80
Aquatic invertebrate herbivores in association with Myriophyllum spicatum
in Otsego Lake, summer 1999
Robert L. Johnson I, Jason A. Toner I , Alison C. C. Colbyl
INTRODUCTION
Two invertebrate herbivores, a small aquatic moth Acentria ephemerella and an aquatic
weevil Euhrychiopsis lecontei occur in Otsego Lake, New York. Present in water bodies
throughout New York State, these herbivores appear to influence submersed aquatic macrophyte
diversity and abundance. Acentia ephemerella and E. lecontei feed on the invasive aquatic
macrophyte Myriophyllum spicatum L. (Eurasian watermilfoil), and have the potential to act as
possible biological control agents of M. spicatum (Sheldon and Creed, 1995; Johnson et al.,
1998; Johnson et aI., in press). Another herbivore, the midge Cricotopus myriophylli, associated
with M spicatum (Oliver, 1984; Macrae et al., 1990) is present in Otsego Lake (Fagnani and
Harman, 1987).
First documented in Otsego Lake in 1986 (Dayton and Swift, 1987), M spicatum is an
introduced species that often dominates an aquatic plant community and can cause lake
management problems. However, previous macrophyte surveys in Otsego Lake indicate a
diverse plant community prior to and following the invasion of M spicatum (Muenscher, 1936;
Harman and Doane, 1970; Brady and Lamb, 1977; Harman et al., 1980; Dayton and Swift, 1987;
Harman, 1994). Harman et al. (1997) reports 22 species of aquatic macrophytes identified in
1969 and 1976, and 23 species identified in 1993. Although at this time M spicatum is a
dominant species in the aquatic plant community, the consensus of most lake users is that this
plant is not at problematic levels in Otsego Lake (Harman, 1998).
One possible reason for this agreement is the failure of M spicatum to form a dense
canopy at the surface of Otsego Lake as it does in many other New York lakes. Creed and
Sheldon (1994) and Johnson et al. (1998) suggest that the feeding on the apical meristem of M
spicatum by invertebrate herbivores limit elongation and canopy formation by this plant.
Merrifield and Harman (1988) collected M spicatum from Otsego Lake in 1982. After two
weeks in an incubator it was observed that many apical meristems were missing and that A. nivea
(= ephemerella) was present. Miner (1997) recorded the presence of A. ephemerella and other
possible herbivores in Otsego Lake from her survey of M spicatum for meroplankton.
Therefore, in 1998 and 1999 we surveyed apical meristems of M spicatum to evaluate the spatial
and temporal distribution, along with the abundance of A. ephemerella and E. lecontei in Otsego
Lake. In addition, we sampled submersed aquatic macrophyte biomass in 1998 to quantify plant
spatial diversity and species abundance to help investigate the association between the plant
community and herbivore density.
1 Department
of Ecology and Evolutionary Biology, 1999 BFS visiting researcher. Cornell University.
81
METHODS
Herbivore Surveys
We sampled four sites chosen by Miner (1997), including Rat Cove (A), South Marina
(B), NW Comer (C), and Hyde Bay (D) in Otsego Lake, by boat for herbivores on 2 July and
11 August 98, and 11 August 99. The herbivore sampling at Rat Cove occurred at three
different locations (quadrants 1, 2, 3) with quadrants 1 and 2 deeper and further from shore than
quadrant 3 (Map 1). We sampled within quadrant 2 on 2 July 98, quadrant 3 on 11 August 98
and 11 August 99, and quadrant 1 on 11 August 99.
At each site, we haphazardly collected M spicatum stems with a grapple hook, and
randomly selected 25 apical meristems (growing tips) from those stems. Each apical meristem
was 25 cm in length, and placed in an individual plastic-zipper bag. We transported the bags
containing the apical meristems in a cooler chest back to our laboratory, and stored samples in a
refrigerator pending examination under a stereoscopic microscope. We recorded the presence
of all herbivores on each 25 cm apical meristem, and from these herbivore counts we estimated
the number of individuals per apical meristem. We report the number of E. lecontei using all
life stages (eggs, larvae, pupae, and adults), and the number of A. ephemerella using larvae,
. pupae, and adults. In addition, we recorded any signs of herbivores (e.g. pupa chambers, eggs,
and shelters) and M spicatum tissue damage.
Biomass
On 11 August 98, we sampled submersed aquatic plant biomass in Rat Cove (quadrant
3), South Marina, NW Comer, and Hyde Bay. To ensure random sampling we tossed a 0.25 m 2
quadrat frame twenty times from a boat at each site. A diver using an air buoy underwater
breathing apparatus hand-harvested all above sediment plant biomass from each tossed quadrat
frame, and placed each harvested sample in a separate plastic bag. In the laboratory, we washed
each sample to remove any non-plant material, and separated each sample to individual plant
species. Determination of dry weight for these separated plant species occurred after oven
drying at 105 C for 48 hours. We placed plant biomass samples not analyzed immediately in a
freezer for later separation and dry weight detennination. We calculated from these individual
dry weights the mean biomass for each plant species at each site. We report aquatic plant
biomass as grams of dry weight per square meter, and as percentages of the total harvested
biomass.
RESULTS AND DISCUSSION
We found the aquatic weevil Euhrychiopsis lecontei and the aquatic moth Acentria
ephemerella in the 1998 and 1999 samples ofM. spicatum apical meristems. In July 1998, we
observed both herbivores present at low densities in the NW Comer and Hyde Bay, and absent
82
Site A:
Rat Cove
Site B:
South Marina
Map 1. Sample sites used for collection of milfoil stems, Otsego Lake, New York.
83
in the South Marina (Figure 1). By August 1998, we found A. ephemerella densities low or
absent in all four sites and E. lecontei densities considerably higher in the NW Comer (Figure
2).
In our July 1998 sampling of quadrant 2 at Rat Cove, we failed to find E. lecontei and
we detected a high density of A. ephemerella (Figure 1). However, in August 1998, we
observed the opposite trend in the shallow Rat Cove site (quadrant 3). In the shallow quadrant
3,our analysis shows A. ephemerella absent, but E. lecontei present at a high density (Figure 2).
In August 1999, we sampled two Rat Cove sites to compare a deep and further from shore site
(quadrant 1) to the near shore quadrant 3 (Figure 3). In 1998 and 1999, A. ephemerella were
the dominant herbivore in the deep Rat Cove quadrants 1 and 2, while E. lecontei dominated the
shallow quadrant 3 (Figure 1,2,3). This observation suggests distance from the shoreline or
water depth may be important to the abundance and life histories of these herbivores.
In August 1999, we found significantly higher densities of A. ephemerella than E.
lecontei at all sites except the shallow Rat Cove site (quadrant 3). Hyde Bay sustained the
highest density of 0.68 A. ephemerella per apical meristem (Figure 3). We associate this high
density of A. ephemerella with the limitation of M spicatum growth. Experiments in the
laboratory and field, and the M spicatum declines reported in Cayuga Lake, New York and
Kawartha Lakes, Canada (Van Dusen et al., 1998; Johnson et aI., 1998; Painter and McCabe,
1988) report this approximate density associated with limited M spicatum growth.
We identified thirteen species of aquatic plants in the 1998 Otsego Lake biomass survey
(Table 1). We found considerable variation in total plant biomass across the four sites, ranging
from 61.0 at Hyde Bay to 125.1 g/m 2 at the NW Comer site (Figure 5). M. spicatum comprises
48,3, 15, and 50 % of the total plant biomass at Rat Cove, South Marina, NW Comer, and
Hyde Bay, respectively (Appendix). The dry biomass of M spicatum ranged from 2.9 in South
Marina to 55.7 g/m 2 in Rat Cove (Figure 6), and is the dominant plant species in Rat Cove and
Hyde Bay. In contrast, we found Elodea and Chara the dominant plant species at the South
Marina and NW Comer sites (Figure 7, Appendix). The density of M. spicatum stems
correspond with the biomass reported at all four sites (Figure 6, 8).
Our comparison of herbivore densities between August 1998 and 1999 found distinct
variation, with A. ephemerella increasing from 0.06 to 0.37 and E. lecontei decreasing from
0.29 to 0.06. However, these densities represent only one point in time, and this variation is
most likely influenced by several factors. One possible reason for this difference is that we
sampled two years with differing climatic conditions that could influence the life histories of
these herbivores. Another consideration for these density differences is the location of the
sampling sites within the lake. The specific locations we sampled in 1998 in Rat Cove and in
the NW comer may directly bias our findings. Although we only have three sampling dates
over two years it appears that there is a difference in herbivore species density, possibly related
to the distance from shore. Our perception is that the Rat Cove and NW comer sites that we
sampled in on August 1998 were closer to shore, because the diver sampling plant biomass
could easily stand in the chest-high water depth in those areas. The E. lecontei densities
reported for these two locations on 11 August 98 are high (Table 3). In August 1999, our
84
reported herbivore densities show a high E. lecontei count only in the shallow near-shore Rat
Cove site (quadrant 3). At the same time, we record A. ephemerella abundant at all sites
including the most distant from shore Rat Cove site (quadrant 1) and the NW comer site, which
we believe is further from shore than the NW August 1998 sampling site.
In addition, we observed a similarly in the relationship of Otsego's surface area and mean
depth, its densities of A. ephemerella and E. lecontei, and its abundance of M spicatum to the
relationships of the same parameters from other sampled lakes. These three parameters fall in
line with the same parameters reported from a survey conducted in 1997 on five New York
Lakes (Johnson et al. in press). The 1997 five-lake survey reveals A. ephemerella densities
correlating positively with lake surface area and mean depth, while E. lecontei densities correlate
negatively. E. lecontei densities correlate positively with percent composition and dry mass of
M spicatum, while A. ephemerella correlates negatively. These results suggest an association
between M spicatum abundance, lake size, and these two herbivore species found on M
spicatum.
The invertebrate herbivores in Otsego Lake cause damage to M spicatum by feeding on
the plant and more than likely limit its elongation. However, it is unclear if this herbivory is the
sole reason for lack of excessive growth which keeps it from forming surface mats which also
might explain why this plant is not perceived as an esthetic problem in the lake.
85
Otsego Lake: July 98 Herbivore Densities
E
(])
......
(J)
'C
A. A. ephemerella
• E. lecontei
0.3
(])
:2:
ro 0.2
o
0­
«
(J)
0.1
(])
~
.§2
.0
~
0.0 ......._iJii-_1IIIIIIIIIiI.....
_ _. . ._ _...._
(])
...
Rat Cove South Marina NN Corner Hyde Cove
I
(quadrant 2)
Sample Site
Figure 1. Density of M spicatum herbivores in July 1998, measured as the mean number of
individuals (±1 SE) per apical meristem (n = 25), collected from four sites in Otsego Lake, New
York. E. lecontei numbers include eggs, larvae, pupae, and adults. A. ephemerella numbers
include larvae, pupae, and adults.
E
(])
......
(J)
'C
Otsego Lake: August 98 Herbivore Densities
1.0­ A. A. ephemerella
'r­
• E. lecontei
(])
:2: 0.75­
u
co
.Q
0­
«
(J)
(])
~
0.5­
0.25­
.§2
.0
~
(])
I
0.0­
I
•
•
Rat Cove
(quadrant 3)
••
II
I
South Marina NN Corner
i­
•
Hyde Cove
Sample Site
Figure 2. Density of M. spicatum herbivores in August 1998, measured as the mean number of
individuals (±1 SE) per apical meristem (n = 25), collected from four sites in Otsego Lake, New
York. E. lecontei numbers include eggs, larvae, pupae, and adults. A. ephemerella numbers
include larvae, pupae, and adults.
86
E
(l)
.....
CJ)
'C
(l)
~
CO
o
Q.
Otsego Lake: August 99 Herbivore Densities
... A. ephemerella
• E. lecontei
0.8
0.7
0.6
0.5
«
- ~.~ II I
I
CJ)
(l)
L.
.~
.n
L.
(l)
Rat Cove
I
I
I
0.0---.........._ - ._ _. ._ _...._ _....
0.1
(quadrant 3)
twV Corner
South Marina
Hyde Cove
Rat Cove
(quadrant 1)
Sample Site
Figure 3. Density of M spicatum herbivores in August 1999, measured as the mean
number of individuals (±1 SE) per apical meristem (n = 25), collected from five sites in Otsego
Lake, New York. E. lecontei numbers include eggs, larvae, pupae, and adults. A. ephemerella
numbers include larvae, pupae, and adults.
E
(l)
.....
CJ)
'C
(l)
~
CO
.2
Q.
«
Annual A. ephemerella Density Variation
,-
0.8
0.7
0.6
0.5
0.4
-I'"
-­
-
0.3 •
0.2 •
0.1 •
0.0 •
1998 •
1999 ...
••
I I I
I
I
•
Rate Cove South -Marina twV Corner
~
I
.
Hyde Cove
(quadrant 3)
Sample Site
Figure 4. Density of A. ephemerella in August 1998 and 1999, measured as the mean number
of individuals (±1 SE) per apical meristem (n = 25), collected from four sites in Otsego Lake,
New York. Numbers include larvae, pupae, and adults.
87
1998 Otsego Lake Total Plant Biomass
150
rJ)
U)
co
E
100
o
co
co
......
o
50
l­
e::
co
<D
~
o
Rat Cove South Marina NN Corner Hyde Cove
(quadrant 3)
Sample Site
Figure 5. Mean total plant biomass, measured as dry weight g/m 2, for 1998 in Otsego Lake,
New York. Biomass is the mean of twenty, O.25m2 samples for each of the four sites. Error
bars indicate one standard error.
1998 Otsego Lake Biomass: M. spicatum
N--
60
.§
50
0)
---
40
E
co
30
.0
20
U)
U)
III
e::
co
10
~
o
<D
I
Rat Cove South Marina NN Corner Hyde Cove
(quadrant 3)
Sample Site
Figure 6. Abundance of M. spicatum, measured as dry weight g/m 2 , for 1998 in Otsego Lake,
New York. Biomass is the mean of twenty O.25m 2 samples for each ofthe four sites. Error bars
indicate one standard error.
88
1998 Otsego Lake Biomass: E. canadensis
--.
N
E
0>
'-'"
(J)
(J)
60
50
40
co
E 30
.0
(0
20
c
co
a>
10
~
o
Rat Cove South Marina twV Corner
(quadrant 3)
Hyde Cove
Sample Site
Figure 7. Abundance of E. canadensis, measured as dry weight g/m2, for 1998 in Otsego Lake,
New York. Biomass is the mean of twenty O.25m2 samples for each of the four sites. Error bars
indicate one standard error.
M. spicatum Stem Density
--.
N
-
E 120.
(J)
E
a>
......
(J)
'-'"
L..
a>
70­
I
.0
E
:::J
z
c
co
a>
~
20­
I
.
Rat Cove
(quadrant 3)
I
::E:
•
South Marina
•
•
twV Corner Hyde Cove
Sample Site
Figure 8. Mean number (± 1SE) of M spicatum stems per m2 in 1998 from four Otsego
Lake, New York sites. Note that quadrats analyzed for stem numbers were n=10 for Rat Cove,
and n=20 for South Marina, NW Comer, and Hyde Cove. Table one. Submersed aquatic plants
identified by 1998 biomass survey of Otsego Lake, NY.
89
Table 1. Submersed aquatic plants identified by 1998 biomass survey of Otsego Lake, NY.
Scientific name
Common name
lvfegalodonta beckii
Ceratophyllum demersum
Chara vulgaris
Elodea canadensis
Heteranthera dubia
l\1yriophyllum spicatum
Nitella spp.
Potamogeton amplifolius
Potamogeton crispus
Potamogeton pectinatus
Potamogeton pusillus
Potamogeton zosteriformis
Vallisneria americana
Water Marigold
Coontail
Muskgrass
Elodea, Canadian waterweed
Water stargrass
Eurasian watennilfoil
Stonewort
Large-IeafPondweed
Curlyleaf pondweed
Sago pondweed
Slender pondweed
Flat-stemmed pondweed
Eelgrass, Wild celery
Table 2. Summary of July 2, 1998 Eurasian watennilfoil apical meristem herbivore survey in
Otsego Lake, New York.
A.
A.
A.
A.
E.
E.
E.
E.
Location:
# of apical meristems:
ephemerella Larvae
ephemerella Pupae
ephemerella Adults
ephemerella Eggs
Total
AcentriaJapical meristem
lecontei Larvae
lecontei Pupae
lecontei Adults
lecontei Eggs.
Total
Euhrychiopsislapical meristem
Locations:
A - Rat Cove (quadrant 2
B - South Marina
C-NWComer
D - Hyde Cove
A
25
4
2
B
25
6
0.24
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
TOTAL
100
13
2
C
25
4
D
25
5
a
a
a
a
a
a
4
0.16
5
0.2
15
mean=0.15
a
a
a
a
a
a
a
1
3
4
0.16
1
6
7
mean=0.07
3
3
0.12
a
a
90
Table 3. Summary of August 11, 1998 Eurasian watennilfoil apical meristem herbivore survey
in Otsego Lake, New Yark.
TOTAL
B
C
D
Location:
A
25
25
25
100
# of apical meristems:
25
1
A. ephemerella Larvae
1
3
1
0
1
2
3
A. ephemerella Pupae
0
0
0
0
A. ephemerella Adults
0
0
0
0
0
0
A. ephemerella Eggs
0
0
1
2
6
3
Total
0
mean=0.06
0.04
0.08
0.12
Acentria/apical meristem
0
E.
E.
E.
E.
lecontei Larvae
lecontei Pupae
lecontei Adults
lecontei Eggs
Total
Euhrychiopsis/apical meristem
Locations: A - Rat Cove (quadrant 3)
B, C, D - Same as Table 1
4
2
1
2
9
0.36
1
0
0
0
1
0.04
7
0
1
10
18
0.72
1
0
0
0
1
0.04
13
2
2
12
29
mean=0.29
Table 4. Summary of August 11, 1999 Eurasian watennilfoil apical meristem herbivore survey
in Otsego Lake, New York.
TOTAL
Location:
B
C
E
D
A
# of apical meristems:
25
25
25
25
12~
25
A. ephemerella Larvae
5
10
7
35
6
7
A. ephemerella Pupae
2
2
11
7
0
0
(
A. ephemerella Adults
0
0
0
0
0
A. ephemerella Eggs
0
0
0
0
0
0
Total
17
7
7
8
7
4f
Acentria/apical meristem
0.28
0.32
0.28 mean=0.37
0.28
0.68
E.
E.
E.
E.
lecontei Larvae
lecontei Pupae
lecontei Adults
lecontei Eggs
Total
Euhrychiopsis/apical meristem
Locations:
A - Rat Cove (quadrant 3)
B - South Marina
C - NWComer
D - Hyde Cove
E - Rat Cove (quadrant 1)
2
1
0
2
5
0.2
0
0
0
0
0
0
1
0
0
0
1
0.04
1
1
0
0
2
0.08
0
0
0
0
0
0
l
2
0
~
"­
10
mean=0.06
91
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Brady, P., and S. Lamb. 1977. Changes in the aquatic flora of Otsego Lake between 1935 and
1976. In 9 th Ann. Rept., 1976. pp. 57-59. SUNY Oneonta Bio. Fld. Sta., SUNY Oneonta.
Creed, R.P., Jr. and S.P. Sheldon. 1994. The effect of two herbivorous insect larvae on
Eurasian watermilfoiI. 1 Aquat. Plant Manage. 32: 21-26.
Dayton, B.R., and D.R. Swift. 1987. Composition of aquatic macrophyte communities in
Otsego Lake: a preliminary study. In 19th Ann. Rept., 1986. pp. 68-78. SUNY Oneonta
Bio. Fld. Sta., SUNY Oneonta.
Fagnani, lP., and W.N. Harman. 1987. The Chironomidae of Otsego Lake with keys to the
immature stages of the subfamilies Tanypodinae and Diamesinae (Diptera). Occas. Pap.
No. 20. SUNY Oneonta Bio. Fld. Sta., SUNY Oneonta.
Harman, W.N., L.P. Sohacki, M.F. Albright, and D.L. Rosen. 1997. The state of Otsego Lake
1936-1996. Occas. Pap. No. 30. SUNY Oneonta Bio. Fld. Sta., SUNY Oneonta.
Harman, W.N. 1994. A comparison of the Otsego Lake macrobenthos communities between
1935 and 1993. In 26 th Ann. Rept., 1993. pp. 131-158. SUNY Oneonta Bio. Fld. Sta.,
SUNY Oneonta.
Harman, W.N., and T.R. Doane. 1970. Changes in the aquatic flora of Otsego Lake, New York,
between 1935 and 1969. N.Y. Fish Game 1 17: 121-123.
Johnson, R.L., PJ. Van Dusen, J.A. Toner, and N.G. Hairston, Jr. In press. Eurasian
watermilfoil biomass associated with insect herbivores in New York. 1 Aquat. Plant
Manage.
Johnson, R.L, E.M. Gross, and N.G. Hairston, Jr. 1998. Decline of the invasive submersed
macrophyte Myriophyllum spicatum (Haloragaceae) associated with herbivory by larvae
of Acentria ephemerella (Lepidoptera). Aquat. Ecol. 31: 273-282.
MacRae, LV., N.N. Winchester, and R.A. Ring. 1990. Feeding activity and host preference of
the milfoil midge Cricotopus myriophylli Oliver (Diptera: Chronomidae). J. Aquat. Plant
Manage. 28: 89-92.
Merrifield, M.l and W.N. Harman. 1987. The taxonomy, distribution and abundance of
Myriophyllum spicatum (Myrtiflorae: Haloragacea) in Otsego Lake, NY. pp 103-116. Ill..­
th
20 Ann. Rept. (1987). SUNY Oneonta BioI. Fld. Sta., SUNY Oneonta.
Miner, M. 1997. An inventory of meroplankton associated with Myriophyllum spicatum,
focusing on Acentria ephemerella, in Otsego Lake, summer 1997. In 30 th Ann. Rept.
1997. pp. 80-102. SUNY Oneonta Bio. Fld. Sta., SUNY Oneonta.
92
Muenscher, W.e. 1936. Aquatic vegetation of the Susquehanna and Delaware areas. In A
biological survey of the Delaware and Susquehanna watersheds. pp. 205-221. N.Y. State
Dep. Environ. Conserv., Albany.
Oliver, D.R. 1984. Description of a new species of Cricotopus van del' Wulp (Diptera:
Chironomidae) associated with Myriophyllum spicatum. Can. Ent. 116: 1287-1292.
Painter, D.S. and KJ. McCabe. 1988. Investigation into the disappearance of Eurasian
watermilfoil from the Kawartha Lakes, Canada. 1. Aquat. Plant Manage. 26: 3-12.
Sheldon, S.P. and R.P. Creed, Jr. 1995. Use ofa native insect as a biological for an introduced
weed. Ecol. Appl. 5: 1122-1132.
Appendix 1A. August 11, 1998 biomass data collected in Rat Cove (quadrant 3). Each dry
weight (g) represents the species composition in one 0 .25m2 quadrat frame. We collected
biomass from twenty quadrat frames.
Site Species
A Chara vulgaris
A Elodea canadensis
A Heteranthera dubia
A Myriophyllum spicatum
A Potomogeton amplifolius
A Potomogeton pectinatus
A Potomogeton zosteriformis
A Vallisneria americana
Total
A Chara vulgaris
A Elodeacanadensis
A Heteranthera dubia
A Myriophyllum spicatum
A Potomogeton amplifolius
A Potomogeton pectinatus
A Potomogeton zosteriformis
A Vallisneria americana
Total
A Chara vulgaris
A Elodeacanadensis
DW98-1
DW98-2
DW98-3
DW98-4
DW98-5
DW98-6
DW98-7
DW98-8
0
2.33
0
18.79
0
0
0
0
21.12
0
6.85
0.1408
16.72
0
0
0
0
23.71
0
5.73
0
0.2552
0
0
1.98
0
7.97
5.64
22.12
0
1.88
0
0.0368
0.002
0
29.68
0.89
0.61
0
19.66
0
0
0
0
21.16
0.68
13.51
0.0164
1.93
0
0
0.5862
0.1739
16.90
0
1.44
0.0438
26.42
0
0
0.002
0
27.91
2.15
33.13
0
0.94
0
0
1.26
0
37.48
DW98-9 DW98-10 DW98-11 DW98-12 DW98-13 DW98-14 DW98-15 DW98-IE
9.64
0
0.6174
0.0542
0
0
0.0177
0
13.46
5.42
15.56
4.48
3.97
8.35
1.68
10.69
0
0
0.0713
0.0271
0
0.3372
1.52
0
31.54
7.37
17.84
19.38
12.01
36.16
1.26
19.52
0
0
0
0
0
0.79
0
0
0
2.15
0
0
0
0.0038
0
0
0
0
0
3.08
0
1.18
0
0
0
0
0
0
0
0
0
0
45.00
38.18
19.22
21.86
7.86
27.95
30.11
38.00
DW98-17 DW98-18 DW98-19 DW98-20 tot98DW %98DW
0.0252
19.94
3.50
0
0.2245
0
45.20
8.32
53.46
257.45
13.12
33.22
g/.25m2
0.997
12.873
g DW/m2
3.988
51.490
93
A Heteranthera dubia
A Myriophyllum spicatum
A Potomogeton amplifolius
A Potomogeton pectinatus
A Potomogeton zosteriforrnis
A Vallisneria americana
Total
0
25.47
0
0.002
3.78
0
0
10.01
0
0
0
0.1245
0
0
0
33.82
0
17.03
0
0
43.45
0
7.73
2.16
278.67
0.38
48.92
0
0
0.002
0.79
2.19
8.22
0.17
569.58
0.14
0.38
1.44
0
61.19
0.03
100.00
0.108
13.933
0.040
0.432
55.733
0.158
0.110
0.411
0.009
28.479
0.438
1.643
0.035
113.917
Appendix 1B. August 11, 1998 biomass data collected in the South Marina. Each dry weight
(g) represents the species composition in one O.25m2 quadrat frame. We collected biomass
from twenty quadrat frames.
Site Species
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
Ceratophyllum demersum
Chara vulgaris
Elodea canadensis
Heteranthera dubia
Myriophyllum spicatum
Nitella spp.
Potomogeton pectinatus
Potomogeton pusillus
Potomogeton zosteriforrnis
Vallisneria americana
Total
Ceratophyllum demersum
Chara vulgaris
Elodea canadensis
Heteranthera dubia
Myriophyllum spicatum
Nitella spp.
Potomogeton pectinatus
Potomogeton pusillus
Potomogeton zosteriforrnis
Vallisneria americana
Total
B Ceratophyllum demersum
DW98-1 DW98-2 DW98-3 DW98-4 DW98-5 DW98-6 DW98-7 DW98-8
0
0.0638
6.81
0.0623
0.77
0
0
0.1248
0
0
7.83
0
3.05
10.43
0
1.36
0.6922
0
0.01
0.3674
0
15.91
0
3.48
7.49
0
0.7266
0
0
0
0
0
11.70
0
0.0874
33.59
1.48
2.03
0.0938
0.3677
0
0
0
37.65
0
0.0342
0
0
0
0
0
0
0
0
0.03
DW98-9 DW98-1O DW98-11 DW98-12 DW98-13
0.02
0
0.0095
0.0292
0
1.38
8.61
0.2973
12.72
17.27
0.0859
15.15
11.91
28.98
3.49
8.53
0.2119
0.3968
0.1818
0.5553
o
0
0.2065
2.09
0.0213
0.5001
0.2496
0.3483
0.1155
0.001
o
0
0
0.0886
0
0.1825
0.0273
O.oI
0.01
0
0.0236
0
1.58
0.0164
0
0.1128
0
0
0
0
26.72
17.02
23.07
31.81
16.79
0
0
0.0875
0
0.64
0
0
0.01
0
0
0.74
0
0.2269
0.0142
0.0828
0.0348
0.88
0
0.0049
0
0
1.24
0
0.4642
3.83
0
0.3891
0
0
10.21
0
0
14.89
DW98-14 DW98-15 DW98-16
0.012
0
0
0.2575
1.49
0
14.46
25.82
0.0228
0.0753
0.4783
0
1.06
1.1
0
0
1.73
0
0.0798
0
0
0
0
0
0
0
0
0.0799
0
0
16.02
30.62
0.02
DW98-17 DW98-18 DW98-19 DW98-20 tot98DW %98DW g/.25m2 g DW/m2
o
0
0
0.4356
0.51
0.13
0.025
0.101
94
B Chara vulgaris
B Elodea canadensis
B Heteranthera dubia
B Myriophyllum spicatum
B Nitella spp.
B Potomogeton pectinatus
B Potomogeton pusillus
B Potomogeton zosteriformis
B Vallisneria americana
Total
1.31
20.59
0
1.22
0.001
3.38
0.2605
0
0
/26.76
0.2148
26.29
0
0.2023
0.002
0.0693
0.1117
0
0
26.89
0.88
28.19
0.1719
0.5461
0.002
0.0093
0.0377
0.78
0
30.62
1.19
34.92
0.4475
2.18
0
1.38
0.0185
0
0
40.57
53.03
272.16
12.67
14.58
4.62
5.37
11.02
2.77
0.19
376.91
14.07
72.21
3.36
3.87
1.22
1.43
2.92
0.73
0.05
100.00
2.651
13.608
0.634
0.729
0.231
0.269
0.551
0.138
O.OlO
18.85
10.605
54.432
2.535
2.915
0.923
1.075
2.204
0.553
0.039
75.38
Appendix 1C. August 11, 1998 biomass data collected in the NW Comer. Each dry weight (g)
represents the species composition in one a.25m 2 quadrat frame. We collected biomass from
twenty quadrat frames.
Site Species
C
C
C
C
C
C
C
C
C
C
C
C
Bidens beckii
Ceratophyllum demersum
Chara vulgaris
Elodea canadensis
Heteranthera dubia
Myriophyllum spicatum
Nitella spp.
Potomogeton crispus
Potomogeton pectinatus
Potomogeton pusillus
Potomogeton zosteriformis
Valisneria americana
C
C
C
C
C
C
C
C
C
C
C
C
Bidens beckii
Ceratophyllum demersum
Chara vulgaris
Elodea canadensis
Heteranthera dubia
Myriophyllum spicatum
Nitella spp.
Potomogeton crispus
Potomogeton pectinatus
Potomogeton pusillus
Potomogeton zosteriformis
Valisneria americana
Total
C Bidens beckii
DW98-1
DW98-2
o
o
DW98-3
DW98-4
DW98-5
DW98-6
DW98-7
DW98-8
0
0
0
0
0
0.0627
0
0
0
0
0.0858
0
0
0
0.9373
0
0
0.0009
4.86
0.96
0.0257
1.13
0.3242
0.0956
0.3194
5.52
0.1789
0.0862
0.2097
0.88
o
0
0
0.0015
2.12
0.3573
0.0277
2.13
2.5
4.32
3.00
0.2954
15.13
12.53
9.32
1.64
o
0
0
0
0
0
0
0
o
0
0
0
0
0
0
0
o
0
0
0
0
0
0
0
o
0
0.4515
0.2121
0.5054
0
0.4257
0.0515
o
0
0
0.0015
0
0
0
0.lO45
o
0
0
0
0
0
0
0
DW98-9 DW98-lO DW98-11 DW98-12 DW98-13 DW98-14 DW98-15 DW98-16
o
0
0
1.96
0
0.0539
0
0.0177
o
0
0
0
0
0.0797
0.0182
0.0182
29.53
12.63
3.04
78.72
0.0346
31.27
41.83
21.62
1.19
0.0185
0
7.55
9.83
11.15
8.48
3.04
0.002
0.002
7.06
0.0637
0.0483
0.68
0.0445
0.4938
2.04
5.46
1.75
6.53
6.91
0.75
3.23
11.75
o
0
0
0.1241
0.2789
0.3876
2.58
0.4398
o
0
0
a 0.0615
0
0.0186
0
o
0
0
0.0715
0
0
0
0
0.0292
0.1444
0.002
0.0465
0.0128
0.1249
0.0483
0
o
0
0
0.002
0.002
0.1938
1.52
0.0394
o
0
0
0
0
0.1838
0
0
32.79
18.25
11.85
93.11
17.18
44.64
57.77
37.40
DW98-17 DW98-18 DW98-19 DW98-20 tot98DW %98DW
g/.25m2 g DW/m2
1.01
0.05
0.5235
0
3.68
0.59
0.184
0.736
95
C
C
C
C
C
C
C
C
Ceratophyllum demersum
Chara vulgaris
Elodea canadensis
Heteranthera dubia
Myriophyllum spicatum
Nitella spp.
Potomogeton crispus
Potomogeton pectinatus
C Potomogeton pusillus
C Potomogeton zosteriformis
C Valisneria americana
Total
o
73.16
7.32
1.00
36.22
20.84
o
o
1.32
2.48
10.79
0.3486
0.05
0.05
0.1575
o
0.0305
o
o
o
0.0575
1.18
o
o
82.31
0.0927
8.48
10.04
0.3874
5.96
2.72
72.70
0.0222
0.7007
0.0271
28.40
o
24.75
15.95
0.2698
0.81
16.24
o
0.3588
0.01
o
0.8017
58.39
1.29
369.20
103.02
13.69
97.73
33.91
0.13
0.64
2.12
0.21
59.02
16.47
2.19
3.80
1.01
625.52
0.61
0.16
100.00
15.62
5.42
0.02
0.10
0.34
0.065
18.460
5.151
0.684
4.886
1.695
0.007
0.032
0.106
0.190
0.051
31.28
0.259
73.840
20.605
2.738
19.545
6.782
0.026
0.128
0.423
0.760
0.203
125.10
Appendix 1D. August 11, 1998 biomass data collected in Hyde Cove. Each dry weight (g)
represents the species composition in one a.25m 2 quadrat frame. We collected biomass from
twenty quadrat frames.
Site Species
D
D
D
D
D
D
Ceratophyllum demersum
Elodea canadensis
Heteranthera dubia
Myriophyllum spicatum
Potomogeton pectinatus
Potomogeton zosteriformis
Total
D
D
D
D
D
D
Ceratophyllum demersum
Elodea canadensis
Heteranthera dubia
Myriophyllum spicatum
Potomogeton pectinatus
Potomogeton zosteriformis
Total
D
D
D
D
D
D
Ceratophyllum demersum
Elodea canadensis
Heteranthera dubia
Myriophyllum spicatum
Potomogeton pectinatus
Potomogeton zosteriformis
Total
DW98-1
DW98-2
DW98-3
DW98-4
DW98-5
DW98-6
DW98-7
DW98-8
3.23
1.52
2.15
5.15
0.4137
1.08
o
4.36
0.1954
4.27
10.27
3.38
24.93
2.37
1.06
o
o
o
o
o
o
o
o
o
30.72
0.0703
0.0002
0.65
3.02
5.57
13.56
25.82
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
35.47
7.37
1.49
0.85
7.38
20.11
41.87
29.25
DW98-9 DW98-1O DW98-11 DW98-12 DW98-13 DW98-14 DW98-15 DW98-16
0.87
0.88
1.19
2.75
0.4097
1.97
3.05
20.42
0.1572
1.99
0.2794
0
2.19
0.7084
2.62
2.12
o
5.22
0
0
0
0
o
o
11.59
2.89
0.83
8.53
17.2
1.42
4.17
0
o
o
0.0231
0
0
0
0
0.1397
o
o
0
0.4245
0
0
o
o
25.30
12.63
16.80
17.61
6.00
7.93
3.81
3.96
DW98-17 DW98-18 DW98-19 DW98-20 tot98DW %98DW
61.69
1.68
2.13
3.22
2.95
20.21
6.95
14.52
8.22
0.2409
84.20
27.58
0
0.68
0
5.90
1.93
0
0.0324
3.93
4.87
18.02
152.89
50.08
0
0
0.16
0.05
0
0
0
0.14
0
0
0.42
0
100.00
8.66
20.58
16.99
21.21
305.27
g/.25m2
3.085
4.210
0.295
7.645
0.008
0.021
15.26
gDW/m2
12.339
16.840
1.180
30.579
0.033
0.085
61.05