Research Progress on the Olfactory Toxicity of Aquatic Pollutants to Fish
Olfaction is crucial for fish survival in complex aquatic environments, enabling detection and discrimination of odor signals that regulate foraging, predator avoidance, social interaction, courtship, and migration. The fish olfactory system, directly exposed to water, is highly susceptible to aquatic pollutants such as heavy metals and pesticides. This review summarizes the composition and structure of the fish olfactory system, the process of olfactory response, and current research on olfactory toxicity of major aquatic pollutants. Key findings indicate that pollutants like copper and cadmium disrupt olfactory epithelium integrity, alter olfactory sensory neuron (OSN) populations, and impair odor-driven behaviors. For instance, copper exposure in larval zebrafish causes differential death and regeneration of OSN populations, leading to neurobehavioral deficits. Cadmium exposure in juvenile coho salmon differentially alters odorant-driven behaviors and olfactory receptor expression. The review highlights the need for further research on mechanisms, mixture effects, and development of biomarkers for early warning. Understanding olfactory toxicity is vital for ecological risk assessment and for developing fish-based biosensors for water quality monitoring.