Zebra Mussel Growth and Seasonal Reproductive Cycles in San

Zebra Mussel Growth
and
Seasonal Reproductive Cycles
in
San Justo Reservoir
Tanya Veldhuizen and Jeff Janik
Department of Water Resources
Operations and Maintenance
Aquatic Nuisance Species Program
[email protected]
[email protected]
San Justo Reservoir
•
•
•
•
•
•
7000 AF, 100 SA, 120 ft depth
USBR and San Benito County
Receives water from Sac-SJ
Delta through CVP/SWP system
ZMs discovered January 2008
Closed to public access
Eradication under evaluation
San Francisco
Bay
DWR’s Interest
• Operate the State Water Project (SWP):
- Largest state-built multi-purpose
U.S. water project
- Convey 2.1 MAF per year
- 30 storage facilities
- 20 pumping plants
- 3 pumping-generating power
plants
- 6 hydroelectric power plants
- 1 salmonid fish hatchery
- +700 miles of canals & pipelines
California’s major water projects.
SWP shown in RED.
What’s Vulnerable in the SWP?
fish screens
pumping plants
trash racks
turn-outs
internal pipes
Projected annual cost ~$40-50 million/year
DWR’s Interest
•
-
San Justo Reservoir acts as a surrogate for SWP
Receives CVP/SWP water thru joint use facility
Understand ZM biology in SWP water
Research allows us to forecast mussel biofouling
rates in SWP
- Incorporate findings into DWRs monitoring and
management plans
- Research began June 2008 to present
Research Elements
• Validation of early detection methods
- PCR, settlement plates
• Growth and mortality rates
- biofouling at depth, limnology as a control
• Timing of spawning and settlement
- entrainment into facilities, timing of control treatments
• Biofouling rates
- performance of infrastructure and “tolerance” level
- frequency of treatments, cleanings
• Test antifouling coatings
Growth and Mortality Study
• Objective: Determine the effects of depth and WQ on growth & mortality
• Study period: May 2009 – July 2010
• Treatment
– 8 depths: 5, 10, 15, 20, 25, 30, 40, 50 (feet)
• Treatment Groups
– 5 size classes
3-6mm
10-12.6mm
12.6-19mm
19-25mm
25+mm
– 8 mussels per size class per treatment
– Caged in a mesh bag (color-coded)
• Record length, displacement volume, mortality on a monthly basis
Growth and Mortality Study
Objective: Determine the effects of depth and WQ on growth and survival
Size Comparison between Depths
Dec 2009
(7 months)
5 ft
Size Class (mm)
3-6
10-12 12-19
19-25
25+
40 ft
Size Comparison between Depths
Dec 2009
(7 months)
5 ft
Size Class (mm)
3-6
10-12 12-19
19-25
25+
40 ft
3-6 mm Size Class
Depth (ft)
Average
Length
ave=19.8 - 26.8mm
max=31mm
Depth (ft)
Depth (ft)
Average
Growth per
Day
July
range= 38-149 µm/day
Dec
ave= 6.5-66 µm/day
July
ave= -42-38 µm/day
Water Quality by Depth
May ‘09-July ‘10
DO <2.0 mg/L
A
Size Class: 3-6mm
B
C
Length
Depth (ft)
Temperature
Stratified
Dissolved Oxygen
Isothermal
Stratified
22.5
20.0
depth
5
10
15
20
25
30
40
50
MLR
A
length (mm)
17.5
15.0
12.5
ANOVA, p<0.001
a≠b≠c
10.0
7.5
a
a
a
a
a
b
c
c
5.0
May-09
Jun-09
Jul-09
Aug-09
Sep-09
depth
5
10
15
20
25
30
40
50
30
B
length (mm)
25
20
15
a
10
Sep-09
Oct-09
Nov-09
Dec-09
Jan-10
length (mm)
a
a
a
a
a
b
Feb-10
depth
5
10
15
20
25
30
40
30
C
ANOVA, p<0.001
25
ANOVA, p<0.001
20
a
15
Feb-10
Mar-10
Apr-10
May-10
Jun-10
Jul-10
a
a
a
a
b
Mortality by Depth
comparison of % live mussels
by depth
- all 5 size classes -
Highest mortality occurred at 50ft,
followed by 40ft.
DO = 0.7mg/L
Seasonal Spawning Pattern
• Derived from veliger abundance data
• Weekly to monthly plankton tows
- vertical tow, 2x20m, 50L
- surface tow, 1x40m, 50L
- analyzed with CPLM
• June 2008 to present
Veliger Abundance
June ‘08 – July ‘10
Increase early detection monitoring efforts
Mussel Settlement July ‘09 – July ‘10
Comparison of Veligers to Settled Mussels
May ‘09 – July ‘10
Conclusions
• Growth and Survival
-
Greater growth rates at upper depths when stratified
Similar growth rates at all depths when isothermal
Survival declined at low DO
Survival may increase with size – largest mussels
survived the low DO period
• Spawning and Settlement
-
Summer spawning event
Peak occurs May - June
Settlement occurs one month later
Higher settlement at upper depths
Conclusions
• Applications
-
Increase veliger monitoring during summer months
Expect entrainment during early summer
Expect higher rates of biofouling at upper depths
Utilize lake limnology to decrease growth and survival
Future Research
• Veliger Abundance vs Plankton
- Abundance and community composition
• Gonad Maturation vs Stress
- Lake drawdown, depth (dissolved oxygen, pH)
• Lifespan
- Life expectancy
Acknowledgements
San Benito County Water District
US Bureau of Reclamation – Mid-Pacific Region
CA Dept Fish and Game