Originating from Europe, the Eurasion watermilfoil has become the number
one burden of lakes across Québec and Canada. Nearly
uncontrollable, it can attack virtually any lake.
in a lake, this plant has the capacity to spread to virtually
all surfaces of the water. In effect, its mode of propagation
is such that the plant spreads at incredible speeds. Since the
plant can easily reach 3 to 4 metres in length, it can rapidly
displace other submerged native aquatic plant species.
Since this plant has a well-developed leaf system around the stem, it
can become extremely dense. By growing in densely packed colonies,
watermilfoil creates a zone of stagnation to the point where the
natural turbulence of the water becomes practically non-existent.
As such suspended particles present in the lake water get trapped
within the milfoil clusters and in turn create new sediments rich
in nutrition. This phenomenon is evident by a significant drop
in oxygen at the sediment level. The impacts
from watermilfoil infestation are numerous. Heading the list is
a loss in biodiversity and the nuisance to residents around the
lake. Fishing becomes almost impractical. With an increased risk
of drowning, water skiing and swimming need to be avoided in the
affected areas. Among the inconveniences is the difficulty in
boating both motorized and by sail for evident reasons.
Eurasion watermilfoil can also cause major physical-chemical changes. During
winter, decomposing plants cause a partial de-oxygenation of the
surrounding water which can cause the disappearance of numerous
species of fish.
During summer, plants reach again for the surface thereby physically
blocking the natural water circulation. As a result water becomes
stagnant resulting in high levels of coliforms and other bacteria.
During photosynthesis of a large number of aquatic plants, the
ph level has a tendency to increase. We can therefore attain ph
levels of 10 to 15 during the summer which can in turn negatively
affect the entire aquatic ecosystem.
into account all these factors, we begin to understand why
this plant has become a real menace and a significant burden
fro our lakes.
There exist a number of methods or products for controlling
watermilfoil including chemical, physical, biological and
even mechanical. Most of these techniques need to be managed
by consultants with expertise in the restoration of lakes.
Current techniques and products include:
the exception of the re-oxygenation approach, these techniques
have had little success to date.