Figure 2
The Stress Addition Model (SAM).
(A,B) Individual stress capacity within a population, beta-distributed. Under stress conditions, individuals with a stress capacity below the given stress level will die (A), orange area - environmental stress, SENV; (B), red area - toxicant stress, STOX) and individuals with a stress capacity above the present stress level will survive (A and B, blue area). (C) The total stress that is exerted on a population is calculated as the sum of single stress levels of independent stressors (orange and red areas). Only individuals with a stress capacity above the total stress will survive. (D) The joint effect expressed as a stress-related survival curve (see Methods for a mathematical description).
