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Cabomba caroliniana(Fanwort) in The
Netherlands
3rd International Symposium on Weeds and Invasive
Plants
Johan van Valkenburg, Rudi Roijackers & Rosalie Léonard
Cabomba caroliniana | October 2011
2
The species involved
• A common component of your Goldfish plant selection
Cabomba caroliniana | October 2011
3
Cabomba caroliniana or Cabomba aquatica ?
• In trade Cabomba aquatica is often misapplied to C. caroliniana plants
C. aquatica C. caroliniana
Flowers Yellow White
Submerse leaves
3-dimensional Mostly 2-dimensional
Emerse leaves
Round Elliptic
Cabomba caroliniana | October 2011
4
Cabomba caroliniana distribution
2010
Published sources
Cabomba caroliniana | October 2011
5
A brief history for The Netherlands
• First record 1989 Maasbracht (Meuse River) NOT invasive
• Since 2005 at Loosdrecht INVASIVE
• Spring 2006 first attempt at eradication
• Summer 2007 Oranje channel
near Orvelte expanding
• Summer 2008 suburban area at Hoogeveen & fish pond Groningen
• Summer 2010 suburban area Hardinxveld, Ridderkerk, Barendrecht
• Summer 2011 suburban area Heerenveen
Cabomba caroliniana | October 2011
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What to do ?
• Identification tools & training of field staff
• Research on habitat requirements
• Research on genetic diversity
• Research on management options
Cabomba caroliniana | October 2011
7
Identification tools
• Field guide
• Info sheet
Cabomba caroliniana | October 2011
8
Habitat requirementsSurvey March, July, October 2008
Visit at the 3-4 known localities
Results:
• Wide tolerance for nutrient levels
• Large range in conductivity level
• Floating plants limit growth
• Competition with Myriophyllum heterophyllum
Conclusions:
• Site conditions do not explain difference in invasive behaviour
• Can grow in any eutrophic stagnant to slow flowing water with a sediment poor to very rich in organic matter
Cabomba caroliniana | October 2011
9
Genetic diversity• In collaboration with Plant
Research International and CSIRO
• Sampling of all known localities in NL
• Additional samples invasive populations in France, Germany and Australia
• Samples from import shipments SE Asia
Cabomba caroliniana | October 2011
10
Management options EUPHRESCO DeCLAIM project
Funding: UK Defra and NL LNV
Partners:
• Plant Protection Service NL
• Wageningen University & Research
• CEH - Wallingford
Target species:
• Cabomba caroliniana
• Hydrocotyle ranunculoides
• Ludwigia grandiflora
• Myriophyllum aquaticum
Cabomba caroliniana | October 2011
11
EUPHRESCO Cabomba trials at Loosdrecht
Cabomba caroliniana | October 2011
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Cabomba management
Field testing 4 methods at Loosdrecht
• Standard practice
• Washing out
• Covering surface
• Covering bottom
CHARISMA model to assist DSS
• Detailed measurements in time
• Predicting competition
• Timing of management actions
Cabomba caroliniana | October 2011
13
Trial lay out
• Standard 3 X 100 m & enclosures
• Washing 3 X 100 m & enclosures
• Surface coverage 2 X 100 m
• Bottom coverage 10 X 10 m
• Scheduled for early April performed by May 20th (standard) and July 14th (washing)
Cabomba caroliniana | October 2011
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Location map trials Loosdrecht
Cabomba caroliniana | October 2011
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Standard practice
May
June
December
July
Cabomba caroliniana | October 2011
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Result of standard practice
• After 1 year dominance Cabomba just like it was before management (June 75-90%; August 80-90%)
Enclosures (1 x 1 m)
• On average 9(3-30) stems of Cabomba present
• Elodea nuttallii July 15-40 % coverage August 40-100%
coverage
Dominance Cabomba resulting from regrowth, inflow of fragments and competitive advantage grazing
Cabomba caroliniana | October 2011
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Washing out with hydro-venturi system
Cabomba caroliniana | October 2011
18
Result of washing out
• After 1 year dominance Cabomba still reduced (June 5-10%; August 25-50%)
Enclosures (1 x 1 m)
• Just 1 cage with a few stems of Cabomba entering from the side
• Elodea nuttallii coverage August 25-100% coverage
Recovery of Cabomba resulting most likely from inflow of fragments and competitive advantage grazing
Cabomba caroliniana | October 2011
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June 2010 enclosure with Cabomba
Cabomba caroliniana | October 2011
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June 2010 outside enclosure
Cabomba caroliniana | October 2011
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August 2010 Elodea nuttallii (other enclosure)
Cabomba caroliniana | October 2011
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Coverage with black woven geotextileCoverage of sediment
• Recolonisation of Cabomba on new sedimentation on top of fabric
Does not work in a situation with siltation and large quantities of propagules in the vicinity
Coverage of surface
• No plant growth in July
• No plant growth after 1 month partial removal of fabric
August 2011
• 1st ‘removed’ stretch
2 Cabomba stems & 5 plants M. verticillatum 50% cover
• 2nd ‘removed’ stretch
No Cabomba & 7 plants M. verticillatum 50% cover
M. verticillatum and U. vulgaris on top of fabric
Non discriminant effective method
Cabomba caroliniana | October 2011
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Surface coverage experiment August 2010
Cabomba caroliniana | October 2011
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Surface coverage experiment August 2011
Cabomba caroliniana | October 2011
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CHARISMA model• Determine growth parameters
• Life-cycle knowledge
• Vulnerable stages in development
• Energy allocation
• First findings
Cabomba caroliniana | October 2011
26
Charisma ‘conclusions’
Predictions on growth and competition do not match field observations
• Growth potential underestimated
• Critical role of root system
• Photosynthesis parameters to be evaluated
April 2011
Cabomba caroliniana | October 2011
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Conclusions
• Standard practice will not eradicate Fanwort in eutrophic waters
• Yearly cleaning in autumn has resulted in 100% dominance of Fanwort in ditches
• Washing out is a quite effective method to remove macrophytes rooting in the sediment (e.g. Cabomba & M. heterophyllum)
• There is no ‘best management ‘ option
• Solution has to be adapted to the actual site conditions:
Dimensions of the waterway
Conditions of the bank
Function of the waterway
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