EFFECTS ASSESSMENT Doug Clarke Douglas.G.Clarke@usace.army.mil
RISK FRAMEWORK RISK ASSESSMENT PARADIGM Exposure Assessment Economic Analysis, Socio-Political, Engineering Feasibility Problem Formulation Risk Characterization Risk Management Effects Assessment Risk = f (Exposure + Effect)
Topics Typical Receptors Modes of impact Dose-Response Relationships Characteristics of Exposure Characteristics of Response Hypothetical examples
Sssssome Receptors of Interest SUBMERGED AQUATIC VEGETATION SEA TURTLES STRIPED BASS STURGEON SALMON SHAD SHELLFISH SEAGULLS SPAWNING HABITAT SENSITIVE LIFE HISTORY STAGES
Some Receptors of Interest AND DON T FORGET TIGER BEETLES PIPING PLOVER MANATEES OYSTERS FLOUNDER WALLEYE CORAL FW MUSSELS LEAST TERN NURSERY OR FORAGING HABITAT
Stressors Chemical Contaminants WQ (e.g., ammonia, sulfides, nutrients, DO) Physical Total Suspended Solids/Turbidity Light Attenuation Deposition Altered Habitat Hydraulic entrainment Noise Blasting
Factors That Influence Effects Ambient conditions Static versus dynamic dose Duration of exposure Intensity of exposure Life history stage Egg Larval Juvenile Adult Species-specific behavior
THRESHOLD MODEL RESPONSE NO OBSERVED ADVERSE EFFECT LEVEL Linear CONTROL DOSE (CONC. X DURATION)
THRESHOLD MODEL Non-Linear RESPONSE NO OBSERVED ADVERSE EFFECT LEVEL CONTROL DOSE (CONC. X DURATION)
Hypothetical Receptors Outmigrating juvenile salmon Adhesive fish eggs at offshore spawning habitat Endangered freshwater mussels
LAKE IMPERIAL Spawning Habitat Mussel Bed Mussel Bed Placement Site Spawning Habitat BURNING BRIDGES, TODDAHO Dredging Site
Hypothetical Fish Receptor Ironhead Salmon (Oncorhynchus whopperi)
Fish Exposure to Plumes Concentration (mg/l) Contours of depth Fish Migration Corridor
Dynamic Dose Concentration Time
Hopper Dredge TSS Time Series 50 45 Top 40 Middle 35 Bottom Concentration (mg/l) 30 25 20 15 10 5 0 16-Aug 17-Aug 18-Aug 19-Aug 20-Aug 21-Aug 22-Aug Time (days)
Bucket Dredge TSS Time Series 500 450 Top 400 Middle Concentration (mg/l) 350 300 250 200 150 Bottom D Cdt 100 2.2 kg*hr/m 3 50 0 15-Aug 17-Aug 19-Aug 21-Aug 23-Aug 25-Aug Time (days)
Depth (m) Bucket Dredge Plume Hopper Dredge Plume Cross-section Distance (m)
Response Characteristics Severity of effect Behavioral Sublethal Lethal Reaction Distance (cm) 120 100 80 60 40 20 EL50s Brook trout Chinook salmon Brook, Lake, and Rainbow trout Rosyside dace 0 0 10 20 30 40 50 60 Turbidity (NTU)
SEV EFFECT 0 No effects 1 Alarm reaction 2 Abandonment of cover 3 Avoidance response 4 Short-term reduction of feeding rate or success 5 Minor physiological stress; coughing or increased respiration rate 6 Moderate physiological stress 7 Moderate habitat degradation or impaired homing 8 Major physiological stress; long-term reduction in feeding rate or success 9 Reduced growth rate; delayed hatching; reduced fish density 10 0-20% mortality; increased predation; severe habitat degradtion 11 >20-40% mortality 12 >40-60% mortality 13 >60-80% mortality 14 >80-100% mortality (based on Newcombe and Jensen 1996)
Juvenile Salmonids 10 6 10 5 Behavioral Sublethal Lethal Concentration, mg/l 10 4 10 3 10 2 Limits of Probable Exposure to Dredge Plumes 10 1 10 0 0.1 1 10 100 1000 Duration, days
Suspended Sediment (mg/l) 1000000 100000 10000 1000 100 10 Juvenile Salmonids Severe Risk Moderate Risk Minor Risk 1 0.01 0.1 1 10 100 1000 Exposure Duration (Days)
Suspended Sediment (mg/l) 1000000 Juvenile Salmonids 100000 10000 1000 100 10 1 0.01 0.1 1 10 100 1000 Exposure Duration (Days) No Effect Behavioral Sublethal 10-25% Mortality 26-75% > 75%
Fish Receptor Response Characteristics Aspects of response relevant to risk management Seasonality Migration rate affects duration of exposure species specific (e.g., 0.75 1.5 miles/hr) Threshold with respect to maximum exposure Threshold with respect to duration Reliance on lab versus field-derived data Behavioral effects based on few observations Sublethal effects based on indirect measures (e.g., levels of stress hormones in blood) Lethal effects based entirely on lab data using a static dose
Hypothetical Fish Egg Receptor Fallguy (Sander toddahoiensis)
12 Number of Days 10 8 6 4 2 0 6 9 Dredge Rate of Advance (m/hr) 12 15 250 18 500 750 1500 1250 1000 SS Plume length (m) Duration of exposure for a sessile receptor such as adhesive fish eggs, bivalve mollusks, or SAV will depend on plume dimensions and dynamics in relation to the rate at which the dredge moves through the project site. (from Wilber and Clarke 2001)
Dredging-Induced Deposition > 0.5 mm depicted in red/yellow contours Bucket Dredge Hopper Dredge
Time Series of Deposition Deposition (mm) 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 Clamshell Deposition Hopper Deposition 0 14-Aug 19-Aug 24-Aug 29-Aug Time (days)
Deposition at Offshore Placement Site Barge Placement Hopper Dredge Placement > 0.5 mm depicted in red/yellow contours
4.5 Time Series of Deposition Deposition (mm) 4 3.5 3 2.5 2 1.5 1 0.5 Scow Hopper 0 15-Aug 17-Aug 19-Aug 21-Aug 23-Aug 25-Aug 27-Aug 29-Aug Time (days)
Effects of SS on Fish Eggs Acute Exposure Abrasion/occlusion of chorion Plugging of micropyle Chronic Exposure Delayed hatching mediated by physiological response to impaired gas exchange Accelerated hatching mediated by turbidity-induced change in water temperature regime
Effects of Sedimentation on Fish Eggs Sublethal Interference with fertilization Abraded surface membranes and impaired gas exchange Loss of adhesion (for adhesive eggs) Delayed cell cleavage and differentiation Interrupted or incomplete development Delayed hatching and impaired larval development Lethal Physical removal during dredging process Mortality associated with partial or total burial
Summary of Deposition Effects on Fish Eggs Timing of acute exposure could be critical Once fertilized, most eggs are relatively tolerant of SS Net deposition of less than half an egg diameter should be tolerated by most species
Hypothetical Mussel Receptor Brainsplitter (Unio idontknowicus)
Potential Mussel Exposures Acute exposures Smothering and burial Chronic exposures Elevated sedimentation rates and persistent overburden Elevated TSS
Effects of Sedimentation on Mussels Behavioral Responses Use of foot to migrate vertically Temporary valve closure Physiological Responses Increased inorganic/organic intake ratio requires greater metabolic expenditure for clearance Change in excretion rate/excretion products Reduced gonad development and interference with reproductive cycle Decreased calcification / growth Increased respiration rate Greater susceptibility to parasites/pathogens Lethal Suffocation
Summary of Effects on Mussels Short-term exposures (up to a week) of elevated SS or deposited sediment tolerated well by clamming up. Thin-shelled lentic species are relatively mobile, capable of migrating upward through overburden Long-term deposition (> month of 2 cm) could cause mortality of thick-shelled lotic species. Thin-shelled lentic species are better adapted to depositional conditions.
The End
Key References Fleming, S. et al. 2005. Magnitude-duration based ecological risk assessment for turbidity and chronic temperature impacts: Method development and application to Millionaire Creek. British Columbia Ministry of Environment, Surrey. Newcombe, C. and Jensen, J. 1996. Channel suspended sediment and fisheries: A synthesis for quantitative assessment of risk and impact. N. Amer. J. Fish. Management 16:693-727 Wilber, D. and Clarke, D. 2001. Biological effects of suspended sediments: A review of suspended sediment impacts on fish and shellfish with relation to dredging activities in estuaries. N. Amer. J. Fish. Management 21(4):855-875