Influences of the antidepressant fluoxetine on stream ecosystem function and aquatic insect emergence at environmentally realistic concentrations

Abstract

Fluoxetine, a selective serotonin reuptake inhibitor (SSRI), is frequently detected in surface waters globally, yet the effects of SSRIs on ecological processes at environmentally realistic concentrations are not currently known. We used a controlled, replicated artificial stream experiment to expose biofilm, algal and stream insect communities to two different concentrations of fluoxetine: 20 ng/L (typical concentration detected in surface waters) and 20 µg/L (concentration shown to influence insect emergence and algal productivity). We quantified a range of community and ecosystem response metrics over the course of the 21d experiment including; algal biomass (chl-a), net ecosystem production (NEP), gross primary production (GPP), ecosystem respiration (ER) and invertebrate emergence. At 20 ng/L, fluoxetine significantly suppressed algal colonization on rocks, and reduced GPP after 13 days, but by day 21 chl-a, NEP and GPP did not differ between treatments and control. Fluoxetine increased ER on leaves where invertebrates were excluded, but had no effect on leaves accessible to invertebrates. Streams receiving 20 ng/L of fluoxetine had adult insects from the order Diptera emerge sooner and at a greater rate than control streams. Our results suggest that ecosystem function, including primary production and respiration, and invertebrate population dynamics are sensitive to SSRIs and that fluoxetine may alter these key processes concentrations found in the environment.

Keywords:

• Ecological effects
• fluoxetine
• insect emergence
• ecological disruption
• emerging contaminant

Acknowledgments

We thank Abigail Bline and Heather Malcom for assistance with data collection and setup and running of the artificial stream experiment.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

Funding for this research was provided by an Australian Research Council Linkage Grant LP130100040 (Grace and Rosi) and a Dean’s Postgraduate Scholarship from the Faculty of Science, Monash University (Richmond).

Notes on contributors

Erinn K. Richmond

Dr. Erinn K. Richmond is a freshwater ecologist with a passion for aquatic insects and the streams and rivers they live in. Erinn completed her Ph.D. in 2017 examining the ecological effects of pharmaceuticals and personal care products on aquatic ecosystems. During her Ph.D. Erinn spent time abroad conducting experiments and working with scientist at the Cary Institute of Ecosystem Studies in NY, USA. Erinn is currently a post-doctoral research fellow within the Water Studies Centre at Monash University, where she is continuing research on the ecological effects of pharmaceuticals and their uptake in food webs.

Emma J. Rosi

Senior Scientist Emma J. Rosi’s research focuses on how human activities affect aquatic life and water quality in diverse ecosystems around the world. She is particularly interested in novel and emerging contaminants such as pharmaceuticals, and also studies the effects of nutrient enrichment. In addition to water quality, her work examines aquatic food webs (invertebrates and fishes), and the role of the hippopotamus in nutrient cycling. Her research seeks to inform sound stewardship of freshwater resources, and she often speaks to the public and policymakers. She serves on the Ecological Processes and Effects Committee of the US Environmental Protection Agency’s Science Advisory Board.

Alexander J. Reisinger

Assistant Professor Alexander J. Reisinger is an assistant professor of urban soil and water quality, and specializes in the ecosystem ecology and biogeochemistry of urban environments. He is a member of the Sustainability Human and Ecological Development group. He focuses on the ecosystem functions of nutrient and energy cycling and the effect of traditional (e.g. nutrients) and novel (e.g. pharmaceuticals) contaminants on these functions. Dr. Reisinger received his Ph.D. from the University of Notre Dame.

Brittany R. Hanrahan

Dr. Brittany R. Hanrahan is a research biologist at the US Department of Agriculture (USDA). She is an aquatic ecologist with expertise in stream biogeochemistry and nutrient cycling in watersheds dominated by agricultural land use. Dr. Hanrahan received her Ph.D. in 2017 from the University of Notre Dame.

Ross M. Thompson

Professor Ross M. Thompson is Director and Chair of Water Science in the Institute for Applied Ecology at the University of Canberra. Ross is a freshwater ecologist with interests in the study of biodiversity and the restoration of landscapes. His fundamental research is in food web ecology; seeking the rules that determine how natural communities assemble and persist. His applied research addresses the ways in which food webs can be influenced by anthropogenic factors including urbanization, land clearance, pharmaceutical contamination, river flow diversion and restoration, and invasion. He has an active research program on aquatic biodiversity and ecosystem function in urban and rural landscapes. Ross has published more than 90 papers, 10 book chapters and more than 200 scientific reports. His work has strong links to government and industry, and Ross sits on a number of senior technical advisory panels for local, state and federal research programs.

Michael R. Grace

Associate Professor Michael R. Grace’s research interests include: aquatic chemistry of lakes, rivers and estuaries; biogeochemical cycling of nutrients (N, P, S and C); environmental analytical chemistry; using stable isotopes to investigate aquatic nutrient cycling and ecosystem functioning; aquatic ecosystem process measurements (e.g. whole stream metabolism, denitrification); investigating the effects of urbanization on aquatic ecosystems; integrating science into Natural Resource Management; and ecosystem ecology.