Assessing microplastic exposure and pollution risk in sympatric Panulirus lobsters using machine learning-based pollution risk modeling

Plastic pollution has escalated globally, with microplastics (MPs; 1 µm–5 mm) and nanoplastics becoming pervasive across marine systems and posing growing ecological and human-health concerns. Decapod crustaceans, particularly lobsters, are vulnerable to MP exposure due to their benthic habits, omnivorous feeding, and long lifespans, yet species-level comparisons remain limited. This study provides the first Machine Learning integrated comparative assessment of MP ingestion across five sympatric spiny lobsters, Panulirus homarus homarus , P. ornatus , P. versicolor , P. regius , and P. penicillatus from tropical Indian waters, offering new insights into species-specific accumulation patterns and their utility as bioindicators of benthic MP pollution. MPs were detected in all species, with concentrations ranging from 0.18 to 1.05 MPs g⁻¹ of gastrointestinal tissue (GIT). P. versicolor exhibited the highest MP density, while P. penicillatus showed the lowest. Fibres and pellets predominated, and blue and red were the most common colours. ATR-FTIR and confocal Raman microscope identified PE, PP, PET, PC, nylon-66 and cellulase as major polymers. PCA demonstrated clear species-level separation driven by MP density and polymer composition. Random Forest classification identified MP concentration, fine-particle proportions ('500 µm), and fibre, pellet dominance as the strongest predictors of exposure risk, classifying P. versicolor as High-Risk. Polymer Hazard Index (PHI) and Pollution Risk Index (PRI) values varied across species, with P. versicolor again showing the highest hazard potential. SEM confirmed synthetic fibre morphology and evidence of environmental weathering. These results demonstrate substantial interspecific variation in MP accumulation and highlight the suitability of Panulirus spp. as bioindicators of benthic MP pollution. The findings provide essential baseline data for seafood safety, ecological risk assessment, and the development of targeted mitigation strategies for plastic-pollution in tropical marine systems.