A method of assessing ecological risk to night heron, Nycticorax nycticorax , population persistence from dichlorodiphenyltrichloroethane exposure

This paper first introduces a probabilistic method for quantitatively evaluating the effects of chemical pollutants in the environment on a wildlife population, which was applied to assess the ecological risk to night heron ( Nycticorax nycticorax ) population persistence from dichlorodiphenyltrichloroethane (DDE) exposure in Tai Lake, China. Intrinsic rate of population increase ( r ) calculated with a population age‐structured matrix model was used to measure the adverse effect on population. To perform a probabilistic analysis of risk, lost intrinsic rate of population increase (Δ Z ) because of DDE exposure was applied to express the exact extent of risk. The result showed that the risk (i.e., the expectancy of Δ Z of the night heron population exposed to DDE in Tai Lake) was 0.0259, indicating a decrease in gross population size of 2.56% every year compared with that of the previous year without DDE exposure.