Distribution and Biomass of Macrophytes

and Metaphyton Associated with Streams Project Goals:•Characterize changes in macrophyte biomass and bed standing crops associated with control and experimental watersheds.

•Determine the relationship between nutrient loading, biomass and standing crop.

•Monitor changes in percent cover of metaphyton

Summer 2002 Participants Isidro Bosch Elizabeth Mis Tom Balzer Eric Caruana Dept. of Biology SUNY Geneseo

The perimeter of Conesus Lake is covered by a narrow but dense band of vegetation consisting primarily of aquatic vascular plants. In some shallow areas, the plants form expansive beds that cover most of the bottom and form thick mats at the water’s surface.

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Depth

(m

) Sago PondweedWild CeleryWater Stargrass

Eel-GrassSago PondweedEurasian Milfoil

Eurasian MilfoilCurly-Leaf PondweedWild CeleryCommon Waterweed

Coontail

Curly-leaf Pondweed

Distance From Shore (m)

Qualitative transects taken from the shoreline to the outer edge (4 m) of these beds revealed that the dominant species in this zone is the invasive “weed” known as Eurasian milfoil (Myriophyllum spicatum) . This milfoil is especially dominant at depths of 1-3 m

Vallisneria

HeterantheraMyriophyllum

Elodea

Ceratophyllum Vallisneria

Heteranthera

Myriophyllum

Elodea

Ceratophyllum

Sand Point 1968

MyriophyllumCoontail

Sago PondweedMyriophyllum

Coontail

Sago Pondweed

Sand Point 2000

15%36%

20%17%

13%

32%

67%

1%

These pie charts provide a comparison of species diversity in 1968 and 2000 at the very same site. In ‘00 the bed is dominated by milfoil. In ‘68 a variety of different species are well represented.

From H. Forest

Sand Point 1968

Sand Point 2000

Eagle Point

Long Point

Old Orchard Point

McPherson Point

Sand Point

During each of the last three years we have mapped the position of milfoil beds (I.e. > 75% milfoil) in Conesus Lake (beds are shown in green for the central part of the lake) using GPS technology. The surface area measurements we obtain by GPS are multiplied by biomass quadrat measures to estimate the standing crops of milfoil at each site.

Six of the beds we monitor, including ones at Sand Point and Long Point on this map,

are part of our USDA watershed manipulation

study

Summary data for six Eurasian watermilfoil beds in Conesus Lake . Cottonwood Gully, Sand Point gully and Graywood are three of the experimental sites. The other sites serve as controls (no BMPs).

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2001 Macrophyte Dry Weights (g . m-2)

R2 = 0.04 p = 0.26 Each point is an

average of 3 quadrats taken at depths of

2 and 3 m. The points

represent a total of six

beds

In 2002 we went back to the very same sites we sampled in 2001. There was no consistent relationship between the ‘01 and ‘02 biomass. The red line describes the points at which ‘01 and ‘02 values would be equal. This graph shows that in 26 of 32 sites, macrophyte biomass was lower for ‘02.

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Loading Total Phosphorus (Kg) August '02 to Jan '03

Linear FunctionR2 = 0.87 p = 0.068

Conesus Lake, Summer 2002

Power FunctionR2 = 0.93p = 0.035

We used stream loading data collected by Joe Makarewicz and co-workers to explore the relationship between loading of phosphorus and plant biomass. In 2002, total P was an excellent predictor of standing crop in milfoil beds

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Loading Soluble Reactive Phosphorus (Kg) August '02 to Jan '03

Linear FunctionR2 = 0.95 p = 0.026

Conesus Lake, Summer 2002

Power FunctionR2 = 0.99p = 0.01

The Loading of soluble reactive phosphorus by streams was an even better predictor of the standing crop of milfoil beds in areas near the mouths of streams.

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Sutton Point

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1015202530

Long Point Cove

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10Cottonwood Gully

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1015202530

McPhersons Point

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10Sand Point Gully

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101520253035 Graywood Gully

ND ND

ND ND

ND ND

Biomass Surface Area Standing Crop

2000 2001 2002 2000 2001 2002 2000 2001 2002

Over the next few years of our project, we will continue monitoring

changes in milfoil biomass and standing

crop near the mouths of our experimental and

control streams to determine the efficacy of farm management practices in reducing macrophyte growth

Subwatershed Rank

P Average StandingLocation Loading Biomass CropSutton Point 2000 6 6 ---

2001 5 2 52002 5 6 6

Cottonwood Gully 2000 5 5 ---2001 6 5 52002 4 2 3

McPherson's Point 2000 1 1 ---2001 2 3 22002 ND 5 4

Long Point Cove 2000 2 2 ---2001 4 6 32002 1 3 1

Sand Point Gully 2000 3 4 ---2001 3 1 42002 2 1 2

Graywood Gully 2000 4 3 ---2001 1 4 12002 3 4 5

Another way to consider these trends is to examine changes in the relative rank of the beds with respect to loading, biomass and standing crop. We see some interesting trends in the data, but there are shifts in rank from one year to the next that are not clearly related to loading.

Excessive growth of metaphyton (filamentous algae) on or around milfoil beds is another serious problem near streams in Conesus Lake.

In the summer 2002 we started to monitor metaphyton biomass (as % cover) near streams using a quadrat sampler

Area near stream dominated by the metaphyton species Zygnema and Spirogyra which grow on Eurasian milfoil

8/02 to 1/03 meters

TP SRP from Depth

Location (Kg) (Kg) stream 1 m 2 m 3 m

Long Point Cove 17.66 13.00 0 24.4 + 13.1 16.0 + 25.0 0100 N 45.5 + 21.9 60.0 + 11.5 7.5+ 15.5157 N 4.9 + 11.0 17.0 + 27.8 0

Sand Point Gully 10.21 2.49 5 N ND ND ND

73 N ND ND ND

137 N ND ND ND

Graywood Gully 3.47 2.72 0 ND 68.5 + 30.8 ND

25 S 78.0 + 22.3 70.2 + 36.0 13.0 + 15.0100 N 46.7 + 26.6 10.5 + 17.1 13.0 + 15.1

Cottonwood Gully 2.95 1.73 0 12.4 + 20.2 0.5 + 1.6 0 N 6.3 + 6.0 1.4 + 2.2 0

N 3.5 + 8.8 ND ND

North Sutton Point 0.25 0.04 0 0 0 050 S 0 0 050 N 0 0 0

McPhersons Point ND ND 10 S 33.0 + 19.5 58.6 + 28.6 0.3 + 0.978 S 17.3 + 20.6 27.4 + 29.8 10.0 + 13.0156 S 44.5 + 27.4 66.5 + 19.6 31.2 + 29.6

The biomass of metaphyton (as indicated by % cover at the water’s surface) is extremely high in some of our experimental sites (see for example Graywood Gully).

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Graywood Gully

McPhersons Point

Long Point Cove

Cottonwood Gully

Sutton Point

S.D = 36

S.D = 31 S.D = 26

S.D = 12Not Measurable

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ANOVA p < 0.0001Tukey's HSD Post Hoc

TP = 3.47SRP = 2.72

TP = 2.95SRP = 1.73

TP = 0.25SRP = 0.04

TP = 18SRP = 13

The sites fall into three statistically distinct groups in terms of percent cover. There is a good correspondence between cover and phosphorus loading by nearby streams.

Conclusions: The summer 2001 and 2002 data represent the

baseline we will use to examine the future effectiveness of agricultural best management practices in reducing the excessive growth of plants near the mouths of streams in Conesus Lake.

We predict that changes in metaphyton biomass will be evident within months after the reduction of nutrient loading through BMPs is achieved.

Eurasian watermilfoil beds may take longer to respond, but the observed close relationship between phosphorus loading and standing crop provides some hope that macrophyte growth can also be managed.