Response of freshwater periphytic diatoms to elevated cadmium concentration: results of an experimental study /
2025
Petrėnas, Gediminas, | Kazlauskas, Martynas, | Karosienė, Jūratė,
The study emphasises the importance of periphytic freshwater diatoms as bioindicators for assessing the impact of cadmium pollution on aquatic ecosystems. This approach offers significant advantages for the detection of ecological changes, such as shifts in diatom species diversity and community composition, as well as morphological changes, thus contributing to a deeper understanding of metal-related environmental risks. The aim of the study was to determine the effects of cadmium on the diversity and structure of periphytic diatom communities under laboratory conditions, and to evaluate the use of diatoms as bioindicators for cadmium exposure. During the entire experiment, in which four cadmium concentrations were tested (0 mg L–1, 0.01 mg L–1, 0.04 mg L–1 and 0.1 mg L–1), a total of 85 diatom taxa were found, with the greatest diversity in the control. However, no significant effect was found on diatom taxa richness, abundance and Shannon-Wiener diversity index. A multivariate analysis (NMDS, PERMANOVA) also showed no clear differences in the structure of the periphytic diatom community under cadmium exposure. However, the cadmium concentration in the treatments was reliably indicated by Navicula lanceolata, Navicula gregaria and Navicula rostellata, whose cell proportion decreased significantly with increasing cadmium content, and by Achnanthidium sp., and Fragilaria sp., whose proportion in the samples increased with increasing cadmium content. The frequency of deformation of frustules increased with higher cadmium concentrations and varied between 8.15% at 0.01 mg Cd L–1 and 12.36% at 0.1 mg Cd L–1. It was found that N. rostellata is the most susceptible to frustule deformation and could therefore represent the most valuable bioindicator among the periphytic diatoms analysed.
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