Evaluation of cadmium's impact on marine mussels: insights from Raman spectroscopy and chemometric analysis

Raman spectroscopy allows rapid, non-invasive characterization of molecular changes in biological tissues, making it a promising tool for ecotoxicology. This study evaluates the potential of Raman spectroscopy combined with chemometrics for detecting changes induced by cadmium in the tissues of Mytilus edulis, a mussel species widely used in environmental monitoring. Adult mussels were exposed to two cadmium concentrations (50 µg/L and 500 µg/L) for 7 days. The cadmium concentrations in water and tissues of mussels (gills and mantle) were quantified by inductively coupled plasma mass spectrometry (ICP-MS) to determine bioavailability and bioaccumulation, with mantle cadmium levels reaching 3.94 ± 0.35 µg/g at 50 µg/L and 57.49 ± 7.16 µg/g at 500 µg/L. Raman spectra were collected from mantle and gill tissues, and were analyzed using principal component analysis (PCA) and K-means clustering. The mantle tissue exhibited a distinct molecular profile in response to cadmium exposure, with spectral variations indicating impairments in lipid, protein, nucleic acid, and carbohydrate metabolism. In contrast, the spectra of gill tissues did not show any discrimination among exposure treatments. These findings indicate that Raman spectroscopy with chemometric analysis could effectively detect early cadmium-induced biochemical alterations in Mytilus edulis tissues, especially in the mantle. This highlights its potential as a sensitive, non-invasive biomonitoring tool in ecotoxicological studies.