MANAGING AND PROTECTING AQUATIC PLANTS FOR THE HEALTH OF WISCONSIN'S LAKES - INSIDE APEEKBENEATHTHEWAVES - LAKE RIPLEY MANAGEMENT DISTRICT
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A P E E K B e n ea t h t h e w a v e s Managing and protecting aquatic plants for the health of Wisconsin’s lakes.
DNR’s aquatic plant management research team has
been working to provide sound science to understand
the complex relationships between plants and the
greater lake ecosystem. Team members include Jen
Hauxwell, Kelly Wagner, Alison Mikulyuk, Michelle
Nault, Martha Barton and Susan Knight, in addition
to many other helping hands over the years.
FRANK KOSHERE
U N D E R ST A N D I N G TH E U N D E R W A T E R W O R L D
A decade of research has led to greater knowledge about our
aquatic plant communities and the way we manage them.
Eric Verbeten
B
eneath the waves of Wisconsin’s leads this team of researchers whose goal
15,000 lakes are a variety of aquatic is to provide sound science for informing
plants and animals living together in management decisions and to share that
a give-and-take relationship, relying knowledge with Wisconsin citizens, visitors
on one another for survival. Understand- and lake associations who are concerned
ing this relationship is key to improving about the health of their lakes.
and protecting lake health in Wisconsin. “When we set out to design an aquatic
DNR scientists have been studying our plant monitoring system, we wanted one
lakes for years to better understand what that would allow us to collect and analyze
it takes to keep a lake healthy. a library of information on a variety of
Challenges are abundant when manag- lakes,” says Hauxwell. “We needed to have
ing aquatic plants. Wisconsin’s lakes differ consistent, accurate and repeatable mea-
in their characteristics and lake users have surements that would allow us to under-
diverse interests. Water quality concerns stand the complex relationships between
and potentially dangerous blue-green al- aquatic plants in lake ecosystems around
gae blooms, due in part to excessive nutri- the state, as well as the ability to track the
ents in the water, as well as the introduc- status of a single lake over time.”
tion of invasive species, can have major The resulting dataset provides not only
impacts on our underwater worlds. a snapshot of a variety of Wisconsin lakes
Understanding these challenges has been today, but also a clearer understanding
a priority of the department, and 10 years of what is happening in lake ecosystems.
ago the aquatic plant management research The team developed a database, which al- Analyzing
team set out to expand and standardize the lows researchers to compare how aquatic plants in the
JEN HAUXWELL
lab is one part
way DNR scientists and lake management plant communities relate to numerous fac-
of the team’s
professionals study and gather data for Wis- tors that affect them, such as water qual- work.
consin’s lake ecosystems. ity (which affects the light plants receive),
Jen Hauxwell is a DNR scientist who temperature, precipitation, management
2
actions and how wildlife and fish respond
to different aquatic plants.
The last 10 years of research and stan-
dardized monitoring have uncovered a
wealth of new information about lake
plant communities, invasive species such
as Eurasian water-milfoil, the effects of
shoreline development and more. Today,
when groups of lakeshore owners come
together to address a problem on their fa-
vorite body of water, the DNR is available
to provide assistance and consultation to
help them make informed decisions. Researchers literally
The initiative to bolster our current dive right into their
knowledge of lakes and aquatic plant work, clipboard in tow.
DNR FILE
ecosystems has three main focus areas:
understanding native plants, managing in-
vasive species and providing outreach to
communities.
Native plants
In the last 10 years the agency has learned
a lot about the importance of native
aquatic plants in our lakes. These plants
are crucial to having a healthy lake ecosys-
tem — they improve water clarity, prevent
erosion and provide habitat and food for a
variety of animals and fish.
DNR’s aquatic plant management re-
search team has discovered more than
120 new occurrences of rare plant spe-
cies living in Wisconsin’s lakes. These dis-
coveries lend themselves to the greater
understanding of the complexities of lake
ecosystems as well as the interconnected
role each plant plays with other species.
By monitoring the health of these plants,
DNR scientists travel to lakes
researchers are able to use them as a “ca- across the state to sample plants
brian ewart
nary in the coal mine” to understand the and collect data.
overall health of a lake and identify areas
that may be at risk.
other invasive species in select lakes, and negative consequences. The department
Invasive species use that information to create detailed works with lake groups, landowners, vol-
To date, more than a dozen different spe- maps showing where certain species have unteers, lake management professionals
cies of invasive aquatic and wetland plants taken hold. and all those interested in managing and
like Eurasian water-milfoil, curly-leaf pond- This standardized survey approach has protecting their lakes by providing the lat-
weed, purple loosestrife and phragmites been used as a model to create more than est scientific information about how lake
have been documented in Wisconsin. 1,300 lake maps for lake groups and pro- systems work.
Invasives can be harmful to a lake eco- fessionals. The department provides these Over the past eight years, the depart-
system in several ways. For example, Eur- maps to anyone interested in sampling a ment has also funded and helped coor-
asian water-milfoil can crowd out other lake to give them an idea of the types of dinate more than a dozen aquatic plant
native plants on localized scales, and can both native and invasive aquatic plants identification workshops around the state
sometimes top out at the water’s surface, species present. Lake maps can be found where anyone can come and learn how to
making boating and swimming difficult. on the DNR Surface Water Integrated Mon- identify the more than 100 aquatic plant
Another invasive, curly-leaf pondweed, itoring System (SWIMS). species found in Wisconsin. Susan Knight,
grows early in the spring, and then rapidly a researcher at UW-Madison’s Trout Lake
dies back during early- to mid-summer. Outreach Station, is a statewide leader in developing
This rapid decomposition of plant material Informing the public of the most current and teaching these workshops and is often
can cause large nutrient releases into the research and data is paramount to the team. assisted by other DNR researchers and
water, potentially triggering algal blooms For every type of lake management managers. Workshops are usually held in
and other water quality issues. technique, there are pros and cons to be June at the Kemp Natural Resources Sta-
The aquatic plant research team’s state- considered. Whether it is the physical re- tion near Tomahawk, in April or May at the
wide survey of 100 lakes containing Eur- moval of aquatic plants or a chemical treat- Wisconsin Lakes Convention, and at vari-
asian water-milfoil documented how this ment for controlling a non-native species, ous fairs and for student groups.
invasive species behaves across different the research efforts of the past 10 years
lakes. Researchers continue to document have uncovered a lot of information about Eric Verbeten is a communications specialist
the locations of Eurasian water-milfoil and the positive and sometimes unintended with the DNR’s Office of Communications.
3
PAUL SKAWINSKI
W I S C O NS I N ’ S H I ST O R Y O F A Q U A T I C
P L A NT M A N A G E M E NT
How we view and manage aquatic plants has
changed significantly over the last 200 years.
Scott Van Egeren and Carroll Schaal
E
xcessive aquatic plant growth has wanted to control aquatic plants to im- equipment and the chemicals used were
been an issue for Wisconsin lakes prove recreation and aesthetics. too dangerous for untrained individuals to
since the 1850s. New human activi- As a result of these differing values, apply.
ties on the landscape, such as farm- Gov. Phillip LaFollette issued an order in Between 1950 and 1969 over 2 million
ing, logging and shoreline construction, 1938 to form an interdepartmental aquat- pounds of sodium arsenite was applied to
increased the amount of nutrients enter- ic nuisance control (ANC) committee to re- 167 Wisconsin lakes. Sodium arsenite was
ing the lakes — stimulating plant growth, view and regulate algae and aquatic plant the only herbicide used for aquatic plant
which was bad for the profitable ice-mak- control in public waters. The ANC commit- control until the 1960s, when it was discov-
ing business which needed “clean ice.” Af- tee was part of the larger Committee for ered that much of the chemical remained
ter the decline of the ice trade, a desire for Water Pollution Control, which later be- in the water and lake sediments for ex-
better aesthetics and improved boating came part of the Department of Resource tended periods of time and did not break
and recreating conditions led to additional Development and then the Department of down into harmless by-products. Legacy
plant removal. Natural Resources (DNR). arsenic can still be found contaminating
Many early Wisconsin lake associations the sediments of lakes in which the chemi-
formed around the turn of the last cen- A shift in herbicides cal was heavily applied.
tury to manage plants, and aquatic plant The ANC committee issued permits for Sodium arsenite was phased out by 1970
management continues to be an impetus aquatic nuisance control projects and ed- in favor of biodegradable herbicides such
for lake organization creation today. Dur- ucated sponsoring organizations on both as 2,4-D, endothall and diquat that were of-
ing the late-1800s and early-1900s most the public benefits and potential ecologi- ten used for control of agricultural weeds.
aquatic plant control was accomplished cal consequences of treating a lake with These herbicides (still used for aquatic plant
by labor-intensive methods of manually chemicals. A few years later, the Wisconsin management today), were more expensive
removing the plants. Legislature granted the ANC committee than sodium arsenite because they were
The development of chemical herbi- the authority to supervise chemical treat- produced in pellet form, which also made
cides created new tools for aquatic plant ments of waters as well as purchase and them easy for anyone to apply. The ease-
management and by the mid-1920s chem- operate aquatic chemical control equip- of-use and high cost of the new herbicides
ical herbicides were being used to control ment, which was even rented to sponsor- largely changed the way herbicides were be-
nuisance plants. A chemical called sodium ing organizations as needed. However, the ing used. Instead of large-scale treatments
arsenite was used to control aquatic plants public demand for the equipment grew sponsored by municipalities or lake orga-
in swimming areas. Counties, cities and too large and the state discontinued the nizations, treatments could be smaller,
lake associations sponsored treatments to rental program in 1949. and more localized treatments could be
control these “nuisance” plant conditions. Municipalities and lake organizations applied to beaches and dock areas by indi-
In time though, controversy brewed be- had originally sponsored large-scale so- vidual citizens. These herbicides were also
tween sporting groups, who prized plants dium arsenite treatments for the public readily available in catalogs, making it easy
as habitat and food for waterfowl and fish, because the treatments were too costly for for individuals to purchase and illegally ap-
and private lakeshore landowners who individual landowners, required specialized ply the herbicides without a permit.
1850s 1890s 1920s 1960s 1970s
Excessive aquatic First lake Chemicals “Silent Spring” Eurasian Federal Insecticide,
plant growth first associations introduced to published, water-milfoil Fungicide and Rodenticide
identified as a formed out of a fight aquatic documenting discovered Act is rewritten giving the
concern in some desire for better plants the effects of in southern Environmental Protection
Wisconsin lakes aesthetics and pesticides and Wisconsin Agency the authority
recreational herbicides on the to regulate pesticides
conditions environment Sodium for the protection of
© FAUERBACH BREWERY
arsenite human health and the
phased out environment
of use
Wisconsin Lakes
Partnership formed
© B. SALEY
HOUGHTON MIFFLIN
Harvesting ice on
DNR FILE
Lake Monona
Applying chemical
Aquatic plants treatments to Lake
on beach Monona
4
Invasives introduced the department recognized that nutrient ing early in the season when the invasive
The goal of the ANC program of the 1940s reduction and runoff management were plants are growing, but most native plants
through 1970s was to control aquatic needed to control the root cause of exces- have not yet emerged, poses a lower risk of
plants for aesthetic and recreational rea- sive aquatic plants and algae. damaging native plant species.
sons, with little focus on how those ef- In the early 1990s, EWM was found in Although recent research has vastly
fects would fit into the overall health of northern Wisconsin and fear rose about improved the state’s collective knowl-
the lake ecosystem. The plants that were the impact the species could have on edge of aquatic plant management,
controlled through the 1970s under this tourism for the many pristine lakes of the there are still challenges and emerging
program were often native aquatic plants, north. Quickly, an emphasis was placed issues. For example, certain strains of
but this would soon change. on preventing the spread of EWM to new EWM have hybridized with native water-
Invasive plants like Eurasian water-mil- lakes and to contain populations in the milfoil, and some hybrids appear to be
foil (EWM) were discovered in several lakes lakes where it already existed. more tolerant to commonly used herbi-
in southern Wisconsin in the mid-1960s, Over the next two decades aquatic in- cides. Chemical control of EWM has also
and by the 1970s had become a major vasive species prevention became an im- been shown to be more difficult to im-
concern for Wisconsin lake managers. portant management goal, starting with plement on smaller plant beds because
This invasion drastically changed the ANC the Clean Boats, Clean Waters watercraft the herbicides will rapidly dissipate away
program over the next several decades. In inspection program and the Citizen Lake from the target area.
addition, the public was becoming increas- Monitoring Network. Scientists also studied Today, the Wisconsin Department of
ingly concerned with the use of pesticides additional methods of controlling EWM, in- Natural Resources is recognized as a na-
and herbicides following the publication cluding manual removal, lake bottom bar- tional leader in the research and dem-
of Rachel Carson’s book “Silent Spring” in riers and the introduction of EWM-eating onstration of aquatic plant management
1962 and subsequent popular interest in insects known as bio-control weevils. techniques, and is committed to working
the environmental movement. with the Wisconsin Lakes Partnership, lake
The role of aquatic plants in a healthy Integrated aquatic plant organizations, landowners, recreationists
lake ecosystem was increasingly studied by management and aquatic plant professionals to update
scientists, and the benefits aquatic plants The 2001-2002 Wisconsin Legislature in- and improve aquatic plant management
provide to lakes were advocated for by creased the DNR’s authority to issue per- and protection in the state.
sporting groups in the 1970s and 1980s. mits for management methods other than The main control methods used today
About this time, the Department of Natu- chemical treatments, including mechanical, are still chemical (herbicides) and mechani-
ral Resources and University of Wisconsin- manual and biological control activities, and cal, though manual hand-pulling or SCUBA-
Extension joined with the Wisconsin As- the ability to require that an Aquatic Plant assisted removal is becoming more com-
sociation of Lakes to form the Wisconsin Management Plan be in place for lakes be- mon for smaller, localized sites. Bio-control
Lakes Partnership. The department provided fore permits are issued. (the stocking of plant-eating insects) is also
technical and financial assistance while UW- The DNR and partners have been con- gaining consideration.
Extension provided education and outreach ducting statewide research since the mid- Millions of dollars are spent annu-
to newly-formed lake organizations for 2000s to study the impacts of lake-wide ally throughout the state on invasive and
aquatic plant management activities, with and localized herbicide treatments for in- nuisance aquatic species management.
the emphasis on long-term benefits be- vasive species control. These studies have Through better communication, informa-
yond seasonal nuisance plant reductions. shown the complexity of how herbicides tion sharing and resources coordination,
The ANC program was increasingly criti- move within a lake and the range of their together we will learn how aquatic plants
cized for destroying aquatic plant habitat effectiveness as a management technique. and people can better coexist for the future
and the department was asked to conduct Aquatic plant and herbicide data collection health and sustainability of our lakes.
an environmental assessment of the ANC has helped to hone appropriate treatment
program in 1988. Aquatic nuisance control strategies and understand the potential
began shifting back to lake-wide aquatic dangers to non-target organisms. Scott Van Egeren is DNR’s statewide Lake and
plant management, but now the aim was to These studies have allowed for the devel- Reservoir Ecologist.
integrate this approach with other holistic opment of best management practices for Carroll Schaal is the DNR’s Lakes and Rivers
lake management activities. For example, invasive species control. For instance, treat- Section Chief in the Bureau of Water Quality.
1980s 1990s 2000s Today
Citizen Lake Eurasian water- “Clean Boats, DNR begins new DNR continues
Monitoring milfoil discovered in Clean Waters” effort to develop research on the
Network begins northern Wisconsin watercraft an aquatic plant effectiveness of
inspection monitoring system aquatic plant
program management
PAUL SKAWINSKI
created techniques including
the use of herbicides,
mechanical
harvesting and
bio-control
weevils
FRANK KOSHERE
FRANK KOSHERE
FRANK KOSHERE
Bio-control
weevil
Mapping with GPS
Eurasian water-milfoil Bobber in EWM
5
Light streams through
the water to the lake bed
below. Just like plants on
land, aquatic plants must
gather sunlight, absorb
carbon and collect nutrients
in order to photosynthesize,
grow and reproduce.
PAUL SKAWINSKI
T h e ( pla n t ) life aqua t ic
Living underwater is as amazing and complex as life on land.
Susan Knight
T
he shallow area near a lakeshore, ment and excessive nutrients — from run- Light and nutrients
with its complex communities of ning into the lake. Plants with floating leaves have an ad-
plants and animals, is the cradle Floating-leaved plants, such as lily pads, vantage over other aquatic plants as they
of life in fresh water. The aquatic grow deeper than emergent plants and have more access to light — another limited
plants found growing near shore are criti- have leaves that float on the surface, gath- commodity for plants living underwater.
cal to the structure and function of the wa- ering sunlight and air like floating solar Like plants in any community, aquatic plants
ter body. panel snorkels. They provide shade and can be shaded by others overtopping them.
Though often considered a nuisance, help calm the waters for near-shore resi- The two most common and most successful
aquatic plants play a vital role in protect- dents like fish. submersed aquatic invasive plant species in
ing and nourishing the near-shore com- Submersed plants, like pondweeds, Wisconsin, Eurasian water-milfoil and curly-
munity. While their understated beauty grow deepest into the water, but they still leaf pondweed, are successful in part be-
may be an acquired taste, the importance require sunlight and their growth is limited cause they overtop native plants very early
of aquatic plants to the lake ecosystem is mainly by water clarity. Submersed plants in the season — gaining a head start and
undisputed. provide a diverse and rich underwater cutting off much of the light to the native
Underwater plants are a home, safe garden — which becomes a shelter and plants growing below them.
haven, nursery and bountiful buffet for food supply for a lake’s many inhabitants. Water also makes plants buoyant and
the diverse parade of creatures that need While emergent and floating-leaved eliminates the need for stiff supporting
water for life, and make living near the aquatic plants have relatively easy access structures like stems or woody trunks,
water worthwhile for us. Depending on to many of the resources necessary for which allows many aquatic plants to grow
their form and location near the shore, survival, submersed plants face special very quickly, racing toward the light-satu-
aquatic plants may be emergent (where challenges in living underwater. Just like rated waters near the surface.
most of the plant is out of the water), their landlubber relatives, submersed Just as they need light and carbon,
floating (usually with roots planted in the plants must absorb carbon, gather light aquatic plants also need nutrients such
lake bottom) or submersed (completely and collect nutrients in order to photo- as phosphorus and nitrogen to grow and
underwater). synthesize, grow and reproduce. Almost reproduce. Most aquatic plants are rooted
Emergent plants, like cattails, bulrush all aquatic plants are flowering plants, and in the lake or stream bottom, and many
or sedges, secure the lake perimeter, an- first learned to live on land before they lat- of them rely on their roots to take up nu-
choring sediments along the wave-swept er adapted to life underwater. Many of the trients from the sediments. Some plants
shoreline. When they are maintained in adaptations displayed by aquatic plants also absorb dissolved nutrients directly
a strip or buffer along the shoreline, they are traits specifically selected for surviving through their leaves.
help slow rainwater — laden with sedi- in a submersed life. Amidst all of this competition, a few
6
aquatic plants like bladderworts, have resembling pea soup. The algae may even few aquatic plants have showy or fragrant
adopted a carnivorous diet as a means become so dense that they eclipse aquatic flowers, the fruits and seeds of many spe-
to supply nutrients. Bladderworts do not plants to the point of starvation. cies are prized as food by waterfowl and
have roots and acquire most of their nu- other animals.
trients by capturing tiny invertebrates Reproduction Though seeds are an important means
with small sac-like traps attached to the Another underwater difficulty for aquatic of reproduction, aquatic plants largely rely
leaves. These traps, or bladders, fire in a plants is sexual reproduction, which is on asexual (clonal) growth for dispersal
fraction of a second, sucking in unwitting necessary for increasing genetic diversity and survival from one season to the next.
prey that have tripped the trigger hairs. and plant dispersal. Almost all aquatic Many species, such as wild celery and
The captured animals die and decompose, plants are flowering plants, meaning they large-leaf pondweed, use runners to send
and the resulting nutritious soup gets ab- produce flowers, fruits and seeds. Plants out new shoots. Others, such as the inva-
sorbed and consumed by the plant. must find a way to exchange pollen in sive Eurasian water-milfoil, can fragment
As with any plant community, plentiful order to fertilize their flowers during repro- and grow into new plants. Many plants,
nutrients generally mean plentiful plants. duction. On land, pollinators usually provide including some pondweeds and bladder-
However, there is a twist to the story this service, and given their ancestral con- worts, produce vegetative buds called
when talking about underwater plants. nections to land, most of these otherwise “turions” in late summer. These turions
Most submersed plants have at least a submersed plants hold their flowers up in lie dormant through the winter and then
bit of a biofilm, or scum, which sticks on the air to await wind or insect pollination. sprout into new plants in the spring.
their leaves and is made up of algae called Some pondweeds produce floating All of the diverse aquatic plant species in
“periphyton.” The attached algae use the leaves that aid in gathering carbon and Wisconsin have different solutions to the
plants as scaffolding and the natural flow light and may serve as a support raft for challenges of living underwater. Each spe-
of water as their nutrient source, absorb- an emergent flower stalk. Wild celery cies is uniquely designed to help them sur-
ing at least some of the nutrients as they plants release a male flower that bobs on vive and compete for their place in the eco-
drift by — nutrients that might otherwise the surface until it collides with and pol- system. While each lake has a few common
supply free-floating algae in the water. linates a female flower, which is tethered species, a healthy lake plant community
This is a balancing act for the light- to the parent plant in the depths below. has dozens living together. This assortment
hungry aquatic plants; although the at- Bladderworts hold their showy yellow or of plants, with their varied architectures,
tached algae shade the plants somewhat, purple flowers above the water surface, provides a complex home and food source
the algae also help maintain clearer water, attracting bumblebee pollinators. for countless other aquatic neighbors.
allowing more sunlight to reach greater A few species, such as slender naiad
depths. However, if water column nutrients and coontail, have underwater flowers Susan Knight is a botanist and aquatic plant
become too abundant, the algae will run and rely on flowing waters to carry pollen specialist working out of the University of
rampant, turning the water into something from one plant to another. Though only a Wisconsin-Madison Trout Lake Station.
ALISON MIKULYUK
FRANK KOSHERE
SUSAN KNIGHT
Lily pads are floating-leaved plants. Algae in the water. Sac-like traps of the bladderwort
as seen under a microscope.
Submersed plants provide a diverse
and rich underwater garden — which
CAROL WARDEN
becomes a shelter and food supply for
a lake’s many inhabitants.
7
Aquatic plants help keep the lake
bottom in place, reduce the amount
of sediment that is swept into the
water and provide essential habitat
for other lake dwellers like fish.
A N C H O R S O F TH E L A K E
Aquatic plants are essential to the health of the lake ecosystem — in mo
Kelly Wagner fish will also eat plants, and even bluegills
A
will eat the leaves and stems of aquatic
quatic plants come in a variety of plants. Beavers chew not only on trees, but
shapes and sizes: some sit quietly also on aquatic plants like sedges, water
on the lake bottom, while others lilies and pondweeds. Even large land-
reach above the water’s surface to dwelling mammals like deer, elk and
take in additional sunlight. Together, this moose will venture to the water for a meal.
mix of plants offers a range of benefits Some water birds are dependent upon
© USFWS
for everything in the lake, from improv- aquatic vegetation. This is evident in the
ing water clarity and controlling erosion, names of aquatic plants like duck weed, duck
to providing food and habitat for insects, Turtles rely on the lake ecosystem for food. potato, watermeal and wild celery. The wild
animals and fish. celery plant, unrelated to the grocery store
One of the main ways aquatic plants help ment and other debris in the water column variety, happens to be favored by canvasback
support life in a lake is through their root to settle to the bottom. Here, those way- ducks. Part of the scientific name for the duck,
systems which act like anchors, helping to ward bits of debris will be broken down Aythya valisineria, comes from the scientific
keep the lake bottom in place. Each time a into nutrients, mainly nitrogen and phos- name of wild celery (Vallisneria). Wild celery is
wave moves toward the shore, the plants phorus, which will be used by the plants as so important to canvasback ducks that resto-
slow the water and deflect energy from the food to grow. ration of the canvasback duck population on
wave to help keep the shoreline from erod- When plants finish growing and ulti- the upper Mississippi River relies on the resto-
ing. These calm water areas are a focal point mately die, they begin to decay and pieces ration of this key aquatic plant.
for lake health because they help start a of the once vibrant plants will float in the Besides being a food source, some animals
chain of events useful for everything in the water column and eventually fall to the will use spongy, buoyant and waterproof
lake ecosystem, from microscopic algae to lake bottom. This recycling of nutrients is plants to build nests. Loons, other water birds
top predators like musky. not only important to replenishing plant and muskrats favor emergent plants that stick
An aquatic plant’s role as an anchor be- life, but also to the rest of the organisms up out of the water for this purpose. The strat-
gins by reducing the amount of sediment in the lake that rely on these fundamental egy is especially useful because the nest will
being swept into the water and later car- building blocks of life. float with the rising and falling of lake levels.
ried downstream or to another part of the Insects like moths have larvae that feed In addition, the nest is built right in the near
lake. But it doesn’t end there. When plants on aquatic plants, as do caddisflies, and shore area, where there is plenty of food and
slow water movement, they allow sedi- even some grasshoppers. Turtles and cray- cover for young fledglings.
8
PAUL SKAWINSKI
Insects, like the giant water bug, will lay
their eggs among aquatic vegetation.
© USFWS
Many water birds, such as the canvasback
duck, will build their nests among aquatic
BOB KORTH
plants where there is cover for young
fledglings.
and largemouth bass, reach their largest siz-
FRANK KOSHERE
es in areas of moderate plant cover. A lake
with very dense plants is less desirable for
predator fish — their growth can be slower
Frogs will dart into plants to escape in the densely-vegetated lakes where the
ore ways than one. predators.
cover impedes their ability to find and cap-
ture prey. Sparse plant cover is associated
Many other lake-dwellers call aquatic with several small non-game fish, as well as
vegetation home. Filter-feeding insects sift populations of rough fish, like carp.
the water and pull algae out of the water Plants are also important to the suc-
column. There are also grazing insects, such cess of fish reproduction. Bass and bluegill
as snails, that scrape algae off of plants, build their nests among vegetation, which
helping the plants absorb more sunlight. shelters the nest and provides cover for
Tall, leafy plants provide hiding spots from the young fish once they hatch. Many
predators. Frogs will dart into plants to es- species, including northern pike, musky
cape the beak of a heron or the jaws of a and yellow perch, spawn within areas of
pike. And, of course, there are fish. aquatic vegetation, depositing their eggs
The shapes and sizes of aquatic plants either on or among low-growing plants.
affect their ability to hide fish. Bass for ex- The young and vulnerable fish of most
ample, need to eat smaller fish to grow, species will also take refuge in plants.
and have a harder time catching fish that In addition to food, refuge and spawn-
feed in the finely divided leaves and highly ing, aquatic plants provide underwater
branched stems of species such as non- animals with something else they need:
native Eurasian water-milfoil than those oxygen. Some oxygen enters the water
that are in the more open architecture of from the air, but much of the dissolved ox-
native pondweeds. Pondweeds (often re- ygen in lakes is produced by either aquatic
ferred to as musky weed, cabbage or bass plants or algae as a byproduct of photo-
weed by anglers), are prized for their indi- synthesis.
cation of good fishing habitat. When aquatic plants are in a healthy
Often, it is the amount and type of plant balance, they offer an essential give-and-
cover — the percentage of the lake bottom take relationship to the lake ecosystem
that is covered by plants — that is most — providing habitat for fish and animals,
important to fish, rather than the particu-
SUSAN KNIGHT
while maintaining clear water and making
lar species of plants. Researchers have our lakes the scenic and desirable places
been trying for many years to zero in on to be year-round.
the optimal amount of plant cover for fish,
but different plant habitats favor different Kelly Wagner is a DNR scientist and conducts
Wild celery plant types of fish. research on aquatic ecology and invasive species
(Vallisneria americana) Many popular game fish, such as bluegill in Wisconsin lakes.
9
M a n agi n g aqua t ic pla n t s :
D iffere n t v alue s . D iffere n t a t t i t ude s .
So often we want our lakes to be everything to everyone,
but not all lakes are created equal.
Carroll Schaal
P
eople’s attitudes about lake plants
reflect their different interests.
Swimmers going to a lake to en-
joy a cool dip may find brushing
up against aquatic plants unappealing.
Lakeshore property owners often curse
the plants around their dock, as do motor
boaters and water skiers if they tangle with
plant mats in open water. Kayakers and
other silent sport boating types may look
for wildlife and take delight in the varied
forms of underwater vegetation. The best
anglers know the sweet spot is between a
dense plant bed and deeper open water,
and hunters know wild rice is where the All lakes are different. The DNR assists lake © RJ & LINDA MILLER
ducks hang out. organizations with developing and implementing
Lakes differ too, and those differences Aquatic Plant Management Plans to understand
are reflected in the kind of plant communi- these differences and balance the lake’s potential
ties they naturally support. with people’s expectations for recreation.
Deep, clear lakes with few nutrients have
fewer and smaller plants. These lakes are
ideal for many people, offering a “swim- non-native species due to these conditions. to sunlight, rooted plants will grow —
ming pool effect” where swimmers and Natural lakes that are completely or sometimes shore-to-shore — if the right
divers can see all the way to the bottom mostly shallow are inherently full of plant species and conditions are present.
and boaters don’t get caught in the plants. life. Generally, lakes with depths of only 15 As a general rule, lakes in the south-
Millponds and reservoirs tend to have feet or less will have extensive plant growth ern part of the state have more excessive
more plant growth than natural lakes be- throughout the lake. These lakes are often aquatic plant growth problems than those
cause they are often shallow and have great for fishing and waterfowl hunting, in the north due to a longer growing sea-
larger watersheds which contribute more but not so much for high-speed boating or son and higher nutrient levels — the re-
sediments and nutrients. Millponds and res- skiing. sult of a long history of watershed distur-
ervoirs are also more prone to invasion by If the lake bottom is mucky and exposed bance. Also, due to European settlement
10may be needed. On some lakes, aquatic
plant management can become almost a
full-time effort. When plant management
actions have a lake-wide effect — that is
when a holistic lake management plan is
most needed.
Wisconsin state laws and administra-
tive rules seek to protect a balanced and
diverse aquatic plant community while
minimizing the impacts of non-native inva-
sive species that threaten to change lake
Waterfowl need aquatic ecosystems and allow for the reasonable
DNR FILE
plants for habitat. control of “nuisance” conditions that inhib-
it recreational uses. Wisconsin law allows
the Department of Natural Resources to
© WISCONSIN DEPARTMENT OF TOURISM
require and develop Aquatic Plant Man-
agement Plans for lakes before issuing
permits.
Management and protection of aquatic The DNR assists lake management or-
plants, the lake and its watershed are ganizations with developing and imple-
important to having a healthy lake menting Aquatic Plant Management Plans
ecosystem, as well as providing safe water
quality conditions for humans and pets.
through grants and technical assistance.
Education and outreach is also available
through programs like Clean Boats, Clean
Waters and the Citizen Lake Monitoring
and recreation patterns, southern Wiscon- Network to help educate citizens, boaters
sin lakes were colonized much earlier by and others on how to recognize and pre-
non-native invasive species like Eurasian vent the spread of invasive plants.
water-milfoil. The DNR encourages lake communities
to work together to set thoughtful and rea-
Making decisions, considering values sonable goals, using both the natural and
and managing expectations social sciences to understand and balance
Choosing what to do with excessive aquat- Healthy, natural fisheries
rely on a vibrant aquatic the lake’s potential and limitations with
ic plant growth and how to do it comes people’s expectations for recreation. This
back to societal values, user expectations, plant community.
DNR FILE
includes careful consideration of all avail-
the lake’s natural conditions and the type able management techniques, costs and
of plant community the waterbody is able long-term impacts to lake health.
to support. moved and the nutrients present, the al- A good plan will be written with input
Property owners and lake users often gae that used to be attached to the surface from a diverse group of people and in-
are not satisfied with a lake’s natural plant of those plants will be replaced with free- clude information on the aquatic plant
community and want to change or “man- floating algal species, turning formerly community present in the lake. A lake’s
age” it. It’s typically not just the presence of clear water “pea-soup” green and possibly ecosystem can be very different from the
plants that creates issues, it is when those toxic. Zooplankton, barely visible inverte- expectations of its users. Each plan should
plants grow thick and high in the water and brates that feed on floating algae help- be unique to the specific lake and yet be
interfere with recreational activity that peo- ing to keep it in check, seek refuge from flexible to address changes in conditions
ple take notice. predators among rooted plants. As plants of the lake and expectations over time.
Less disturbed, low-nutrient waters decline so do zooplankton, potentially After implementation, a thorough eval-
tend to have lower-growing plant species. compounding algae problems. Fisheries uation of management activities is needed
As more development occurs on a lake, may decline or change with these associ- to determine if all goals are being met. Fail-
these species are replaced by taller, more ated changes in water quality. ure to do an evaluation can create a cycle
disturbance-tolerant species, thus creat- Many game fish spawn on aquatic of continuous management that doesn’t
ing a potential conflict with recreation- plants and then use their shelter as nurs- work or does more harm than good.
ists. Many lake organizations get stuck in eries shielding them from predators. Non- Aquatic plants are an important re-
a costly, often escalating annual cycle of game species like carp do very well in lakes source and fundamental to the ecological
battling lake plants to maintain open wa- with no plants. health of our waterways. With the help of
ter or out of fear that an invasive species lake organizations, property owners and
will take over the lake. Aquatic Plant Management Plans individual recreationists, the DNR aims to
When it comes to aquatic plant man- Most native water plants don’t need to maintain its long-standing mission to bal-
agement there needs to be reasonable be managed — they do quite fine without ance the environmental, recreational, so-
expectations and careful considerations. our assistance. When plant growth gets cial and economic needs of all of Wiscon-
Not very many lakes are capable of being out of hand, the first step for a property sin’s lakes users — not always an easy task
a swimming pool. owner can be to selectively hand-pull the as different people like to enjoy the lakes
What can go wrong if lake plants are nuisance plants. Manual removal of any in their own way.
managed incorrectly? When rooted plants plant within a single 30-foot wide access
are removed, a void is created and more area around docks can be done without a Carroll Schaal is the DNR’s Lakes and Rivers
aggressive and tolerant invasive species permit and invasive species can be hand- Section Chief in the Bureau of Water Quality
may replace those removed. In addition, pulled anywhere. If the plant problem where he has worked for 20 years with the
depending on how many plants are re- grows, mechanical or chemical control Wisconsin Lakes Partnership.
11A SCUBA diver
uses a hydraulic
harvester to
uproot and remove
Eurasian water-
milfoil plants.
SUBMITTED BY CHUCK DRUCKREY
P A R TN E R I N G F O R H E A L TH Y L A K E S
Pulling out all the stops to manage a Wisconsin lake invader.
Lisa Gaumnitz “When you knock back 99.3 percent of it results, numerous lake groups and the DNR
I
and still retain most of the (native) aquatic — which typically share the costs of the
n Oneida County’s Squash Lake, SCUBA plants, we would have to consider it a suc- treatments, are considering alternatives.
divers working from ice-out to ice-in, five cess,” says Stan Gruszka, the lake associa- A decade of research by the Depart-
days a week to remove Eurasian water- tion president. ment of Natural Resources, the U.S. Army
milfoil (EWM) by hand have substantially A growing number of Wisconsin lake Corps of Engineers and the University
reduced the amount of the invasive plant associations, sanitary districts and other of Wisconsin-Extension, is shedding light
in the lake. caretakers of the state’s freshwater gems on how to increase the effectiveness of
“A lot of people are beside themselves are successfully reducing EWM while pro- chemical treatments as well as what some
because they have Eurasian water-milfoil,” tecting native aquatic plant communities. of the limitations and drawbacks are for
says Stephanie Boismenue, the lead vol- They’re using a growing suite of tools — a using chemicals in lakes.
unteer behind the effort. “But it can be strategy called integrated aquatic plant Ongoing research has shown that cer-
reduced and managed.” management — to make sure the right tain chemical treatments may affect non-
In Pewaukee Lake in Waukesha County, tool is used at the right place and at the target plant species and aquatic life, and
the sanitary district runs mechanical har- right time. that repeated treatments may also result
vesters daily to cut EWM, but also purchas- in the invasive plants developing a toler-
es land containing wetlands, restores prai- Chemical treatment ance to certain chemicals, or encourage
ries and stabilizes shorelines to reduce Chemical treatment has historically the growth of even more aggressive hy-
erosion and trap excess nutrients that can been the go-to tool when EWM is found in brid plants over time. Collaborative re-
fuel plant growth. a lake. Today it is still the most common search in Wisconsin has also shown that
“To fix a problem, you need to go to the management strategy with 301 permits for many of the small-scale chemical treat-
source of the problem,” says Lake Pewau- lake treatments approved in 2013. ments so widely used now, in which high
kee sanitary district manager Tom Koepp. Chemical treatments can range in price doses of liquid or granular herbicides are
And in Price County, a 6-foot drawdown from hundreds to thousands of dollars applied to small target areas, are not per-
of Lac Sault Dore, a 561-acre impound- per acre. As the costs of annual chemical forming as once hoped. In many cases
ment, was extended to freeze out and treatments add up, and the data collected the chemicals rapidly dilute and immedi-
control EWM plants, providing dramatic, regarding the short- and long-term effective- ately dissipate, and concentrations of the
positive results for the lake. ness of such treatments has shown mixed chemicals do not remain high enough to
12effectively kill the target plants.
At the same time, the growing track re-
cord of EWM in Wisconsin suggests that
the plant does not necessarily become
widespread or as problematic in all of the
lakes it invades.
“Eurasian water-milfoil isn’t always gloom
and doom for a lake,” explains Carroll
Schaal, who leads the DNR’s lakes and riv-
ers program. “In most lakes with EWM, it’s
only 10 percent or less of the overall plant
community.”
The plant was first detected in southern
Wisconsin in the 1960s. It spread to other
southern and central Wisconsin waters
and in many cases became prolific, flour-
ishing in the soft, mucky bottoms and
forming dense mats at the water’s surface
that ensnarled swimmers and boat pro-
pellers, hampered fishing and shaded out
beneficial native plants.
In more recent years, EWM has invaded
several northern Wisconsin lakes, but the
shorter growing season, sandy lake beds
FRANK KOSHERE
and lower nutrient levels appear to have
BOB KORTH
limited the spread, as have communities
mobilizing to prevent the invader from en-
Volunteers with the Citizen Lake Monitoring Loading herbicides into a boat to tering their lakes.
Network help collect data for lake chemistry, be applied to a lake to help control Many associations participate in inva-
temperature, dissolved oxygen and water Eurasian water-milfoil. sive species training through the state’s
quality, identify and map plants, and also
watch for the appearance of Eurasian
Clean Boats, Clean Waters program. This
water-milfoil. program has helped build a network of
volunteers who educate boaters and an-
glers on invasive species prevention steps.
Volunteers interested in lake science can
also participate in the Citizen Lake Moni-
toring Network. The citizen scientists in
this program keep a close eye on their
lakes to allow for a rapid response if in-
vaders are discovered.
“A lot of how we respond depends on
the lake,” says Jim Kreitlow, a DNR lakes
management specialist in northern Wis-
consin. “It’s not a one-size fits all.”
If Eurasian water-milfoil is at a low level
in the lake, “we might leave it alone for a
while because it may not get any worse
than it is now,” he says. “If it’s out of con-
trol, perhaps we do a whole lake treat-
ment with the chemicals at a lower con-
centration. We need to pick and choose
where we use chemical treatment and
perhaps look at some other tools.”
ONEIDA COUNTY SQUASH LAKE ASSOCIATION
Hand-pulling
Stephanie Boismenue had been look-
ing for EWM in Squash Lake for about
five years when she spied two fragments
wrapped around her dock in the summer
ANDY SCHATSCHNEIDER
of 2009.
“I said, oh darn, please don’t let this be
what I think it is,” says Boismenue, leader
of the Squash Lake Association invasives
Nate Rice holds one of the many garbage Stephanie Boismenue uses an aqua scope to
committee. But it was, and was found to
cans full of Eurasian water-milfoil that SCUBA monitor for Eurasian water-milfoil on Squash cover about seven of the lake’s 400 acres.
divers and kayakers removed by hand on Lake in Oneida County. When the consultant who the group
Silver Lake in Waukesha County. hired recommended using 2,4-D in spring
13PAUL SKAWINSKI
FRANK KOSHERE
A volunteer holds a Eurasian water-milfoil A close-up of the Eurasian water-milfoil plant as it reaches to the water’s surface near the
plant pulled from the water. lakeshore. Lake associations and others are successfully reducing EWM populations while
protecting native plants by using a suite of tools — a strategy called integrated aquatic plant
management.
2010 on the scattered clumps of EWM, the — it’s the nature of the beast,” she says. “Our membership supports this re-
group decided to take a step back. “But there is hope.” quest,” Gruszka says. “Most of us would
“Because the treatment wasn’t going to like to avoid drawing down the lake; it’s a
be until the following spring, we had time Drawdown tool of last resort. Hand-pulling and some
to dig our teeth into what we really wanted Eurasian water-milfoil was first spotted possible chemical control in isolated areas
to do,” Boismenue says. “We wanted the in Lac Sault Dore — a.k.a. Soo Lake — in might be possible, but our big stick is the
best for our lake. It’s healthy and well-bal- Price County in 2006. By 2009, it covered drawdown.
anced and we wanted to preserve that.” 200 acres. “My advice to other lakes battling Eur-
Lake association members searched “It was tough to boat, tough to fish,” re- asian water-milfoil is that there is no silver
for information to see how lakes treated calls Stan Gruszka, president of the Soo bullet treatment. Each lake is different and
20 years ago were faring today, not just in Lake United Association. “We had too they [the associations] have to go through
terms of Eurasian water-milfoil, but for their many fish competing for the same food, the process of exploring what is best for
water quality, whether lake bed sediments too many hiding places.” their lake,” he says.
contained chemicals used during the treat- The association got a DNR lakes plan-
ment, the health of frogs and other aquatic ning grant to evaluate options and design Early detection and a one-two punch
creatures living in the lake and the health of a plan. Their consultant concluded the Chemical treatment was one of the right
people living around the lakes. lake wasn’t a good candidate for chemi- tools for Little Newton Lake in Marinette
They found few answers. “Until we knew cal treatment because the connecting County. When EWM was first discovered,
for sure, we decided we were going to find Elk River would carry the chemical away it was limited to a few dense colonies that
another route,” she says. before it could act. Mechanical harvest- totaled less than two acres.
The association discovered they could ing also wasn’t a viable option due to the “We used early season 2,4-D treatments
get SCUBA divers to hand-pull the plant. lake’s shallow depth and woody bottom. to control the larger beds. Good seasonal
They hired three people to hand-pull that But as luck would have it, a drawdown was control was achieved and we followed up
first summer and are now up to eight div- scheduled to allow dam repairs. The group with hand-pulling,” says Chuck Druckrey,
ers, many of them recruited from local asked to extend the drawdown through Marinette County water resource special-
dive and rescue teams and paid through the winter with hopes of freezing or drying ist. “The main site required a second herbi-
DNR grants. Boismenue coordinates the out the invasive plants and killing them. It cide treatment and at one point we found
effort and stays on top of the water in a worked. The drawdown eliminated nearly additional sites that were treated as well.”
boat, collecting the bags of invasive plants all of the invasives that year. Druckrey says the Little Newton Lake
handed to her by the divers and changing “It didn’t really impact the native plants experience was a good lesson on the
out oxygen tanks. but did kill some smaller bluegills,” ex- benefits of early detection and adaptive
She also coordinates a crew of mostly plains Gruszka. management to control EWM before it be-
lake residents to keep a close watch for When some re-growth occurred, Phillips comes widespread.
new growth so she can get divers on any High School students joined association “My advice to others is to use all the
new sites immediately. members to hand-pull the invasive plant. tools that are available (and appropriate)
The first two years of hand-pulling re- The association is now asking the county and keep at it,” he says.
sulted in the biggest reduction; now the to re-write the dam’s operating orders Scott Provost, the DNR’s statewide aquat-
divers work to reduce the number of so that if the lake has to be drawn down ic plant management coordinator agrees.
clumps on the lake’s north end. again, it can be to the 6-foot level — the “Using various tools is not only com-
“I have to keep reminding everybody on mark which produced the best results for mon sense, it has become part of the legal
this lake, we’re never going to get rid of it killing the invasive plants. framework behind permit decisions, says
14Provost. “Using all the tools available, such “Aquatic plant management doesn’t coordinator) is also instrumental as they
as manual and mechanical removal in have to always be flashy. It’s small, but truly understand and care about the lakes
combination with other methods, is what effective steps, one at a time,” she says. in our area — they are not thinking about
is meant by Integrated Pest Management Other southeastern Wisconsin lakes what some people think is a quick fix.”
(IPM), which is required to be part of the Bunk’s worked with, like Delavan Lake “The truth is nothing is broken, we sim-
DNR’s permit process.” in Walworth County and Pewaukee ply have an ever-changing ecosystem that
Federal law, through the Clean Water Lake in Waukesha County, have em- needs some serious attention and man-
Act, requires permits for activities that barked on watershed approaches that agement,” explains Koepp, who fully un-
discharge chemicals to surface waters be- involve scores of partners working over derstands the effort needed to maintain a
cause these activities can have substantial hundreds of square miles. healthy lake. “I don’t use hope in my equa-
impacts on humans and the environment. “This is a big job, a long-term ap- tion. This WILL happen. It is working and
Wisconsin has responded by allowing lake proach, one that takes real collabora- the momentum is gaining. Our lake is go-
groups or individuals to apply for a Wis- tion with nonprofits and government ing to get better and better.”
consin Pollutant Discharge Elimination entities,” says Koepp. “Heidi Bunk has
System general permit. been great to work with and Bob Wake- Lisa Gaumnitz is a former public affairs manager
One of the criteria for a successful per- man (DNR’s aquatic invasive species for the DNR’s Office of Communications.
mit application is that the person or group
applying must evaluate and implement
IPM for their lake. Pa r t ne r in g f o r P e wa u k ee L a k e
“Utilizing IPM helps minimize discharge
of excess biological or chemical agents
while maintaining federal water quality
standards and encouraging effective man-
agement decisions that weigh the costs
and benefits of all management options,”
explains Provost.
A long-term approach
SUBMITTED BY TOM KOEPP
SUBMITTED BY TOM KOEPP
Such persistence and adaptive manage-
ment strategies are paying off for volun-
teers on Silver Lake in Waukesha County.
With EWM present in their lake, they be-
gan participating in the Clean Boats, Clean
Waters education program to prevent
Pewaukee sixth graders helping remove One of the mechanical harvesters the
another invasive from coming in. They’ve debris from the Pewaukee River. district uses to remove invasive plants.
also been carrying out an ongoing moni-
toring and hand-pulling effort in the shal- Managing a lake and its watershed can • T he Pewaukee Chapter of Walleyes
low water area. be a big task, involving numerous part- For Tomorrow installed the first
“That area is now nearly completely free ners working over hundreds of square “Fish Sticks” project in southeastern
of Eurasian water-milfoil and the native miles. For Pewaukee Lake in southeast- Wisconsin this past winter, anchoring
plant community has thrived,” says Nate ern Wisconsin, here’s some of what that felled trees to the shoreline to add
Rice, who has coordinated the volunteer management looks like: more woody habitat for fish as part
effort. of multiple efforts to boost walleye
This year, SCUBA divers will remove • T he Town of Delafield has a zoning and populations in the lake.
the EWM plants by hand in a deeper wa- open space requirement that allows
ter location. The project, planned for the rain water and snowmelt to soak into • T he Pewaukee River Partnership is
next three years, is supported by the the ground. This filters out pollutants, working with the district on proj-
Southeastern Wisconsin Invasive Species keeping them from entering the lake. ects along the Pewaukee River and
Consortium, Inc., and will be carried out conducting stream monitoring on the
entirely by volunteers, from SCUBA divers • T he Village of Pewaukee provides a site creeks flowing into the lake.
and kayakers with skimmer nets, to those for a shared conveyor belt to handle
aboard a pontoon boat collecting the bags harvested plants, and the district • T he district received a Waterways
of pulled plants. returns the favor by picking up aquatic Commission Grant to buy two new
“Start small. Think big,” Rice says. “We are plants that village residents pile on harvesters and a trailer/conveyor,
fortunate to have a limited number of areas their shores. which will allow an increase in the
on our lake that are infested with Eurasian volume of Eurasian water-milfoil
water-milfoil. This makes hand-pulling the • T he Lake Pewaukee Sanitary District and other invasive aquatic plants
best choice for our lake, especially given a is teaming with the DNR to acquire removed from the lake.
committed group of volunteers. wetlands through Lake Protection
“Also, as we’ve learned from the ex- Grants; the Pewaukee Kiwanis and • T he district, using DNR Lake Pro-
perts, to be realistic, follow up, continue Pewaukee Water Ski Club are raising tection Grant funds, purchased a
prevention and education efforts and stay money to maintain those wetlands and wetland with some uplands that will
informed about best practices and new in- to add educational boardwalks; and the allow space for harvested plants to be
vasives to watch out for,” Rice adds. Pewaukee Women’s Club is donating turned and decomposed before being
DNR Lakes Specialist Heidi Bunk says money to re-establish native prairies on spread on farm fields.
the volunteers stand a good chance of the wetland fringes.
controlling EWM in their lake.
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