ssdtools v2: An R package to fit Species Sensitivity Distributions
Joe Thorley, Rebecca Fisher, David R. Fox, Carl James Schwarz · The Journal of Open Source Software · 2025
Species sensitivity distributions (SSDs) are cumulative probability distributions that are used to estimate Hazard Concentrations (HC 𝑥 ) -the concentration of a chemical that is expected to affect a given 𝑥% of species.HC 5 values, which are intended to protect 95% of species, are often used for the derivation of environmental quality criteria and ecological risk assessment for contaminated ecosystems (Posthuma et al., 2001).The Hazard Proportion (HP 𝑢 ) is the proportion of species affected by a given concentration 𝑥.ssdtools is an R package (R Core Team, 2024) to fit SSDs using Maximum Likelihood (Millar, 2011) and estimate HC 𝑥 and HP 𝑢 values by model averaging (Schwarz & Tillmanns, 2019) across multiple distributions (Thorley & Schwarz, 2018).The shinyssdtools R package (Dalgarno, 2021) provides a Graphical User Interface to ssdtools.