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Jessica D. Bennett

Effects of Methylmercury and Acidity on Macroinvertebrate Gills from the Neversink Reservoir Tributaries. Jessica D. Bennett. Background. MeHg accumulates in the gills via water Some fish, crab and lobster Herbivores Gills are especially sensitive Increased surface area

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Jessica D. Bennett

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  1. Effects of Methylmercury and Acidity on Macroinvertebrate Gills from the Neversink Reservoir Tributaries Jessica D. Bennett

  2. Background • MeHg accumulates in the gills via water • Some fish, crab and lobster • Herbivores • Gills are especially sensitive • Increased surface area • Rapid movement of water over their surface • Ability to accumulate compounds and gases

  3. Ephemeroptera Respiration Movie courtesy Alexander J. Smith of NYS DEC

  4. Field Study Sites

  5. Materials and Methods • Organism collection • Kick samples in riffle zone • Field Study • Insects identified to family in composite samples • Methylmercury concentration analysis • Cebam Analytical Inc. labs in Seattle, Washington • Laboratory Study • Aquaria establishment

  6. Materials and Methods • Laboratory Study • Laboratory study- Acidity trials • pH of 4,5,6,9 and a control of 7 • 4 week long trials • Laboratory study- Methylmercury trials 1 • 0.3 ppm at pH 4-5 and pH 7 • 0.15 ppm at pH 4-5 and pH 7 • 2 week long trials

  7. Materials and Methods • Laboratory study- Methylmercury trials 2 • 6 ppm at pH 4-5 and pH 7 • 3 ppm at pH 4-5 and pH 7 • 2 week long trials • Insect identification to species • Insect gill preparation • Gills removed at their proximal location

  8. Materials and Methods Insect Gill Deformity Identification Rating: 0 Rating: 1 Puckers, dimples, deterioration discoloration Puckers, dimples, deterioration Rating: 2 discoloration Rating: 3 Puckers, dimples, deterioration almost uniform Entire branch/stalk dimpled etc. Rating: 4 Few red spots Rating: 5 . Several red spots present

  9. Field Data Table Site: Tison Estate pH: 5.38 Temperature (ºC): 10.41 DO (mg/L): 9.41 Methylmercury concentration (ppm/wet weight): 0.00204

  10. Laboratory Data Table Methylmercury Trial 2

  11. Photographs of Impairment Primitive minnow mayfly Siphlonurus sp. Experimental Control

  12. Photographs of Impairment Northern case maker caddisfly Pycnopsyche sp. Control Experimental

  13. Photographs of Impairment Giant stonefly Pteronarcys proteus Experimental Control

  14. Photographs of Impairment Spiny crawler mayfly Eurylophella bicolor Experimental Control

  15. Photographs of Impairment Northern case maker caddisfly Pycnopsyche sp. Experimental Experimental Control

  16. Summary • Gill deformations are plausible in aquatic insect larvae • Gill deformations may be progressive • Dark discolorations to dimpling and red spots to singeing • Methylmercury and acidity may be synergistic

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