Aquatic Plants of the Three Lakes

Transcription

1 Aquatic Plants of the Three Lakes Chris Doyle, CLM Senior Aquatic Biologist/Water Quality Program Supervisor Allied Biological, Inc. 580 Rockport Road Hackettstown, NJ Phone:

2 Rake Toss Methods Based on Point Intercept Methods Developed by Cornell University Standard Weed Anchor Used Two 13 wide metal rakes attached back to back 10 meter rope Two Rake Tosses per Site Sites GPS-referenced Midtech RX 400p GPS Receiver Smartpad II (Ver. 4.02) Data Logger Standard Plant Densities Used Submersed and floating plant densities separated All plants identified to species (if possible) All plants digitally photographed Voucher specimens collected to verify field identification Survey Conducted August 6 & 7, 2008 (~17 hours on the water) Dense Medium Sparse Trace

3 Factors Affecting the 2008 Survey Littoral Zone Usually defined as >15 feet Limited at the Three Lakes Restricted to shoreline zones, East and West ends of lakes, and shallow coves Rocks Restricted the retrieval of the weed anchors Two anchor tosses per site Methodology tends to result in increased occurrence, but a decrease in overall density Hand Pulling Alters aquatic plant assemblage Canal Sampling One anchor toss per site

4 The Aquatic Plants of the Three Lakes Aquatic Macrophyte Scientific Name Lake Waccabuc Lake Oscaleta Lake Rippowam Arrowhead (rosette) Sagittaria sp. X X Bass Weed Potamogeton amplifolius X X Benthic filamentous Algae X X X Brazilian Elodea Egeria densa X Brittle Naiad Najas minor X Common Waterweed Elodea canadensis X X Coontail Ceratophyllum demersum X X Creeping Bladderwort Utricularia gibba X X Curly-leaf Pondweed Potamogeton crispus X Dwarf Water Milfoil Myriophyllum tenellum X Eurasian Water Milfoil Myriophyllum spicatum X X X Flat-stem Pondweed Potamogeton zosteriformis X Floating Filamentous Algae X X Leafy Pondweed Potamogeton foliosus X X Ribbon-leaf Pondweed Potamogeton epihydrus X Robbins Pondweed Potamogeton robbinsii X X Spatterdock Nuphar variegata X X X Spiral-fruited Pondweed Potamogeton spirillus X Stonewort Nitella sp. X Water Stargrass Zosterella dubia X Watershield Brasenia schreberi X X Water-thread Pondweed Potamogeton diversifolius X White Water Lily Nymphaea odorata X X X

5 Eurasian water milfoil Myriophyllum spicatum Aggressive, exotic Most common aquatic plant found during 2008 survey Tolerates a wide range of substrate types Creates canopies at surface to shade out other plants Monoculture stands reduce aquatic biota diversity Reproduces via fragmentation (but seeds and roots, too)

6 Pondweeds Diverse group of aquatic plants Most are desirable natives Create excellent fish habitat, cover, and food sources Most are prolific seed producers Robbins Pondweed creates dense bottom cover Bass Weed (Potamogeton amplifolius) Robbins Pondweed (Potamogeton robbinsii)

7 Pondweeds (con t) Leafy Pondweed (P. foliosus) Fine leaves, low growing Often crowded out by invasives Ribbon-leaf Pondweed (P. epihydrus) Produces floating leaves Flat-stem Pondweed (P. zosteriformis) Easily confused with water stargrass Leafy Pondweed (P. foliosus) Ribbon-leaf Pondweed (P. epihydrus) Flat-stemPondweed (P. zosteriformis)

8 Pondweeds (con t) Curly-leaf Pondweed (P. crispus) Aggressive, exotic plant Native to Europe Early season grower Naturally dies back in June-July Produces pine cone-like turions Can overwinter under the ice Very common throughout New York

9 Waterweeds Brazilian Elodea (Egeria densa) Aggressive, Exotic Discovered in Lake Waccabuc Isolated in cove First documented infestation in Westchester county Likely the result of an aquarium dump (2-3 years ago?) 2009 Eradication Program 4 to 6 leaves in whorl Common Waterweed (Elodea canadensis) Desirable native, very common Questionable identification? 3 leaves in whorl

10 Coontail Ceratophyllum demersum Very common submersed plant in NY Lacks a true root system Can move around basin Can also be loosely anchored via modified leaves Desirable native species But can reach nuisance densities Coontail Pods used by pond managers as a nutrient sink Leaves arranged in a whorl (5-12) Typically stiff and calcified

11 Arrowhead Actually an emergent plant, found along the shoreline Submersed rosettes recovered during survey Difficult to determine species from rosette Excellent wildlife habitat and food source Stabilizes the shoreline and acts as a nutrient buffer

12 Dwarf water milfoil Myriophyllum tenellum Related to Eurasian water milfoil Uncommon in NY But often overlooked Slender, unbranched stems 2-15 cm tall Leaves reduced to scales Excellent sediment stabilizer Often creates a dense carpet on bottom Prefers shallow water with sandy substrate

13 Stonewort Nitella sp. Actually, a multi-branched algae Shares the ecological niche of other macrophytes Creeping Bladderwort Utricularia gibba Only bladderwort collected in 2008 Lacks true roots Bladders used to capture prey Protozoa, insect larvae

14 Water Lilies Leaves float on the surface Provide shade and cover Can reach nuisance density Reproduce via rhizomes Three species observed at the Three Lakes during 2008 survey White Water Lily (Nymphaea odorata) Round leaves with prominent notch; white flower Watershield (Brasenia schreberi) Underside and stem covered with gelatinous mucus; tiny purple flower Spatterdock (Nuphar variegata) Large oval leaves; also called yellow lily

15 Additional Aquatic Plants

16 Lake Oscaleta 2008 Aquatic Plant Distribution Aquatic Macrophyte Total Abundance Trace Abundance Sparse Abundance Medium Abundance Dense Abundance Sites % Sites % Sites % Sites % Sites % Total Sites 60 Total Submersed Vegetation 53 88% 20 38% 17 32% 11 21% 5 9% Eurasian water milfoil 40 67% 18 45% 10 25% 12 30% Bass weed 28 47% 19 68% 5 18% 4 14% Coontail 25 42% 13 52% 9 36% 3 12% Robbins Pondweed 19 32% 10 53% 7 37% 1 5% 1 5% Creeping Bladderwort 10 17% 9 90% 1 10% Arrowhead Rosette 8 13% 8 100% Common Waterweed 4 7% 3 75% 1 25% Ribbon-leaf Pondweed 3 5% 2 67% 1 33% Benthic Filamentous Algae 1 2% 1 100% Stonewort 1 2% 1 100% Leafy Pondweed 1 2% 1 100% Total Floating Vegetation 52 87% 15 29% 19 37% 10 19% 8 15% White Water Lily 41 68% 16 39% 10 24% 7 17% 8 20% Spatterdock 26 43% 13 50% 11 42% 2 8% Watershield 12 20% 9 75% 3 25%

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32 Lake Oscaleta: Bass Weed vs. Eurasian Watermilfoil Robust bass weed beds are limiting the Eurasian water milfoil distribution at the East and West Ends of Lake Oscaleta? (2003) What about in 2008?

33 Questions?