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Projects Details

Executive Summary

Assessment of Biocontrol Agents in the Lower Columbia River Estuary: 2006-2008

The Goal of this project, funded by the Army Corps of Engineers, is to assess Biocontrol Agent populations at 15 release sites made in 2005 in the Columbia River Estuary (RM 18-52).











Release Sites

Results will be used to determine where future biocontrol agents releases will be made and will help to identify environmental factors that lead to successful establishment and control of the invading plant.

We have found adult Galerucella at 13 of the 15 USACE release sites during 2006 and 2007. This strongly suggests that these biocontrol agent populations are becoming established (organisms need to be recovered for three years before populations are considered to be established).



Table 1. Project elements by year.

Element 2006 2007 2008
I a: Estimate plant damage
X
X
X
b: Estimate presence/absence and population levels of biocontrol agents using adults, larvae and eggs
X
X
X
II a: Elevation
X
b: Distance to shrub/forest and high ground
X
X
c: Tidal stage/water depth
X
X
III Helicopter surveys of 35 transects/remote sensing
X
X
IV Model optimal release sites
X
X
X
V Tolerance of Galerucella pusilla to submersion
X
X




Quadrats arranged along four transects at a release site. Circles represent buffered distances from release site to evaluate spread of biocontrol agents.

We are now beginning to look at environmental factors that may favor biocontrol agent populations at some site and not others.


Table 2. Galerucella spp. found.

Galerucella spp.
Site
2006
2007
Devil's Elbow
Y
Y
Dry Dock
Y
Y
Eureka Bar Downstream
Y
Y
Eureka Bar Upstream
Y
Y
Fitzpatrick Island
Y
Y
Karlson Island
Y
Y
March Island
Y
Y
Miller Sands Downstream
N
N
Miller Sands Upstream
Y
Y
Mott Island
Y
Y
Pillar Downstream
N
N
Pillar Upstream
Y
Y
Svensen Island
Y
Y
Tenasillahe Island
Y
Y
Wallace Island
Y
Y



Chris helping out with a transect, hiding in the jungle.