ssdtools v2: An R package to fit Species Sensitivity Distributions
Joe Thorley, Rebecca Fisher, David R. Fox, Carl J. Schwarz
Abstract
Species sensitivity distributions (SSDs) are cumulative probability distributions that are used to estimate Hazard Concentrations (HC ) -the concentration of a chemical that is expected to affect a given % 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 ) is the proportion of species affected by a given concentration .ssdtools is an R package (R Core Team, 2024) to fit SSDs using Maximum Likelihood (Millar, 2011) and estimate HC and HP 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.