SLIDE 1
National Cabomba map
Draw down in Miriam vale...
National Cabomba map Draw down in Miriam vale... Mildura Victoria- - - PowerPoint PPT Presentation
National Cabomba map Draw down in Miriam vale... Mildura Victoria- - - PowerPoint PPT Presentation
National Cabomba map Draw down in Miriam vale... Mildura Victoria- Cabomba Mildura during drawdown-6 x months after re-filling still no cabomba Lake Benalla - Victoria Lake Benalla pre drawdown After draw down Earth works to minimize
SLIDE 2
SLIDE 3
Mildura Victoria- Cabomba
SLIDE 4
Mildura during drawdown-6 x months after re-filling still no cabomba
SLIDE 5
Lake Benalla - Victoria
SLIDE 6
Lake Benalla pre drawdown
SLIDE 7
After draw down
SLIDE 8
Earth works to minimize ‘puddles’
SLIDE 9
Lake Benalla, benthic blanket during draw down
SLIDE 10
Lake Benalla after re-filling...
DPI Vic photos
SLIDE 11
11
Regeneration experiment
Questions What is the regeneration potential of
cabomba after a winter drawdown?
Does this vary with exposure status and weed
mounds?
SLIDE 12
12
Regeneration experiment
Exposed dry
SLIDE 13
13
Regeneration experiment
Exposed saturated weed free (i.e. weed mound absent).... Fragment present.
SLIDE 14
14
Regeneration experiment
Exposed saturated weed mound
SLIDE 15
15
Regeneration experiment
SLIDE 16
16
Regeneration experiment
After 90 days
SLIDE 17
17
Regeneration experiment
Results
50 100 150 200 250 300
ED ESWF ESWM
- No. of propagules m-2
crowns sprouted stems sprouted
ED Exposed dry ESWF Exposed saturated weed free ESWM Exposed saturated Weed mound
SLIDE 18
18
Stem and crown viability
After 70 days of exposure:
- 95% of stems under mounds were viable where
substrate remained saturated
- 20% where sediment was ‘dry’
- 40% of crowns viable regardless of substrate
being dry or wet
SLIDE 19
19
Regeneration experiment
Conclusion
- 1. Cabomba control was poor??
But wait…
SLIDE 20
* * * *
SLIDE 21
Why has the cabomba gone?
1.
Floods?
Lower light due to the high water and turbidity.
Less carbohydrate reserves at the end of the 2010 drawdown because of the recovery required after the 2009 drawdown.
Dislodgement of damaged cabomba
Deposition of sediment on top of the cabomba
- 2. Multiple stressors
- 3. Would the cabomba decline have occurred
with floods but not drawdown?
SLIDE 22
Key findings
1.
Winter drawdown works for control, under certain circumstances:
a.
Repeated drawdowns
b.
Poor growth conditions after refilling
c.
Likely to hold for herbicide application too
2.
Active monitoring program (abundance and viability), allows us to plan next steps (adaptive management)
1.
Change from control / protection of downstream to eradication
2.
Understand recolonisation
3.
Develop site specific control programs
SLIDE 23
SLIDE 24
SLIDE 25
SLIDE 26
SLIDE 27