Investigations of the Acute
Effects of Mosquito Control
Activities on Water Quality,
Fish, and Shrimp in the Salt
Marshes of Suffolk County, NY
R. Turner1, A. McElroy2, C. Gobler2,
B. Brownawell2, R. Barnes2,
S. Terriciano3, and B. Gibbins1
1 – Long Island University 2 – Stony Brook University 3 – U.S. Geological Survey
A study funded by Suffolk County
as part of the
Suffolk County Vector Control and Wetlands
Management Long Term Plan & Generic
Environmental Impact Statement
see
http://www.suffolkmosquitocontrolplan.org
Background
1930s
Ditches were dug in salt
marshes throughout the U.S.
to reduce standing water and
decrease mosquito
populations.
Over 90% of Suffolk County’s
17,000 acres of salt marsh are
“grid-ditched.“ That amounts
to over 4,000,000 feet of
ditches that are maintained by
the county.1
1 - http://www.co.suffolk.ny.us/webtemp5.cfm?id=75&dept=9
Background
1940s – 1960s
DDT and other pesticides are applied in
marshes and wetlands to combat
mosquitoes.
1995
Suffolk County Vector Control Program
begins spraying Altosid® (methoprene) as
a larvicide and Scourge® (resmethrin) as
an adulticide.
Background
Pesticides are applied via helicopter,
truck, and backpack spraying, mostly from
late spring through September.
Altosid
•
•
•
•
•
•
•
Larvicide
Helicopter application at 1 ounce/acre, 10-20 feet above ground level1
20% Methoprene1
Juvenile hormone mimic, growth regulator
Tightly sorbed to soil
Slightly soluble in water
Half-life in water ~ 30 hours Half-life in soil < 10 days1, 2
1 – http://www.suffolkmosquitocontrolplan.org
2 – ECOTOXNET
Background
Scourge
•
•
•
•
Adulticide
Helicopter application at 0.6 ounces/acre.
Application between 7-10pm, from 150 feet above ground level.1
Mix of Resmethrin (18%) and piperonyl butoxide (54%).1
Resmethrin
• Pyrethroid
• Neurotoxic: sodium channel modulator leading to insect paralysis1
• Half-life in water < 1 hour
Half-life in soil < 30 days2
Piperonyl Butoxide
• Synergist, microsomal enzyme inhibitor slows chemical metabolism1, 2
• EPA acute toxicity category IV compound (low toxicity)2
1 – http://www.suffolkmosquitocontrolplan.org
2 – ECOTOXNET
Pesticides used on Long Island
Background
Resmethrin:
Methoprene:
 Insect growth regulator (Altosid®)
 2LC50s (fish) ~ > 100 mg/L
 3LC50s (shrimp) ~ not usually
observed on adults even at 1 mg/L
 4LC50’s of S-methoprene
(shrimp) ~ 14 g/L
 Log Kow > 6 (hydrophobic)
 Pyrethroid (Scourge®) neurotoxin
 1LC50s (fish) ~ generally < 10
g/L
 1LC50s (shrimp) ~ typically <
1g/L
 Log Kow = 5.4 - 6.5 (hydrophobic)
Methoprene
11 Bradbury & Coats, 1989
Bradbury & Coats, 1989
33 Wirth et al., 2001
Wirth et al., 2001
22 http://pesticideinfo.org
http://pesticideinfo.org
44 Brown et al., 1996
Brown et al., 1996
Background
1999
West Nile Virus, carried by mosquitoes,
infects at least 62 people in the New York
metropolitan area, resulting in 7 fatalities.1
1999 - present
West Nile Virus spreads across the nation.
Cumulatively, 19,707 cases have been
reported and 785 people have died.1
1 – Center for Disease Control web site
Background
2003
Suffolk County begins work on the
Suffolk County Vector Control and
Wetlands Management Long Term Plan &
Generic Environmental Impact Statement,
as required by the Council on
Environmental Quality.
Comments received in the scoping
process underscore the need to study the
potential impacts of mosquito spraying on
salt marsh and estuarine organisms.
Background
2003
Matthew Vilbas,
working on a
fellowship with the
Southampton
College Estuarine
Research Program,
conducts a caged fish study in marshes
subject to mosquito spraying.
Background
2003
The Vilbas study finds:
– Growth and survival of sheepshead minnows
in a mosquito ditch subjected to aerial
application of larvicide in Oakdale were
significantly lower relative to control sites.
– Growth rates of sheepshead minnows in a
mosquito ditch subjected to aerial application
of adulticide in Mastic Beach were
significantly lower relative to control sites.
Background
2003
However!
There was minimal analysis of environmental
parameters…
– No continuous monitoring of temperature,
dissolved oxygen, or water depth.
– No analysis of water and sediment samples
for pesticide concentrations.
And fish growth and survival was only monitored
during one larvicide event and one adulticide
event. No replication.
Which leads us to…
The 2004 Caged Fish Study
Hypotheses of Caged Fish 2004
The null hypothesis is that there will be no
statistically significant difference in:
–
–
–
–
the mortality rate of caged fish or shrimp;
the growth rate of caged fish;
the prey capture ability of caged shrimp; or
the fecundity of caged shrimp;
that have been exposed to an aerial application
of larvicide (Altosid) or adulticide (Scourge)
while in a salt marsh mosquito ditch compared to
organisms that have been placed in a “control”
marsh not subjected to mosquito pesticide
application.
Methods
Biological Effects of Mosquito Spray
• Monitor survival of caged organisms in
sprayed vs. non-sprayed marshes.
• Monitor growth of caged fish.
• Monitor prey capture ability and fecundity
of surviving shrimp.
• 96 hr static renewal shrimp toxicity tests
using water collected 30 min. post spray.
• Comparative survey of benthic organisms
in sprayed vs. non-sprayed marshes.
Methods – Shrimp Lab Tests
Test Type:
Static Tests:
Prey Capture Tests:
Dosing Experiments:
Method Summary:
Why Studied?
-water taken after spray
-replenished daily in lab
-independent measure of
toxicity without
environmental variables
-1 or 2 h in duration
-5 brine shrimp prey
-replenished every 15 m
-assessment of non-lethal
effects of pesticide
exposure on shrimp
-3 or 4 replicates
-dosed 1 time/day for 4 d
-water & acetone controls
-measure acute toxicity of
LI pesticides on shrimp
Prey Capture Experiments
Static & Dosing Experiments
Methods
Efficacy of Mosquito Spray
• Monitor survival of caged mosquitoes in
sprayed vs. non-sprayed marshes.
• Monitor “fly-up” of field collected mosquito
pupae.
• Confirmation of
surface deposition.
• Modeling of air
dispersion and
deposition.
Methods
Water and Sediment Chemistry
• Continuous monitoring of dissolved
Oxygen concentrations and temperature
(data stored every 30 minutes).
• Analysis of water samples for pesticide
concentrations before a spray event and
30 min to 96 hrs post spray.
• Analysis of sediment samples for pesticide
concentrations before and after a spray
event.
Methods
Water and Sediment Chemistry
• Surface water (upper 6”) was sampled both
including the air-water interface and excluding it.
• USGS measured filtered water employing
GC/MS methods (reporting limits of 5 ng/L for 6
target chemicals.
• USB measured unfiltered water and splits of
above using HPLC-time-of-flight-MS methods
with method detection limits of 0.5 ng/L in water.
• Composite sediment samples (0-1 cm) were
collected at ditch bottoms, intertidal locations,
and selected high marsh locations; analysis
based on GC-MS.
Methods
Caged Organism Logistics
• Deployment of at least 168 adult grass shrimp
and 240 juvenile sheepshead minnows one
day before a spray event in flow-through
cages in marsh ditches or small tidal creeks.
• Simultaneous deployment in two sprayed and
two reference marshes.
• 3 cages of shrimp and 3 cages of fish per site.
• Length of fish measured immediately prior to
deployment.
• Monitoring of caged fish and shrimp mortality
on a daily basis for 5 days.
Juvenile Sheepshead
minnows Cyprinodon
variegatus
20 fish per cage
3 cages per site
Grass shrimp Paleomonetes
pugio, 14 per cage, 3 cages
per site
Methods
Blue = reference site
Red = spray site
Field Sites
• Finding suitable salt marsh locations for the study
was more difficult than anticipated. Unacceptable
mortality of caged fish and/or shrimp occurred in
marshes at the following locations.
– Beaverdam Creek, Captree Island, Fireplace Neck (3
sites), Gilgo State Park, Stokes/Podges, Tanners Neck,
Timber Point, West Gilgo, West Shinnecock.
– Reconnaissance done at several other marshes as well.
• Most ditches in most marshes are too shallow at
low tide for use in the study.
Field Sites
Johns Neck – Spray Site
Field Sites
Havens Point - Control
Field Sites
Havens Point Control Site
Johns Neck Spray Site
Field Sites
Timber Creek – Spray Site
Field Sites
Flax Pond – Control
Field Activities
What was done… where and when
Table 1: Site and Spray Event Description
Experiment
Dates:
Spray
Dates:
Spray
Type:
Sites
Involved:
7/20 - 7/26
7/20
L
8/2 - 8/7
8/3
8/9 - 8/14
Coordinates of
Sites Involved:
Spray
Sites:
Animals
Involved:
Chemistry
Performed:
DO
Evaluated:
John's Neck
Timberpoint
Old Fort Pond
Haven's Point
JN & TP
Fish
None
No
No
No
No
L
Timberpoint
John's Neck
Haven's Point
Flax Pond
JN & TP
Fish & Shrimp
water samples at 1,
2, 24, 48 & 96 h postspray; sed. Samples at
1 & 4 days post-spray
Yes
Yes
Yes
Yes
8/10
L
Timberpoint
John's Neck
Haven's Point
Flax Pond
JN & TP
Fish & Shrimp
water samples at prespray & 30min., 1d & 4d
post-spray; sed. Samples
at 1 & 4d post-spray
only 8/9-8/12
only 8/9-8/13
only 8/9-8/14
Yes
8/17 - 8/22
8/18
A
(L on 8/17)
John's Neck
Haven's Point
JN
Fish & Shrimp
water & sed samples same
as on 8/3.
Yes
Yes
8/25 - 8/29
8/25
A
John's Neck
Haven's Point
JN
Fish & Shrimp water & sed samples at pre &
post 30min. & 1d & 4d post
Yes
Yes
8/31 - 9/5
9/1
L
John's Neck
Timberpoint
Haven's Point
TP
Fish & Shrimp
Yes
Yes
Yes
water & sed samples as on
8/25
Results
Percent survival
120
Survival of Fish Over Time
100
Blue squares =
sprayed sites
80
Timber
John's
60
Havens
40
OFP
20
0
18-Jul
20-Jul
22-Jul
24-Jul
26-Jul
28-Jul
Results from first larvicide experiment
DO data not available
Results
120
Survival of Fish Over Time
Percent Survival
100
80
Timber
60
John's
40
Haven's
20
Flax
0
1-Aug 2-Aug 3-Aug 4-Aug 5-Aug 6-Aug 7-Aug 8-Aug
-20
-40
Results from second larvicide experiment
Timber Point survival significantly lower than Flax and Haven’s
Fish and
Shrimp Survival
for 8/3/04
Fish and
Shrimp
Survival
for 8/3/04
Fish
120
100
80
Timber
Johns
Havens
Flax
60
Percent Survival
40
20
0
L
-20
2-Aug
3-Aug
4-Aug
5-Aug
6-Aug
7-Aug
Shrimp
120
100
80
60
40
20
0
-20
L
2-Aug
3-Aug
4-Aug
5-Aug
Date
6-Aug
7-Aug
Results
120
Survival of Fish Over Time
Percent survivial
100
80
60
40
John's
Timber
Havens
20
Flax
0
8-Aug
9-Aug
10-Aug
11-Aug
12-Aug
13-Aug
14-Aug
15-Aug
Results from third larvicide experiment
DO data not available for JN or HP after 12 Aug
Timber significantly higher DO than all other sites.
Results
120
Survival of Fish Over Time
Percent survival
100
80
60
40
20
John's
Haven's
0
16-Aug
-20
17-Aug
18-Aug
19-Aug
20-Aug
21-Aug
22-Aug
23-Aug
Results from first adulticide experiment
Results
Survival of Fish Over Time
120
John's Neck
Percent survival
100
Haven's Point
80
60
40
20
0
24-Aug
25-Aug
26-Aug
27-Aug
28-Aug
29-Aug
30-Aug
Results from second adulticide experiment
DO higher at John’s Neck than Haven’s Point for full experiment
Results
Comparison of Fish and Shrimp Survival Over Time
Corrected Percent Survival
Fish
120
John's Neck Ditch
100
Haven's Point
80
John's Neck
Channel
J.N. Ditch
SURFACE
Haven's Point
SURFACE
60
40
20
0
-20
25-Aug
26-Aug
27-Aug
28-Aug
29-Aug
Shrimp
120
100
80
60
40
20
0
-20
25-Aug
26-Aug
27-Aug
28-Aug
29-Aug
Date
Results from second adulticide experiment
Results
Summary of Mortaltiy Observed in Caged Organisms
Summary of
Mortality of
Caged
Organisms
Spray Type:
Larvicide
Dates: Species
7/20/04
Fish
8/3/04
Fish
Spray Sites:
TP #
JN ~
Control Sites:
FP
HP
Shrimp
8/10/04
Fish
Shrimp
9/1/04
Fish
Shrimp
Adulticide
8/18/04
Fish
Shrimp
8/25/04
Fish
Shrimp
* denotes that Old Fort Pond was used instead of Flax Pond
# after 8/3 TP cages moved to deeper water
~ after 8/18 JN S cages moved to deeper water
Statistically significant mortality relative to another site at
one or more days
What’s the Problem with
Haven’s Point?
Time of day
12:16
9:16
6:16
3:16
0:16
21:16
18:16
15:16
12:38
9:38
6:38
3:38
0:38
21:38
18:38
15:49
12:49
9:49
6:49
3:49
0:49
21:49
18:49
15:51
140
120
30
100
25
80
20
60
15
40
10
20
5
0
0
Temperature (degrees Celcius)
Problem!
12:51
9:51
6:51
3:51
0:51
21:51
18:51
16:00
13:00
10:00
7:00
4:00
1:00
22:00
19:00
Oxygen Saturation (%)
Results – Dissolved Oxygen
Haven's Point (Adulticide 8/18)
35
Dissolved Oxygen and Temperature Time Series
140
35
120
30
100
25
80
20
60
15
40
10
20
5
0
0.00
20.00
40.00
60.00
80.00
100.00
120.00
Temperature (degrees Celcius)
Johns Neck
Dissolved Oxygen Saturation (%)
Larvicide 8/3: John's Neck DO and Temperature
0
140.00
DO
<20%
Time (hours)
Larvicide 8/3: Timberpoint DO and Temperature
140
35
120
30
100
25
80
20
60
15
40
10
20
5
0
0.00
20.00
40.00
60.00
80.00
Time (hours)
100.00
120.00
0
140.00
Temperature (degrees Celcius)
Timber Point
Dissolved Oxygen Saturation (%)
Diel DO - Spray Sites
DO
TEMP
140
35
120
30
100
25
80
20
60
15
40
10
20
5
0
Temperature (degrees Celcius)
Channel
vs.
Ditch
Dissolved Oxygen Saturation (%)
Adulticide 8/25: John's Neck Channel DO and Temperature
0
0.0
20.0
40.0
60.0
80.0
100.0
120.0
140.0
Time (minutes)
Time (hours)
140
35
120
30
100
25
80
20
60
15
40
10
20
5
0
0
0.0
20.0
40.0
60.0
80.0
Time (minutes)
Time (hours)
100.0
120.0
140.0
Temperature (degrees Celcius)
photosynthesis
respiration
flood tide
ebb tide
Dissolved Oxygen Saturation (%)
Dissolved
Oxygen
Saturation
Adulticide 8/25: John's Neck Ditch DO and Temperature
Results – Fish Growth
Table 3: Fish Growth
Date:
Site:
20-Jul
Haven's
3-Aug
0.140
0.140
John's
0.228
-0.180
Timber
0.270
0.280
Old Fort Pond 0.120
0.320
Timber
John's
Haven's
Flax
9-Aug
Total
Total
Average
Standard
Growth: Growth Growth Rate Growth Rate Deviation:
(cm)
(mm) (mm/day) (mm/day)
Timber
John's
Haven's
Flax
0.075
0.075
0.058
0.120
0.080
0.060
0.085
0.075
0.150
0.070
1.400
1.400
2.280
-1.800
2.700
2.800
1.200
3.200
0.280
0.280
0.456
-0.360
0.540
0.560
0.240
0.640
0.280
0.000
0.048
0.577
0.550
0.014
0.440
0.283
0.750
0.750
0.583
1.200
0.150
0.150
0.117
0.240
0.139
0.019
0.800
0.602
0.850
0.750
1.500
0.700
0.160
0.120
0.170
0.150
0.300
0.140
0.050
0.055
-0.005
0.003
0.038
0.035
0.053
0.500
0.550
-0.050
0.033
0.383
0.350
0.525
0.100
0.110
-0.010
0.007
0.077
0.070
0.105
0.020
0.025
-0.025
0.040
0.200
0.250
-0.250
0.400
0.040
0.050
-0.050
0.080
Fish growth was low, averaging only
0.05 to 0.5 mm/day with no differences
observed between sites
18-Aug
0.240
n/a
0.150
0.026
0.197
0.090
0.085
0.035
0.850
0.350
0.170
0.070
0.120
0.071
Haven's
0.115
0.050
1.150
0.500
0.230
0.100
0.165
0.092
0.160
n/a
0.225
0.064
0.145
0.064
0.044
0.064
0.144
0.015
0.221
n/a
0.078
0.040
0.471
n/a
0.258
0.040
25-Aug John's--normal
normal
normal
channel
channel
surface ditch
surface ditch
Haven's--normal
normal
normal
surface
surface
1-Sep
0.067
John's
0.072
0.067
0.027
0.039
0.046
0.068
0.800
1.350
0.900
0.500
0.950
0.583
0.100
-0.025
0.775
0.667
0.160
0.270
0.180
0.100
0.190
0.117
0.020
-0.005
0.155
0.133
0.051 0.510
0.102
0.025 0.250
0.030 0.300
0.062 0.620
0.050
0.060
0.124
Haven's
Timberpoint
0.051
0.080
0.135
0.090
0.050
0.095
0.058
0.010
-0.003
0.077
0.067
John's--normal
normal
normal
channel
channel
channel
0.109
0.150
0.110
0.127
1.088
1.500
1.100
1.268
0.218
0.300
0.220
0.254
(Note: n/a was inserted where there was too few data to perform the functions)
Table 4: Shrimp Prey Capture
Number of
Avg. eaten Std. Dev.:
Shrimp Tested: after 60 min.:
Date:
Site ID:
8/3/04 Larvicide
Flax
Haven's
John's Neck
Timberpoint
Flax static (#1)
J.N. static (#1)
T.P. static (#1)
7
7
5
2
5
5
5
9.14
10.29
18.60
9.00
8.40
10.00
8.60
7.01
5.44
1.67
9.90
5.98
4.64
2.19
8/9/04 Larvicide
Flax
Haven's
J.N. static (#1)
T.P
10
10
6
10
12.10
12.90
12.50
10.20
4.72
5.07
6.69
5.03
8/18/04 Adulticide
Haven's
J.N. static (#1)
H.P. static (#1)
10
5
5
11.80
10.20
9.40
4.85
3.27
4.72
8/25/04 Adulticide
H.P.
H.P. static #1
J.N. channel
J.N. static #1
6
5
14
5
12.67
11.00
11.00
9.00
2.73
1.22
3.26
1.41
9/1/04 Larvicide
Haven's
John's Neck
T.P
9
10
11
12.78
5.80
9.82
2.95
3.55
4.60
Results
Shrimp
Prey
Capture
Ability
The ability of surviving
shrimp to capture prey
was highly variable,
with no statistical
decreases associated
with pesticide
exposure
Table 2: Shrimp Static Exposure Experiments Concurrent with Spray Events
Start Date:
Site:
methoprene
8/3/2004
Flax Pond
Timberpoint
John's Neck
100.0
100.0
83.3
0.0
0.0
40.8
methoprene
8/10/2004
Flax Pond
Timberpoint
John's Neck
100.0
100.0
100.0
0.0
0.0
0.0
resmethrin
8/18/2004
John's Neck
Haven's Point
100.0
100.0
0.0
0.0
resmethrin
8/25/2004
John's Neck
Haven's Point
100.0
100.0
0.0
0.0
9/1/2004
Timberpoint
Haven's Point
83.3
66.7
40.8
51.6
methoprene
Mean % Survival: Std. Dev.:
(after 96 hours)
No evidence of toxicity resulting from exposure to
water collected from the spray sites
96 h Mortality Curves for 12/19/04
Results
100
Dosing Experiment
Percent Mortality
80
60
96 h Mortality Curves for 3/19/05
Resmethrin
100
Sumethrin
40
Scourge
80
0
0
1
2
3
BOWL Concentration (ug/L)
4
5
Percent Mortality
20
Average LC50s:
Scourge® ~ 0.58 g/L
Sumethrin: ~ 1.1 g/L
Resmethrin ~ 1.2 g/L
TOXICITY:
Scourge® > Sumethrin ~ Resmethrin
60
Resmethrin
Sumethrin
Scourge
40
20
0
0
0.5
1
1.5
2
2.5
BOWL Concentration (ug/L)
NOTE: no methoprene-based
chemical was toxic up to 1 mg/L
concentrations
3
Results
Benthic Species Abundance
800
Other
700
Polyps
Midge larvae
Species Abundance
600
snail 1
500
Streblospio
400
Nereis
succinea
Spionidae
300
foram
tick
200
Crustacean 1
100
Paranaitis
speciosa
Oligochaetes
0
Havens Point
Flax Pond
Timber Point
Captree Island
Site
Note: “Other” represents the remaining 1% of species
Johns Neck
nemetodes
Results
Methoprene water column concentrations
Johns Neck - Unchachoque Creek 8/3 Spray
Timber Point - Connetquot River 8/3 Spray
Time Post Spray Sample Type ng/L
Lab
Time Post Spray Sample Type ng/L
Lab
0.5 hrs
3,300
216
490
82
USB
USGS
USB
USGS
0.5 hrs
23
<5
>2,500
10
USB
USGS
USB
USGS
Interface
Subsurface
2 hrs
Subsurface
6.3
<5
USB
USGS
24 hrs
Subsurface
17
<5
USB
USGS
48 hrs
Subsurface
<5
96 hrs
Subsurface
<5
Interface
Subsurface
2 hrs
Subsurface
<5
USGS
24 hrs
Subsurface
<0.5
<5
USB
USGS
USGS
48 hrs
Subsurface
<5
USGS
USGS
96 hrs
Subsurface
<5
USGS
Results
Methoprene continued
8/10 Spray
Location
Time Post Spray
Sample Type
ng/L
Lab
Johns Neck
0.5 hrs
Subsurface
1,100
USB
24 hrs
Subsurface
24
USB
0.5 hrs
Subsurface
8
USB
24 hrs
Subsurface
22
USB
Timber Point
Results
Disposition of Methoprene in marsh
• Methoprene not detected in water pre spray or in
reference marshes.
• [Methoprene] exceeding 1,000 ng/L were observed 30
min post spray in waters after 3 of 4 sprays. Interface
values not always highest.
• 2 hrs post spray [methoprene] < 25 ng/L with detectable
levels persisting for 1 to 2 days post spray.
• Methoprene in sediment was more persistent with
concentrations ranging between 3-60 ng/g in samples
collected within a week of spraying, but no evidence of
accumulation due to repeated sprays was observed.
Results
Scourge® water column concentrations
8/18 Spray
Resmethrin PBO
Time Post Spray Sample Type ng/L
ng/L
Lab
8/25 Spray
Resmethrin PBO
Time Post Spray Sample Type ng/L
ng/L
Lab
0.5 hrs
Interface
320
270
Subsurface 7.8
<5
18,000
59,800
210
1,310
USB
USGS
USB
USGS
0.5 hrs
Interface
<.5
<5
Subsurface 0.8
<5
26
12
11
15
USB
USGS
USB
USGS
2 hrs
Subsurface 36
38
2,900
457
USB
USGS
2 hrs
Subsurface <.5
<5
2
28
USB
USGS
9 hrs
Subsurface <.5
<5
24
61
USB
USGS
9 hrs
Subsurface <.5
<5
88
113
USB
USGS
48 hrs
Subsurface <5
6
USGS
48hrs
Subsurface <5
<5
USGS
96 hra
Subsurface <5
<5
USGS
96 hrs
Subsurface <5
<5
USGS
Johns Neck - Unchachoque Creek
Results
Disposition of Scourge® active ingredients in
marsh
• Neither PBO nor Resmethrin found in pre-spray samples of water or
sediment, nor in sediments after spraying
• [Resmethrin] much higher at water interface (320 ng/L) than inches
below water surface (60 ng/L) – highest levels found
• [Resmethrin] drops rapidly in water becoming undetectable >2 hrs
after spray
• PBO more persistent with trace amounts detected up to two days
after spray
• PBO/Resmethrin in water samples >> than in Scourge® formulation
(3:1) with median values of 46:1
• The first spray event delivered a greater amount of Scourge® to the
water than the second spray event
Summary of Mortaltiy Observed in Caged Organisms - Oxygen Effect
Spray Type:
Larvicide
Dates: Species
7/20/04
Fish
8/3/04
Fish
Spray Sites:
TP #
JN ~
Control Sites:
FP
HP
Shrimp
8/10/04
DO unknown
Fish
Shrimp
9/1/04
Fish
Shrimp
Adulticide
8/18/04
Fish
Shrimp
8/25/04
Fish
Shrimp
* denotes that Old Fort Pond was used instead of Flax Pond
# after 8/3 TP cages moved to deeper water
~ after 8/18 JN S cages moved to deeper water
Statistically significant mortality relative to another site at
one or more days
DO toxicity
likely
Related Experiments
Non-caged fish exposure to pollutants
Median # of Fish
Lab experiments to
determine if fish
would choose to
avoid pesticides
Median Number of Sheepshead Minnows in Trough
Section - Before and After Addition of Lemon Juice to
Section 1
4
3
Before Addition
2
After Addition
1
0
1
2
3
Trough Section
4
Conclusions
• No significant differences in fish growth
rates (control sites vs. sprayed).
• No significant differences in shrimp
fecundity or prey capture ability (controls
vs. sprayed)
• No significant difference in species
abundance or composition of benthic
organisms (controls vs. sprayed)
Conclusions
• Neither larvacide nor adulticide active ingredients
persist at appreciable levels in marsh surface
water more than a couple of hours.
• New analytical methods allow for low part per
trillion levels to be detected in water for up to 2
days after spraying for PBO and methoprene.
• Analytical results suggest that delivery of
pesticides to the marsh surface from aerial sprays
can be quite variable.
• Greater persistence of methoprene in sediments
suggests that chronic effects on infaunal
organisms should also be assessed.
Conclusions
• Fish in lab experiments did not choose to
avoid methoprene enriched water.
• 3 caged organism experiments exhibited
decreased survival where pesticide applied.
• 2 experiments showed no such effect.
• Low dissolved oxygen around dawn most
likely cause of mortality in ditches.
• Small changes in placement of cages had
significant impacts on survival.
Conclusions
• Aerial application of Altosid® and Scourge®
on Suffolk County marine wetlands had no
demonstrable effect on caged fish and
shrimp, although field study compromised by
low DO at many sites.
• Data observed is consistent with the low and
rapidly declining concentrations of pesticides
measured in waters where cages were
deployed after pesticide application, and
data available on the toxicity of these
compounds to fish and shrimp (LC50 of 0.5
μg/L for Scourge®, > 1mg/L for Altosid®).
Acknowledgements
Suffolk County Legislature (funding)
Cashin Associates (coordination)
Anne McElroy – Stony Brook University (Lead P.I.)
Bruce Brownawell Lab - Stony Brook University (sampling & analysis)
Long Island University (caged fish assessment)
Suffolk County Department of Health Services
Division of Environment Quality (sampling)
Suffolk County Department of Public Works – Vector Control (spraying)
U.S. Geological Survey (sampling & analysis)
RTP Environmental Corp. (modeling)
Last Slide!
Thanks for listening.