A rapid Lemna bioassay empowered by open-source image analysis.

Authors

Kübra Şentürk Azak, Sena Karin Kotancilar, Meryem Dindar, Nazlı Başaran, Sertan Genc, Ömer Bilen, Mete Yilmaz

Published in

Environmental monitoring and assessment. Volume 198. Issue 7. Jun 25, 2026. Epub Jun 25, 2026.

Abstract

Aquatic ecosystems are increasingly affected by complex combinations of pollutants, underscoring the need for rapid, economical, and efficient phytotoxicity assays. Despite Lemna minor being a standardized test organism, traditional bioassays predominantly depend on frond counting and visual assessment, which are time-consuming and subjective. This study enhanced a smaller, plate-based Lemna bioassay through quantitative, open-source image analysis, creating an efficient digital ecotoxicology procedure that requires minimal test volume. Potassium dichromate (K_₂Cr_₂O_₇) served as a reference toxicant for assay optimization. An image-based concentration-response study (0-160 ppm) demonstrated a distinct, dose-dependent inhibition of growth. The negative control exhibited a significant increase in frond area (from 20.56 ± 5.01 to 52.03 ± 1.78 px), while exposure to 40 ppm K_₂Cr_₂O_₇ led to nearly total growth inhibition and net tissue loss (growth rate: - 0.66 ± 1.78; growth inhibition: 104.97 ± 13.40%). Forty parts per million (ppm) was identified as the appropriate positive control based on biological significance and statistical validity. In the optimized time-course assay, control plants demonstrated sustained exponential growth over six days, whereas chromium-treated plants showed negligible or adverse effects on frond area, with a noticeable difference between treatments by day six. The frond area was measured using available software (GIMP and ImageJ), yielding objective, reproducible results with interobserver variability not exceeding 5%. The suggested small-volume, image-based Lemna assay improves sensitivity, repeatability, and throughput, while minimizing reagent consumption and experimental costs and providing a reliable instrument for regular aquatic toxicity assessment.

PMID:
42348010
Bibliographic data and abstract were imported from PubMed on 25 Jun 2026.

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