Macrophyte Communities of Owasco Lake

Bin ZhuFinger Lakes Institute601 South Main StreetGeneva, New York 14456

Bruce GilmanFinger Lakes Community College4355 Lakeshore DriveCanandaigua, New York 14424

Holistic Lake Management

• Environmental issues• Comprehensive study• Our team focus: research

questions– What macrophyte species are

present?– How productive are the macrophyte

communities?– What influences their productivity?

Sampling Design

• Shallow lake areas– northern shoals– southern shoals– eastern and western

shorelines

• Repetitive sampling in June, July, August

• In situ data• Substrate collection

and analyses

Methods – Lake Sampling

• Submerged ½ m2 quardats

• SCUBA diving or snorkeling

• Collection of aquatic plants in mesh bags

• Sample rinse• Water depth

measurement

Methods – Laboratory Work Sorting by species

Air drying in college greenhouse

Methods – Laboratory Work

Standing crop biomass reported in g/m2

Results

• 18 different macrophyte species– 16 vascular plants, 1 moss, 1 macro-algae

• 2 species are considered invasive: curly leaf pondweed and Eurasian milfoil

• Our data represent significant additions to historic records for Owasco Lake

• First record for a NYS rare plant, the spotted pondweed (Potamogeton pulcher)

Spotted Pondweed

Potamogeton pulcher

0.30 to 5.20 meters

Water Depths

Frequency of Occurrence(based on 93 samples)

Elodea EelgrassLeafy Pondweed

Eurasian Water Milfoil

80.6% 72.0% 64.5% 55.9%

Frequency of Occurrence(based on 93 samples)

Water StargrassCurly leafPondweed

CoontailStonewort

54.8% 50.5% 47.3% 31.2%

Frequency of Occurrence(based on 93 samples)

Flat-stemPondweed

Slender Naiad Small PondweedWater Buttercup

24.7% 15.1% 12.9% 9.7%

Sample Richness

June

July

August

east/west

2 – 8 species, mean = 5.11

2 – 9 species, mean = 5.81

1 – 9 species, mean = 5.37

(3 – 11 species, mean = 6.58)

Biomass Measured(based on 93 samples)

Stonewort – 40.3%

Elodea – 27.1%

Eurasian Water Milfoil – 8.7%

Eelgrass – 6.1%

Leafy Pondweed – 5.7%

Curly leaf Pondweed – 2.5%

Water Stargrass – 1.8%

Standing Crop Biomass

June

July

August

2 – 1263 g/m2, mean = 225 g/m2

50 – 1031 g/m2, mean = 389 g/m2

4 – 1143 g/m2, mean = 390 g/m2

Annual Productivity Estimate

59 – 1332 g/m2, mean = 625 g/m2

Amazing amounts!

Regression Analyses(Productivity and Environment)

r2 = .01

r2 = .09

r2 = .28

r2 = .04

r2 = .04

r2 = .00

Depth

Substrate phosphorus

Substrate organic matter

Substrate % sand

Substrate % silt

Substrate % clay

Questions?Answers?