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 (ΔZ) because of DDE exposure was applied to express the exact extent of risk. The result showed that the risk (i.e., the expectancy of ΔZ 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.