Psychoactive Pollutant Impacts Baseline Immune Traits but Not Behavior and Microbiome in a Fish
6 affiliations
- 1School of Biological Sciences, Monash University, Melbourne, Victoria 3800, Australia
- 2School of Medical Sciences, Faculty of Biology, Medicine, and Health, University of Manchester, Manchester, Greater Manchester M13 9PL, United Kingdom
- 3Department of Pharmacology, Biomedicine Discovery Institute, Faculty of Medicine, Nursing and Health Sciences, Monash University, Melbourne, Victoria 3800, Australia
- 4Victorian Heart Institute, Monash University, Clayton, Victoria 3168, Australia
- 5Baker Heart and Diabetes Institute, Melbourne, Victoria 3000, Australia
- 6Centre for Evolutionary Biology, School of Biological Sciences, The University of Western Australia, Perth, Western Australia 6009, Australia
Abstract
Pharmaceutical pollution is an increasing global threat to freshwater ecosystems. Psychoactive drugs, such as antidepressants, are of particular concern because they affect evolutionarily conserved neuroendocrine pathways in nontarget organisms. As these pathways regulate interconnected biological systems, understanding the ecological consequences of pharmaceutical exposure requires an integrative approach. Here, we investigated the effects of 28-day exposure to control (freshwater), low (4.2 ± 0.3 ng/L), and high (637.5 ± 173.84 ng/L) fluoxetine concentrations on behaviors, baseline immune traits, and skin mucus microbiome composition in the Murray River rainbowfish (Melanotaenia fluviatilis). Fluoxetine exposure did not impact fish behavior, including activity, freezing behavior, shelter use, or microbiome composition. In contrast, immune traits were significantly altered. Both fluoxetine concentrations reduced total white blood cell (WBC) count, while only fish exposed to the low concentration showed reduced lymphocyte counts and elevated neutrophil counts, consistent with a stress-associated WBC redistribution response. Our findings show that different, but interconnected, biological systems can differ in their sensitivity to pollutants and suggest that immune traits may be an early, sensitive indicator of exposure to psychoactive pharmaceuticals. These findings highlight the importance of integrating multiple biological end points to obtain a more comprehensive understanding of the ecological consequences of pharmaceutical contamination.
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BibTeX
@article{melhado2026psychoactive,
title = {{Psychoactive Pollutant Impacts Baseline Immune Traits but Not Behavior and Microbiome in a Fish}},
author = {Gabriel Melhado and Rhiannon V. Eastment and Francine Z. Marques and Upama Aich and Anne Peters and Bob B. M. Wong},
journal = {Environmental Science \& Technology},
year = {2026},
month = oct,
doi = {10.1021/acs.est.6c12057},
url = {https://doi.org/10.1021/acs.est.6c12057},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Psychoactive Pollutant Impacts Baseline Immune Traits but Not Behavior and Microbiome in a Fish
AU - Gabriel Melhado
AU - Rhiannon V. Eastment
AU - Francine Z. Marques
AU - Upama Aich
AU - Anne Peters
AU - Bob B. M. Wong
PY - 2026
DA - 2026/10/20
JO - Environmental Science & Technology
DO - 10.1021/acs.est.6c12057
UR - https://doi.org/10.1021/acs.est.6c12057
AB - Pharmaceutical pollution is an increasing global threat to freshwater ecosystems. Psychoactive drugs, such as antidepressants, are of particular concern because they affect evolutionarily conserved neuroendocrine pathways in nontarget organisms. As these pathways regulate interconnected biological systems, understanding the ecological consequences of pharmaceutical exposure requires an integrative approach. Here, we investigated the effects of 28-day exposure to control (freshwater), low (4.2 ± 0.3 ng/L), and high (637.5 ± 173.84 ng/L) fluoxetine concentrations on behaviors, baseline immune traits, and skin mucus microbiome composition in the Murray River rainbowfish (Melanotaenia fluviatilis). Fluoxetine exposure did not impact fish behavior, including activity, freezing behavior, shelter use, or microbiome composition. In contrast, immune traits were significantly altered. Both fluoxetine concentrations reduced total white blood cell (WBC) count, while only fish exposed to the low concentration showed reduced lymphocyte counts and elevated neutrophil counts, consistent with a stress-associated WBC redistribution response. Our findings show that different, but interconnected, biological systems can differ in their sensitivity to pollutants and suggest that immune traits may be an early, sensitive indicator of exposure to psychoactive pharmaceuticals. These findings highlight the importance of integrating multiple biological end points to obtain a more comprehensive understanding of the ecological consequences of pharmaceutical contamination.
SN - 0013-936X
SN - 1520-5851
ER -