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

0.30 to 5.20 meters Water Depths

Frequency of Occurrence (based on 93 samples) ElodeaEelgrassLeafy Pondweed Eurasian Water Milfoil 80.6%72.0%64.5%55.9%

Frequency of Occurrence (based on 93 samples) Water StargrassCurly leaf Pondweed CoontailStonewort 54.8%50.5%47.3%31.2%

Frequency of Occurrence (based on 93 samples) Flat-stem Pondweed Slender NaiadSmall PondweedWater Buttercup 24.7%15.1%12.9%9.7%

Sample Richness June July August east/west 2 – 8 species, mean = – 9 species, mean = – 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/m 2, mean = 225 g/m 2 50 – 1031 g/m 2, mean = 389 g/m 2 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) r 2 =.01 r 2 =.09 r 2 =.28 r 2 =.04 r 2 =.00 Depth Substrate phosphorus Substrate organic matter Substrate % sand Substrate % silt Substrate % clay

Questions? Answers?