1. Pesticides in Chesapeake Bay Tributaries and Potential Impacts
Thanks for change to speak and want to cover where your efforts fit into USGS Chesapeake Science strategy and meeting the needs of the Bay Program
Vicki Blazer, PhD
U.S. Geological Survey
National Fish Health Research Laboratory
Leetown Science Center

2. Fish Health Issues in the Chesapeake Watershed
Skin lesions and mortality of adult fishes – spring, adult fish
South Branch of the Potomac
Shenandoah
Monocacy
Young-of-year mortality
Susquehanna
Finding high prevalence of intersex in the same areas as mortalities

3. Fish Kills and Skin Lesions
2003 – first indications of major fish kills in the South Branch, Potomac
– first observations of major kills in the North Fork and South Fork Shenandoah
2009 – major kill in the Monocacy
State agencies estimated losses of >60% of the adult bass populations in affected stretches of the rivers in first few years
Primarily centrarchids (smallmouth bass, sunfish) but also suckers, rock bass, etc.
Still sporadic kills, skin lesions and low chronic mortality

4. Complexities of Pesticides and Other Chemicals of Emerging Concern in Wild Populations
Many were produced to have a biological effect and so may affect nontarget organisms at very low levels
Endocrine/Immune systems - chemical communication and feedback mechanisms
Lack of classic dose response curve – hormesis
Multiple contaminant exposure routes - water, sediment, food (yolk sac)
Short term exposure at sensitive life stages can have long term effects
Additive, synergistic

5. Affected Adult Fish in the Potomac
Multiple bacterial pathogens, but no consistent findings
Aeromonas hydrophila and other motile Aeromonads
Aeromonas salmonicida
Flavobacterium columnare
Multiple, often heavy parasite infestations
Leeches, trematodes, myxozoans, cestodes
Opportunistic fungal infections
Skin papillomas
Largemouth Bass Virus
High prevalence of intersex, vitellogenin in male fishes
Impaired Ecosystem
Immunosuppression

6. Young-of-year Smallmouth Bass Susquehanna Drainage
Aeromonas hydrophila and other motile Aeromonads
Flavobacterium columnare
Largemouth Bass Virus
Trematodes
Myxozoan parasites

7. What We Learned from the “Historic Summary”
Bass are very sensitive to estrogenic endocrine disruption in agricultural watersheds
Did not see a relationship with disease or indicators of estrogenic exposure (intersex, vitellogenin) with wastewater treatment effluent
Did see relationships with % agricultural landuse, confined animal feeding operation and agricultural herbicides/pesticides
See considerable spatial variation as well as temporal variation monthly and yearly in total estrogenicity as well as fish health indicators

8. Correlations with Landuse and Chemicals PA Drainages
Study done in late summer, 16 sites in three river drainages – Ohio, Susquehanna, Delaware
Discrete water samples at time of fish sampling
Chemical
Contaminants or Landuse
Intersex Prevalence
rho p
Intersex Severity
rho p
Estrone (water)
0.7609
0.0055
Agricultural landuse
0.7044
0.0129
WWTP/sewage facilities
0.0936
Prevalence of males with vitellogenin

9. Potomac Spawning Study
7 sites in Potomac/Shenandoah
Conducted at spawning sites
Intersex prevalence only significantly correlated with % ag and animal density in watershed above the site; intersex severity correlated with % ag, animal density, # of AFO, # poultry houses and WWTP flow
No estrogen hormones were detected in discrete water samples; atrazine and metolachlor conc. correlated with prevalence and severity; total biogenic hormones and plants sterols in sediment correlated with prevalence and severity

10. Intersex and Chemical Contaminants Spawning Study
Intersex Prevalence
Intersex Severity
rho P p
Atrazine
0.88
0.009
Deethylatrazine
0.68
0.090
Acetochlor
0.79
0.036
Metolachlor
0.81
0.028

11. Sediment Chemical Results
Intersex Metric*
ρ = 0.986, p<0.001
Total Biogenic Hormone + Plant Sterol, in μg/kg