1. Risk Assessment of Atrazine on Blue Crabs and Chesapeake Bay Ecosystem Caitlin Andrews Russell Ford David Lucero Henrietta Oakley Satish Serchan

2. Overview of the presentation Atrazine production and application Controversy surrounding Atrazine Chesapeake Bay and Blue Crab habitat Studies of Atrazine on crustaceans, Submerged Aquatic Vegetations (SAV) Alternatives to Atrazine

3. Purpose of this study Atrazin e Amphibians Crustacean s SAVs Blue Crab

4. Blue Crab Alert Blue crabs-the stock has undergone an 85% decline since 1990. (SERC) –Complex migratory life cycle –Salinity gradient –SAVs and zooplanktons

6. Atrazine Use & Application Broad-leafed herbicideBroad-leafed herbicide –Inhibiting the photosynthesis 19581958 Syngenta CorporationSyngenta Corporation CornCorn 76 to 85 million pounds annually76 to 85 million pounds annually

7. Atrazine Cont’d regulated under water statutesregulated under water statutes Maximum Contaminant Level Maximum Contaminant Level –MCL of 3.0 ppb Surface and groundwater persistenceSurface and groundwater persistence –Chesapeake Bay show that levels can exceed 100 μg/L (ppb) with at least 30 days of persistence (EPA 2007)

8. Controversy (EPA Story) Low acute toxicity (EPA) Not likely to be human carcinogen Hormonal effects on lab animals resulted from short term exposure

9. Dr. Tyrone Hayes Studies Scientific Advisory Panel hired by Syngenta > 0.1 ppb of Atrazine in surface water effectively turning males into hermaphrodites Compare EPA’s MCL 3.0 ppb to 0.1 ppb

10. Hermaphroditic, demasculinized frogs after exposure to the herbicide atrazine at low ecologically relevant doses Tyrone B. Hayes, et al. UC Berkeley Laboratory for Integrative Studies in Amphibian Biology

16. Demasculinized frogs found near Mid-western Farm Fields where Atrazine in use

20. Blue Crabs: An Indicator Species

21. Indicator Species Ecological Reasons Socioeconomic Reasons Distributes itself based on ecological and anthropogenic changes

22. Blue Crab Life Cycle

23. Megalopae Responsible for selecting a secure habitat which will influence their survival into adulthood. Eel Grass Smooth Cordgrass Prefer structural complexity -3D grass habitats Actively seeks prey

24. Megalopae and juveniles live in estuaries in and close to the mouth of the nine large rivers and numerous other creeks that flow into the Chesapeake Bay. Atrazine in agriculturally dominated area reach as high as 100 μ /L for periods as long as 30 days. Atrazine’s Influence on the Food Chain

25. Phytoplankton in Chesapeake Bay 354 species of phytoplankton The bloom and bust cycles of these species of phytoplankton are complicated with a few species dominating the resources in different sections of the estuary. Green algae and Dinoflagellates – lowest tolerance (<50μg/L) Diatoms – higher tolerance (250μg/L)

26. SAV’s Submerged Aquatic Vegetation How atrazine affects SAV’s –Chloroplast function –Oxygen production –Habitat Hypoxia Habitat structure Predator/prey relationships and trophic cascades

27. Studied effects of atrazine on Elodea canadensis Found increased levels of fluorescence inversely associated with levels the effective quantum yield of photochemical conversion 50% inhibition in Oxygen production when atrazine concentrations were 50-75 ug/l –Damage to Chloroplast function No Oxygen production at 500 ug/l atrazine Microbioreactor Study

28. Effects of Hypoxia Increases cannibalism by adult Blue Crabs –Chronic hypoxia causes predator densities to increase in shallower habitats –Juvenile Blue Crab densities decrease exponentially in response –Periodic hypoxic up swellings do not have the same affect; adult Blue Crabs migrate to suitable waters Changes habitat structure and function

31. Hypoxia Alterations in predator/prey interactions –Species have different responses and tolerances –Crustaceans have relatively low hypoxia tolerance –Blue Crabs migrate from hypoxic regions, as well as use them to hunt impaired species Change in behavior –Prey dumber by hypoxia – behavioral differences observed –Species interactions important in ecosystem structure

32. Crustaceans: the Blue Crab How the Blue Crab will be affected by –Loss of SAV production SAV’s are primary producers, providing oxygen, nutrient cycling, and serving as food and shelter –Hypoxia Chesapeake Bay experiences periodic low oxygen stress, especially in the summer Often has sublethal effects Alters habitat structure and function –Predator/prey interactions

33. Land Use and Crustacean Abundances Negative correlation with agricultural land use and Blue Crab abundances Hypoxia associated with Ag land use –Seasonal (summertime) hypoxia coincides with herbicide/pesticide/ fertilizer applications –Atrazine part of this mix supports negative feedback loop Increases hypoxia

34. Summary 85% stock Blue Crab Decline since 1990 High levels of Atrazine in Chesapeake Bay Dr. Tyrone B. Hayes extensive research of Demasculinized frogs Seen the affects of Atrazine on SAV So let’s just get rid of Atrazine?

35. Alternative University of Kentucky College of Agriculture: Reduce the use of atrazine with post- emergence herbicides Only use post-emergence herbicides

36. Pros The amount of herbicide needed will be better judged Can be cheaper since extra herbicide will not be used Can also be cheaper because post- emergence herbicide can be cheaper than pre-emergence

37. Cons May require re-application Requires more training and careful management by the farmer Can cost more because re-application is needed: more herbicide and energy needed Injury to corn crop can occur

39. Alternatives/Whats next? More testing needed; more field data vs. lab data Atrazine is one of many chemicals entering the watershed and the specific affects may be difficult to determine May have an additive quality, enforcing negative feedback loops in the presence of other pollutants