R. Turner 1 , A. McElroy 2 , C. Gobler 2 , B. Brownawell 2 , R. Barnes 2 , S. Terriciano 3 , and B. Gibbins 1

1. 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

2. 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

3. 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

4. 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.

5. 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

6. Scourge Background • 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

7. Background (hydrophobic) (hydrophobic)

8. 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

9. 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.

10. 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.

11. 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.

12. 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.

13. Which leads us to… The 2004 Caged Fish Study

14. 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.

15. 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.

16. Methods – Shrimp Lab Tests

17. Prey Capture Experiments Static & Dosing Experiments

18. 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.

19. 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.

20. 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.

21. 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.

22. Juvenile Sheepshead minnows Cyprinodon variegatus 20 fish per cage 3 cages per site

23. Grass shrimp Paleomonetes pugio, 14 per cage, 3 cages per site

24. Methods

25. Blue = reference site Red = spray site

26. 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.

27. Field Sites Johns Neck – Spray Site

28. Field Sites Havens Point - Control

29. Field Sites Havens Point Control Site Johns Neck Spray Site

30. Field Sites Timber Creek – Spray Site

31. Field Sites Flax Pond – Control

32. Field Activities What was done… where and when

33. Results Survival of Fish Over Time Blue squares = sprayed sites DO data not available Results from first larvicide experiment

34. Results Survival of Fish Over Time Results from second larvicide experiment Timber Point survival significantly lower than Flax and Haven’s

35. Fish and Shrimp Survival for 8/3/04 Fish and Shrimp Survival for 8/3/04 L Percent Survival L

36. Results Survival of Fish Over Time Results from third larvicide experiment DO data not available for JN or HP after 12 Aug Timber significantly higher DO than all other sites.

37. Results Survival of Fish Over Time Results from first adulticide experiment

38. Results Survival of Fish Over Time Results from second adulticide experiment DO higher at John’s Neck than Haven’s Point for full experiment

39. Results Comparison of Fish and Shrimp Survival Over Time Corrected Percent Survival Results from second adulticide experiment

40. Results Summary of Mortality of Caged Organisms

41. What’s the Problem with Haven’s Point?

42. Results – Dissolved Oxygen Problem! Dissolved Oxygen and Temperature Time Series

43. Johns Neck DO <20% Diel DO - Spray Sites Timber Point DO TEMP

44. ebb flood Channel vs. Ditch Dissolved Oxygen Saturation Time (hours) photosynthesis respiration flood tide ebb tide Time (hours)

45. Results – Fish Growth Fish growth was low, averaging only 0.05 to 0.5 mm/day with no differences observed between sites

46. Results Shrimp Prey Capture Ability The ability of surviving shrimp to capture prey was highly variable, with no statistical decreases associated with pesticide exposure

47. methoprene methoprene resmethrin resmethrin methoprene No evidence of toxicity resulting from exposure to water collected from the spray sites

48. ResultsDosing Experiment Average LC50s: Scourge® ~ 0.58 g/L Sumethrin: ~ 1.1 g/L Resmethrin ~ 1.2 g/L TOXICITY: Scourge® > Sumethrin ~ Resmethrin NOTE: no methoprene-based chemical was toxic up to 1 mg/L concentrations

49. Results Benthic Species Abundance Note: “Other” represents the remaining 1% of species

50. Results Methoprene water column concentrations