Macrophyte Communities of Owasco Lake Bruce Gilman Finger

Macrophyte Communities of Owasco Lake Bruce Gilman Finger Lakes Community College 4355 Lakeshore Drive Canandaigua, New York 14424 Bin Zhu Finger Lakes Institute 601 South Main Street Geneva, New York 14456

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 m 2 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/m 2

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

Water Depths 0. 30 to 5. 20 meters

Frequency of Occurrence (based on 93 samples) Elodea Eurasian Water Milfoil Leafy Pondweed Eelgrass 80. 6% 72. 0% 64. 5% 55. 9%

Frequency of Occurrence (based on 93 samples) Curly leaf Pondweed 54. 8% Stonewort Coontail Water Stargrass 50. 5% 47. 3% 31. 2%

Frequency of Occurrence (based on 93 samples) Slender Naiad 24. 7% Water Buttercup Small Pondweed 15. 1% 12. 9% Flat-stem Pondweed 9. 7%

Sample Richness June 2 – 8 species, mean = 5. 11 July 2 – 9 species, mean = 5. 81 August 1 – 9 species, mean = 5. 37 east/west (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 2 – 1263 g/m 2, mean = 225 g/m 2 July 50 – 1031 g/m 2, mean = 389 g/m 2 August 4 – 1143 g/m 2, mean = 390 g/m 2

Annual Productivity Estimate 59 – 1332 g/m 2, mean = 625 g/m 2 Amazing amounts!

Regression Analyses (Productivity and Environment) Depth Substrate phosphorus Substrate organic matter Substrate % sand Substrate % silt Substrate % clay r 2 =. 01 r 2 =. 09 r 2 =. 28 r 2 =. 04 r 2 =. 00

Questions? Answers?