"Estimation of indirect effect potential of chemicals for fish population using an ecosystem effects model (CASM_SUWA) " 

Wataru Naitou¹, Ken-ichi Miyamoto¹, Junko Nakanishi¹, Shigeki Masunaga², Steven M. Bartell³

¹National Institute of Advanced Industrial Science and Technology
²Yokohama National University
³The Cadmus Group, Inc

SETAC North America 23rd Annual Meeting (Salt Lake City, USA 2002/11/19)

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Abstract

With increasing awareness of the importance of cost-effective and efficient methods for assessing the ecological impact of chemicals, population and ecosystem models could be used to explore the consequences of exposure to chemicals.

 Comprehensive Aquatic Systems Model (CASM) is a bioenergetic ecosystem effects model that simulates the daily production dynamics of populations, including predator-prey interactions, with time in relation to daily changes in light intensity, water temperature, and nutrient availability. 

In this study, we used a Lake Suwa version of Comprehensive Aquatic Systems Model (CASM_SUWA), which includes five phytoplankton populations, three zooplankton populations, two benthic invertebrate populations, a single macro-crustacean population, three omnivorous fish populations, and a single piscivorous fish population, to demonstrate the risk estimation of 10 different chemicals (e.g., LAS, PCP, atrazine, copper, chlorpyrifos, diazinon, DEHP) and examined the applicability and reliability of the model in ecological risk assessment.

We also propose an index to quantify the potential of indirect effect (IEP) of chemical for fish population based on the results of CASM_SUWA simulations. The qualitative comparison of the model results with those of the reported mesocosm tests indicated that some evidence observed in mesocosm studies supported the indirect effects predicted from simulation using the model. 

Atrazine, diazinon and chlorpyrifos were examples of chemicals which showed higher IEP values indicating that these chemicals may pose higher potential of indirect effect on fish population. Our study demonstrated that the model can be used in evaluating potential indirect effects of chemical exposure in some general aquatic ecosystems and in making effective risk management decisions by enhancing the values of risk estimates.

Keywords

ecological risk, indirect effect, ecological model, CASM