1. Complexities of Understanding Chemical Exposures
Many current use chemicals are 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

2. Adults - recrudescence
Key Exposure Periods
Nest/eggs – sediment/water
Water food, sediment
Water, maternal, sediment
Final maturation,
sperm quality
YOY – sexual differentiation
and organ development
Adults - recrudescence
April – May June – July August – Dec - March

3. 2013-2014 Temporal Sampling Big Pipe Creek/Bruceville, MD
Herbicides were the most commonly measured chemicals
Date
Atrazine
Metolachlor
Simazine
5/15/2013
364
228
343
6/11/2013
223
215
7/11/2013 45 61 20
8/28/2013 37 34 13
4/4/2014 26 30 12
4/15/2014 46 63 24
4/30/2014
3270
703
2420
5/12/2014
201 93
112
5/16/2014
5400
4640 76
5/30/2014
2870
1610
1980

4. Chemicals Less Commonly Observed
Clothianidin – neonicotinoid insecticide
Thiamethoxam – neonicotinoid insecticide
Metalaxyl - systemic fungicide
Carbaryl – carbamate insecticide
Carbamazepine - anticonvulsant
Dimethylxanthine – caffeine metabolite
Methadone – synthetic opioid

5. Mercury in Smallmouth Bass Fillets
2013 – ranged from 0.88 to 2.19 ppm
Mean of all 20 fish was
<0.09 ppm is considered low
0.09 to 0.29 is considered moderate
0.3 to 0.49 is considered high