Hydrobiologia (2005) 551:147–157
J.N. Beisel, L. Hoffmann, L. Triest & P. Usseglio-Polatera (eds), Ecology and Disturbances of Aquatic Systems
DOI 10.1007/s10750-005-4457-y
Springer 2005
Response of Elodea nuttallii (Planch.) H. St. John to manual harvesting
in the North-East of France
Fiorant Di Nino*, Gabrielle Thiébaut & Serge Muller
Laboratoire de Biodiversite´ & Fonctionnement des Ecosyste`mes, Universite´ de Metz, Avenue Ge´ne´ral Delestraint,
57070, Metz, France
(*Author for correspondence: E-mail: fiorant_dinino@yahoo.fr)
Key words: invasive aquatic plant, Elodea nuttallii, morphological traits, stream, management
Abstract
Elodea nuttallii (Planch). H. St John is an introduced aquatic macrophyte which was first observed in
France in the early 1950s. The impact of two frequencies of harvesting on the biomass and regrowth
strategy of this invasive species was evaluated by assessment of morphological traits monthly from February to October 2003. The effect of this management on the floristic biodiversity was also analysed.
Harvesting caused a drastic reduction of biomass of E. nuttallii. Two harvests caused almost total disappearance of E. nuttallii. Furthermore, no significant difference was observed in the architecture of
E. nuttallii between an unharvested site and harvested site. In one year, harvest did not allow the development of native aquatic plants.
Introduction
As a result of the increased influence of man on
aquatic systems, many waterways in the world have
become eutrophic and unwanted growth of aquatic
invasive vegetation has become a considerable
problem. Native to temperate North America,
Elodea nuttallii (Planch.) H. St John was first
introduced into Europe in 1939 (Wolff, 1980;
Simpson, 1984) and has received far less investigations into its biology than other invasive species. In
Europe, E. nuttallii was first identified in 1955 (Sell,
1959). Only female plants were observed, introduced certainly via the trade in live aquarium plants
(Cook & Urmi-Köning, 1985), legal or otherwise.
Apparently, E. nuttallii is actively spreading in
many parts of Europe and seems to be replacing
Elodea canadensis Michaux in many localities
(Mériaux & Géhu, 1979; Simpson, 1990; Thiébaut
et al., 1997; Barrat-Segretain, 2001; Tremp, 2001;
Demierre & Perfetta, 2002). Dispersal has mostly
been by stem fragments floating downstream. Vegetative buds are more easily distributed between
catchments than stem fragments by wildlife. The
continued spread of E. nuttallii is likely encouraged
by eutrophication (Grime, 1988). E. nuttallii grows
in still or slow flowing eutrophic waters. It is often
found in species poor macrophyte communities
subject to boat traffic, management and in eutrophic ditches. It is tolerant of disturbance, oil pollution, metal pollution and salinity up to 14 per
thousand (Sabbatini & Murphy, 1996; BarratSegretain, 2001; Newman, 2001). Its important
biomass varied from 500 to 800 g Dry Weight/m2 in
lakes (Kunii, 1984; Ozimek et al., 1990).
Dense stands of macrophytes have several negative consequences on the balance of the hydrosystem, for example the decomposition of
E. nuttallii at the end of the growth season inducing
a secondary eutrophication. Conducing to an
intense bacterial metabolism produces anoxic,
reducing conditions, which results in decreased
148
rates of mineralization and in the accumulation of
fermentation endproducts that are toxic to many
plants (Santamaria, 2002). Jones et al. (1996)
established that the stands of E. nuttallii greatly
restricted water movement which, together with the
plantÕs photosynthetic and respiratory activity,
resulted in a highly structured water column with
very steep dissolved gas and pH gradients through
the stands. The impact of the spread of E. nuttallii
on biodiversity was relatively unknown. Finally,
invasion of E. nuttallii caused very important economic problems. Effectively the important biomass
produced by E. nuttallii modifies water flow, often
increases the risk of adjacent land flooding, causes
disagreements for human activities (navigation,
fishing, tourism) and induces important cost for the
management (Demierre & Perfetta, 2002).
In many bodies of water, it has been necessary
to control overabundant aquatic plants. There are
several methods of managing aquatic plants:
mechanical or manual harvesting, biological control, changing the aquatic environment and chemical control. The management techniques chosen
must be appropriate both to the type of weed
problem and to the uses and function of the body
water. Chemical control (Diquat and Acrolein) are
used in New South Wales or in Australia (Cook &
Urmi-Köning, 1985; Bowmer et al., 1995), but it
does not solved the problem of the secondary
eutrophication. That is why Newman (2001) suggested that remove by mechanical means following
by application of herbicide (Diquat) or a biological control option by using Grass Carp
(Ctenopharyngodon idella), were the best options in
England. However several herbicides seem to
require long contact time for effective control,
making management difficult in flowing waters
(Bowmer et al., 1995), and grass carp consumption
also lead to eutrophication because fits inefficient
digestion of macrophyte material. To regulate the
spreading of E. nuttallii in Lake Léman, harvest is
used (Demierre & Perfetta, 2002). To our knowledge, no research on the impact of harvest of
E. nuttallii in flowing shallow waters has been
done.
To evaluate the impact of harvesting on the
invasive E. nuttallii and precisely investigate the
process of regrowth, an approach based on measurements of morphological traits was used. In this
paper, we aim to determine:
(i)
the impact of the number of harvests on
E. nuttallii regrowth,
(ii) which regrowth strategy E. nuttallii adopts,
through measurement of morphological
traits,
(iii) the impact of harvest of E. nuttallii stands on
the floristic biodiversity.
Materials and methods
Study area
The study was performed in the Vosges mountain,
in the Northern Vosges (NE France). The landscape pattern consists of sandstone mountains of
200–580 m in altitude topped by rock conglomerate, surrounded by steep cliffs. The regional climate is sub continental. Winters are cold, with
more than 100 days of frost and an annual temperature of 8.6 C. Summer is relatively hot. The
mean rainfall is 900 mm. The streams are subject
to eutrophication (Muller, 1990; Thiébaut &
Muller, 1998). The mean sources of pollution are
fish farms and domestic sewage. A biomonitoring
of flowing waters by aquatic macrophytes was
realized since 1993 (Thiébaut & Muller, 1998,
1999). The invasive species E. nuttallii colonized
the streams of this area since the end of 1970s
(Muller, 1990; Thiébaut & Muller, 1999). The
population of E. nuttallii are clonal in Northern
Vosges streams (Di Nino, 2002). The sampling
sites located in the Falkensteinbach stream (49 1¢
N, 7 23¢ E), were characterized by overabundance
of E. nuttallii (mean cover percentage visually
estimated between 70 and 90% in July by imaging
a birdÕs eye view of the channel). A 100 m length
of stream was chosen. Two spot-checks (Reference
site, experimental site E divided in two sub-units:
E1 and E2) located at 45 m intervals (buffer zone)
were selected (Fig. 1).
Materials
Elodea is a genus of perennials with submerged
leaves and floating flowers. The leaves are in
whorls of 3 and sessile. Leaves usually folded
along the midrib, somewhat recurved, with undulate margins. E. nuttallii over winters as prostrate
shoots which start to regenerate new lateral shoots
149
Figure 1. Description of the experimental site.
as the temperature reaches 10 C (Kunii, 1981,
1982). The shoots grow rapidly towards the surface without branching when they form a densely
branched canopy (Fig. 2).
Physical features (width, water velocity, depth)
and aquatic vegetation were recorded monthly
from February to October 2003 at each site (Reference site, experimental sites E1 and E2).
24 h after sample collection). Alkalinity was
determined by titration (AFNOR, 1990). Conductivity and pH were measured using a combined
glass electrode and corrected for temperature
(25 C). Reactive soluble phosphorus and ammonia were analysed using spectrophotometer (single
reagent ascorbic acid technique for phosphorus,
and indophenolÕs technique for ammonia,
AFNOR, 1990). Samples for nitrate, sulfate and
chloride analyses were determined in the laboratory with ion chromatography.
Chemical survey of the water
Experimental protocol
In mid-stream, 500 ml of water were collected
monthly from the end of February to the end of
October 2003. Analyses were performed immediately upon returning to the laboratory (less than
The factor tested was the number of harvests:
Physical features
– one total harvest was practised on E1 and E2 on
February 26,
150
Figure 2. Diagram illustrating E. nuttallii and its morphological traits.
– a second total harvest was realised on E2 on
May 26. In the east of France, E. nuttallii starts
to regenerate at the end of February. Its low
biomass in February favours the harvest (Kunii,
1984; Di Nino, 2002). A preliminary study
showed that fragmentation of the plant begins
in June in Vosges mountain (Di Nino, 2002), we
choose May for the second harvest to reduce the
dispersion of the species. During the harvest, to
avoid the dispersal by floating stem fragments, a
netting was placed a few metres downstream the
experimental area.
After the harvest, regrowth and biomass
production were surveyed each month until the
end of experiment (October 26).
Biomass production
Ten plots (0.2 m2 area/plot) were randomly placed
each month in each site (reference, E1 and E2).
The vegetation of plot was dug out manually by
species. E. nuttallii was weighted separately. Three
replicates of E. nuttallii were dried at 65 C for
3 days. Results were expressed in Dry Weight/m2.
Regrowth strategy
Thirty plants were collected each month in each
site (reference, E1 and E2). Apical shoots of 3 cm
length, corresponding to the optimal growth area,
was cut off. Lateral shoots included the initial
lateral which developed from the nodes on the
apical original shoot and the others lateral which
was a development either from the same nodes, or
from the nodes on the lateral shoots (Kunii, 1981).
Nine morphological traits were measured of each
plant by a ruler (Fig. 2):
– trait 1: Main shoot length
– 2: Lateral shoot length (initial + secondary
shoots)
– 3: Number of lateral shoots (initial shoot)
– 4: Length of total shoot (main + lateral)
– 5: Density. It corresponded to the ratio between
dried biomass of the plant and length of total
shoot.
– 6: Length of ten internodes after the cut of 3 cm
apex.
A preliminary statistical study showed that
leaves from the sixth whorl is the most representative leaf of the ten internodes (Di Nino, 2002).
– 7: Length of a leaf located at the sixth whorl
– 8: width of a leaf located at the sixth whorl
– 9: Surface of a leaf located at the sixth whorl.
One leaf on this sixth whorl is cut, fixed on a
paper with sailor tape. Surface was calculated by
using logician Scion image V. 1.63.
Statistical analysis
Data were analysed using Minitab. After the
verification of the normal distribution of the
151
parameter and homogeneity of variance, ANOVA
were used to show difference between population
and evolution during the seasonal growth. The
significance level for each comparison was adjusted according to them by the Bonferroni
method to p < 0.05.
Results
Chemical characteristics of the water
The water was neutral (pH = 6.95 ± 0.12), buffered (alkalinity = 291 ± 29 leq/l), low mineral
content (conductivity = 71 ± 6 lS/cm). Sampling sites were characterised by a high nitrogen
concentration (NNH+
and
4 = 109 ± 40 lg/l)
a moderate concentration of phosphate
(PPO3)
4 = 37 ± 10 lg/l).
During the experimental period, these chemical
characteristics were stable (Table 2).
Physical features
The total surface of the harvested sites was 150 m2
(30 m length · 5 m width) against 170 m2 (36 m
length · 4.70 m width) for the reference site. At
the beginning of the experiment, the main physical
features of the two sampling sites (E1, E2) and
reference site were homogenous (Table 1). In the
end of summer, depth was higher in reference site
than in the two harvested sites, whereas the mean
flow velocity was lower. The flow velocity and the
depth of the two harvested sites were similar after
May (Table 1).
Impact of harvesting on the biomass and the
regrowth of E. nuttallii
Biomass production
The lowest biomass was measured in March
(DW = 10 g/m2), whereas the highest was
obtained in August (DW = 822 g/m2) in the reference site. The harvest had a significant impact on
the production of biomass. There was a significant
difference in the biomass produced among one
harvest and two harvests. The second harvest in
May reduced the biomass of E. nuttallii to a mean
Table 1. Mean physical features of the experimental site
Physical features
Depth (m)
Flow velocity (m s)1)
Month
Reference site
E1 (one harvest February
E2 (two harvest Feb 03 and
03)
May 03
Mini
Maxi
Mean value
Mini
Maxi
Mean value
Mini
Maxi
Mean value
26/2/03
0.10
0.70
0.35 ± 0.13
0.12
0.61
0.39 ± 0.14
0.12
0.58
0.32 ± 0.10
26/3/03
26/4/03
0.10
0.01
0.70
0.65
0.35 ± 0.13
0.31 ± 0.16
0.12
0.12
0.61
0.53
0.39 ± 0.14
0.30 ± 0.13
0.12
0.12
0.58
0.43
0.32 ± 0.10
0.26 ± 0.10
26/5/03
0.08
0.65
0.38 ± 0.16
0.15
0.60
0.33 ± 0.12
0.05
0.42
0.27 ± 0.09
26/6/03
0.10
0.87
0.42 ± 0.20
0.15
0.50
0.30 ± 0.10
0.18
0.42
0.27 ± 0.08
26/7/03
0.10
0.90
0.49 ± 0.19
0.18
0.50
0.31 ± 0.06
0.10
0.40
0.28 ± 0.07
26/8/03
0.15
1.02
0.53 ± 0.21
0.20
0.51
0.33 ± 0.1
0.15
0.51
0.32 ± 0.11
26/9/03
0.10
0.90
0.45 ± 0.22
0.10
0.40
0.26 ± 0.09
0.18
0.48
0.27 ± 0.10
26/10/03
0.12
1.06
0.45 ± 0.23
0.08
0.55
0.32 ± 0.12
0.08
0.40
0.28 ±0.10
26/2/03
26/3/03
0.40
0.40
0.40
0.40
0.40 ± 0.00
0.40 ± 0.00
0.40
0.40
0.40
0.40
0.40 ± 0.00
0.40 ± 0.00
0.40
0.40
0.40
0.40
0.40 ± 0.00
0.40 ±0.00
26/4/03
0.32
0.43
0.39 ± 0.06
0.24
0.45
0.34 ± 0.11
0.24
0.45
0.34 ± 0.11
26/5/03
0.22
0.62
0.43 ± 0.17
0.37
0.45
0.42 ± 0.05
0.37
0.45
0.42 ± 0.05
26/6/03
0.26
0.30
0.27 ± 0.02
0.25
0.30
0.28 ± 0.03
0.25
0.30
0.28 ± 0.03
26/7/03
0.27
0.34
0.30 ± 0.04
0.33
0.40
0.36 ± 0.04
0.33
0.40
0.36 ± 0.04
26/8/03
0.25
0.33
0.28 ± 0.04
0.32
0.40
0.37 ± 0.04
0.32
0.40
0.37 ± 0.04
26/9/03
0.26
0.32
0.30 ± 0.03
0.32
0.40
0.36 ± 0.04
0.32
0.40
0.36 ± 0.04
26/10/03
0.37
0.48
0.42 ± 0.06
0.36
0.40
0.38 ± 0.02
0.36
0.40
0.38 ± 0.02
152
Table 2. Physico-chemical composition of water
pH
Conductivity
Alkalinity
P-PO3)
4
NNH+
4
NNO)3
SSO2)
4
Cl)
(lS/cm)
(leq/l)
(lg/l)
(lg/l)
(mg/l)
(mg/l)
(mg/l)
26/2/03
6.97
74
250
15
121
0.72
9.94
5.92
26/3/03
26/4/03
6.98
7.01
71
61
254
314
41
31
193
74
0.57
0.57
10.45
9.75
5.94
5.82
26/5/03
6.99
71
320
45
115
0.48
9.25
5.39
26/6/03
6.99
69
285
33
126
0.59
9.85
5.77
26/7/03
7.13
85
308
48
97
0.36
8.22
5.36
26/8/03
6.70
69
260
41
50
0.54
8.39
5.74
26/9/03
6.93
71
308
40
105
0.48
8.88
5.73
26/10/03
6.85
68
318
37
97
0.60
9.60
5.63
Mean value
Std
6.95
0.12
71
6
291
29
37
10
109
40
0.55
0.10
9.37
0.75
5.70
0.21
level of 14 g DW/m2 in July in E2 against
120 g DW/m2 in E1 and 565 g DW/m2 in the
reference site. No stands of E. nuttallii were found
after July in site E2 (Table 3). Only some individuals were present.
Regrowth strategy
Significant differences in morphological traits
appeared among the dates for five traits (1, 2, 3, 4
and 6). A significant reduction of the length
response (traits 1, 2, 3, 4, 6) was observed in the two
experimental sites in August (ANOVA, p < 0.05).
These morphological traits were the highest in
August and September in reference site (Fig. 3).
Relationships between species after the regrowth
At the beginning of the study, the biodiversity
was low. Elodea nuttallii was the dominant species. Four other species were recorded: Elodea
canadensis, Ranunculus peltatus, Callitriche
platycarpa and Fontinalis antipyretica in less than
1% of the stream. At the end of the experimental period, the cover percentage of native
macrophytes did not increase. The exotic
E. canadensis disappeared in the harvested sites
and F. antipyretica was not found (Table 4). The
decrease of E. nuttallii stands did not allow the
development of native aquatic plants such as
R. peltatus.
Table 3. Biomass production
Month
Discussion
Dry weight g/m2
Reference E1 (one harvest E2 (two harvest
site
February 03)
Feb 03 and May 03)
26/2/03
5
5
5
26/3/03
10
2
2
26/4/03
90
2
2
26/5/03
51
32
32
26/6/03
26/7/03
330
565
180
120
1
14
26/8/03
822
54
1
26/9/03
610
101
0
26/10/03 567
60
0
Mean value (n = 10).
Impact of harvesting on the biomass
and regrowth of E. nuttallii
No significant difference was established for biological traits after one or two harvests. Our results
corroborated partially the conclusions of Abernethy et al. (1996) that showed no significant change
for length response after one cut and only 44%
reduction after two cuts. Harvests caused no
morphological change in the architecture of
regrown plants in our area, except in August.
In August, a significant reduction of growth of
plants was established. E. nuttallii appeared as a
Figure 3. Morphology on the regrown plants of E. nuttallii. Temporal changes of nine different morphological traits: trait 1: main shoot length; 2: lateral shoot length; 3:
number of lateral shoots (initial + secondary shoots); 4: length of total shoot (main + lateral); 5: density; 6: length of ten internodes; 7: length of a leaf located of the sixth
whorl; 8: width of a leaf located of the sixth whorl; 9: surface of a leaf located of the sixth whorl. The significance level for each comparison was adjusted according to the
Bonferroni method ( p < 0.05) and indicated by the letters (A, B, C, D).
153
154
Table 4. Aquatic vegetation survey
Month
Vegetation cover (%)
Reference site
E1 (One harvest February 03)
E2 (Two harvest Feb 03 and May 03)
Species: E. nuttallii E. canadensis Ranunculus Callitriche
E. nuttallii E. canadensis Ranunculus Callitriche
E. nuttallii E. canadensis Ranunculus Callitriche
peltatus
platycarpa &
peltatus
platycarpa &
peltatus
platycarpa &
C. hamulata
C. hamulata
C. hamulata
26/02/03 20
1
0
0
20
1
0
0
20
1
0
0
26/03/03 40
1
0
0
3
0
0
0
3
0
0
0
26/04/03 20
1
4
4
3
0
0
2
3
0
0
2
26/05/03 20
1
4
4
20
0
2
5
20
0
2
5
26/06/03 60
1
0
2
35
0
0
2
5
0
0
2
26/07/03 70
26/08/03 90
1
1
0
0
1
4
35
15
0
0
0
0
2
0
5
3
0
0
0
0
2
0
26/09/03 80
1
0
4
20
0
0
0
5
0
0
0
26/10/03 70
1
0
2
15
0
2
2
3
0
2
2
Estimation of vegetation cover in percent.
155
disturbance-tolerant species. The plant did not
adopt the prostrate form characteristic of overwintering in the end of experiment in October in
Northern Vosges stream. E. nuttallii grows on
yearly cycle in Northern Vosges streams.
The biomass response of Elodea was more
marked in our area (reduction of 94 and 100%
after one and two harvests, respectively) than in
the study of Abernethy et al. (1996), which measure biomass reductions of 41 and 59% after one
and two cuts, respectively. In our study, the
maximum of biomass was obtained in August in
accordance with literature data (Kunii, 1984; Best
& Dassen, 1987; Newman, 2001). After July, biomass will be reduced by washout in the experimental sites E1 and E2 and in lesser extend in
reference site. Harvesting induced modification of
physical characteristics of the stream. The stream,
overrun with sand in harvested sites, was characterized by a highest water velocity and lowest
depth. However, dense stands of E. nuttallii
reduced flow velocity in reference site.
Relationships between E. nuttallii and
other species
Differences in biological traits of the two Elodea
species E. canadensis and E. nuttallii are particularly important to consider in the analysis of the
invasive or competitive success of the species
(Williamson, 1996). Barrat-Segretain et al. (2002)
showed few differences in traits (regeneration and
colonisation of vegetative fragments, resistance to
water current, herbivory) between the two Elodea
species. The displacement of E. canadensis by
E. nuttallii as usually observed in field could not be
explained by morphological traits or by physiological differences (Jones et al., 2000). For example, no clear differences in photosynthetic
behaviour were observed between the Elodea species (James et al., 1999). However, the species
E. nuttallii seems to be less sensitive to ammonium
and had higher phosphorus storage ability than
E. canadensis (Rolland & Trémolières, 1995;
Robach et al. 1995). It had a higher growth rate
than E. canadensis both in field and under laboratory
conditions (Simpson, 1990; Eugelink 1998).
An invading species such as E. nuttallii may be
able to exploit the unused resource even though its
ecology is not fundamentally different from that
of the native species Callitriche platycarpa. Thiebaut & Muller (2003) showed that Elodea nuttallii
had higher phosphorus storage ability than
C. platycarpa in Northern Vosges streams. A
competition for resources between native species
(C. platycarpa, R. peltatus) and alien species such
as E. nuttallii was suggested in our streams (Garbey
et al., 2003; Thiébaut & Muller, 2003).
The spread of E. nuttallii seems to be the cause
of the disappearance of Myriophyllum alterniflorum, in Northern Vosges stream (Thiebaut et al.,
1997) and the regression of Potamogeton compressus in lake Kawaguchi (Nagasaka et al., 2002).
However, the loss of biodiversity induced by
E. nuttalliiÕs spread was not clearly established.
These results are in concordance with the study of
Tremp (2001).
Is harvest an efficient tool to manage
E. nuttallii?
The kind and biomass of plants vary in different
aquatic environments – canals, streams, rivers,
lakes, ponds marshes and wetlands. The use to
which a body of water is being put determines the
management objectives, and whether there is a
need for the management or control of aquatic
plants. There is a choice between total control and
some form of selective control.
Elodea appeared to be less susceptible to cutting-based weed control measures than Myriophyllum spicatum, a native species (Abernethy
et al., 1996). From the practical management point
of view, the results of the study of Garbey et al.
(2003) imply that the disturbance-causing weed
control measure will tend to favour species with
stronger disturbance – tolerant strategies, such as
E. nuttallii. Newman (2001) considered that the
effectiveness of mechanical control depended on the
date of the harvest. During June, the roots of
E. nuttallii die and in September the plant attains
maximum biomass. For him, cutting before the end
of June will require a second cut later in the season
and to limit the amount of biomass required to be
harvested it is also necessary to cut before September. Sabbatini & Murphy (1996) using a multivariate approach, showed that E. nuttallii has a
strong tolerance of management based on disturbance, such as cutting. Cutting, specially mechanical control, could induce a reduction of the biomass
156
of indigenous plants and allow Elodea to spread to
new areas because harvest break up the plant.
However harvesting can be quite useful in areas
where the weed is already established as in Northern Vosges streams, or when the weed will disperse
into areas unfavourable to its survival (Bowmer
et al., 1995).
An other solution was to do nothing and
to ‘‘wait and see’’. After a spreading period,
E. canadensis became rare in our area. E. nuttallii
will probably have a similar invasion pattern than
E. canadensis. A noticeable decline in E. nuttallii
indeed was also reported after the peak of the
outburst in JapanÕs lake (Nagasaka et al., 2002).
E. nuttallii populations exhibited a genetic uniformity that made them vulnerable to attack by fungi
or pathogens. However, eutrophication increases
E. nuttalliiÕs invasibility. Growth of E. nuttallii was
favoured by nitrogen level (Ozimek et al., 1990,
1993; Best et al., 1996). No environmental factor
could limit the spread of E. nuttallii in our area.
Conclusion
Harvesting caused a drastic reduction of biomass
of E. nuttallii. After two harvests E. nuttallii almost disappeared. However, no effect of harvest
was observed on the architecture of regrown plants
except in August. In the end of the year, the impact
of harvest on biodiversity was low and did not
favour the development of native aquatic plants.
Further work is needed to improve our
knowledge to estimate the ecological risk of harvesting on biodiversity and on ecosystem function.
The risk of adverse side-effects for users of the
water and for the ecosystem health must always be
taken into account. Accordingly, aquatic weed
management system must be developed which are
socially and environmentally acceptable.
Acknowledgements
The assistance of Muriel Julita was greatly
appreciated. This study was funded by the
Northern Vosges Biosphere Reserve. This project
is sponsored by the French Ministry of Ecology
and Sustainable Development Program ‘‘Biological Invasions’’.
References
Abernethy, V. J., M. R. Sabbatini & K. J. Murphy, 1996.
Response of Elodea canadensis Michx. and Myriophyllum
spicatum L to shade, cutting and competition in experimental culture. Hydrobiologia 340: 219–224.
Association Française de NORmalisation (AFNOR), 1990.
Recueil de normes françaises. Eaux. Méthodes dÕessais. 4
ème ed. Paris.
Barrat-Segretain, M. -H., 2001. Invasive species in the Rhône
River floodplain (France): replacement of Elodea canadensis
Michaux by E. nuttallii St. John in two former river channels. Archiv fur Hydrobiologie 152: 237–251.
Barrat-Segretain, M. -H., A. Elger, P. Sagnes & S. Puijalon,
2002. Comparison of three life-history of invasive Elodea
canadensis Michx and Elodea nuttallii (Planch) H. St. John.
Aquatic Botany 74: 299–313.
Best, E. P. & J. H. A. Dassen, 1987. A seasonal study of growth
characteristics, and the levels of carbohydrates and proteins
in Elodea nuttallii, Polygonum amphibium and Phragmites
australis. Aquatic Botany 28: 353–372.
Best, E. P. H., H. Woltman & F. H. H. Jacobs, 1996. Sedimentrelated growth limitation of Elodea nuttallii as indicated by a
fertilization experiment. Freshwater Biology 36: 33–44.
Bowmer, K. H., S. W. L. Jacobs & G. R. Sainty, 1995. Identification, Biology and Management of Elodea canadensis,
Hydrocharitaceae. Journal of Aquatic Plant Management
33: 13–19.
Cook, C. D. K. & K. Urmi-König, 1985. A revision of the
genus Elodea (Hydrocharitaceae). Aquatic Botany 21: 111–
156.
Demierre A., & J. Perfetta, 2002. Gestion du faucardage des
macrophytes sur les rives genevoises du Léman (Suisse).
Proceedings of the 11th EWRS International Symposium on
aquatic Weeds, Moliets et Maâ (France), Septembre 2–6
septembre 2002, 345–347.
Di Nino, F., 2002. Caractérisation morphogénétique des élodées de Lorraine et de la Plaine dÕAlsace. Univesité de Metz
(France). DEA Toxicologie de lÕEnvironnement, 41 pp.
Eugelink, A. H., 1998. Phosphorus uptake and active growth of
Elodea canadensis Michx. and Elodea nuttallii (Planch.)
St. John. Water Science and Technology 37: 59–65.
Garbey C., G. Thiébaut, S. Muller, 2003. Impact of manual
spring harvesting on the regrowth of a spreading aquatic
plant: Ranunculus peltatus Schrank Archiv fur Hydrobiologie 156(2): 271–286.
Grime, J. P., 1988. The CRS model of primary plant strategies:
origins, implications, and tests. In L. D. Gottlieb & S. K.
Jain (eds), Plant Evolutionary Biology. Chapman & Hall,
London, 371–393.
James, C. S., J. W. Eaton & K. Hardwick, 1999. Competition
between the three submerged macrophytes, Elodea canadensis Michx, Elodea nuttallii (Planch.) St. John and Lagarosiphon major (Ridl.) Moss. Hydrobiologia 415: 35–40.
Jones, J. I. & K. J. W. Hardwick Eaton, 1996. Diurnal carbon
restrictions on the photosynthesis of dense stands of Elodea
nuttallii (Planch.) St. John. Hydrobiologia 340: 11–16.
Jones, J. I. & J. W. K. Eaton Hardwick, 2000. The effect of
changing environmental variables in the surrounding water
157
on the physiology of Elodea nuttallii. Aquatic Botany 66:
115–129.
Kunii, H., 1981. Characteristics of the winter growth of
detached Elodea nuttallii (Planch) St. John in Japan. Aquatic
Botany 11: 57–66.
Kunii, H., 1982. The critical temperature for the active growth
of Elodea nuttallii (Planch.) St. John. Japanese Journal of
Ecology 32: 111–112.
Kunii, H., 1984. Seasonal growth and profile structure development of Elodea nuttallii (Planch.) St.John in pond OjagaIke, Japan. Aquatic Botany 18: 239–247.
Meriaux, J. -L., & J. -M., Gehu, 1979. Réactions des groupements aquatiques et subaquatiques aux changements de
lÕenvironnement. Epharmonie 1979. Tüxen, Cramer in der
A.R Gantner Verlag Kommanditgesellschaft, 121–142.
Muller, S., 1990. Une séquence de groupements végétaux bioindicateurs dÕeutrophisation croissante des cours dÕeau faiblement minéralisés des Basses Vosges gréseuses du Nord.
Comptes Rendus de lÕAcadémie des Sciences Paris 310:
509–514.
Nagasaka, M., K. Yoshizawa, K. Ariizumi & K. Hirabayashi,
2002. Temporal changes and vertical distribution of macrophytes in Lake Kawaguchi. Oecologia 3: 107–114.
Newman, J., 2001. NuttallÕs pondweed. Centre for Aquatic
Plant Management information 28.
Ozimek, T., R. Gulati & E. van Donk, 1990. Can macrophytes
be useful in biomanipulation of lakes? The lake Zwemlust
example. Hydrobiologia 200/201: 399–407.
Ozimek, T., E. Van Donk & R. D. Gulati, 1993. Growth and
nutrient uptake by two species of Elodea in experimental
conditions and their role in nutrient accumulation in a
macrophyte-dominated lake. Hydrobiologia 251: 13–18.
Rolland, T. & M. Tremolières, 1995. The role of ammonium in
the distribution of two species of Elodea. Acta Botanica
Gallica 142: 733–739.
Robach, F., I. Hajnsek, I. Eglin & M. Tremolières, 1995. Phosphorus sources for aquatic macrophytes in running waters:water or sediment?. Acta botanica Gallica 142: 719–731.
Sabbatini, M. R. & K. J. Murphy, 1996. Submerged plant
survival strategies in relation to management and environmental pressures in drainage channel habitats. Hydrobiologia 340: 191–195.
Santamaria, L., 2002. Why are most aquatic plants widely
disturbed? Dispersal, clonal growth and small-scale heterogeneity in a stressfull environment. Acta Oecologica 23:
137–154.
Sell, Y., 1959. Étude comparative de quelques espèces du
genre Elodea à propos de lÕapparition à Strasbourg et ses
environs dÕune espèce nouvelle pour lÕEurope continentale.
Bulletin de lÕAssociation Philomatique dÕAlsace Lorraine
10: 121–133.
Simpson, D. A., 1984. A short history of the introduction and
spread of Elodea Michx. in The British Isles. Watsonia 15:
1–9.
Simpson, D. A., 1990. Displacement of Elodea canadensis
Michx. by Elodea nuttallii (Planch.) St. John in the British
Isles. Watsonia 18: 173–177.
Thiébaut, G. & S. Muller, 1998. The impact of eutrophication
on aquatic macrophyte diversity in weakly mineralised
streams in the Northern Vosges mountains (N-E, France).
Biodiversity and Conservation 7: 1051–1068.
Thiébaut, G. & S. Muller, 1999. A macrophyte communities
sequence as an indicator of eutrophication and acidification
levels in weakly mineralised streams in North-Eastern
France. Hydrobiologia 410: 17–24.
Thiébaut, G. & S. Muller, 2003. Linking phosphorus pools of
water, sediment and macrophytes in running waters. International Journal of Limnology 39: 307–316.
Thiébaut, G., T. Rolland, F. Robach, M. Trémolières & S.
Muller, 1997. Quelques conséquences de lÕintroduction de
deux espèces de macrophytes, Elodea canadensis Michaux et
Elodea nuttallii St. John, dans les écosystèmes aquatiques
continentaux:exemple de la Plaine dÕAlsace et des Vosges
du Nord (Nord-Est de la France). Bulletin Français de la
Pêche et de la Pisciculture 344/345: 441–452.
Tremp, H., 2001. Standörtliche Differenzierung der Vorkommen von Elodea canadensis Michx.und Elodea nuttallii
(Planch.) St. John in Gewässern der badischen Oberrheinebene Ber. Inst. Landschafts- Pflanzenökologie Univ.
Hohenheim 10: 19–32.
Williamson, M., 1996. Biological Invasions. Chapman and
Hall, London.
Wolff, P., 1980. Die Hydrilleae (Hydrocharitaceae) in Europa.
Gött. Flor. Rundbr 14: 33–56.