Effectiveness of Aquatic Invasive Plant Control In Emerald Bay, Lake - - PowerPoint PPT Presentation

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Aug 30, 2023 239 likes •463 views

Effectiveness of Aquatic Invasive Plant Control In Emerald Bay, Lake Tahoe Dan Shaw CA State Parks Zach Hymanson CA Tahoe Conservancy Kim Boyd Tahoe RCD Tamara Sasaki CA State Parks 1995 2000 13 milfoil sites Milfoil filled in

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Effectiveness of Aquatic Invasive Plant Control In Emerald Bay, Lake Tahoe

Dan Shaw – CA State Parks Zach Hymanson – CA Tahoe Conservancy Kim Boyd – Tahoe RCD Tamara Sasaki – CA State Parks

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1995 13 milfoil sites many of which were small and sparse 2003

P. crispus

Curly-leaf Pondweed Detected- Roughly 1 sparse acre 2000 Milfoil filled in south shore and spread along west shore and for 4 miles down Truckee River 2006 14 curly-leaf sites milfoil spreading rapidly in Emerald Bay Slide Credit: Lars Anderson

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Eurasian watermilfoil (Myriophyllum spicatum)

Photo: Zach Hymanson

1995 – First Discovered in Emerald Bay 2000 – Few Plants 2003 – Approximately 1 Acre 2010 – Well over 3 Acres of Milfoil

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Photo :Doug Freeland A.C.E

Emerald Bay milfoil infestation

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Floating fragments colonize unvegetated substrate

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Challenges to working in Emerald Bay

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Recreation

Project Area

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Avalanche Vikingsholm Parson’s Rock Approximate infestation area boundaries

100 meters

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Underwater transects to measure treatment effectiveness

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Benthic Barriers

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Photo: Jim Brockett

Swimming Barriers into place

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Photo: Jim Brockett

Barriers don’t work in hard to reach places, but suction removal does

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Laying out 10X40 Barriers for Installation

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Milfoil Sandy Bottom After Barrier Removal

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10 20 30 40 50 60 70 No Barrier After Barrier No Data

Fall 08 Spring 09 Fall 09 Spring 10 Fall 10

Mean No. of Shoots per 0.25m2

EWM Densities at Parsons Rock Site

Bottom barriers in place

Spring 08

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10 20 30 40 50 60 70 80 90 100 2008 2009 2010 2011 spr 2011 fall

Avalanche Vikingsholm Parson's Rock PERCENT COVER – EURASIAN WATERMILFOIL VIKINGSHOLM COMPREHENSIVE TREATMENT- PARSON’S LIMITED TREATMENT AVALANCHE NONE VIKINGSHOLM MAINTENANCE TREATMENT PARSON’S COMPREHENSIVE AVALANCHE LIMITED

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20 40 60 80 100 120 140 Avalanche Vikingsholm Parsons Rock

2008 2009 2010 2011

DENSITY – MEAN NO. PLANTS PER 0.25 M2

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Comprehensive treatment of all Invasive Aquatic Weeds in Emerald Bay is within our reach in 2012

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