What this Bayesian Species Sensitivity Distribution RShiny app does

This Bayesian Species Sensitivity Distribution web app performs a single-site ecological risk assessment for microplastic particles by translating your measured particle data into two complementary risk outputs:

• Fraction affected (predicted fraction of aquatic species expected to be affected at your site), reported as a posterior median with a Bayesian credible interval. (yuichiwsk.shinyapps.io)
• Converted concentration (µg/L): your measured mixture expressed as an equivalent concentration of a reference particle category (non-fiber, large ≥83 µm) to visualize the relative contribution of different particle categories to overall risk. (yuichiwsk.shinyapps.io)
• Measured concentration (µg/L) (your observed, mass-based site concentration as calculated from your upload + analyzed water volume). (yuichiwsk.shinyapps.io)

Methodological basis (why it’s interesting)

The app implements species sensitivity distributions (SSDs) built using a hierarchical Bayesian framework that is explicitly designed to incorporate particle characteristics and intra-species variation (multiple tests per species), rather than forcing a single value per species.

The paper describing this approach (Iwasaki et al. (2026). “Bayesian species sensitivity distribution modeling for microplastic particles: integrating particle characteristics and intra-species variation”, Environmental Toxicology and Chemistry.) emphasizes that particle traits like length and shape can meaningfully influence SSD-derived hazard patterns.

The manuscript also notes that, while HC5 values for real environmental mixtures are difficult to estimate directly with these models, the fraction of species affected can be estimated when paremeters are available – and it points to this exact web app as an available implementation.

Inputs

Upload a CSV where each row is one particle, with these required headers (must match exactly): (yuichiwsk.shinyapps.io)

• major axis length µm
• minor axis
• You must also enter how much water (L) you analyzed so the app can compute concentration. (yuichiwsk.shinyapps.io)
  Extra columns (e.g., station ID, polymer) are allowed. (yuichiwsk.shinyapps.io)

How to interpret outputs

• Fraction affected is the most “risk-direct” output: it is already on an ecological effect scale (fraction of species). The app explains that the “50%” value is the posterior median, and the 5–95% range corresponds to a 90% credible interval. (yuichiwsk.shinyapps.io)
• Converted concentration is explicitly not meant to be interpreted as a literal environmental concentration; it’s a normalization/visualization to show how different particle categories change inferred risk relative to the reference particle. (yuichiwsk.shinyapps.io)

Focus keywords

• microplastics SSD app
• fraction of species affected
• Bayesian species sensitivity distribution
• microplastic ecological risk assessment
• particle size and shape toxicity

“Try the Tool” callout (copy/paste box)

Try it: Upload a particle-level CSV (major axis, minor axis, mass) + analyzed water volume to estimate fraction of species affected and SSD-based summary metrics. (yuichiwsk.shinyapps.io)

Internal-link recommendations (Plastiverse)

• Sampling & QA/QC pages (to ensure particle-level measurements are comparable and defensible)
• Analytical methods pages (spectroscopy/py-GC/MS etc., depending on how mass was derived)
• Risk assessment frameworks (SSD basics, alignment approaches, and mixture interpretation)

If you want, paste your standard Plastiverse “Tools & Resources” template sections (or a prior post URL you like), and I’ll drop this content into your exact house format without changing your voice.