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

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

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

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

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