
rhizome
growth
and
curly
leaf
pondweed
biomass
often
reaches
its
maximum
in
early
summer
while
flowering
and
fruiting
occur
from
April
to
May.
This
seasonal
pattern
allows
curly
leaf
pondweed
to
3
Proposal: Tahoe Research Supported by SNPLMA 2010
avoid
competition
from
other
species,
giving
it
ecological
advantages
as
an
invasive
species
in
freshwater
systems
(Tobiessen
and
Snow
1984).
Turion
production
is
curly
leaf
pondweed
main
source
of
vegetative
reproduction
(Rogers
and
Breen
1980)
and
sexual
reproduction
occurs
through
seed
production
(Waisel
1971).
However,
seed
germination
is
extremely
low
(<0.1%)
and
not
commonly
thought
of
as
an
important
source
of
recruitment
(Rogers
and
Breen
1980).
Additionally,
turions
also
act
as
a
storage
unit
for
carbohydrate
(Madsen
and
Crowell
2002),
which
can
enable
dormancy
until
environmental
conditions
are
more
favorable.
Though
curly
leaf
pondweed
is
known
to
be
susceptible
to
contact
herbicide
treatment,
plant
biomass
regrowth
often
occurs
due
to
turion
formation
as
the
major
form
of
re‐infestation
during
the
following
growing
season
(Netherland
et
al.
2000).
Thus,
curly
leaf
pondweed
turions
are
not
only
the
main
means
of
population
propagation,
reproduction
and
dispersal,
but
also
can
expand
the
window
of
opportunity
for
successful
recruitment
for
this
species
through
carbohydrate
storage,
herbicide
evasion
and
season
based
competition.
While
turion
germination
can
enable
the
sustainability
of
curly
leaf
pondweed
populations,
it
can
be
limited
by
a
number
of
physical
factors.
Laboratory
and
field
studies
have
found
that
germination
is
generally
controlled
by
temperature,
light
intensity
and
photoperiod
(Rogers
and
Breen
1980,
Sastroutomo
1981,
Kadono
1982,
Tobiessen
and
Snow
1984,
Jian
et
al.
2003).
However,
in
Asian
systems
where
curly
leaf
pondweed
is
native
and
used
to
restore
degraded
lakes,
turion
germination
has
ceased
as
a
result
of
low
light
availability
and
anoxic
conditions
(Wu
et
al.
2009,
Short
et
al.
1987,
Lauridsen
et
al.
1993,
Clarke
and
Wharton
2001,
Ni
2001).
Understanding
turion
germination
behavior
is
key
to
assessing
the
population
dynamics
of
this
species
and
the
potential
for
non‐chemical
treatment
in
Lake
Tahoe.
d.
Goals,
objectives,
and
hypotheses
to
be
tested
The
goals
of
this
study
are
to
employ
field
and
laboratory
methods
to
understand
the
impact
of
curly
leaf
pondweed
on
Lake
Tahoe’s
littoral
zone
ecology
and
the
potential
for
non
chemical
treatment
using
benthic
barriers.
Specifically
we
would
like
to
understand
the
how
the
life
history
of
curly
leaf
pondweed
impacts
(a)
the
likelihood
of
population
growth
in
a
large,
subalpine
oligotrophic
lake
given
its
current
distribution,
biomass
and
turion
bank,
and
(b)
its
ability
to
be
effectively
managed
in
Lake
Tahoe
with
benthic
barriers
to
reduce
both
macrophyte
biomass
as
well
as
turion
viability.
We
seek
to
achieve
these
goals
by
pursuing
the
following
objectives:
1. To
assess
the
potential
for
curly
leaf
pondweed
population
growth
and
risk
of
further
establishment
by
quantifying:
plant
biomass
and
stem
density
in
multiple
locations
in
south
Lake
Tahoe,
the
asexual
reproductive
potential
of
curly
leaf
pondweed
by
quantifying
the
turion
bank
as
it
relates
to
plant
biomass/density,
and
habitat
quality.
2. We
will
use
a
compliment
of
laboratory
and
field
studies
to
assess
the
impact
of
three
different
bottom
barrier
fabrics
on
curly
leaf
pondweed
vegetation
and
turion
germination.
Sediment
anoxia
and
light
reduction
has
been
shown
to
inhibit
turion
germination
of
curly
leaf
pondweed
in
its
native
range
(Wu
et
al.
2009).
We
will
apply
two
gas
permeable
fabrics
(polyethylene
and
jute)
and
one
gas
impermeable
fabric
(EPDM)
to
test
the
relationship
between
anoxia,
light
reduction
and
turion
germination.
3. To
evaluate
the
recolonization
rate
of
curly
leaf
pondweed
6
months
and
1
year
after
treatment
with
variable
bottom
barrier
fabric
types.
4. To
predict
the
population
recruitment
rate
of
curly
leaf
pondweed
based
on
plant
biomass,
habitat
quality,
and
turion
germination
in
Lake
Tahoe
under
natural
and
managed
(i.e.,
bottom
barriers)
conditions
in
order
to
make
recommendations
for
non‐chemical
or
chemical
control
of
this
species.
4
Proposal: Tahoe Research Supported by SNPLMA 2010
5. Indentify
specific
regions
in
Lake
Tahoe
that
present
the
greatest
curly
leaf
pondweed
invasion
pressure
based
on
life
history
traits
and
make
recommendations
for
areas
and
methods
of
non‐
chemical
treatments.
The
specific
hypotheses
to
be
tested
are
as
follows:
1.
Curly
leaf
pondweed
plant
biomass
is
dependent
on
habitat
variability
(nitrogen,
phosphorus,
dissolved
inorganic
carbon,
pH,
turbidity,
temperature,
light).
2.
Curly
leaf
pondweed
turion
density
is
dependent
on
plant
biomass.
3.
Bottom
barriers
that
reduce
light
permeability
will
reduce
curly
leaf
pondweed
macrophyte
biomass
and
not
turion
germination
rates.
4.
Bottom
barriers
that
reduce
light
permeability
and
dissolved
oxygen
concentrations
will
reduce
curly
leaf
pondweed
macrophyte
biomass
and
turion
germination.
5.
Bottom
barriers
that
reduce
light
permeability
and
dissolved
oxygen
concentrations
will
have
a
lower
rate
of
recolonization
than
barriers
that
only
reduce
light
permeability.
6.
Based
on
the
turion
bank
and
habitat
quality,
curly
leaf
pondweed
populations
are
expected
to
increase
in
Lake
Tahoe.
7.
Effective
treatment
that
targets
both
biomass
and
turion
viability
reduction
will
reduce
overall
curly
leaf
pondweed
population
range
in
Lake
Tahoe.
e.
Approach,
methodology
and
location
of
research
Approach:
We
will
utilize
a
combination
of
field
and
laboratory
surveys
and
experiments
to
understand
the
relationship
between
curly
leaf
pondweed
population
biomass,
asexual
reproduction
(via
turion
production),
and
management
using
bottom
barriers.
This
research
will
utilize
a
field
survey
to
assess
curly
leaf
pondweed
plant
and
turion
density
in
five
locations
in
South
Lake
Tahoe,
measure
habitat
quality
in
each
location,
field
installation
of
three
types
of
barriers
to
test
impacts
on
plant
biomass
and
turion
viability,
and
the
collection
of
turions
from
both
control
sites
and
from
under
barriers
to
quantify
germination
rates
in
a
laboratory
setting.
Methodology
and
location:
To
acquire
quantitative
estimates
for
curly
leaf
pondweed
vegetative
biomass,
we
will
use
SCUBA
to
place
1
m2
quadrats
(N
=
5)
to
collect
stem
counts
in
five
locations
with
variable
density
of
curly
leaf
pondweed
populations:
(Ski
Run
marina,
Tahoe
Keys
marina,
Lakeside
marina,
outside
of
Tahoe
Keys
marina
(open
lake
population),
outside
of
Ski
Run
marina
(open
lake
population).
We
will
seek
monoculture
stands
of
curly
leaf
pondweed,
however,
due
to
the
presence
of
other
submersed
macrophyte
species
in
these
areas,
we
will
note
all
species
present
in
each
grid
and
their
relative
abundance.
Following
methods
of
Eichler
et
al.
(1995),
a
Daubenmire
scale
(1968)
will
used
to
determine
abundance
classes
in
addition
to
quantitative
estimates
of
density.
Shoot
biomass
will
be
collected
from
each
quadrat,
dried
(55°C),
weighed
and
analyzed
for
tissue
nutrient
concentrations
(carbon,
nitrogen,
and
phosphorus).
To
characterize
habitat
at
each
location
sediment
particle
size
distribution,
DIC,
pH,
turbidity,
and
sediment
porewater
and
water
column
samples
will
be
collected
to
measure
nitrogen
and
phosphorus
concentrations.
Two
temperature
probes
(iButtons®)
will
be
installed
at
each
location
to
measure
temperature
for
a
1
year
period.
These
values
will
be
used
as
independent
variables
to
predict
curly
leaf
pondweed
biomass
and
density
(dependent
variables)
to
test
for
habitat
driven
spatial
differences
in
populations.
Using
methods
of
Johnson
(2007)
we
will
estimate
the
turion
bank
in
Lake
Tahoe.
A
petite
Ponar
sampler
device
(Wildco,
Inc.)
will
be
used
to
carry
out
the
sediment
turion
survey
in
autumn
2011
in
order
to
target
the
period
of
highest
turion
abundance
and
least
plant
5
Proposal: Tahoe Research Supported by SNPLMA 2010
biomass
(for
ease
of
sampling)
prior
to
ice
formation
(in
marina
sites).
Three
types
of
bottom
barrier
fabric
will
be
installed
at
three
curly
leaf
pondweed
locations:
polyethylene
fabric
(already
used
in
Lake
Tahoe
for
Eurasian
watermilfoil
treatment,
blocks
light
but
is
gas
permeable),
EPDM
rubber
barrier
(used
in
Lake
Tahoe
for
Asian
clam
treatment,
will
block
light
and
gas
impermeable),
and
jute
(a
biodegradable
material
that
will
block
a
majority
of
light,
however,
increases
BOD
to
decrease
DO
concentrations).
Fifteen
turions
(collected
from
the
immediate
area)
will
be
placed
underneath
each
barrier
to
ensure
their
presence
and
availability
for
laboratory
testing
after
barriers
are
removed.
An
in
situ
dissolved
oxygen
probe
(Zebra
Tech
D‐Opto
Logger,
Accuracy:
1%
or
0.02
PPM)
will
be
placed
under
each
barrier
type
and
also
in
the
control
condition.
Plant
biomass
and
density
estimates
as
well
as
barrier
installation
will
occur
in
July
2011
(abundant
curly
leaf
pondweed
biomass
present
at
this
time
in
Lake
Tahoe,
due
to
unique
seasonality
of
this
species
in
this
region,
Lars
Anderson
pers.
comm.)
All
barriers
will
be
removed
in
September
2011
and
estimates
of
any
plant
biomass
and
density
underneath
each
barrier
site
plus
one
control
site
(untreated)
will
be
taken.
We
will
attempt
to
recover
a
total
of
180
turions:
15
from
an
adjacent
control
plot
(N
=
1),
as
well
as
the
15
placed
underneath
each
barrier
type
(N
=
3),
at
each
location
(N
=
3).
The
collected
turions
will
be
assessed
for
dormant
or
non‐dormant
status
(Sastroutomo
1981)
and
returned
to
the
laboratory
for
viability
analysis.
Following
methods
of
Sastroutomo
(1980,
1981)
we
will
estimate
germination
rates
of
turions
from
each
barrier
type
warm
treatment
(35°C)
in
dark
for
4
weeks
before
germination
at
20°C
and
12
h
light
(Bouldan
et
al.
1994).
We
will
return
to
barrier
treatment
plots
6
months
and
1
year
after
removal
to
observe
recolonization
rates
of
the
variable
barrier
types.
To
model
population
growth
and
expansion
of
curly
leaf
pondweed
in
Lake
Tahoe,
we
will
use
biomass
and
density
estimates,
habitat
quality
measurements,
annual
water
temperature,
and
germination
rates
of
treated
and
untreated
turions
to
utilize
a
recruitment‐based
population
viability
analysis
(Morris
and
Doak
2003)
to
estimate
the
5,
10
and
15
year
estimates
of
population
size
for
curly
leaf
pondweed.
This
population
model
will
have
two
scenarios:
one
in
which
(benthic
barrier)
management
occurs
(impacts
to
plant
biomass
reduction
and/or
turion
viability
dependant
on
laboratory
experimentation)
and
one
in
which
the
population
is
allowed
to
increase
without
control
method
is
applied.
f.
Relationship
of
the
research
to
previous
and
current
relevant
research,
monitoring,
and/or
environmental
improvement
efforts
Dr.
Marion
Wittmann
(PI)
is
currently
a
project
partner
with
the
Tahoe
Resource
Conservation
District,
Tahoe
Regional
Planning
Agency,
and
California
State
Parks
in
the
Emerald
Bay
Eurasian
watermilfoil
control
program.
She
and
Dr.
Sudeep
Chandra
(co‐PI)
are
also
members
of
the
Nearshore
Aquatic
Weed
Working
Group.
The
proposed
research
builds
upon
an
ongoing
program
in
Lake
Tahoe
to
control
Eurasian
watermilfoil
using
a
combination
of
bottom
barriers
and
hand
removal.
However,
this
is
new
and
novel
research
since
no
direct
scientific
investigations
have
occurred
on
this
invasive
species
to
date
in
Lake
Tahoe.
By
observing
the
densities
of
the
curly
leaf
pondweed
turion
bank
as
it
relates
to
plant
biomass
in
the
field,
a
predictive
model
of
population
expansion
can
be
used
to
design
a
management
strategy
(e.g.,
site
selection
based
on
source
versus
satellite
populations)
for
this
species.
Additionally,
while
it
is
known
that
gas
permeable
barriers
can
reduce
plant
biomass
in
other
systems,
it
has
not
shown
to
be
an
effective
long
term
treatment
for
this
species
due
to
turion
based
recruitment.
As
discussed
above,
the
reduction
of
light
availability
and
dissolved
oxygen
concentrations
has
shown
to
inhibit
turion
germination,
and
the
use
of
gas
impermeable
barriers
to
potentially
control
this
species
could
be
a
low‐cost
resource
to
managers
in
the
basin
in
the
current
chemical‐free
AIS
treatment
program.
This
methodology
could
ultimately
improve
the
ecological
health
and
aesthetic
of
the
nearshore
zone.
This
proposal
is
directly
related
to
the
conservation
element
of
the
TRPA
regional
plan
6
Proposal: Tahoe Research Supported by SNPLMA 2010
update.
Specifically,
as
cited
in
the
wildlife
and
fisheries
sub‐element,
this
proposal
lends
directly
towards
the
continued
work
with
state
and
federal
managers
in
the
response
to
aquatic
invasive
species
through
the
study
of
implemented
management
actions.
Additionally,
there
is
a
nearshore
component
to
the
TRPA
regional
plan
update.
While
the
details
of
this
component
have
not
been
supplied
to
the
public
by
the
TRPA,
invasive
macrophyte
populations
of
Lake
Tahoe
are
already
having
an
impact
to
the
nearshore
water
clarity
and
navigability
via
biomass
accumulation.
The
efficient
management
and
reduction
of
invasive
aquatic
macrophyte
populations
has
the
potential
to
remediate
these
impacts
to
the
Tahoe
nearshore.
g.
Strategy
for
engaging
with
managers
and
obtaining
permits
We
will
engage
with
managers
by
presenting
results
to
the
Lake
Tahoe
Aquatic
Invasive
Species
Coordination
Committee
(LTAISCC)
on
a
biannual
basis,
with
a
presentation
of
final
findings
at
the
project
conclusion.
We
will
attend
Nearshore
Aquatic
Weed
Working
Group
(NAWWG)
meetings
to
present
findings
and
provide
information
related
to
curly
leaf
pondweed
location
and
management
in
Lake
Tahoe.
We
will
present
findings
to
the
Lake
Tahoe
Science
Symposium
in
2012.
We
will
continue
to
work
closely
with
Lars
Anderson
of
the
USDA
Agricultural
Research
Service
Exotic
and
Invasive
Weed
Research
to
ensure
that
this
experimentation
compliments
ongoing
USDA‐ARS
curly
leaf
pondweed
experimentation.
This
project
will
require
permits.
We
will
work
closely
with
Kim
Boyd
of
Tahoe
Resource
Conservation
District
and
Ted
Thayer
and
Rita
Whitney
of
the
Tahoe
Regional
Planning
Agency
to
obtain
the
necessary
field
based
permits
for
barrier
application
from
the
Lahontan
Regional
Water
Quality
Control
Board,
the
Army
Corps
of
Engineers
and
the
California
Department
of
State
Lands.
All
proposed
experimental
sites
are
in
California
and
therefore
no
Nevadan
agencies
will
need
to
issue
a
permit
for
this
work.
Annual
permits
for
Eurasian
watermilfoil
treatment
with
benthic
barriers
are
already
held
by
the
Tahoe
Resource
Conservation
District,
and
at
the
time
of
this
proposed
project
period,
those
permits
will
be
amended
to
incorporate
regions
of
the
Lake
specific
to
this
project.
h.
Description
of
deliverables/products
and
plan
for
how
data
and
products
will
be
reviewed
and
made
available
to
end
users
A
primary
product
of
this
research
will
be
the
understanding
of
the
use
of
gas
impermeable
barriers
for
use
as
an
eradication
(rather
than
population
reduction)
tool
for
the
management
of
curly
leaf
pondweed
in
Lake
Tahoe.
Low
light
availability
and
reduced
dissolved
oxygen
concentrations
in
other
systems
has
shown
to
inhibit
turion
germination;
the
ability
to
artificially
create
these
conditions
in
Lake
Tahoe
can
provide
a
feasible
method
for
the
removal
of
this
early
invasion
stage
nuisance
plant.
We
will
provide
the
results
as
a
report
showing
the
effectiveness
of
variable
barrier
fabrics,
as
well
as
the
costs
associated
with
implementing
this
strategy.
A
secondary
product
of
this
research
will
be
an
identification
of
the
population
growth
potential
of
curly
leaf
pondweed
in
Lake
Tahoe
based
on
a
unique
life
history
trait,
the
vegetative
turion.
Once
the
population
growth
model
is
developed,
we
will
provide
estimates
of
population
density
based
on
habitat
quality
and
management
effort.
We
will
be
able
to
create
a
long‐
term
(multi‐year)
scenario
of
population
change
that
can
be
used
to
identify
priority
areas
for
management
based
on
life
history
traits.
We
will
be
working
closely
with
Kim
Boyd
(TRCD)
and
Ted
Thayer
and
Rita
Whitney
(TRPA)
who
have
been
working
on
the
development
of
a
comprehensive
management
strategy
for
invasive
aquatic
macrophytes
in
the
basin.
A
preliminary
report
(end
of
year
1)
and
a
final
report
(end
of
year
2)
will
be
prepared
and
findings
presented
to
members
of
the
Lake
Tahoe
Nearshore
Aquatic
Weed
Working
Group.
Finally,
we
will
publish
these
results
in
a
peer
reviewed
journal
and
present
findings
to
academic
and
management
motivated
meetings
(Western
Aquatic
Plant
Management
Society
and
National
Lake
Management
Society).
7
Proposal: Tahoe Research Supported by SNPLMA 2010
III.
Schedule
of
major
milestones/deliverables
Milestone/Deliverables
Start
Date
End
Date
Initiate
June
1,
2011
June
15,
2011
project/establish
field
plan
Prepare
quarterly
July
2011
April
2013
progress
reports
Initiate
field
collections:
plant
survey
and
barrier
installation/removal
Finalize
field
collections,
begin
laboratory
experimentation:
turion
germination
Annual
accomplishment
report
Description
Plan
field
surveys
and
communication
with
Forest
Service
Submit
brief
progress
report
to
Tahoe
Science
Program
coordinator
by
the
July
1,
2011,
October
1,
2011,
January
1,
2012,
and
April
1,
2012,
July
1,
2011
June
2011
November
2011
Objectives
1,
2:
Field
characterization
of
pondweed
populations,
biomass
and
density
estimates
habitat
quality
sample
collection,
installation
and
removal
of
barriers
November
March
2012
Objective
2:
Germinate
turions
from
field/barrier
2011
collections
to
test
for
viability
or
germination
rates
as
a
result
of
barrier
treatment,
Field
collections
using
Ponar
to
quantify
turion
bank
counts
September
2011
September
Prepare
annual
summary
of
accomplishments
in
2012
September.
Recolonization
observations
May
2012
November
2012
Objective
3:
Six
month
and
12
month
observation
of
recolonization
in
barrier
plots
Data
synthesis
and
predictive
model
building
December
2012
Final
reporting
March
2013
March
2013
Objectives
4,
5:
Begin
data
summarization
and
analysis,
build
population
viability
model
based
on
field
and
laboratory
collections
June
2013
Draft
final
report
(to
be
submitted
in
May
2013)
and
Final
Report
(to
be
submitted
June
2013)
8
Proposal: Tahoe Research Supported by SNPLMA 2010
IV.
Literature
cited/References
Anderson,
L.W.J.,
Spencer,
D.
1996.
Survey
of
Lake
Tahoe
for
presence
of
Eurasian
watermilfoil.
USDA
Agricultural
Research
Service
Aquatic
Weed
Control
Investigations,
Annual
Report.
Dept.
of
Vegetable
Crops,
Weed
Science
Program,
UC
Davis.
Baker,
H.G.
1989.
Some
aspects
of
the
natural
history
of
seed
banks.
In:
Leck,
M.A.,
V.T.
Parker,
and
R.L.
Simpson
eds.
Ecology
of
Soil
Seed
Banks.
Academic
Press,
Inc.
San
Diego,
USA.
pp
9‐21.
Boulduan,
B.R.,
G.C.
Van
Eeckhout,
H.W.
Quade
and
J.E.
Gannon.
1994.
Potamogeton
crispus
the
other
invader.
Lake
and
Reservoir
Management
10:113‐125.
Clark,
S.J.,
Wharton,
G.
2001.
Sediment
nutrient
characteristics
and
aquatic
macrophytes
in
lowland
English
Rivers.
Science
of
the
Total
Environment
266:103‐112.
Crowell,
W.
2003.
Curlyleaf
pondweed:
New
Management
Ideas
for
an
Old
Problem.
Notes
to
the
Minnesota
Department
of
Natural
Resources
Exotic
Species
Program.
http://www.lakewashingtonassn.com/pdfs/curlyleaf.pdf
Daubenmire,
R.
1968.
Plant
Communities:
A
Textbook
of
Synecology.
Harper
and
Row,
New
York.
300
pp.
Dotson,
H.
2007.
Aquatic
weed
management
in
Tahoe
Keys.
Presentation
at
the
Western
Aquatic
Plant
Management
Society,
Tahoe
City,
CA.
Eichler
LW,
Bombard
RT,
Sutherland
JW,
Boylen
CW
(1995)
Recolonization
of
the
littoral
zone
by
macrophytes
following
the
removal
of
benthic
barrier
material.
Journal
of
Aquatic
Plant
Management
33:
51‐54
Engel,
S.
1984.
Evaluating
stationary
blankets
and
removable
screens
for
macrophyte
control
in
lakes.
Journal
of
Aquatic
Plant
Management
22:
43‐48.
Gunnison
D,
Barko
JW
(1992)
Factors
influencing
gas
evolution
beneath
a
benthic
barrier.
Journal
of
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10
Proposal: Tahoe Research Supported by SNPLMA 2010
V.
Figures
Figure
1.
The
distribution
of
Eurasian
watermilfoil
(Myriophyllum
spicatum)
and
curly
leaf
pondweed
(Potamogeton
crispus)
in
Lake
Tahoe,
1995
–
2006.
Red
circles
indicate
the
presence
of
M.
spicatum,
yellow
triangles
indicate
the
presence
of
curly
leaf
pondweed,
which
was
discovered
in
2003.
Map
created
and
provided
by
Lars
Anderson,
USDA‐ARS.
11
Proposal: Tahoe Research Supported by SNPLMA 2010
Figure
2.
A
schematic
of
the
theoretical
relationship
between
the
abundance
of
an
invasive
species
over
time
in
relation
to
management
stage
(Hobbs
and
Humphries
1995).
When
population
numbers
are
low
early
in
a
species
invasion,
the
rate
of
invasive
species
abundance
changes
slowly
because
of
limits
to
reproductive
capacity
per
unit
time.
These
low
abundance
periods
occur
during
an
invasion
where
quarantine,
eradication
and
control
are
priorities
for
managers
because
of
the
potential
for
management
when
invasive
species
abundance
is
low.
Once
populations
have
increased
over
an
extended
amount
of
time,
effective
control
is
unlikely
without
massive
resource
inputs.
12
Proposal: Tahoe Research Supported by SNPLMA 2010
Figure
3.
Curly
leaf
pondweed
life
cycle
as
observed
in
North
America
(Madsen
and
Crowell
2002).
Seasonal
patterns
observed
in
Lake
Tahoe
have
different
temporal
scales
than
plant
populations
observed
in
the
northeastern
regions
of
North
America
(Lars
Anderson,
pers
comm.)
13