Control of Eurasian Watermilfoil in Lake Pémichangan

Control of Eurasian Watermilfoil
(Myriophyllum spicatum) in Lake
Pemichangan using Jute Burlap
Experimental project
Final report to the
Ministry of forests, wildlife and parks (MFFP)
By
Geneviève Michon
Chief Biologist
(original document in French)
June 2015
733 boul. Saint-Joseph • Bureau 430
Gatineau (Québec) • J8Y 4B6
Téléphone : (819) 771-5025
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Project team
Supervision :
Giorgio Vecco, ABV des 7
Coordination :
Geneviève Michon, ABV des 7
Research and writing :
Geneviève Michon, ABV des 7
Review :
Giorgio Vecco, ABV des 7
Bénédicte Rivière, ABV des 7
Anne-Marie Gosselin, MFFP
Julie Deschênes, MFFP
Mapping and geomatics :
Élodie Roy, ABV des 7
Geneviève Michon, ABV des 7
Field Assistants
Élodie Roy, ABV des 7
Marie-Pier Tremblay, ABV des 7
Marine Galliot, stagiaire ABV des 7 (2012)
Manon Dellanoy, stagiaire ABV des 7 (2012)
Tiphaine Bonnier, stagiaire ABV des 7 (2012)
Marion Loubière, stagiaire ABV des 7 (2012)
Marine Tollet, stagiaire ABV des 7 (2012)
Émilie Vallières, stagiaire ABV des 7 (2012)
Bastien Bellemin-Noël, stagiaire ABV des 7 (2012)
Kelly Nkouka, stagiaire ABV des 7 (2013)
Pauline Gillaizeau, stagiaire ABV des 7 (2013)
Émilie Prévost, stagiaire ABV des 7 (2013)
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Field Assistants
Héloïse Gornard, stagiaire ABV des 7 (2014)
(continued)
Jean-Sébastien Joseph, stagiaire ABV des 7 (2014)
Aline Blandin, stagiaire ABV des 7 (2014)
Alexandre Cussonneau, stagiaire ABV des 7 (2014)
Joanie Corbeil, MFFP
Vincent Greco-Lemay, MFFP
James Hayes, MFFP
Philipe Houde, MFFP
Martin Plante, MFFP
Référence à citer : Michon, G., 2015. Contrôle du myriophylle à épi (Myriophyllum
spicatum) par l’utilisation de toiles de jute au lac Pémichangan. Agence de bassin versant
des 7, 57 p.
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Acknowledgements
The ABV7 team wishes to thank several individuals and organizations for their role in the
realisation of this project. Indeed, this ambitious and innovative project could only be
realised thanks to the support of several partners. First, we would like to thank Mr Henri
Fournier, Mrs Julie Deschênes and Madame Lyne Cossette of the Ministère des Forêts,
de la Faune et des Parcs (MFFP) de l'Outaouais. This project was initiated in the first
place following a suggestion made by Mr. Fournier.
Subsequently, several organizations have dared to join us in this endeavour. The
Conférence régionale des élus de l'Outaouais (CREO), the regional natural resources
Commission and public territory de l'Outaouais (CRRNTO), the Fondation de la Faune
du Québec (FFQ), the Ministry of forests, wildlife and parks (MFFP), the Ministère du
développement durable, environment and the fight against climate change (MDDELCC),
friends of Lake Pemichangan Gatineau Fish & Game Club, la Sablière Alie and la
Sablière of Gracefield have each contributed financially or in-kind to the project.
Our partners:
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Summary
In recent years, Eurasian Water-milfoil (Myriophyllum spicatum) has become more
prolific and problematic in North America. Currently, no sustainable solution exists for the
control and eradication of this exotic and invasive aquatic plant.
This report presents the results of an experimental project which explores a new
approach to control Eurasian Water-milfoil using jute burlap, a biodegradable material.
This new approach was tested in Lake Pemichangan, located in the region of Outaouais,
Quebec, between 2012 and 2014. 5 985 m2 of jute burlap have been installed on three
monospecific beds of Eurasian Water-milfoil. Initial results are promising; in the months
following installation, native flora has managed to push through the burlap while the
Eurasian Water-milfoil was unable to. The burlap decomposed naturally and gradually;
its complete disappearance was observed to occur in less than three years. After three
years, approximately 87% of the total treated area were free of Eurasian Water-milfoil
and either supported native plants or had a total absence of plants. In addition, a
success rate of 95% was achieved at the site where the bed of Eurasian Water-milfoil
had been fully covered by burlap.
The two principal success factors of this technique were found to be ensuring full
coverage of milfoil beds and careful installation which takes into account irregularities of
the river bed (such as the presence of dead trees or rock piles). This pilot project
concludes that this innovative method is promising in its ability to control of the spread of
this invasive plant in lakes.
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Contents Table
PROJECT TEAM .............................................................................................................................II
ACKNOWLEDGEMENTS .............................................................................................................IV
SUMMARY ......................................................................................................................................V
CONTENTS TABLE .......................................................................................................................VI
ACRONYMS .................................................................................................................................VII
INTRODUCTION ..............................................................................................................................I
STUDY AREA ...............................................................................................................................VI
MATERIALS AND METHODS .......................................................................................................IX
CHOICE OF SITES ..........................................................................................................................IX
ASSEMBLY OF THE JUTE BURLAP SHEET........................................................................................XVI
INSTALLATION OF BURLAP ...........................................................................................................XVII
FOLLOW-UP VISITS ....................................................................................................................XVIII
RESULTS AND DISCUSSION ....................................................................................................XIX
FOLLOW-UPS ..............................................................................................................................XIX
PRESENCE OF EURASIAN WATERMILFOIL .....................................................................................XXV
THE DECOMPOSITION OF BURLAP ...............................................................................................XXX
THE RECOVERY OF NATIVE FLORA .............................................................................................XXXI
GENERAL COMMENTS ..............................................................................................................XXXIV
CONCLUSION .........................................................................................................................XXXV
RECOMMENDATIONS ...........................................................................................................XXXVI
REFERENCES......................................................................................................................XXXVIII
GLOSSARY ..................................................................................................................................XL
ANNEXE 1- LA MÉTHODOLOGIE EN IMAGES ..........................................................................42
ANNEXE 2 – MODÈLE DE FICHE TERRAIN POUR LES SUIVIS ..............................................46
ANNEXE 3- PHOTOGRAPHIES SOUS-MARINES DES SITES TRAITÉS ..................................50
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Acronyms
ABV des 7
Agence de bassin versant des 7
CRÉO
Conférence régionale des élus de l’Outaouais
CRRNTO
Commission régionale sur les ressources naturelles et le territoire public de
l’Outaouais
FFQ
Fondation de la Faune du Québec
GPS
Global positioning system
INSPQ
Institut National de Santé Publique du Québec
MDDEFP
Ministère du Développement durable, de l’Environnement, de la Faune et des
Parcs
MDDELCC Ministère du Développement durable, de l’Environnement et de la Lutte contre les
changements climatiques
MDDEP
Ministère du Développement durable, de l’Environnement, et des Parcs
MEF
Ministère de l'Environnement et de la Faune
MFFP
Ministère des Forêts, de la Faune et des Parcs
MRC
Municipalité régionale de comté
MRN
Ministère des Ressources naturelles
MRNF
Ministère des Ressources naturelles et de la Faune
Oz
Onces
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Introduction
Quebec is an immense territory, abundant with natural resources. Its beauty is matched
only by its grandeur and its biodiversity. These resources are supported by the regions
many lakes and rivers. In Quebec, there are more than a million lakes and 130 000
water courses. This means that Quebec has the privilege of benefitting from, and the
responsibility to govern, around 3% of the world’s fresh water resources. The value of
this resource is immeasurable, particularly in a context of increasing global water
scarcity.
The availability of our precious water resource places us at an advantage in comparison
to the rest of the world. Threats to the richness of biodiversity it supports must therefore
be taken seriously and ways to mitigate against risks investigated and explored. The
introduction and spread of invasive species in our water bodies is currently one of the
most serious threats to biodiversity in the province’s aquatic habitats. An invasive
species of particular concern is Eurasian Water-milfoil (Myriophyllum spicatum), which is
an exotic aquatic plant that has been introduced in several regions of Quebec. The
presence of Eurasian Water-milfoil has been linked to public dissatisfaction with water
quality by other researchers. Newroth (1985, in Auger, 2006), for example, reports that
citizens of Peachland Irrigation District, British Colombia (a region whose water source
was contaminated with Eurasian Water-milfoil) had concerns about water quality as
water had an unusual smell and taste. Scientific theory provides an explanation for the
link between the presence of Eurasian Water-milfoil and water taste; Eurasian Watermilfoil greatly increases sediment load and phosphorus in water which helps the
proliferation of cyanobacteria (Auger, 2006) effecting the taste of water (INSPQ, 2008).
Eurasian Water-milfoil is therefore responsible for indirectly altering water quality, among
other things.
Eurasian Water-milfoil is native to Europe and Asia (Couch and Nelson, 1985 in Auger,
2006). The precise time and location of its introduction into North American territory is
unknown, but it is thought that it made its appearance in the mid-1940s (Couch and
Nelson in Lavoie, 2010 1985). It is hypothesised that the plant was used in aquariums
which were then later emptied into rivers and lakes (Redd, 1977 in Auger, 2006). The
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species spreads easily because small fragments of the plant are able to establish
themselves in, and then colonise, new territory (Aiken et al.., 1979;) Smith and Barko,
1990; Arsenault and Légaré, 2000 in Auger, 2006). Fragments are carried naturally by
currents and human aquatic activities exacerbate the problem as fragments are caught
in and distributed by boat propellors, trailers and fishing gear. Eurasian Water-milfoil is
now well established in Lake Erie, and the Laurentian and Ottawa Regions, and is
spreading rapidly through Quebec.
Its introduction has had a significant impact on the aquatic ecosystem of North America,
impacting on native wildlife and fauna. The abundance of this plant causes deterioration
to water quality in affected Lakes and affects fish habitat, including the habitat of Lake
trout (Salvelinus namaycush) (Sly, 1988; Bérubé et al.., in preparation in Auger, 2006).
Eurasian Water-milfoil, like the majority of submerged aquatic plants, tends to retain fine
sediments (Bates et al.., 1985 in Auger, 2006). This is catastrophic for Lake Trout, who
prefer habitat where the substrate is course and devoid of vegetation to spawn (Evans et
al.., 1991a; Legault et al.., 2004 in Auger, 2006). For this reason an infestation of
Eurasian Water-milfoil in water courses is associated with a reduction in Lake Trout
reproduction.
When well established, this plant accelerates ageing of the Lake and creates
monospecific plant beds that occupy spaces previously uninhabited (Truelson, 1985;
Newroth, 1985; Boylen et al., 1996; Eiswerth et al., 2000; Anderson, 2004 in Auger,
2006) and encroach on native plant habitats (Newroth, 1985; Gibbons and Gibbons,
1985; Smith and Barko, 1990; Boylen et al.., 1999 in Auger, 2006). Once established,
the Eurasian Water-milfoil obstructs the sunlight for submerged indigenous plants, which
eventually die because they are no longer able to photosynthesise (Madsen et al.., 1991;
Boylen et al.., 1999 in Auger, 2006). This also results in lower water temperatures below
the surface, as water is shaded from the Sun (Carpenter and Lodge, 1986 in Auger,
2006). Eurasian Water-milfoil alters the pH gradient, dissolved oxygen content (Frodge
et al.., 1990 in Auger, 2006) and the concentration of phosphorus in the water column
(Carignan and Kalff, 1982 in Auger, 2006) which greatly affects indigenous species
which are adapted to the former ecosystem conditions (Auger, 2006). The lack of
dissolved oxygen in particular, greatly increases fish mortality (Frodge et al.., 1995;
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Killgore and Hoover, 2001 in Auger, 2006). The complexity of the Eurasian Water-milfoil
root system prevents burrowing species from accessing food sources within the
substrate (Pardue and Webb, 1985 in Auger, 2006). Its density also increases
compounds in the water body when it dies (Sly, 1988; Sloey et al., 1997; Cheruvelil,
2002 in Auger, 2006), decreases the water flow (Newroth, 1985 and Auger, 2006) and
prevents the movement of certain species (Savino and Stein, 1989a, b in Auger, 2006).
While the Eurasian Water-milfoil is beneficial for a limited number of species, many more
native species are threatened by its presence (Auger, 2006). It is considered an invasive
species because it is not native and it spreads quickly in areas where it has been
introduced (Aiken et al.., 1979; Smith and Barko, 1990; Arsenault and Légaré, 2000 in
Auger, 2006).
In addition, the presence of this plant has several socio-economic repercussions as it
inhibits activities such as swimming, recreational boating (boats motor, canoe, pedal
boat, kayak) and sportfishing (Gibbons and Gibbons, 1985; Arsenault and Légaré, 2000
in Auger, 2006).
Several methods have been employed to try to control the spread of Eurasian Watermilfoil. They are often separated into three categories: biological, chemical and physical
methods (Auger, 2006).
The acid 2,4-dichlorophenoxyacetic (2,4-D) is a chemical that is used for Eurasian
Water-milfoil treatment. The process must be carried out annually, however, which can
be very expensive (Parsons et al.., 2001 in Auger, 2006). To comply with l'Institut
National de Santé Publique du Québec (INSPQ) standards, the concentration of 2,4-D
must not exceed 100 (µg/L) (INSPQ, 2013) due to potential risk of cancer and other
serious health problems (2006). This method is prohibited in Quebec, but in any case is
not to advocated due to the increased risk it presents to humans and the fact that it
involves the addition of chemicals into the ecosystem.
Biological methods involve the use living species to help control the Eurasian Watermilfoil. One example is the use of the native weevil (Euhrychiopsis lecontei), to control
plant growth. Although biological methods are more respectful of the ecosystem than
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chemical methods, biological methods have not been found to be very effective in the
past. The natural cycle of the native weevil is often too slow to control a problem of the
magnitude often presented by Eurasian Water-milfoil, particularly when winters are long
and cold. In addition, the population of weevils is affected by predation by pumpkinseed
(Lepomis gibbosus), which makes the method even less effective in some regions
(Lavoie, 2010).
Physical methods include harvesting the Eurasian Watermilfoil either by hand by divers,
or with the help of machinery. Using this method it is necessary to install barriers to
prevent dispersal of the plant during its harvest (Bates et al., 1985; Newroth, 1985; Looll,
1993; Environment Canada, 2005a in Auger, 2006). The manual method is more
expensive than the mechanical method (Truelson, 1985 in Auger, 2006), but the milfoil is
harvested more effectively (Environment Canada, 2005a in Auger, 2006). On the whole,
however, this approach does not have a great impact because after treatment the
Eurasian Watermilfoil re-establishes without difficulty (Truelson, 1985; Environment
Canada, 2005 a in Auger, 2006) and this method of harvesting is prone to breakup the
Eurasian Watermilfoil, which greatly increases its dispersion despite barriers put in place
to prevent this (Truelson, 1985). Another technique employed is to lower the level of the
water during the winter in order to expose the Eurasian Watermilfoil to the cold, which
kills it off. The major constraints for this process are the need to minimise the impact on
the entire ecosystem, and the need to use a system to control the water level (Truelson,
1985 in Auger, 2006). A final method, the one employed during the use of jute burlap, is
the use of physical barrier like mosquito netting or geotextiles to pave the bottom of the
waterbody. There are often maintenance requirements when this method is used
because the barrier needs to be cleaned resulting in additional costs (Maxnuk, 1985;
Newroth, 1985; Environment Canada, 2005 a). This problem is not encountered with the
use of jute burlap, however, as the jute is biodegradable.
Innovative research has been conducted in Ireland on another invasive exotic plant,
curly waterweed or high lagarosiphon (Lagarosiphon major), between January 1st, 2009
and January 31, 2013 (Caffrey, 2013). In this study, the principal investigator, Dr. Joe
Caffrey, compared three different techniques of control. He manually removed the plants
with underwater divers, he cut the plants mechanically with a V blade, and he used
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burlap as a physical barrier. The purpose of this experiment was to identify the most
effective method for the control or eradication of the invasive plant. Jute burlap was
installed by divers during summer (May to October), mechanical cutting was carried out
during the coldest months (November to April) and hand picking of plants was used to
treat areas with a low density of infestation, particularly newly infested areas (Caffrey,
2013).
It was found that, of the three methods considered, the control of the invasive plant by
burlap was more convenient and much more efficient than mechanical cutting and
manual uprooting (Caffrey, 2013). The results of this study were extremely positive; on
the 92 hectares initially infested with the invasive plant and treated with burlap, only 9.7
hectares were infested a period of 5 years after treatment (Caffrey, 2013). Furthermore,
by decreasing the quantity of invasive plants present in the study Lake, the risks of
propagation and multiplication of the species to other areas has been reduced (Caffrey,
2013).
What makes this technique even more interesting, is that burlap is composed of entirely
natural and biodegradable material that requires no extraction after installation, unlike
plastic or geotextile synthetic cloths. According to Caffrey et al. (2011), burlap is able to
control lagarosiphon major to a certain extent locally but is not able to completely
eliminate it when the plant is abundant and dense (Caffrey et al.., 2011). This project,
however, aimed to allow the opening of areas previously inaccessible for boating,
swimming or other activities because of the abundance and density of plants (Caffrey,
2013).
As the results achieved in Ireland were positive, it was thought likely that such a process
could also be effective with Eurasian Watermilfoil. The plants are very similar as both
reproduce by fragmentation of their stem and invade new territory by displacement of the
stem fragments; both plants tend to take over territory once they have invaded by,
creating monospecific plant beds that prevent the growth of other species (Caffrey et al..,
2011 in Auger, 2006).
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The overall objective of the project described in this report is to ascertain whether burlap
can be effectively used to control Eurasian Watermilfoil in the Lakes of the Ottawa
Regions, in the same way that it has been shown to effectively control lagarosiphon
major in Ireland.
According to Dr. Caffrey (personal communication, 2012), similar results to those
obtained in Ireland can be expected, as the physiological characteristics of the two
species of aquatic plants are similar as describe above. The present document reports
experience of the control of Eurasian Watermilfoil in Lake Pemichangan from 2012 to
2014 using jute burlap.
Study area
Lake Pemichangan is located approximately 129 km North of downtown Gatineau, with
geographical coordinates of 46o02'51 N; 75o51'13 W. The area of the Lake is 16 km2,
and its basin slope is about 246 km2 (figure 1). Lake Pemichangan is divided between
two municipalities in the Gatineau Valley MRC, Gracefield and Lac-Sainte-Marie. The
study area was exclusively in the section of the Lake within the municipality of Gracefield
(figure 2).
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Figure 1 - Watershed of Lake Pemichangan
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Figure 2 - Location of the study in the Pemichangan Lake area
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Materials and methods
Choice of sites
MFFP biologist and technicians have been observing Eurasian Watermilfoil in Lake
Pemichangan, as well as several other lakes in the Ottawa region, since 2004. Their goal
has been to follow the invasion of the species through the region, with a particular interest in
the consequent impact on Lake Trout spawning. The data they have collected was used to
identify stable, monospecific plant beds of a reasonable size for trials of jute burlap
treatment. Figures 3 and 4 represent all beds mapped at Lake Pemichangan. These figures
show that the Eurasian Watermilfoil is not well established on the Eastern side of the Lake
and the beds present on this side are small, unstable and not dense. For this reason, effort
has been concentrated on the Western side of the Lake.
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Figure 3 -Evolution of Eurasian Watermilfoil in 2004 and 2010-2011 in zone 1 of the study area
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Figure 4 -Evolution of Eurasian Watermilfoil in 2004 and 2010-2011 in zone 2 of the study area
The watermilfoil beds were studied in 2004, 2010 and 2011 from a boat motor, using an
Aquascope (figure 5) and a GPS system. Following each field visit, a map of the watermilfoil
was developed using ArcGIS (various versions depending on the year).
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Figure 5 - Photograph of an Aquascope
The choice of the six test sites was based on the size of the milfoil bed. For this project,
only isolated beds of an acceptable size were chosen as test sites. For each test site a
control site, a bed of a similar size in the same locality, was selected that would not be
treated. This step was taken to ensure that results obtained were a direct consequence
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of the use of burlap and not just a change in the state of the lake or the milfoil. It is
important to note that the areas of milfoil presented here are approximate.
All test sites, both those to be treated and control sites, were dense and monospecific
(100% Eurasian Milfoil) prior to the implementation of the project. The depth of the beds
ranged between 0.5 m and 6 m deep. Riparian zones had different conditions (table 1).
Riparian zones adjacent to sites 01 and 02 was partially built up, while the zones of sites
03 and 04 were more extensively built up. The riparian zones of sites 05 and 06 were
100% natural, with no developments.
Table 1 -Photographs of the shoreline of each of the sites
Treated Sites
Control Sites
Site 01
Site 02
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Site 03
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Site 04
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Site 05
Site 06
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Test site 01 had an area of 1 660 m2; while the control site 02 had an area of 3 255 m2
(figure 6).
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Figure 6 - Map showing areas of the test site 01 and control site 02
Test site 03 had an area of 3 473 m2; while the control site 04 had an area of 2 822 m2 (figure
7).
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Figure 7 - Map showing areas of the test site 03 and the control site 04
Test site 05 had an area of 852 m2; while the control site had an area of 591 m2 (figure 8).
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Figure 8 - Map showing areas of the test site 05 and the control site 06
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Assembly of the jute burlap sheet
The methodology for installation of the jute burlap is shown in Appendix 1.
46 rolls of burlap of 91.44 m long by 1.83 m wide were purchased. The burlap was
selected on the basis of its accessibility and affordability. The canvas dimensions were
not ideal because the burlap was too narrow and too long. Therefore, it was necessary
to sew together strips to create a single canvas of 7 m wide by 22 m long. Sewing was
easily achieved using a portable sewing machine (industrial Fischbein®, Innovex
company F model).
Two strips of jute were first sown together along the long edge. They were then cut in
half to half the length and the two panels sown back together to further increase the
width. Finally the length was then halved again with a further cut to create the final
panel size. The method is shown in figure 9. A total of 40 such canvasses were created;
it took the ABV7 team and five volunteers around 10 days to complete the process.
ABV des 7, 2012
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Figure 9 - Schema for the burlap sewing
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Installation of Burlap
During installation of the jute burlap in Lake Pemichangan, jute sandbags were used to
secure the burlap to the bottom of the Lake. This method was selected as it was not
necessary to return to the site to remove the weights as the weights were made of
natural and biodegradable material. In addition, the sand bags were cheap to make as
there was a sand pit in the Lake Pemichangan watershed and the owners offered free
sand. The installation of the burlap was undertaken in two stages with the help of
professional divers and volunteers. The first stage was conducted between the 27th and
30th of April 2012, and the second between the 18th and 20th of June 2012. It turned out
that the installation of burlap in the month of April was very difficult because of the
weather and the danger of hypothermia to the team and divers. For this reason the
second installation period was undertaken when the temperature of the water was more
accommodating.
A total of 12 sheets were installed at site 01, 18 at site 03 and 6 at site 05 in 2012.
During the summer of 2013 site 03 was extended with five additional sheets installed.
This was done because residents near site 03 wanted to cutback a Eurasian Watermilfoil
bed adjacent to the site which would have led to cuttings propagating to the test site. To
avoid this disturbance, the site was expanded.
Several obstacles were encountered on the first day of installation of the jute burlap.
Thus, several techniques were tried before identifying the one that worked best.
The most effective method was to immerse the rolls of jute burlap near the shore so that
the sheets soaked up water. Subsequently, two lengths of jute twine were attached to
each end of the sheet and each of the lengths of twine connected a sandbag. Two
motorboats were then used to extend the burlap. In each boat, a person held a sandbag
and the boat was taken to a position where the canvas is stretched and in the right
place. On the shore, two others held the remaining two sandbags. Once the canvas is
stretched and well positioned, the sandbags in the boats were lowered one after another.
Finally, both bags held at the shore were released at the signal of the divers.
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Subsequently, the divers went under water to reposition the canvas as necessary. They
ensured that the overlay was well positioned and distributed sandbags on the canvas.
These were designed to prevent the burlap moving following disturbance due to the
formation of gas bubbles under canvas as the plants decompose. Each of the treated
sites was identified by yellow buoys and floating signs prohibiting the movement of
boats. Control sites had only buoys to delineate the milfoil beds.
Follow-up Visits
Follow-ups were conducted during the ice-free months of June, August and October of
each year over a period of three years (2012, 2013 and 2014). In each follow-up, the
same observation Protocol was used, using a power boat and an aquascope. The
observation sheet used is presented in annex 2.
Three follow-ups were undertaken each year. Thus, a total of nine follow-ups were made
during the three years of the project. For purposes of clarification, the follow-ups will be
numbered according to table 2.
Table 2 - Name and date of follow-up in the three years of the project
Observation
2012
2013
2014
Start of summer
2012-1 (4 July)
2013-1 (13 June)
2014-1 (26 June)
End of summer
2012-2 (16 Aug)
2013-2 (15 Aug)
2014-2 (27 Aug)
Autumn
2012-3 (24 Oct)
2013-3 (30 Oct)
2014-3 (15 Oct)
On the observation sheet, several types of data were collected. For the treated sites, the
extent of recovery of aquatic plants, including the Eurasian Watermilfoil, on the jute
burlap was evaluated according to the following classes: 0% recovery, 1-10% recovery,
11-25% recovery, 26-50% recovery and >50% recovery. Where indigenous species
were present, their number and species were noted. In addition, the number of Eurasian
Watermilfoil present on the burlap was recorded according to the following classification
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system: 0 plants, 1-15 plants, 16-30 plants, 31-45 plants or >46 plants. Classes were
evaluated by extrapolation of five sites chosen randomly during each visit.
At the treated sites, sedimentation and the State of jute were also evaluated. With regard
to sedimentation, the site was classified as having no sedimentation, partial
sedimentation or total sedimentation. For the State of jute, five measures were taken by
placing a stick randomly at each site. The state of the jute burlap was classified
depending on whether the web was intact, intact but breaks easily, intact but
disintegrates into contact with an object or absent. It was noted if there were holes in the
canvas or other relevant observations were made.
The control sites were also visited each time and the state of aquatic plants at each site
was classified according to the following categories:
▪
100% coverage of Eurasian Watermilfoil;
▪
dense patches and extensive where it could be seen that the Eurasian Watermilfoil
was dominant, but there were native species or the bed of the Lake exposed;
▪
scattered plots where the Watermilfoil was not dominant, but present;
▪
absence of Eurasian Watermilfoil.
In addition to the observations made using the Aquascope, scuba diving observations
helped to document the evolution of sites with photos and videos. The last dive, of
September 29, 2014, was also used to assess areas of jute canvas covered with
Eurasian Watermilfoil on the entire surface of each canvas. Buoys were there located
where the Watermilfoil was pushing through and GPS points were taken on the surface
to delineate the area covered.
Results and discussion
Follow-ups
Each of the three test sites are associated with a control site that is similar in terms of
location, lake level, the extent of shoreline development and the area of the plant bed.
Underwater photos taken during the project showing development at each of the three sites
are provided in annex 3.
!xix
!
Treated site 01
During follow-ups, test site 01 experienced a small increase in the average recovery of
aquatic plants (variant 1-10% 11-25%) over the three years (table 3). This site had a lot of
Eurasian Watermilfoil present during the second year, to the extent that the success of the
project appeared to be in danger. However, during the third year, the average recovery of
aquatic plants (indigenous and exotic) decreased greatly.
Table 3 - Developments at test site 01 during the three years of follow-up based on each
variable.
Site 01
Variables
Visit
12-1
12-2
12-3
Moy
13-1
13-2
13-3
Moy
14-1
14-2
14-3
Moy
1-10
1-10
1-10
1-1
0
0
1-10
>50
11-2
5
11-25
11-2
5
11-25
11-2
5
Eurasian Watermilfoil
plants
N/D
N/D
N/D
N/D
0
1-15
>46
16-3
0
1-15
1-15
16-30
1-15
Sedimentation
50
100
100
100
100
100
100
100
100
100
100
100
State of the burlap
(average)
Int
Int
Int
Int
Dec
h
Des
Dec
h
Dec
h
Dech
Abs
Abs
Abs
Recovery of aquatic
plants (%)
N/A: Not available, Int: intact, Dech: intact but breaks in contact with an object, Des: intact but disintegrates
into contact with an object, Abs: absent
It can be seen that, after three years, this site was almost free of aquatic plants (figure 10).
The burlap decomposed over the three years and was largely absent by the summer of
2014. All that remained of the burlap was small sections where the canvas had been thicker
due to seams or overlap.
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!
ABV des 7, 2014
!
ABV des 7, 2014
!
Figure 10 -Photographs of site 01 after three years
Test site 03
Of the three test sites, site 03 saw the fastest-growing and most abundant aquatic plants.
Indeed, by the first follow-up there was 11-25% aquatic plant coverage, and this percentage
has increased over time, ranging to > 50% (table 4).
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!
Table 4 - Developments at test site 03 during the three years of follow-up based on each
variable.
Site 03
Variables
121
12-2
12-3
Moy
13-1
13-2
13-3
Moy
14-1
14-2
143
Moy
1-1
0
11-2
5
11-2
5
1125
1-10
11-2
5
>50
2650
11-2
5
>50
>50
>50
Eurasian Watermilfoil
plants
N/D
N/D
N/D
N/D
1-15
31-4
5
31-4
5
3145
31-4
5
>46
>46
>46
Sedimentation
50
100
100
100
100
100
100
100
100
100
100
100
State of the burlap
(average)
Int
Int
Int
Int
Dec
h
Des
Dech
Dec
h
Dech
Dec
h
Abs
Dec
h
Visit
Recovery of aquatic
plants (%)
N/A: Not available, Int: intact, Dech: intact but breaks in contact with an object, Des: intact but disintegrates
into contact with an object, Abs: absent
Soon after the installation of the burlap at this site, three phenomena occurred: the
appearance of periphyton on the canvas, the formation of filamentous algae in the folds of
the cloth (figure 11) and the accumulation of gases under the liner due to the decomposition
of the Eurasian Watermilfoil. These gases raised the canvas to the surface at the site (figure
12). This phenomenon was not observed at the other test sites.
The densest Eurasian
Watermilfoil was found initially at this site. It is thought that the formation of the gas bubble
under the canvas, which formed a gap of about 2 m2, allowed the Eurasian Watermilfoil to
continue its growth and its spread.
!
ABV des 7, 2012
Figure 11 -Filamentous algae and periphyton on burlap
!xxii
!
!
!
Figure 12 - Photographs of the lifted burlap at site 03
Test site 05
Burlap at site 05 was installed a little over a month after the installation of the burlap at sites
01 and 03. One can therefore observe a slight lag in the variables that were measured during
follow-up (table 5). At this site, very few indigenous and exotic aquatic plants were found
during the three years of follow-up.
Table 5 - Developments at test site 05 during the three years of follow-up based on each
variable.
Site 05
Variables
121
122
123
Moy
13-1
13-2
13-3
Moy
14-1
14-2
14-3
Moy
0
1-1
0
1-1
0
1-1
0
0
1-10
11-2
5
1-1
0
1-10
11-2
5
11-2
5
1125
Eurasian Watermilfoil
plants
N/D
N/D
N/D
N/D
1-15
31-4
5
31-4
5
3145
16-3
0
31-4
5
16-3
0
1630
Sedimentation
50
50
100
50
100
100
100
100
50
50
100
50
State of the burlap
(average)
Int
Int
Int
Int
Dec
h
Dech
Dech
Dec
h
Dech
Dech
Abs
Dec
h
Visit
Recovery of aquatic
plants (%)
N/A: Not available, Int: intact, Dech: intact but breaks in contact with an object, Des: intact but disintegrates
into contact with an object, Abs: absent
At this site, very few plants were found even once the canvas was decomposed. Eurasian
Watermilfoil continued to grow in two specific locations as there were obstacles and
irregularities on the lake bed that prevented the canvas from fully settling in the on the bed
(figure 13). This would have allowed the Eurasian Watermilfoil to continue to grow.
!xxiii
!
ABV des 7, 2014
!
Figure 13 - Photographs of a dead tree at site 05 which allowed the growth of Eurasian
Watermilfoil
Control sites
Eurasian Watermilfoil has been observed at the control sides at each followup over three
years. Eurasian Watermilfoil cover varied at each of the sites according to the seasons and
years (table 6). This variation was from a plant bed of 100% Eurasian Watermilfoil, to
scattered beds where the Watermilfoil was present, but not dominant. At no time at the
control sites was Eurasian Watermilfoil found not to be present(figure 14).
Table 6 -Coverage of the control sites by Eurasian Watermilfoil in the three years of followup
Variable
Coverage
of
Eurasian
Watermilf
oil
Sites
20121
2012-2
2012-3
20131
2013-2
2013-3
2014-1
2014-2
2014-3
02
ME et lit
100 % ME
100 % ME
ME et lit
100 % ME
100 % ME
ME et lit
100 % ME
100 % ME
04
ME et
lit
100 % ME
100 % ME
Épars
e
100 % ME
100 % ME
100 % ME
ME et esp.ind.
100 % ME
06
ME et lit
ME et esp.ind.
ME et lit
ME et lit
ME, lit et esp.ind.
ME et lit
ME et
lit
ME et esp.ind.
100 % ME
100% ME: 100% coverage of Eurasian Watermilfoil, ME et lit: dense patches and extensive where Eurasian
Watermilfoil is a dominant plant, but there are the exposed lake bed, ME et esp.ind. : Dense and extensive
patches where Eurasian Watermilfoil is a dominant plant, but there are native species, Ésparce: sparse plots
where the Watermilfoil is present, but not dominant.
!xxiv
!
!
ABV des 7, 2012
Figure 14 -Photograph of Eurasian Watermilfoil at a control site
Presence of Eurasian Watermilfoil
Once the Burlap had decomposed, Eurasian Watermilfoil was able to reestablish at some
locations in the three test sites. Patches of Watermilfoil where they did return were often
localised. At site 01, Eurasian Watermilfoil grew at the end of the burlap to a width of about a
meter because the plant bed was not fully covered. At this location, it was observed that the
Robbins pondweed grows profusely under the milfoil. It was found that the pondweed totally
covered the ground and the Eurasian Watermilfoil pushed through the pondweed. Eurasian
Watermilfoil also reestablished locally in a place where it had not been possible to install the
burlap properly due to the presence of a dead spruce trunk in the water. The presence of the
spruce meant that the burlap was not installed on the bed of the Lake,which means that it
quickly breaks up in the decomposition process. The rest of the site remained without
Eurasian Watermilfoil and only very few native plants were observed.
!xxv
!
!
Figure 15 - Test site 01 and the presence of Eurasian Watermilfoil in 2014
At test site 03, the reappearance of Eurasian Watermilfoil was observed on the edge of the
bed, and at one place where the canvas was raised due to excessive accumulation of gas.
When the canvas was dropped to the bottom of the Lake, there was less overlap between
canvases, which helped the Eurasian Watermilfoil to grow. The overlap between canvas
prevents an opening between the burlap sheets, thus providing more protection against the
!xxvi
!
reappearance of the milfoil. This milfoil bed was present throughout the project as it was not
covered in full during the initial installation of the canvas.
!
Figure 16 - Test site 03 and the presence of Eurasian Watermilfoil in 2014
Test site 05 features two small beds of Eurasian Watermilfoil within the area covered by
burlap. These islands are relatively small and Eurasian Watermilfoil did not grows at the
edge of the burlap as the milfoil beds were covered entirety.
!xxvii
!
!
Figure 17 - Test site 05 and the presence of Eurasian Watermilfoil in 2014
To summarise, test sites 01, 03, 05 have an area of Eurasian Watermilfoil which has returned
by approximately 6%, 19% and 5% of the total area of the jute burlap respectively (table 7).
In total, the proportion of Eurasian Watermilfoil present after 3 years is 13%.
!xxviii
!
Table 7 - Percentage of Eurasian Watermilfoil present at the test sites during the third year
of follow-up
Area (m
Proportion
%
Percentage
Success (%)
95
6 94
3 473
666
19 81
Site 05
852
41
5 95
Total
5 985
802
13 87
Test
Site
Burlap
Site 01
1 660
Site 03
Eurasian
Watermilfoil
Following observations made during this project, it is thought that the decomposition of
Eurasian Watermilfoil is caused by its inability to push through the mesh of burlap, which
seems to be caused by reduction of sunlight and/or the weight of the canvas. Indeed,
light levels under the burlap have been measured by a volunteer diver, who found that
sunlight is half that without burlap. This value corresponds to light levels found at the
maximum depth of plant growth, which was observed by volunteer divers to be at 9
meters in Lake Pemichangan. In addition, the weight of the burlap seems to physically
prevent the Eurasian Watermilfoil from growing. The stem of the milfoil is thought to be
too soft and have too many branches to be able to pass through the mesh, unlike
pondweed stems.
By the end of this experimental project, Eurasian Watermilfoil had been treated with an
average success of 87% across the test sites. Eurasian Watermilfoil was found in only
six distinct areas, and the reason for its presence in each of these areas is easily
explainable. Two major sections at the end of two sites had Eurasian Watermilfoil
following decomposition of the burlap. Each of these areas were directly in contact with
Eurasian Watermilfoil not covered by burlap, because the bed had not been fully
covered. Note that Robbins pondweed was found to have established in such an area of
!xxix
!
site 01. It is believed that the burlap was in fact successful in eliminating the milfoil,
which allowed native flora to return. As the bed was not fully covered, however, the
milfoil began to quickly reestablish once the burlap had begun to decompose. A third
area where Eurasian Watermilfoil was not adequately treated in this first test in Quebec
was at site 01, in an area where the burlap was unable to be installed properly due to the
presence of a dead spruce trunk in the water. The presence of the spruce, which was
about 2 metres deep, meant that the canvas was not installed completely on the bed of
the Lake and that the canvas quickly broke up during the decomposition process. Finally,
two small patches of water milfoil at site 05 and a third at site 03, in the middle of the
treated sites, are believed to have been caused by several things including hole in the
canvas, the presence of a dead tree, a pile of rocks, and an inadequate overlap or
burlap sheets. These patches represent barely 1% of the surface of the treated sites. In
short, if all of the milfoil bed had been covered and the tree trunk was covered more
tightly with canvas, Eurasian Watermilfoil would probably have disappeared from 99% of
the test site area.
It has been found that the Eurasian Watermilfoil returned to Lake Peminchangan at a
rate of 1 to 2 metres in three years. It would be interesting to continue to visit the test
sites to assess how many years it would take for complete recolonization to occur.
The decomposition of burlap The decomposition of the burlap was observed from the second year onwards (table 5).
The burlap quick changed to a state where it was still intact but would tear easily if hit by
an object. After three years the burlap had almost entirely decomposed.
However, it was found that the thread used for stitching the burlap had not been broken
down after three years. This thread is composed of nylon, a synthetic material, but it
could be easily removed at the end of the project.
As the jute burlap was found to decompose at the test sites in Lake Pemichangan it
seems appropriate for use in the Lakes of Quebec, despite the harsh winters. The
burlap began to decompose as quickly as the first summer, and was fragile after a year
!xxx
!
of installation. It had almost completely disappeared from all sites treated by the third
year of follow-up. It was noticed that the burlap sections near the shore in shallow water
had decomposed more and were more torn than the rest of the sheet. It is likely that ice
formations have slashed the burlap placed at shallow depths. In a harsh climate such as
Quebec, it would be interesting to test resistance of a jute burlap made of a tighter mesh.
Since these very shallow sections had only Eurasian Watermilfoil in very small quantities
and of small size, the ripping of the burlap at depths of < 1 m did not impact on the
success of the project.
The recovery of native flora
During follow-up visits, abundance of native plants was noted. The results varied with time
and between sites. At the first follow-up, barely 2 months after the installation of Burlap,
some indigenous plant species were observed at test site 03 (figure 18).
ABV des 7, 2012
!
Figure 18 - Native flora and fauna observed at site 03 of July 04, 2012
An increase in the abundance and diversity of native plants has been seen over time. In
total, six species of native plants have been identified (table 8) and at least three other
species were seen but not identified.
Table 8 - List of species of native plants encountered during followup visits
French Name
Latin Name
English Name
Plant
Number
Charophyte sp.
Chara sp.
Charophyte sp.
1
Élodée du Canada
Elodea canadensis
Canada waterweed
2
Petit nénuphar jaune
Nuphar microphylla
Small yellow pond-lily
3
!xxxi
!
Potamot à grandes
feuilles
Potamogeton amplifolius
Large-leaved pondweed
4
Potamot de
Richardson
Potamogeton
richardsonii
Richardson’s pondweed
5
Potamot de Robbins
Potamogeton robbinsii
Robbins’ pondweed
6
Large-leaved pondweed and a species of charophyte were the first species encountered at
the test sites (figure 19). They began their growth as soon as the canvas had killed off the
Eurasian Watermilfoil plants. At the July 2012 follow-up, which was barely two months after
the installation of the canvas, they were already well established at site 03.
!
!
Figure 19 -Photographs of the colonizers of test site 03 (July 2012).
Large-leaved pondweed left and a species of charophyte sp.
Table 9 show the appearance of native plants at test sites at each follow-up. In the table, the
abundance is represented with different abbreviations. To summarise, the majority of plants
were found at site 03 and their number has increased each year. Sites 01 and 05 had, even
in 2014, very few native plants compared to site 03.
!xxxii
!
Table 9 -Abundance of different species of native plants at sites treated between 2012 and 2014
Abundance of each species
Visit
2012-1
Test
Site
Plant
num
ber
(see
table
8)
2012-2
2012-3
2013-1
2013-2
2013-3
2014-1
2014-2
2014-3
1 3 5 1 3 5 1 3 5 1 3 5 1 3 5 1 3 5 1 3 5 1 3 5 1 3 5
3
-
-
-
-
-
T
P
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
T
P
-
-
-
-
2
-
T
P
-
-
P
-
-
P
-
-
-
-
-
-
-
-
-
-
-
-
-
-
M
-
-
A
-
1
-
-
-
-
P
-
-
P
-
-
T
P
-
-
P
-
-
A
-
P
P
-
-
A
P
-
A
P
4
T
P
T
P
-
T
P
P
T
P
T
P
P
T
P
-
-
-
T
P
P
T
P
-
A
P
P
P
-
T
P
A
P
M
A
P
5
-
T
P
-
-
-
-
-
-
-
-
-
-
-
-
-
A
-
-
-
-
-
T
P
M
-
-
M
-
6
-
-
-
-
-
-
-
-
-
-
-
-
T
P
-
-
-
-
-
-
-
-
-
-
-
A
-
-
In the table, "-" means absent or 0% recovery, "TP" means very little or 1-10% recovery, 'P' means
little or 11-25% recovery, "M" means way or 25-50% of recovery and "A" means abundant or > 50%
recovery.
The appearance of the first native plants was rapid. Native species had already begun to
grow barely two months after the installation of burlap. Thus, it is assumed that, as
Caffrey (2013) noted in his research, there is a seed bank in sediments and their
germination and growth starts rapidly after installation of burlap. This phenomenon has
not been found to occur with Eurasian Watermilfoil (Caffrey, 2013). The Eurasian
Watermilfoil did not appear to be able to grow in this manner; its primary means of
reproduction is asexual by fragmentation, and the stem of the plant lacks the rigidity to
withstand the weight of the canvas. Native plants that have a hard, straight stem are
able to push through the burlap before opening completely. Thus, some native plants
!xxxiii
!
seem able reestablish from seed banks in the sediment and can push through the burlap
to thrive.
The abundance and diversity of native plants which recolonize the environment
increased as the years passed. A few specific native species could be observed the first
year, while about eight different species were observed after three years. The two first
colonizing species were large-leaved pondweed and a species of charophyte. It was
observed that the site with the greatest abundance of indigenous and exotic plants was
site 03, which is also the one with the most disturbance in the shoreline. This abundance
of plants could be explained by several factors, which need to be validated, but may
include a greater concentration of phosphorus, greater brightness and a higher water
temperature.
General comments
In addition to the above, other observations were made during the visits to Lake
Pemichangan.
At the end of the summer period, it was observed that the Eurasian Watermilfoil divides
itself and creates roots in order to settle elsewhere quickly (figure 20). This is why there
are many fragments of Eurasian Watermilfoil in September, despite the fact that ships
are not circulating to a greater extent on the Lake.
!
ABV des 7, 2014
Figure 20 -Fragment of Eurasian Watermilfoil with roots
!xxxiv
!
In addition to native aquatic flora that grows through the canvas, it was noticed that aquatic
fauna appeared to quickly rehabilitate in areas which had been modified by the Eurasian
Watermilfoil. Indeed, many snails, fish and crayfish were observed where the burlap had
been installed.
Conclusion
Results confirm that jute burlap, when installed correctly, can be used to control Eurasian
Watermilfoil effectively in the short- and medium-term. It is clear that this new method of
control is not a solution well suited to all situations, and that it has limitations in terms of
efficiency as it is more effective against newly colonised and less dense plant beds.
That said, when the burlap is installed correctly to completely cover the plant bed, and if
recolonisation of the site by invasive plant fragments is prevented, these results indicate
that jute burlap could provide an efficient means to control newly colonized,
monospecific plant beds of Eurasian Milfoil, such as those found at Lake Pémichangan,
in the long term.
To conclude, results to date are highly promising. During the follow-up visits, the
effectiveness of jute fabric has been seen to effectively block the growth of Eurasian
Watermilfoil, while several native plant species have been able to push through. It is
important to note that the effectiveness of the method was found to increase when the
plant bed was covered completely. Where this was achieved, the regrowth of Eurasian
Watermilfoil was found to be very low.
Over the course of the project, several other factors have been found to influence the
effectiveness of the use of jute burlap. Factors identified as having a direct impact on the
growth of Eurasian Watermilfoil include: the weather, the ability of the burlap to allow gas
bubbles to escape, the quality of the installation, and the presence of irregularities on the
lake bed. An undamaged canvas (no breach) covering the whole of the plantbed, well
stretched on the bed of the Lake with strong and well-made seams is much more
effective than loose, perforated burlap with gaps between sheets.
!xxxv
!
Recommendations
Given that this project is a first test in Quebec, several recommendations can be
formulated to improve the project. Indeed, we suggest that jute burlap sheets are
produced that are wider for already sewn together to reduce, and ideally eliminate, the
task of sewing since this task is extremely time-intensive. The dimension of the sheets
used during this project (7 X 22 m) was found to be an ideal size in terms of weight, ease
of transport and installation in the Lake using two boats. It would be preferable to use a
biodegradable thread for sewing of fabrics or plan the removal of thread from the Lake
once the burlap has decayed.
It was found not to be essential to do the installation in the spring as initially thought due
to the fact that at this time of year the milfoil is not mature; this is good news as the water
is very cold at this time of year which makes installation difficult and uncomfortable. No
significant problems associated with installing the burlap over larger plants were
identified when installation took place in June. In fact, where installation took place in
the spring it was found to be necessary to add additional sheets in the sumer as the
Eurasian Watermilfoil had begun to grow in a greater area than that covered in the
spring. Installing the burlap later did, however, lead to a an increased likelihood of gas
pockets forming, which has the potential to disturb the burlap if it is not sufficiently
secured.
A further recommendation is that it is important to properly identify the sites to be treated,
because the plant bed area can be much larger than expected and the efficiency
decreases when the bed is not covered in full. In addition, to increase the likelihood of
success of such a project, we recommend returning to treated sites the two years
following the installation in order to make repairs to the burlap if required. This was not
done during this project due to its experimental nature. However, if there is a gap
between two sheets which allows the growth of the invasive plant, it would be very
appropriate to close it in practice.
Despite the fact that this method appears to work, it is important to stress that it is
necessary to obtain a certificate of authorization under article 22 of the law on the quality
!xxxvi
!
of the environment (EQA) from the Quebec Government. Also, if possible it is best to ban
motorboats, swimming and fishing on the treated sites as waves, trampling and hooks
can disturb the burlap.
Finally, there are further parameters which need to be checked in order to validate the
hypotheses posed during this project. For example, the impact of the burlap on
physicochemical parameters in addition to the concentration of phosphorus in water and
sediments under the tarpaulin should be measured over time. Also, it is possible that
efficiency could be further improved with a canvas with a different mesh (5 oz, 6 oz, 8.9
oz or 10 oz), or another natural fiber, such as coconut or hemp fiber that would vent the
gases formed during the decomposition of aquatic plants under canvas. This could
prevent the formation of bubbles like those observed at one of the sites treated with
Lake Pemichangan.
!xxxvii
!
References
Auger, I (2006) Évaluation du risque de l’introduction du myriophylle à épi sur l’offre de
pêche et la biodiversité des eaux à touladi. Revue de la littérature. Ministère des
Ressources naturelles et de la Faune, Direction de la recherche sur la Faune, Québec, p.
88
Caffrey JM (2013) Control of aquatic invasive species and restoration of natural
communities in Ireland (CAISIE) project Final Report covering the project activities from
01st January 2009 to 31st January 2013, Life Project, p. 69
Caffrey JM, Millane M, Evers S, Moran H and Butler M (2010) A novel approach to aquatic
weed control and habitat restoration using biodegradable jute matting. Aquatic Invasions
5(2): 123-129
Caffrey JM, Millane M, Evers S and Moran H (2011) Management of Lagarosiphon major
(ridley) moss in lough corrib - a review. Biology and Environment: Proceedings of the
Royal Irish Academy 111B(3):1-8
Conseil régional de l’environnement des Laurentides (2011) Rapport d’interprétation des
résultats 2009-2010 au Lac Paul, municipalité de Mille-Isle, Bleu Laurentides, p. 41
Gouvernement du Québec (2012) Loi sur la qualité de l'environnement (LQE), http://
www2.publicationsduquebec.gouv.qc.ca/dynamicSearch/telecharge.php?type=2&file=/
Q_2/Q2.HTM, consulté en ligne le 20 décembre 2012
Groupe scientifique sur l'eau (2008), Cyanobactéries et cyanotoxines (eau potable et eaux
récréatives), Dans Fiches synthèses sur l'eau potable et la santé humaine, Institut
national de santé publique du Québec, p. 20
Institut national de santé publique du Québec (INSPQ) (2013) Fiches synthèses sur l’eau
potable et la santé humaine, Québec, p. 232
Institut national de santé publique du Québec (INSPQ) (2006) Profil toxicologique du 2,4-d et
risques à la santé associés à l’utilisation de l’herbicide en milieu urbain. Avis scientifique,
Direction de la toxicologie humaine, Québec, p. 57
Lavoie, M. (2010) L'utilisation du Charançon pour le contrôle biologique du myriophylle à épi.
Maîtrise en biologie. Université du Québec à Montréal (UQAM), Montréal, p. 75
Ministère du développement durable, de l’environnement et des parcs (MDDEP) (2012)
Critère de qualité de l’eau de surface au Québec, www.gouv.qc.ca/eau/criteres_eau/
details.asp?code=S0365, consulté en ligne le 19 décembre 2012
Wetzel RG (2001) Limnology - Lake and river ecosystems, 3e edition. Elsevier Science
(USA), p. 1006
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Glossary
Aquascope
Plastic tube, with a window allowing sight underwater
without entering the water.
Biodiversity
Variety of the living organisms from all sources including,
inter alia, terrestrial, marine and other aquatic ecosystems
and the ecological complexes of which they are part.
Biomass
Mass or total quantity of organic matter which comes or
derives from living or dead organisms in a particular
environment at a given time.
Dissolved oxygen
Percentage of oxygen dissolved in water (%)
Epilimnion
Layer of water which, in a stratified water body, is located
above the thermocline.
Eutrophication
Enrichment of water, be it freshwater or saline, with
nutrients (especially by nitrogen and phosphorus
compounds, which will accelerate the growth of algae and
more developed forms of plant life).
Hypolimnion
Deep layer in a lake with a low temperature and slow
convection movements.
Invasive species
A species that was not originally in a given area, but
which is now due to, directly or indirectly, human activity.
Littoral zone
Shallow marginal zone of a body of water where light
penetrates to the bottom; generally colonized by plant
roots.
Metalimnion
Part of a stratified water body for which the temperature
gradient reaches a maximum. It is the layer between the
epilimnion and hypolimnion.
Monospecific plant bed
A plant bed composed of only one species
Native species
Species native to the area of concern.
Oligotrophic
Term used to describe a very poor environment with few
nutrients.
Shoreline
Border more than three metres on each side of a stream
that must be covered with herbaceous plants or shrubs to
stabilize the slope and the banks, and which also allows
biodiversity (fauna and flora) and can filter some
agricultural contaminants (manure, nitrates, phosphates,
sediment, pesticides) before they enter the water.
Thermal stratification
Presence of layers of different temperatures in a lake.
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Thermocline
Part of a stratified water body for which the temperature
gradient reaches a maximum.
Total phosphorus
An essential nutrient which limits the growth of aquatic
plants. The concentration of total phosphorus is used to
assess the trophic level of a lake.
Trophic state
The quantities of nitrogen, phosphorus, and other
biologically useful nutrients are the primary determinants
of a body of water's trophic state index
Water column
Vertical volumetric space in a water body considered
overall from the bottom up without specification of depth,
i.e. from the bottom to the surface.
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Annexe 1- La méthodologie en images
1.
Couture des toiles et roulement de la toile
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2.
Confection des sacs de sable
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3.
Les rouleaux sont mis dans l’eau afin d’imbiber la toile
_
4.
Les plongeurs font une reconnaissance du site
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5.
Les plongeurs mettent des bouées à l’extrémité la plus éloignée afin de guider les
bateaux qui amènent la toile de jute sur place
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6.
Des sacs de sable sont attachés à deux extrémités de la toile et une personne par
bateau tient la corde dans un bateau
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7.
Deux ou trois bateaux reculent lentement afin de dérouler la toile de jute tandis que
des gens sur la berge attachent des sacs de jute à la fin de la toile avec des ficelles de
jute afin de faire couler la toile
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8.
Les bateaux se dirigent vers l’endroit et une tension est maintenue sur la toile avant
de la laisser couler à l’endroit désigné par le plongeur et les bouées
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9.
Une personne dans chacun des bateaux doit tenir un coin de la toile lors de son
déroulement et de son déplacement au bon endroit
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10.
Lorsque la toile est tendue, les coins sont laissés tombés afin qu’ils coulent
tranquillement au fond du lac. Le plongeur a pour fonction d’aller replacer la toile au
bon endroit et de distribuer les sacs de sable sur la jute afin qu’elle tienne en place.
_
11. Installation des bouées et des affiches limitant l’accès aux bateaux sur les sites traités
et témoins.
_
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Annexe 2 – Modèle de fiche terrain pour les suivis
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Observateurs
Date (J/M/A)
Heure :
Conditions
météorologiques
Nuageux
et % PM
% AM
Ensoleillé
et % PM
% AM
Vent :
Température :
Sites traités - Recouvrement de plantes aquatiques
Sites
01
03
05
0 % de recouvrement
1-10 % de
recouvrement
11-25 % de
recouvrement
26-50 % de
recouvrement
>50 % de
recouvrement
Nombre espèces
indigènes
Espèces indigènes
présentes
Myriophylle à épi
0 plant
1 – 15 plants
16 - 30 plants
31 - 45 plants
46 et plus
Profondeur
Données spécifiques- Sédimentation sites traités
Sites
01
03
05
Aucune sédimentation
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Sédimentation
partielle
Sédimentation totale
Observations
Données spécifiques- État de la jute
Sites
01
Mesures
1
2
3
03
4
5
1
2
3
05
4
5
1
2
3
4
5
Intacte
Intacte, mais se
déchire
facilement
Intacte, mais se
désagrège au
contact d’un objet
Absente
Présence de
trous ou autre
problèmes
Sites témoins - Recouvrement de plantes aquatiques
Sites
02
04
06
100 % de couverture de
myriophylle à épi
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Parcelles denses et
extensives
(myriophylle à épi est plante
dominante, mais il y a
indigène ou lit du lac exposé)
Parcelles éparses
(myriophylle à épi pas
dominant, mais présent)
Absence de myriophylle à épi
Observations :
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Annexe 3- Photographies sous-marines des sites
traités
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Juillet 2012 – site 03
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Juillet 2013- site 03
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