The neglected role of ciliates as bioindicators

The impacts of anthropogenic synthetic contaminants are becoming a serious concern, primarily due to their harmful effects on human health and adverse effects on ecosystems, biodiversity, and human well-being. Of more than 100 million chemicals, ~0.36% are regularised, as recorded in the Chemical Abstracts Registry database. Such chemicals ultimately contaminate water bodies and reduce the amount of potable water. It is estimated that about 50% of the human population will suffer from water shortages by 2025 if the present trend continues. Gause’s classical work in population ecology stimulated interest in working with ciliates as model organisms in ecotoxicology. Ciliates are good indicators for assessing saprobic water quality due to their abundance, ubiquity, and sensitivity to anthropogenic impacts. However, although more than 50 ciliate species are now in use as bioindicators, researchers should attempt to utilize the excellent potential of ciliates as bioindicators in large-scale studies, considering their availability and cost-effectiveness. Any change in the community composition of ciliates in response to environmental shifts is a powerful tool for biomonitoring and bioassessment.