Assessing Ecological Risks Posed by Commercial Navigation on the Upper Mississippi River. S. M. Bartell, SENES Oak Ridge, Inc., Center for Risk Analysis, 102 Donner Drive, Oak Ridge, TN 37830
Methods and approaches for assessing ecological risks have
been developed primarily to characterize the risks associated
with the release of toxic chemicals into the environment.
However, ecological risks can also result from physical
disturbances. This presentation will address the potential
ecological risks posed by projected increases in commercial
navigation traffic on the Upper Mississippi River System (UMRS).
Ecological resources possibly at risk include populations of a
diverse fish community, freshwater mussels, and rooted aquatic
plants. Risks might result directly, for example, through the
mortality of fish eggs and larvae that become entrained in the
volume of high energy and physical shear stress surrounding the
propellers and hulls of moving tugboats and barges. Risks might
also result indirectly, for example, from shoreline or backwater
habitat degradation associated with an increase in the frequency
of passing barges. The ecological risk assessment of increased
navigation, currently in progress, uses a combination of
site-specific ecological and environmental data, ecological
models, and physical models to estimate the probability of
different magnitudes of ecological impacts as a function of
anticipated traffic intensity. Forecasts of the expected increase
in commercial traffic are based on economic model projections
developed for the UMRS over a 50-year period (2000-2050).
Particular challenges offered by this assessment include the
large spatial-temporal ecological scale of the UMRS, incomplete
understanding of the biology and ecology of the species of
concern, and the paucity of environmental data for the UMRS.
Preliminary evaluation of the navigation assessment suggests that
ecological risks posed by physical disturbances can be analyzed
effectively using a general conceptual framework developed to
assess risks posed by toxic chemicals.
Work supported by Harland Bartholomew & Associates, Inc.
under Contract DACW43-93-D-0514.