Katherine von Stackelberg, ScD E Risk Sciences, LLP Bioaccumulation and Potential Risk from Sediment- Associated Contaminants in Dredged Materials

Risk depends on exposure and toxicity There is no zero- risk option Population variability in response Uncertainty –Exposure concentrations –System dynamics Integration with other analyses Different approaches available Bioaccumulation vs. Risk Years Risk A B B-A=Risk Reduction Benefit MNR Dredging Option A

TrophicTrace/BRAMS –“Screening” tool –Rapid evaluation of bioaccumulation potential –Steady state model – rophictrace/ rophictrace/ FishRand-Migration –Greater complexity –Incorporates spatial and temporal aspects of aquatic biota exposure –Probabilistic, time-varying Tiered Approaches to Bioaccumulation Modeling

Not Just a Single Number

Importance of Characterizing Uncertainty

Exposure Characterization in Bioaccumulation Models Bioaccumulation models do not represent fish behavior, foraging strategy, life history, habitat preferences Exposures represented by external processing (average, SWAC, etc.) Changes in exposure over time Either exposed or not – doesn’t capture dynamics of fish behavior Don’t consistently capture uncertainty and variability

FishRand Modeling Approach Sampling from a population of fish Movements and foraging strategies contribute to the distribution of predicted tissue concentrations Takes advantage of GIS-based data Probabilistic linkages –Decision analytic approaches –Integration with economic and other data

Pre-Remedy Selection

Post-Remedy Selection MDS Daily Movements Attraction Factor Seasonal Movement Home Range Foraging Area

FishRand Application

Results for Largemouth Bass

Implications for Risk Assessment

Linkages to Other Analyses

Conclusions Tiered approaches to modeling: “screening” to complex –Balance data availability, resources, objectives Even screening level assessments should quantify uncertainty Important to consider linkages to other analyses Sustainable sediment solutions and complexity of data and analyses require integrative approaches –Watershed scale –Decision analytic frameworks