2010 BIOSENTINEL MERCURY MONITORING IN THE NORTH BAY SALT PONDS
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Transcript of 2010 BIOSENTINEL MERCURY MONITORING IN THE NORTH BAY SALT PONDS
2010 BIOSENTINEL MERCURY MONITORINGIN THE NORTH BAY SALT PONDS
Darell Slotton Shaun AyersDepartment of Environmental Science and PolicyUniversity of California, Davis Letitia Grenier
Ben GreenfieldSan Francisco Estuary Institute
Feedback Tool for Watershed Management
Using small, young fish as localized, time-sensitive, fish based measures of methylmercury exposure
Biosentinel Mercury Monitoring
• Year-to-year trends and variability
• Within-year seasonal trends
• Spatial patterns to a local scale
• Performance measures forrestoration and remediation
UC Davis Delta Silverside Hg• Established clear, regional pattern:
elevated periphery, lower central
• Silversides ideal biosentinels:widespread; relatively site-specific
North Bay UC Davis / SFEI 2010 Mercury Biosentinel Monitoring• Dec-2009 – Sep-2010• 30 samplings total 6 ‘intensive’
seasonal sites: Dec/Mar/May/Jul
Kennedy Park
Pond 9/10
Pond 4/5
Pond 2A
Pond 2
Pond 1
Additional one-time sites: July
PetalumaMarsh
Hamilton
Wingo P 7
6A
Pre-Cullinan
Wash ponds
Multiple Individual Fish Analyses (n = 30)
• Within pre-defined size ranges with consistent Hg
• Strong statistical power
• Detailed individual information
Mean Hg±
95% C.I.
45 ± 2ng/g
0
20
40
60
80
100
120
140
30 35 40 45 50 55 60 65 70 75 80 85 90Individual silverside total length (mm)
Hg
(ng/
g w
et w
t, w
hole
bod
y)
Oct 6: 44 ± 4
Suisun Marsh Managed Seasonal Flooding:Suisun Slough North, October through February
Discharge from seasonally flooded,
managed ponds
0
20
40
60
80
100
120
140
30 35 40 45 50 55 60 65 70 75 80 85 90Individual silverside total length (mm)
Hg
(ng/
g w
et w
t, w
hole
bod
y)
Oct 18: 43 ± 3Oct 6: 44 ± 4
0
20
40
60
80
100
120
140
30 35 40 45 50 55 60 65 70 75 80 85 90Individual silverside total length (mm)
Hg
(ng/
g w
et w
t, w
hole
bod
y)
Dec 21: 75 ± 5
Oct 6: 44 ± 4Oct 18: 43 ± 3
0
20
40
60
80
100
120
140
30 35 40 45 50 55 60 65 70 75 80 85 90Individual silverside total length (mm)
Hg
(ng/
g w
et w
t, w
hole
bod
y)
Feb 7: 100 ± 5
Oct 6: 44 ± 4Oct 18: 43 ± 3
Dec 21: 75 ± 5
Sacra-mentoRiver
San Joaquin River
Merced
Tuolumne
ClearCreek
Ham-iltonCity
Cache Ck
Mud Slough Region
LowerSacramentoSeries
Vernalis
UC Davis BiosentinelMonitoring Region:2005-2007 CBDA Fish Mercury Project
• Over 3,000 individualsmall fish analyses/yr
• High precision, high cost
1 Comp40-50 mm
1 Comp50-60 mm
1 Comp60-70 mm
1 Comp70-80 mm
SFEI Compositing Approach:• 4 composites, 4 analyses (vs 30)• 5 fish per composite• 10 mm size increments
• less precise statistics• large cost saving on analytical
SFEI’s 2008-2010 RMPSmall Fish Program
Fixed, long-term sites
Potential source sites(urban, mines, POTWs)
Additional 1-time sites(12 wetland, 12 bay)
Silverside
Topsmelt
Composites(4 comps x 5 fish)
1 Comp45-50 mm
1 Comp50-55 mm
1 Comp55-60 mm
1 Comp60-65 mm
1 Comp65-70 mm
1 Comp70-75 mm
Hybrid/Compromise Plan:• 6 composites (vs 4)• 8 fish per composite (vs 5)• Narrower size range (45-75 mm vs 40-80 mm)
2010 Seasonal Silverside Mercury
KennedyPark
Pond 9/10
Pond 4/5
Pond2A
Pond 2
Pond 1
Dec-2009
Mar-2010
May
Jul
71
66
72
13875
75
68
63
54
186
83
57
8596
59
41
5446
44
78
79
55
94
46
PetalumaMarsh Wing
o
P 7Wash ponds
29
6568
63
Other species data from siteswithout silversides (July samplings)
Hamilton
Pond 7
Pond 6A
Pre-Cullinan
Silverside
Topsmelt
Killifish
Stickleback
59
24
88
16
44
5324
50
49
42
29juv. Striped Bass
North Bay Silverside Mercury Trend, Fall 2005 , Fall 2006 Dec-2009
Pond 2
Silverside Fall 2005 Mercury Spatial Distribution:Entire CBDA Range With Silversides
Pond 2
Means of Comps ± SE
Spatial patterns
Silverside
Pond 2
North Bay 2005-2006 Seasonal Silverside Mercury Trend, Oct, Feb, May, Jul, Sep, Nov
FromPond 2?
Interim Conclusions from 2010 WorkIt is possible to use small fish as biosentinels of methylmercury exposure in this region, spatially and seasonally.
Significant changes in exposure can occur both seasonally and between sites.
The lower cost, hybrid compositing approach can provide a reasonable alternative when funding is limited.
Different sites can show different patterns.