Quantitative aquatic plant surveys were undertaken for Burr Pond and Lake Hortonia, Vermont, in September 2010 to obtain post-treatment data for treatments of Lake Hortonia in 2010 with the aquatic-labeled herbicide fluridone (SONARTM A/S). No treatment was conducted on Burr Pond in 2010. Aquatic plant surveys were designed to be comparable to earlier pre and post-treatment data collected by the US Army Corps of Engineers in 1999 & 2000 and by the author annually from 2003 thru 2009. The survey consisted of collection of: a) herbarium specimens throughout both lakes for compilation of species lists, b) frequency data for points distributed throughout the lakes, and c) line-intercept transect data for wetland communities in both lakes.
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In-lake Species Frequency. Species richness in both lakes was quite high, with a large number of species occurring in more than 5% of survey points (Table 1). In Lake Hortonia, the macroalga Chara/Nitella were the most common native species (64% of survey points). For Burr Pond, Vallisneria americana was the most common native species (32% survey points). Eurasian watermilfoil remained the most widely distributed plant in Burr Pond, increasing from 56% of survey points in 2009 to 72% of survey points in 2010 (Figures 1 & 3). In Lake Hortonia, Eurasian watermilfoil declined in frequency of occurrence from 54% of survey points in 2009 to 33% of survey points in 2010 (Figures 2 & 4). A number of native species were commonly observed in both lakes. Common native species for Burr Pond included Chara sp. (25%), Lemna minor (17%), Utricularia minor (13%), Potamogeton natans (13%), Potamogeton robbinsii (11%), Potamogeton zosteriformis (11%), Potamogeton illinoensis (9%), Chara sp. (8%), Nuphar variegata (7%) and Potamogeton epihydrus (5%).
Wetlands Transects. Wetland communities differed from whole-lake littoral plant communities, although many individual species were represented in both (Tables 1 & 3). In the Burr Pond wetland, the most common species were Myriophyllum spicatum (96%), Nuphar variegata (34%), Ceratophyllum demersum (19%), Nymphaea odorata (16%), Lemna minor (13%), Potamogeton illinoensis (9%), and Vallisneria americana (7%). In the Lake Hortonia wetland, the most common species were Nymphaea odorata (65%), Utricularia vulgaris (33%), Myriophyllum sibiricum (31%), Myriophyllum spicatum (30%), Ceratophyllum demersum (25%), Utricularia gibba (21%), Najas flexilis (17%), Potamogeton illinoensis (17%), Elodea canadensis (13%), Nymphaea odorata (9%), and Potamogeton natans (6%). For Lake Hortonia, common native species included Potamogeton robbinsii (30%), P. illinoensis (24%), Vallisneria americana (22%), Elodea canadensis (15%), Utricularia vulgaris (11%), Utricularia gibba (6%), Zosterella dubia (6%), and Potamogeton zosteriformis (5%).
Table 1. Aquatic plant percent frequency for Burr Pond and Lake Hortonia, Vermont.
Species |
Burr Pond |
Lake Hortonia |
|
2006 |
2007 |
2008 |
2009 |
2010 |
2006 |
2007 |
2008 |
2009 |
2010 |
Brasenia schreberi |
|
|
|
|
|
|
|
|
|
1% |
Ceratophyllum demersum |
2% |
2% |
2% |
2% |
2% |
3% |
|
|
1% |
3% |
Chara sp. |
48% |
47% |
45% |
39% |
25% |
63% |
56% |
58% |
50% |
64% |
Eleocharis acicularis |
|
|
2% |
4% |
|
|
|
1% |
|
|
Elodea canadensis |
|
17% |
19% |
15% |
13% |
1% |
11% |
16% |
20% |
15% |
Megalodonta beckii |
|
|
|
|
|
1% |
|
|
|
|
Myriophyllum sibiricum |
|
|
|
|
|
|
2% |
2% |
1% |
3% |
Myriophyllum spicatum |
4% |
23% |
55% |
56% |
72% |
1% |
23% |
36% |
54% |
33% |
Najas flexilis |
17% |
34% |
19% |
24% |
17% |
12% |
23% |
31% |
23% |
1% |
Nuphar variegata |
4% |
2% |
9% |
7% |
2% |
1% |
1% |
1% |
1% |
2% |
Nymphaea odorata |
9% |
9% |
8% |
9% |
9% |
5% |
4% |
7% |
6% |
4% |
Potamogeton amplifolius |
|
|
|
|
2% |
|
|
|
2% |
2% |
Potamogeton crispus |
|
|
|
|
|
2% |
4% |
2% |
|
|
Potamogeton epihydrus |
2% |
|
|
|
|
|
|
1% |
|
|
Potamogeton gramineus |
2% |
13% |
9% |
2% |
|
|
2% |
4% |
|
|
Potamogeton illinoensis |
26% |
11% |
26% |
7% |
17% |
25% |
33% |
45% |
37% |
24% |
Potamogeton natans |
|
|
2% |
2% |
6% |
0.7% |
2% |
4% |
1% |
2% |
Potamogeton praelongus |
|
|
|
|
|
|
2% |
4% |
2% |
4% |
Potamogeton pusillus |
7% |
6% |
8% |
2% |
|
3% |
3% |
3% |
4% |
|
Potamogeton robbinsii |
7% |
8% |
6% |
4% |
2% |
23% |
22% |
22% |
20% |
30% |
Potamogeton zosteriformis |
4% |
15% |
6% |
4% |
|
3% |
8% |
7% |
5% |
5% |
Ranunculus longirostris |
|
|
2% |
|
2% |
|
|
1% |
|
|
Scirpus sp. |
2% |
|
2% |
2% |
2% |
1% |
|
|
|
|
Spagnum |
|
|
|
|
|
0.7% |
|
2% |
1% |
|
Stukenia pectinatus |
|
|
|
|
|
5.8% |
10% |
7% |
3% |
1% |
Typha sp. |
|
|
2% |
2% |
|
|
|
|
|
|
Utricularia gibba |
41% |
36% |
32% |
22% |
21% |
7.9% |
12% |
12% |
4% |
6% |
Utricularia minor |
|
|
|
7% |
|
|
2% |
1% |
10% |
|
Utricularia vulgaris |
4% |
2% |
|
2% |
|
7% |
3% |
4% |
9% |
11% |
Vallisneria americana |
30% |
26% |
28% |
28% |
32% |
22% |
32% |
34% |
31% |
22% |
Warnstorfia fluitans |
|
|
|
|
|
|
|
|
|
1% |
Zosterella dubia |
9% |
9% |
4% |
4% |
|
3% |
12% |
9% |
13% |
6% |
Figure 1. Burr Pond frequency of occurrence summaries.
Figure 2. Lake Hortonia frequency of occurrence summaries.
Table 2. Aquatic plant percent frequency by species for the wetland transects for Burr Pond and Lake Hortonia, Vermont.
|
Burr Pond |
Lake Hortonia |
Species |
2006 |
2007 |
2008 |
2009 |
2010 |
2006 |
2007 |
2008 |
2009 |
2010 |
|
|
|
|
|
|
|
|
|
|
|
Ceratophyllum demersum |
33% |
18% |
53% |
41% |
19% |
6% |
12% |
24% |
16% |
25% |
Chara sp. |
|
|
|
|
|
2% |
|
|
1% |
8% |
Eleocharis acicularis |
|
7% |
|
|
|
|
|
|
|
|
Elodea canadensis |
6% |
2% |
28% |
37% |
2% |
1% |
1% |
4% |
2% |
1% |
Lemna minor |
15% |
1% |
44% |
35% |
13% |
13% |
22% |
20% |
37% |
17% |
Lemna trisulca |
|
|
|
|
2% |
2% |
1% |
4% |
18% |
1% |
Myriophyllum sibiricum |
|
27% |
|
|
|
9% |
42% |
80% |
83% |
31% |
Myriophyllum spicatum |
35% |
39% |
76% |
96% |
96% |
|
|
8% |
13% |
30% |
Najas flexilis |
6% |
|
|
|
|
90% |
10% |
4% |
10% |
|
Nuphar variegata |
45% |
10% |
60% |
57% |
34% |
1% |
2% |
1% |
11% |
7% |
Nymphaea odorata |
23% |
80% |
23% |
20% |
16% |
53% |
94% |
64% |
66% |
65% |
Polygonum sp. |
3% |
|
|
|
1% |
|
|
|
|
|
Pontederia cordata |
|
|
|
|
|
|
1% |
|
1% |
1% |
Potamogeton crispus |
|
|
|
|
|
|
1% |
|
|
|
Potamogeton epihydrus |
|
3% |
|
|
|
6% |
2% |
4% |
5% |
5% |
Potamogeton gramineus |
|
1% |
|
|
|
|
|
|
|
|
Potamogeton illinoensis |
49% |
8% |
9% |
11% |
9% |
10% |
14% |
5% |
5% |
9% |
Potamogeton natans |
|
3% |
|
|
|
4% |
1% |
2% |
3% |
13% |
Potamogeton pusillus |
10% |
|
17% |
17% |
|
|
|
|
3% |
|
Potamogeton robbinsii |
|
7% |
1% |
|
|
|
|
2% |
|
11% |
Potamogeton zosteriformes |
|
|
1% |
|
|
4% |
2% |
7% |
12% |
11% |
Ranunculus longirostris |
13% |
|
1% |
5% |
2% |
|
|
|
|
3% |
Scirpus sp. |
|
7% |
|
|
|
|
|
|
1% |
|
Sparganium sp. |
1% |
1% |
1% |
3% |
2% |
|
1% |
|
|
1% |
Sphagnum sp. |
|
|
3% |
|
|
|
|
14% |
|
|
Typha sp. |
1% |
|
|
3% |
1% |
|
|
|
|
|
Utricularia gibba |
1% |
3% |
11% |
4% |
|
|
|
31% |
|
|
Utricularia intermedia |
|
1% |
|
|
|
|
|
|
|
|
Utricularia minor |
3% |
1% |
|
|
|
18% |
24% |
17% |
40% |
13% |
Utricularia vulgaris |
6% |
14% |
7% |
|
|
45% |
23% |
14% |
20% |
33% |
Vallisneria americana |
51% |
7% |
13% |
12% |
7% |
|
3% |
|
|
|
Zosterella dubia |
13% |
2% |
|
5% |
|
3% |
6% |
|
2% |
1% |
Figure 3. Distribution of Eurasian watermilfoil in Burr Pond in September 2010.
Figure 4. Distribution of Eurasian watermilfoil in Lake Hortonia in September 2010.
|
