Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Rising Ocean Acidification Leads to Anxiety in Fish

Study shows acidity levels projected by the end of the century results in behavioral changes that could impact feeding, fisheries

A new research study combining marine physiology, neuroscience, pharmacology, and behavioral psychology has revealed a surprising outcome from increases of carbon dioxide uptake in the oceans: anxious fish.

Researchers tracked the movements of fish in highly acidic waters, represented above in a movement "heatmap."

A growing base of scientific evidence has shown that the absorption of human-produced carbon dioxide into the world’s oceans is causing surface waters to decline in pH, causing a rise in acidity. This ocean acidification is known to disrupt the growth of shells and skeletons of certain marine animals but other consequences such as behavioral impacts have been largely unknown.

In a study published in the journal Proceedings of the Royal Society B (Biological Sciences), scientists at Scripps Institution of Oceanography at UC San Diego and MacEwan University in Edmonton, Canada, have shown for the first time that rising acidity levels increase anxiety in juvenile rockfish, an important commercial species in California. Using a camera-based tracking software system, the researchers compared a control group of rockfish kept in normal seawater to another group in waters with elevated acidity levels matching those projected for the end of the century.

They measured each group’s preference to swim in light or dark areas of a testing tank, which is a known test for anxiety in fish. The researchers found out that normal juvenile rockfish continuously moved between the light and dark areas of the tank. However, experiments have shown that fish administered with an anxiety-inducing drug (anxiogenic) prefer the darker area and seldom venture into the light. Hence, dark-preference is indicative of increased anxiety in juvenile rockfish.

Next, the researchers found that rockfish exposed to acidified ocean conditions for one week also preferred the dark area of the tank, indicating they were significantly more anxious than their normal seawater counterparts. Rockfish exposed to acidified ocean conditions remained anxious even one week after being placed in seawater with normal carbon dioxide levels. Only after the twelfth day in normal seawater did the anxious fish behave like the control group and resumed normal behavior.

The researchers say the anxiety is traced to the fish’s sensory systems, and specifically “GABAA” (neural gamma-aminobutyric acid type A) receptors, which are also involved in human anxiety levels. Exposure to acidified water leads to changes in the concentrations of ions in the blood (especially chloride and bicarbonate), which reverses the flux of ions through the GABAA receptors. The end result is a change in neuronal activity that is reflected in the altered behavioral responses described in this study.

“These results are novel and thought-provoking,” said Martín Tresguerres, a Scripps marine biologist and study coauthor, “because they reveal a potential negative effect of ocean acidification on fish behavior that can possibly affect normal population dynamics and maybe even affect fisheries.”

Tresguerres says anxious behavior is a concern for juvenile rockfish because they live in highly dynamic environments such as kelp forests and drifting kelp paddies that offer variable lighting and shading conditions.

“If the behavior that we observed in the lab applies to the wild during ocean acidification conditions, it could mean that juvenile rockfish may spend more time in the shaded areas instead of exploring around,” said Tresguerres. “This would have negative implications due to reduced time foraging for food, or alterations in dispersal behavior, among others.”

Alteration of GABAA receptor function in fish exposed to ocean acidification was originally described by Phil Munday (James Cook University, Australia), Göran Nilsson (University of Oslo) and collaborators, who found that ocean acidification impaired olfaction in tropical clown fish. The study by Hamilton, Holcombe, and Tresguerres adds anxiety behavior to the list of biological functions that are susceptible to future ocean acidification, and it is the first to describe effects of ocean acidification on the physiology and behavior of Californian fish.

“Behavioral neuroscience in fish is a relatively unexplored field, but we do know that fish are capable of many complicated cognitive tasks of learning and memory. Increased anxiety in rockfish could have a detrimental impact on many aspects of their daily functioning,” said Trevor James Hamilton, a neurobiologist at MacEwan University and coauthor of the study.

Tresguerres noted that laboratory tests cannot fully model the steady progression of acidity levels that will be seen in the wild over years and decades. “Nonetheless, our results suggest that ocean acidification may affect an important aspect of fish behavior.”

In addition to Tresguerres and Hamilton, Adam Holcombe of MacEwan University coauthored the study.

The National Science Foundation, UC San Diego Academic Senate, Scripps Institution of Oceanography, The Alfred P. Sloan Foundation, MacEwan Research Office, Arts and Science, and Student Enrichment Fund supported the research.

About Scripps Institution of Oceanography Scripps Institution of Oceanography at the University of California, San Diego, is one of the oldest, largest, and most important centers for global science research and education in the world. Now in its second century of discovery, the scientific scope of the institution has grown to include biological, physical, chemical, geological, geophysical, and atmospheric studies of the earth as a system. Hundreds of research programs covering a wide range of scientific areas are under way today on every continent and in every ocean. The institution has a staff of about 1,400 and annual expenditures of approximately $170 million from federal, state, and private sources. Scripps operates robotic networks and one of the largest U.S. academic fleets with four oceanographic research ships and one research platform for worldwide exploration. Birch Aquarium at Scripps serves as the interpretive center of the institution and showcases Scripps research and a diverse array of marine life through exhibits and programming for more than 425,000 visitors each year. Learn more at

Mario Aguilera | EurekAlert!
Further information:

More articles from Ecology, The Environment and Conservation:

nachricht Invasive Insects Cost the World Billions Per Year
04.10.2016 | University of Adelaide

nachricht Malaysia's unique freshwater mussels in danger
27.09.2016 | The University of Nottingham Malaysia Campus

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Etching Microstructures with Lasers

Ultrafast lasers have introduced new possibilities in engraving ultrafine structures, and scientists are now also investigating how to use them to etch microstructures into thin glass. There are possible applications in analytics (lab on a chip) and especially in electronics and the consumer sector, where great interest has been shown.

This new method was born of a surprising phenomenon: irradiating glass in a particular way with an ultrafast laser has the effect of making the glass up to a...

Im Focus: Light-driven atomic rotations excite magnetic waves

Terahertz excitation of selected crystal vibrations leads to an effective magnetic field that drives coherent spin motion

Controlling functional properties by light is one of the grand goals in modern condensed matter physics and materials science. A new study now demonstrates how...

Im Focus: New 3-D wiring technique brings scalable quantum computers closer to reality

Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.

"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...

Im Focus: Scientists develop a semiconductor nanocomposite material that moves in response to light

In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.

A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...

Im Focus: Diamonds aren't forever: Sandia, Harvard team create first quantum computer bridge

By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.

"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...

All Focus news of the innovation-report >>>



Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

Agricultural Trade Developments and Potentials in Central Asia and the South Caucasus

14.10.2016 | Event News

World Health Summit – Day Three: A Call to Action

12.10.2016 | Event News

Latest News

Ice shelf vibrations cause unusual waves in Antarctic atmosphere

25.10.2016 | Earth Sciences

Fluorescent holography: Upending the world of biological imaging

25.10.2016 | Power and Electrical Engineering

Etching Microstructures with Lasers

25.10.2016 | Process Engineering

More VideoLinks >>>