Sound stimulus effects on dusky damselfish behavior and cognition.

Anthropogenic noises are widespread and affect marine wildlife. Despite the growing knowledge on noise pollution in the marine environment, its effects on fish cognition are scarce. Here, we investigated the effects of sound exposure on anxiety-like behavior and memory retention on dusky damselfish Stegastes fuscus. The animals were trained in a conditioned place aversion task, and exposed to two daily sessions of music at intensities of 60-70 dBA or 90-100 dBA, while the control group was kept at 42-46 dBA (no music) for five days. After that, fish were tested in the novel tank paradigm and tested for the memory of the aversive task. In the novel tank, animals exposed to sound spent more time still and decreased the distance from the bottom of the tank. Animals also spent more time on the aversive side of the conditioning tank. These results suggest that anthropogenic noise applied through high-intensity music can increase anxiety and decrease memory retention in S. fuscus, suggesting the deleterious potential of noise for reef species.

The role of auditory and vibration stimuli in zebrafish neurobehavioral models.

Strongly affecting human and animal physiology, sounds and vibration are critical environmental factors whose complex role in behavioral and brain functions necessitates further clinical and experimental studies. Zebrafish are a promising model organism for neuroscience research, including probing the contribution of auditory and vibration stimuli to neurobehavioral processes. Here, we summarize mounting evidence on the role of sound and vibration in zebrafish behavior and brain function, and outline future directions of translational research in this field. With the growing environmental exposure to noise and vibration, we call for more active use of zebrafish models for probing neurobehavioral and bioenvironmental consequences of acute and long-term exposure to sounds and vibration in complex biological systems.

The effects of auditory enrichment on zebrafish behavior and physiology.

Environmental enrichment is widely used to improve welfare and behavioral performance of animal species. It ensures housing of laboratory animals in environments with space and complexity that enable the expression of their normal behavioral repertoire. Auditory enrichment by exposure to classical music decreases abnormal behaviors and endocrine stress responses in humans, non-humans primates, and rodents. However, little is known about the role of auditory enrichment in laboratory zebrafish. Given the growing importance of zebrafish for neuroscience research, such studies become critical. To examine whether auditory enrichment by classical music can affect fish behavior and physiology, we exposed adult zebrafish to 2 h of Vivaldi's music (65-75 dB) twice daily, for 15 days. Overall, zebrafish exposed to such auditory stimuli were less anxious in the novel tank test and less active, calmer in the light-dark test, also affecting zebrafish physiological (immune) biomarkers, decreasing peripheral levels of pro-inflammatory cytokines and increasing the activity of some CNS genes, without overt effects on whole-body cortisol levels. In summary, we report that twice-daily exposure to continuous musical sounds may provide benefits over the ongoing 50-55 dB background noise of equipment in the laboratory setting. Overall, our results support utilizing auditory enrichment in laboratory zebrafish to reduce stress and improve welfare in this experimental aquatic organism.

Acute exposure to waterborne psychoactive drugs attract zebrafish.

Psychotropic medications are widely used, and their prescription has increased worldwide, consequently increasing their presence in aquatic environments. Therefore, aquatic organisms can be exposed to psychotropic drugs that may be potentially dangerous, raising the question of whether these drugs are attractive or aversive to fish. To answer this question, adult zebrafish were tested in a chamber that allows the fish to escape or seek a lane of contaminated water. These attraction and aversion paradigms were evaluated by exposing the zebrafish to the presence of acute contamination with these compounds. The zebrafish were attracted by certain concentrations of diazepam, fluoxetine, risperidone and buspirone, which were most likely detected by olfaction, because this behavior was absent in anosmic fish. These findings suggest that despite their deleterious effects, certain psychoactive drugs attract fish.

Waterborne psychoactive drugs impair the initial development of Zebrafish.

The contamination of rivers and other natural water bodies, including underground waters, is a current reality. Human occupation and some economic activities generate a wide range of contaminated effluents that reach these water resources, including psychotropic drug residues. Here we show that fluoxetine, diazepam and risperidone affected the initial development of zebrafish. All drugs increased mortality rate and heart frequency and decreased larvae length. In addition, risperidone and fluoxetine decreased egg hatching. The overall results points to a strong potential of these drugs to cause a negative impact on zebrafish initial development and, since the larvae viability was reduced, promote adverse effects at the population level. We hypothesized that eggs and larvae absorbed the drugs that exert its effects in the central nervous system. These effects on early development may have significant environmental implications.