Effects of Anthropogenic Sound on Aquatic Life
Overview
There has been, and continues to be, a growing concern about the potential effects of human-made (anthropogenic) sounds on aquatic life. While the initial interest in the subject was with potential effects on marine mammals, concerns have now spread to fishes and invertebrates. Indeed, with fishes and aquatic invertebrates making up the vast majority of the aquatic animal biomass, and their being so critical for the food chains of humans (and marine mammals), any effect on the survival of populations and ecosystems can have profound implications for a wide variety of life.
Over the years, my lab has conducted studies examining potential effects of anthropogenic sound on fishes. These sounds have included potential effects of very intense signals such as those from pile driving (e.g., construction), seismic air guns (e.g., oil and gas exploitation) , high-powered sonars and from explosions. We have also investigated potential effects of quieter, but longer-lasting, sounds such as those found in aquaculture facilities and from boats and ships. Some of these studies are described below.
I have also been engaged with the development of ideas about regulatory criteria and guidelines that would help control the amount of sound to which aquatic life could be exposed. See this link for a discussion of that work. We recently published a paper in Trends in Ecology and Evolution that considers anthropogenic sounds and its regulation from the perspective of the animals potentially affected by the sounds.
One of the real problems, however, is that very little is known about the impact of high intensity sounds on fishes and little is also known about the effects of just a small increase in background noise on fish. Thus, setting of regulations and criteria is still very difficult since there is not the body of knowledge upon which to base decisions.
(Picture in header is from our recent study of the effects of explosives on fishes - Dahl et al., 2019.)
See bottom of this page for links to specific research projects
Figure: Representative sound sources that produce anthropogenic sounds and the animals that are potentially affected. Note that sounds may be both in water (from vessel engines and propellers, seismic air guns, operational wind turbines, or construction work) on the bottom, and in the substrate. Moreover, while most sounds arise from in-water operations, it is well known that sounds on land, such as from auto traffic, may get into the water through the substrate. Thus, the underwater acoustic environment, especially near shore, can be very complex. Figure © 2020 Anthony D. Hawkins, all rights reserved. (From Popper, Hawkins, and Thomsen, 2020)
Thinking about Anthropogenic Sound and Fishes
Over the past several years, colleagues and I have been giving new consideration as to how one should be thinking about potential impacts of anthropogenic sound on fishes and aquatic invertebrates. The origin of this consideration is that the vast majority of funding and research on aquatic anthropogenic sound has focused on marine mammals, and very little on other animals.
At the same time, we realize that marine mammals, while of course important and fascinating, make up far less than 1% of marine life (measured in any way - such as number of species, number of animals, biomass, etc.). In contrast, fishes and aquatic invertebrates, besides being vast in number of species, are critically important to ecosystems and as sources of protein for a large portion of the human populartion.
In a set of recent papers, we have explored a number of important issues that we think need to be part of the thinking about potential impacts of anthropogenic sound.
In considering fishes and aquatic invertebrates, measures of sound needs to include (indeed focus on) particle motion rather than sound pressure, since particle motion is the component of sound that all of these species detect. Tony Hawkins and I discuss this in Popper and Hawkins (2018).
For animals living close to, on, or in the substrate, investigators need to consider sound in the substrate in addition to sound energy in the water. This is especially the case where sound is projected into the substrate as in pile driving or seismic exploration. See Hawkins et al., 2021..
In thinking about impact of anthropogenic sound on any animals, there needs to be consideration of what signals are detected and affect animals. However, In most cases, such as in design of bubble curtains to suppress sounds from pile driving, designers rarely think in terms of what animals detect, but rather only in terms of how much sound can be mitigated. Thus in thinking about fishes, designers do not take into consideration that bubble curtains do a poor job of mitigating lower frequency sounds that fishes hear, or that there is no mitigation of substrate vibrations that impact animals associated with the substrate. As Tony Hawkins, Frank, Thomsen and I argued (Popper et al., 2020), thinking about mitigation should start with considering the sounds that impact a species (or group of species) and then design systems that mitigate those sounds. This means that we need considerably more funding for work on fishes and aquatic invertebrates in terms of anthropogenic sound and how it may impact these animals.
There are relatively few research publications that examine anthropogenic sound and fishes, and even fewer papers that focus on invertebrates. Moreover, there are several “problems” with many of these papers. See Guan et al. (2024) for a fuller discussion.
Species are often selected based on convenience such as availability, ease of handling, size that can be studied in tanks, etc. But, very often these species are not representative to species that are likely to encounter many anthrpogenic sounds in the wild. We would argue that while interesting animals, goldfish, zebrafish, and other freshwater species cannot be used as analogs for species of far greater importance such as, for example, Atlantic cod, tunas, salmonids, etc.
Many studies are done in fish tanks or other small enclosures. While studies in such environments have value for exploring things like physiology and such, there is the problem that the acoustics in such environments are very different from a normal environment in which animals live. Thus, extrapolation of results related to particular sounds from studies in small enclosures to what may happen in the wild must be done with extreme caution.
Research questions vary widely and often reflect the interest of the investigators and not whether the questions have direct relevance to anthropogenic sources.
One conclusion from the above (and other) points is that we need a body of data on potential impacts of anthropogenic sound and fishes (and aquatic invertebrates). But, since funding is limited, and likely to remain so, perhaps it is time to “rethink” the approach for this work. Perhaps a far more effective approach would be to set up a single, international, funding source for this work and then, through funding, focus on work that would be considered by experts to have the biggest payback. For example, limit species studied to those of most importance for the ecosystem and/or human food source. Then the actual studies supported would be those that provide the maximum amount of highly relevant data rather than funding studies that may not provide the greatest insights into protecting species of most importance.
A final point is that animals (including humans) generally are exposed to many different anthropogenic signals at the same time, such as sound and light, and perhaps chemicals and other things. The same occurs for aquatic animals. Indeed, a fish exposed to the sounds of a motor boat might also experience shadows and chemicals. Moreover, it is likely that an animals response to one anthropogenic signal might be altered if it is simultaneously receiving other signals. Thus,In thinking about this, Frank Thomsen and I (2024) propose the idea that one cannot just think about sound alone as a stressor. Instead, we propose that, in addition to thinking about sound as a stressor, one must also consider how other simultaneous stressors may impact how the animals is affected, and how it responds to anthropogenic signals.
Research on Effects of Sound on Fishes
Work in my laboratory has been involved in a wide range of studies on the effects of anthropogenic sounds on fishes. The following links lead to these studies.
Effects of pile driving on fishes
Effects of seismic air guns on fishes
Increased background noise and fish hearing
Plan on attending the seventh international conference on The Effects of Noise on Aquatic Life which will take place in Prague at the end of June, 2025. The papers from our 2022 meeting in Berlin can be found here.. Visit our home page at www.aquaticnoise.org. To see a picture of attendees at the first meeting in 2007 go to the bottom of this page.