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Burton Suedel, C.H. Lutz, J.U. Clarke, D.G. Clarke USACE-ERDC-EL , Vicksburg, MS PowerPoint Presentation
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Burton Suedel, C.H. Lutz, J.U. Clarke, D.G. Clarke USACE-ERDC-EL , Vicksburg, MS

Burton Suedel, C.H. Lutz, J.U. Clarke, D.G. Clarke USACE-ERDC-EL , Vicksburg, MS

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Burton Suedel, C.H. Lutz, J.U. Clarke, D.G. Clarke USACE-ERDC-EL , Vicksburg, MS

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  1. Burton Suedel, C.H. Lutz, J.U. Clarke, D.G. Clarke USACE-ERDC-EL, Vicksburg, MS C. Godard-Codding and J. Maul The Institute of Environmental and Human Health Texas Tech University Lubbock, TX Dredging 2012 San Diego, CA 24 October 2012 The Effects of Suspended Sediment from Western Lake Erie on Walleye (Sander vitreus) Eggs and Fingerlings?

  2. Sediment Resuspension The most frequently cited concern related to restrictions imposed on dredging schedules Exposures may affect: Spawning or foraging behavior Egg hatching success and larval development Disrupt anadromous fish migrations Physical disturbance of habitat by increased sedimentation rates Engbretson Underwater Photography WEDA 32 & TAMU 43

  3. Setting Environmental Windows is Controversial EW: Time periods that allow dredging No consistent, broadly accepted methodology for objectively setting EWs has emerged Often set without scientific basis Established by negotiations emphasizing conservative professional judgments Lack of effects data for suspended sediments on species used to set EW WEDA 32 & TAMU 43

  4. Maumee Bay Study Area Spawning Area Larval Nursery Area WEDA 32 & TAMU 43

  5. Near-field Plume Conditions Maumee Bay Study Area Distance from Dredge: 3m Entrained Air Plume Width 50 m Max. TSS 800 mg/l LWC Max. Turb. 700 NTU (15 m) < 300 NTU (30m) 15 m 46 m 30 m UWC Max. Turb. 175 NTU (15 m) 50 NTU (30m) Ambient in < 50 m

  6. Materials and Methods • Flow-through Fish Larvae and Egg Exposure System (FLEES) • 3 modules/3 500 L water baths/15 aquaria • Aquaria (15) constructed from 20 L polyethylene carboys • Pump recirculated water and suspended sediment in aquaria • Sediment mixed with water and stored in 375 L tank via double diaphragm pump • Slurry routed through FLEES and reused • Sediment concentrations monitored using OBS WEDA 32 & TAMU 43

  7. Materials and Methods • Walleye (Sander vitreus) • Four experiments: northern and southern strain eggs (newly spawned) and fingerlings (45-60 d old) • Sediment: Maumee Bay, Ohio (Lake Erie) • Concentrations: 0, 100, 250, 500 mg/L TSS • Duration: 3 days (72 h) • Temp: 10-13°C eggs; 14-17°C fingerlings • PVC cups for containment WEDA 32 & TAMU 43

  8. Experiments and Endpoints Two Phases 2010 2011 Northern and Southern Strains Fingerlings – survival, coiling, scoliosis, lordosis/kyphosis, gill integrity Eggs – viability and hatchability, wet and dry mass WEDA 32 & TAMU 43

  9. 2010 No. Viable Northern Strain Eggs No significant differences among treatments were observed for viable eggs (Anova, F=0.38, P=0.7678). WEDA 32 & TAMU 43

  10. 2010 No. Viable Southern Strain Eggs No significant differences among treatments were observed for viable eggs (Anova, F=3.53, P=0.0681). WEDA 32 & TAMU 43

  11. Southern Strain Fingerling Survival Fingerling survival did not differ significantly among TSS treatments (Anova, F=2.74, P=0.113). WEDA 32 & TAMU 43

  12. Northern Strain Fingerling Gill Lamellae Fingerling gill lamellae did not differ significantly among TSS treatments. WEDA 32 & TAMU 43

  13. Percent Hatch of Northern Strain Eggs No significant differences among treatments were observed for percent hatch (Anova, F=1.15, P=0.386). WEDA 32 & TAMU 43

  14. Number of Viable Northern Strain Eggs No significant differences among treatments were observed for viable eggs (Anova, F=0.56, P=0.6533). WEDA 32 & TAMU 43

  15. Wet Mass Northern Strain Eggs No significant differences among treatments were observed for viable eggs. WEDA 32 & TAMU 43

  16. Implications • These experimental data can be used with dredge plume characterization data that were obtained for bucket dredging in Maumee Bay to assess potential risk to walleye. • Current EW restrictions in Lake Erie may merit review in light of reduced uncertainty regarding risk associated with effect thresholds within the range of dredging-induced perturbations. WEDA 32 & TAMU 43