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Effects of mid-frequency active sonar on hearing in fish
Abstract
Caged fish were exposed to sound from mid-frequency active (MFA) transducers in a 5 × 5 planar array which simulated MFA sounds at received sound pressure levels of 210 dB SPL(re 1 μPa). The exposure sound consisted of a 2 s frequency sweep from 2.8 to 3.8 kHz followed by a 1 s tone at 3.3 kHz. The sound sequence was repeated every 25 s for five repetitions resulting in a cumulative sound exposure level (SEL(cum)) of 220 dB re 1 μPa(2) s. The cumulative exposure level did not affect the hearing sensitivity of rainbow trout, a species whose hearing range is lower than the frequencies in the presented MFA sound. In contrast, one cohort of channel catfish showed a statistically significant temporary threshold shift of 4-6 dB at 2300 Hz, but not at lower tested frequencies, whereas a second cohort showed no change. It is likely that this threshold shift resulted from the frequency spectrum of the MFA sound overlapping with the upper end of the hearing frequency range of the channel catfish. The observed threshold shifts in channel catfish recovered within 24 h. There was no mortality associated with the MFA sound exposure used in this test.
... The addition of these sounds can interfere with ecologically important sounds for fish (i.e., used for habitat selection, migration, mating, or territory defense) (Hawkins et al., 2015;Simpson et al., 2015). High-intensity sounds can inflict physical trauma (McCauley et al., 2003;Dahl et al., 2020;Jenkins et al., 2022) and temporary hearing loss (Smith et al., 2004;Halvorsen et al., 2012;Popper et al., 2007), whereas lower-intensity sounds can mask acoustic signals (Popper and Hawkins, 2019;Putland et al., 2019), alter fish physiology (Debusschere et al., 2016), or modify fish behavior (Slabbekoorn et al., 2010;Purser and Radford, 2011;Simpson et al., 2016a;Pieniazek et al., 2020). However, research gaps remain, with little understanding of how anthropogenic noise affects fish communities and natural fish behavior and how long-term noise affects fish (Hawkins et al., 2015;Nedelec et al., 2016a;Hawkins et al., 2020;Popper et al., 2020). ...
... However, AEPs have previously been successful when performed in the field (Chapman, 1973;Chapman and Hawkins, 1973;Chapman and Johnstone, 1974;Hawkins et al., 2014). There were three studies that were included in this review; however, it is important to note that the fish were exposed to noise in the field and then transported to a laboratory setting for AEP assessment (Popper et al., 2005;Popper et al., 2007;Halvorsen et al., 2012) [ Fig. 2(b)]. Understandably, AEP studies are logistically difficult to conduct in a field setting, as the equipment required to determine AEPs is expensive; however, it is possible, as shown by the studies included here. ...
... Artificially derived sounds were used in eight papers and can allow for a deeper understanding of fish hearing through field-based behavioral audiograms (Hawkins et al., 2014;Mickle et al., 2020) and offer the opportunity to control the sound structure and variability during noise exposure experiments (Neo et al., 2016;Hubert et al., 2020b) [ Fig. 4(a)]. The studies using tones focused on behavioral effects (Hawkins et al., 2014;Mickle et al., 2020;Brown et al., 2021), physiological effects (Halvorsen et al., 2012), habituation (Neo et al., 2018), and effects that were dependent on data metrics ( Fig. 3; Hubert et al., 2020b). Two of the behavioral studies used tones to establish a threshold of responsiveness with free-swimming sprat (Sprattus sprattus) and mackerel (Scomber scombrus; Hawkins et al., 2014) and enclosed southern stingrays (Hypanus americanus; Mickle et al., 2020), which could assist in creating guidelines for policymakers to guide implementation. ...
Anthropogenic noise is globally increasing in aquatic ecosystems, and there is concern that it may have adverse consequences in many fish species, yet the effects of noise in field settings are not well understood. Concern over the applicability of laboratory-conducted bioacoustic experiments has led to a call for, and a recent increase in, field-based studies, but the results have been mixed, perhaps due to the wide variety of techniques used and species studied. Previous reviews have explored the behavioral, physiological, and/or anatomical costs of fish exposed to anthropogenic noise, but few, if any, have focused on the field techniques and sound sources themselves. This review, therefore, aims to summarize, quantify, and interpret field-based literature, highlight novel approaches, and provide recommendations for future research into the effects of noise on fish.
... In response to anthropogenic noise, marine animals have exhibited hearing threshold shifts (e.g., Halvorsen et al., 2012b;Finneran, 2015), direct physical damage to auditory structures (e.g., Casper et al., 2013;McCauley et al., 2003), interference with communication (i.e., masking of biological acoustic signals) (e.g., Slabbekoorn et al., 2010;Vasconcelos et al., 2007), reduced predator avoidance (e.g., Bruintjes and Radford, 2013;Peng et al., 2015), and increased stress levels (e.g., Nichols et al., 2015;Neo et al., 2015). In damselfish (Chromis chromis), brown meagre (Sciaena umbra), and red-mouthed goby (Gobius cruentatus), boat noise reduced auditory sensitivity; decreased time spent by adults in nests and caring for young; and increased time spent by fish in shelters (Codarin et al., 2009). ...
... Loud anthropogenic noise sources associated with seismic air guns, sonar, construction operations like pile driving, and large ships have the potential to injure or kill fishes because their source SPLs are extremely high (Popper and Hastings, 2009;Bolle et al., 2012;Casper et al., 2013;Halvorsen et al., 2012a;Halvorsen et al., 2012b). One clear mechanism of injury and mortality is the rapid motion of the swim bladder wall against other organs, which can lead to hemorrhaging of these tissues (e.g., Halvorsen et al., 2012a). ...
... Similar peak frequencies between chorusing fish and recreational boats could result in communication interference, which may have significant impacts on the reproductive success of fish that utilize courtship sounds (Vasconcelos et al., 2007;Codarin et al., 2009;Slabbekoorn et al., 2010;Halvorsen et al., 2012b;McCormick et al., 2018). For example, in the case of sciaenids (e.g., silver perch, spotted seatrout, and red drum), it is thought that acoustic signals serve in the formation of spawning aggregations, where males and females synchronize the release of gametes (e.g., Connaughton and Taylor, 1996;Myrberg and Lugli, 2006;Lowerre-Barbieri et al., 2009;Montie et al., 2015;Monczak et al., 2017). ...
The impact of boat related noise on marine life is a subject of concern, particularly for fish species that utilize acoustic communication for spawning purposes. The goal of this study was to quantify and examine the risk of boat noise on fish acoustic communication by performing acoustic monitoring of the May River, South Carolina (USA) from February to November 2013 using DSG-Ocean recorders. The number of boats detected increased from the source to the mouth with the highest detections near the Intracoastal Waterway (ICW). Boat noise frequency ranges overlapped with courtship sounds of silver perch (Bairdiella chrysoura), black drum (Pogonias cromis), oyster toadfish (Opsanus tau), spotted seatrout (Cynoscion nebulosus), and red drum (Sciaenops ocellatus). In the May River estuary, red drum may experience the greatest risk of auditory masking because of late afternoon choruses (21% time overlap with boat noise) and only one spawning location near the noisy ICW.
... They can be roughly divided into three categories depending on their primary frequency of operation; low frequency (LF) for 1 kHz and less, mid frequency (MF) for 1 kHz to 10 kHz, and high frequency (HF) for 10 kHz and greater. Low, and possibly mid, frequency sonars are most relevant to fi shes and sea turtles because of the low frequency hearing ranges of these animals (e.g., Popper et al. 2007 ;Halvorsen et al. 2012b ). Sonar usually operates with duty cycles (transmission time/total time) below 10 to 20% and with generally brief durations. ...
... Fishes : Data for mortality and injury related to low-and mid-frequency sonar are based on Popper et al. ( 2007 ), Halvorsen et al. ( 2012b ), and Kane et al. ( 2010 ), which showed no effect on the ear or non-auditory tissues when the maximum received sound pressure levels were at 193 dB re 1 μPa rms for low frequency sonar, and at 210 dB re 1 μPa rms for mid-frequency sonar. Injury, if it occurs, is thought to begin at higher sound levels than tested to date. ...
... To resolve these issues, some studies on the hearing abilities of aquatic animals have been carried out with specialized facilities designed to provide predictable and appropriate acoustic conditions. These facilities included sound ranges established in the sea (Chapman and Hawkins 1973 ;Schuijf 1975 ;Schuijf and Buwalda 1975 ;Popper et al. 2007 ;Halvorsen et al. 2012b ) and specialized wave tubes (e.g., Hawkins and MacLennan 1976 ;Halvorsen et al. 2011Halvorsen et al. , 2012a. ...
... They can be roughly divided into three categories depending on their primary frequency of operation; low frequency (LF) for 1 kHz and less, mid frequency (MF) for 1 kHz to 10 kHz, and high frequency (HF) for 10 kHz and greater. Low, and possibly mid, frequency sonars are most relevant to fi shes and sea turtles because of the low frequency hearing ranges of these animals (e.g., Popper et al. 2007 ;Halvorsen et al. 2012b ). Sonar usually operates with duty cycles (transmission time/total time) below 10 to 20% and with generally brief durations. ...
... Fishes : Data for mortality and injury related to low-and mid-frequency sonar are based on Popper et al. ( 2007 ), Halvorsen et al. ( 2012b ), and Kane et al. ( 2010 ), which showed no effect on the ear or non-auditory tissues when the maximum received sound pressure levels were at 193 dB re 1 μPa rms for low frequency sonar, and at 210 dB re 1 μPa rms for mid-frequency sonar. Injury, if it occurs, is thought to begin at higher sound levels than tested to date. ...
... To resolve these issues, some studies on the hearing abilities of aquatic animals have been carried out with specialized facilities designed to provide predictable and appropriate acoustic conditions. These facilities included sound ranges established in the sea (Chapman and Hawkins 1973 ;Schuijf 1975 ;Schuijf and Buwalda 1975 ;Popper et al. 2007 ;Halvorsen et al. 2012b ) and specialized wave tubes (e.g., Hawkins and MacLennan 1976 ;Halvorsen et al. 2011Halvorsen et al. , 2012a. ...
Chapters cannot be read stand-alone. Please see complete SpringerBrief at: http:// link. springer. com/ book/ 10. 1007/ 978-3-319-06659-2.
... They can be roughly divided into three categories depending on their primary frequency of operation; low frequency (LF) for 1 kHz and less, mid frequency (MF) for 1 kHz to 10 kHz, and high frequency (HF) for 10 kHz and greater. Low, and possibly mid, frequency sonars are most relevant to fi shes and sea turtles because of the low frequency hearing ranges of these animals (e.g., Popper et al. 2007 ;Halvorsen et al. 2012b ). Sonar usually operates with duty cycles (transmission time/total time) below 10 to 20% and with generally brief durations. ...
... Fishes : Data for mortality and injury related to low-and mid-frequency sonar are based on Popper et al. ( 2007 ), Halvorsen et al. ( 2012b ), and Kane et al. ( 2010 ), which showed no effect on the ear or non-auditory tissues when the maximum received sound pressure levels were at 193 dB re 1 μPa rms for low frequency sonar, and at 210 dB re 1 μPa rms for mid-frequency sonar. Injury, if it occurs, is thought to begin at higher sound levels than tested to date. ...
... To resolve these issues, some studies on the hearing abilities of aquatic animals have been carried out with specialized facilities designed to provide predictable and appropriate acoustic conditions. These facilities included sound ranges established in the sea (Chapman and Hawkins 1973 ;Schuijf 1975 ;Schuijf and Buwalda 1975 ;Popper et al. 2007 ;Halvorsen et al. 2012b ) and specialized wave tubes (e.g., Hawkins and MacLennan 1976 ;Halvorsen et al. 2011Halvorsen et al. , 2012a. ...
Chapters cannot be read stand-alone. Please see complete SpringerBrief at: http:// link. springer. com/ book/ 10. 1007/ 978-3-319-06659-2.
... They can be roughly divided into three categories depending on their primary frequency of operation; low frequency (LF) for 1 kHz and less, mid frequency (MF) for 1 kHz to 10 kHz, and high frequency (HF) for 10 kHz and greater. Low, and possibly mid, frequency sonars are most relevant to fi shes and sea turtles because of the low frequency hearing ranges of these animals (e.g., Popper et al. 2007 ;Halvorsen et al. 2012b ). Sonar usually operates with duty cycles (transmission time/total time) below 10 to 20% and with generally brief durations. ...
... Fishes : Data for mortality and injury related to low-and mid-frequency sonar are based on Popper et al. ( 2007 ), Halvorsen et al. ( 2012b ), and Kane et al. ( 2010 ), which showed no effect on the ear or non-auditory tissues when the maximum received sound pressure levels were at 193 dB re 1 μPa rms for low frequency sonar, and at 210 dB re 1 μPa rms for mid-frequency sonar. Injury, if it occurs, is thought to begin at higher sound levels than tested to date. ...
... To resolve these issues, some studies on the hearing abilities of aquatic animals have been carried out with specialized facilities designed to provide predictable and appropriate acoustic conditions. These facilities included sound ranges established in the sea (Chapman and Hawkins 1973 ;Schuijf 1975 ;Schuijf and Buwalda 1975 ;Popper et al. 2007 ;Halvorsen et al. 2012b ) and specialized wave tubes (e.g., Hawkins and MacLennan 1976 ;Halvorsen et al. 2011Halvorsen et al. , 2012a. ...
Chapters cannot be read stand-alone. Please see complete SpringerBrief at: http:// link. springer. com/ book/ 10. 1007/ 978-3-319-06659-2.
... They can be roughly divided into three categories depending on their primary frequency of operation; low frequency (LF) for 1 kHz and less, mid frequency (MF) for 1 kHz to 10 kHz, and high frequency (HF) for 10 kHz and greater. Low, and possibly mid, frequency sonars are most relevant to fi shes and sea turtles because of the low frequency hearing ranges of these animals (e.g., Popper et al. 2007 ;Halvorsen et al. 2012b ). Sonar usually operates with duty cycles (transmission time/total time) below 10 to 20% and with generally brief durations. ...
... Fishes : Data for mortality and injury related to low-and mid-frequency sonar are based on Popper et al. ( 2007 ), Halvorsen et al. ( 2012b ), and Kane et al. ( 2010 ), which showed no effect on the ear or non-auditory tissues when the maximum received sound pressure levels were at 193 dB re 1 μPa rms for low frequency sonar, and at 210 dB re 1 μPa rms for mid-frequency sonar. Injury, if it occurs, is thought to begin at higher sound levels than tested to date. ...
... To resolve these issues, some studies on the hearing abilities of aquatic animals have been carried out with specialized facilities designed to provide predictable and appropriate acoustic conditions. These facilities included sound ranges established in the sea (Chapman and Hawkins 1973 ;Schuijf 1975 ;Schuijf and Buwalda 1975 ;Popper et al. 2007 ;Halvorsen et al. 2012b ) and specialized wave tubes (e.g., Hawkins and MacLennan 1976 ;Halvorsen et al. 2011Halvorsen et al. , 2012a. ...
Chapters cannot be read stand-alone. Please see complete SpringerBrief at: http:// link. springer. com/ book/ 10. 1007/ 978-3-319-06659-2.
... They can be roughly divided into three categories depending on their primary frequency of operation; low frequency (LF) for 1 kHz and less, mid frequency (MF) for 1 kHz to 10 kHz, and high frequency (HF) for 10 kHz and greater. Low, and possibly mid, frequency sonars are most relevant to fi shes and sea turtles because of the low frequency hearing ranges of these animals (e.g., Popper et al. 2007 ;Halvorsen et al. 2012b ). Sonar usually operates with duty cycles (transmission time/total time) below 10 to 20% and with generally brief durations. ...
... Fishes : Data for mortality and injury related to low-and mid-frequency sonar are based on Popper et al. ( 2007 ), Halvorsen et al. ( 2012b ), and Kane et al. ( 2010 ), which showed no effect on the ear or non-auditory tissues when the maximum received sound pressure levels were at 193 dB re 1 μPa rms for low frequency sonar, and at 210 dB re 1 μPa rms for mid-frequency sonar. Injury, if it occurs, is thought to begin at higher sound levels than tested to date. ...
... To resolve these issues, some studies on the hearing abilities of aquatic animals have been carried out with specialized facilities designed to provide predictable and appropriate acoustic conditions. These facilities included sound ranges established in the sea (Chapman and Hawkins 1973 ;Schuijf 1975 ;Schuijf and Buwalda 1975 ;Popper et al. 2007 ;Halvorsen et al. 2012b ) and specialized wave tubes (e.g., Hawkins and MacLennan 1976 ;Halvorsen et al. 2011Halvorsen et al. , 2012a. ...
Chapters cannot be read stand-alone. Please see complete SpringerBrief at: http:// link. springer. com/ book/ 10. 1007/ 978-3-319-06659-2.
... They can be roughly divided into three categories depending on their primary frequency of operation; low frequency (LF) for 1 kHz and less, mid frequency (MF) for 1 kHz to 10 kHz, and high frequency (HF) for 10 kHz and greater. Low, and possibly mid, frequency sonars are most relevant to fi shes and sea turtles because of the low frequency hearing ranges of these animals (e.g., Popper et al. 2007 ;Halvorsen et al. 2012b ). Sonar usually operates with duty cycles (transmission time/total time) below 10 to 20% and with generally brief durations. ...
... Fishes : Data for mortality and injury related to low-and mid-frequency sonar are based on Popper et al. ( 2007 ), Halvorsen et al. ( 2012b ), and Kane et al. ( 2010 ), which showed no effect on the ear or non-auditory tissues when the maximum received sound pressure levels were at 193 dB re 1 μPa rms for low frequency sonar, and at 210 dB re 1 μPa rms for mid-frequency sonar. Injury, if it occurs, is thought to begin at higher sound levels than tested to date. ...
... To resolve these issues, some studies on the hearing abilities of aquatic animals have been carried out with specialized facilities designed to provide predictable and appropriate acoustic conditions. These facilities included sound ranges established in the sea (Chapman and Hawkins 1973 ;Schuijf 1975 ;Schuijf and Buwalda 1975 ;Popper et al. 2007 ;Halvorsen et al. 2012b ) and specialized wave tubes (e.g., Hawkins and MacLennan 1976 ;Halvorsen et al. 2011Halvorsen et al. , 2012a. ...
Chapters cannot be read stand-alone. Please see complete SpringerBrief at: http:// link. springer. com/ book/ 10. 1007/ 978-3-319-06659-2.
... Previous studies conducted for conservation purposes have shown that high-pressure sound sources such as seismic exploration technology, active sonar, and pile driving have adverse effects on fish physiology, including hearing (Casper et al., 2013;Gross et al., 2013;Halvorsen et al., 2012Halvorsen et al., , 2013Popper et al., 2005Popper et al., , 2007. High-pressure acoustic energy can fracture otoliths and damage inner ear sensory hair cells (Casper et al., 2013;McCauley et al., 2003;Coffin and Gross, unpublished observations). ...
... Most studies of the effects of anthropogenic noise on fishes report little hearing loss in any species surveyed, and even fewer observed visible hair cell damage. Exposure to low-or mid-frequency active sonar (193 and 210 dB re 1 μPa peak received intensity for low-and mid-frequency sonar, respectively) caused significant, albeit subtle, temporary threshold shifts in channel catfish (Ictalurus punctatus) and rainbow trout (Oncorhynchus mykiss) but no hearing loss in largemouth bass (Micropterus salmoides) or yellow perch (Perca flavescens) (Halvorsen et al., 2012Popper et al., 2007). Channel catfish are otophysan fishes, a taxonomic group characterized by specialized swim bladder-inner ear connections, the Weberian ossicles, which enhance hearing sensitivity (Ladich and Popper, 2004). ...
... Halvorsen et al., 2012 2 Halvorsen et al., 2013 3 Smith et al., 2006 ...
High-pressure acoustic sources, such as seismic exploration technology or sonar, can temporarily or permanently affect the auditory system of some fish species. The majority of studies done on fish hearing aim to determine safe acoustic operating thresholds for different fishes in order to mitigate possible negative effects of these anthropogenic noise sources. In contrast, the present study was designed to evaluate the effects of a hydraulic watergun on invasive round goby in Lake Michigan as a potential population suppression tool to protect critical spawning habitat for native fishes. The goal of the present study was to evaluate the potential sub-lethal effects of pulse pressure sound technology on the hearing end organs of round goby. Round goby from Little Traverse Bay near Charlevoix, MI were exposed to 6 discharges from a seismic watergun at an average peak sound pressure level of 229 dB re 1 μPa. Fish were monitored for 60 h post-exposure and assessed for damage to otoliths and inner ear sensory hair cells. We found no significant hair cell loss or otolith damage, suggesting that a higher peak pressure level or longer duration of discharges are needed to cause significant damage to round goby inner ear anatomy.
... They can be roughly divided into three categories depending on their primary frequency of operation; low frequency (LF) for 1 kHz and less, mid frequency (MF) for 1 kHz to 10 kHz, and high frequency (HF) for 10 kHz and greater. Low, and possibly mid, frequency sonars are most relevant to fi shes and sea turtles because of the low frequency hearing ranges of these animals (e.g., Popper et al. 2007 ;Halvorsen et al. 2012b ). Sonar usually operates with duty cycles (transmission time/total time) below 10 to 20% and with generally brief durations. ...
... Fishes : Data for mortality and injury related to low-and mid-frequency sonar are based on Popper et al. ( 2007 ), Halvorsen et al. ( 2012b ), and Kane et al. ( 2010 ), which showed no effect on the ear or non-auditory tissues when the maximum received sound pressure levels were at 193 dB re 1 μPa rms for low frequency sonar, and at 210 dB re 1 μPa rms for mid-frequency sonar. Injury, if it occurs, is thought to begin at higher sound levels than tested to date. ...
... To resolve these issues, some studies on the hearing abilities of aquatic animals have been carried out with specialized facilities designed to provide predictable and appropriate acoustic conditions. These facilities included sound ranges established in the sea (Chapman and Hawkins 1973 ;Schuijf 1975 ;Schuijf and Buwalda 1975 ;Popper et al. 2007 ;Halvorsen et al. 2012b ) and specialized wave tubes (e.g., Hawkins and MacLennan 1976 ;Halvorsen et al. 2011Halvorsen et al. , 2012a. ...
Chapters cannot be read stand-alone. Please see complete SpringerBrief at: http:// link. springer. com/ book/ 10. 1007/ 978-3-319-06659-2.
... Roughly, they can be divided into those based on the analysis of sounds/acoustics [18,19], some of which produce images (i.e., [20]) and the more common methods based on the analysis of video images. Both the sensors themselves and their deployment may influence fish behaviour; for example, acoustic telemetry requires the invasive process of tagging a certain number of fish [19,21], the sonar may influence the fishes' hearing [22], and the use of recording instruments handled by human or robots have been shown to influence their behaviour [23,24]. [14] with permission from the authors. ...
... Roughly, they can be divided into those based on the analysis of sounds/acoustics [18,19], some of which produce images (i.e., [20]) and the more common methods based on the analysis of video images. Both the sensors themselves and their deployment may influence fish behaviour; for example, acoustic telemetry requires the invasive process of tagging a certain number of fish [19,21], the sonar may influence the fishes' hearing [22], and the use of recording instruments handled by human or robots have been shown to influence their behaviour [23,24]. Fixed sensors (fixed cameras and passive hydroacoustic sensing) interfere least with the behaviour of the fish. ...
Analysis of fish behaviour is an effective way to indirectly identify the presence of environmental pollutants that negatively affect fish life, its production and quality. Monitoring individual and collective behaviours produces large amounts of non-linear data that require tailor-suited computational methods to interpret and manage the information. Fractal dimension (FD) and entropy are two groups of such non-linear analysing methods that serve as indicators of the complexity (FD) and predictability (entropy) of the behaviours. Since behavioural complexity and predictability may be modulated by contaminants, the changes in its FD and entropy values have a clear potential to be embedded in a biological early warning system (BEWS), which may be particularly useful in Precision Fish Farming settings and to monitor wild populations. This work presents a review of the effects of a wide range of environmental contaminants, including toxic compounds, cleaning and disinfecting agents, stimulant (caffeine), anaesthetics and antibiotics, heavy metals (lead, cupper, and mercury), selenium, pesticides and persistent environmental pollutants, on the FD and entropy values of collective and individual behavioural responses of different fish species. All the revised studies demonstrate the usefulness of both FD and entropy to indicate the presence of pollutants and underline the need to consider early changes in the trend of the evolution of their values prior to them becoming significantly different from the control values, i.e., while it is still possible to identify the contaminant and preserve the health and integrity of the fish.
... Further, sonar and echosounders are general terms under which system parameters may vary widely; thus, extrapolating between studies should done with caution. Many sonar systems generally operate within frequency ranges that are not detectable by fishes and invertebrates (Popper et al., 2007;Halvorsen et al., 2012b), suggesting limited effects. Overall, there has been substantial research on the effects of midfrequency active sonar (MFA; a somewhat general term for naval sonars between 1 kHz and 7 kHz). ...
... Although actual studies are sparse, direct mortality or damage to internal tissues are not expected, and overall populations are not considered at risk from these types of signals (Sivle et al., 2014). MFA sonar induces marginal effects on fish hearing; no effects were observed for rainbow trout (Oncorhynchus mykiss), and minimal, inconsistent, temporary auditory threshold shifts were observed for channel catfish (Ictalurus punctatus) (Halvorsen et al., 2012b). In limited studies, Popper et al. (2007) found that low-frequency sonar may induce hearing loss (but not detectable hair cell damage), but these impacts were at high levels (193 dB re 1 µPa 2 · s). ...
Offshore wind farms are proliferating around the world, and their presence is expected to expand substantially within US waters. Wind farm lifetimes involve 40–50-year commitments, including site surveys, construction, operation, and eventual decommissioning. Because their areas often overlap with essential fisheries habitats, there is a need to understand, mitigate, and manage offshore wind farm impacts on fisheries and ecosystems. Activities during all phases of wind farm lifetimes produce underwater sound, a concern because high noise levels and/or persistent anthropogenic noise can impact marine life in many ways. Here, we review the current understanding of impacts of wind energy activities on fisheries resources, taking into account the varied noise conditions that occur from site survey to decommissioning. For certain portions of wind farm development, such as construction and operation, there is a small amount of available data that allows stakeholders to evaluate impacts for at least some taxa. Yet, we are data deficient for most species’ populations, life stages, and other phases as they relate to wind farm development. Thus, it is difficult to evaluate impacts with any certainty, underscoring the need for further studies to adequately address impacts of offshore wind farms on vulnerable and ecologically and economically important taxa.
... However, ethical considerations preclude investigation of the empirical relation between exposure metrics (sound exposure, peak sound pressure, kurtosis) and long-term hearing impairment, or loss of hair cells in aquatic mammals. On the other hand, experimental studies have demonstrated TTS Halvorsen et al., 2012;Popper et al., 2005a;Popper et al., 2005b), injury, and mortality (Casper et al., 2013;Halvorsen et al., 2011;Halvorsen et al., 2012) in fishes, and suggested injury and mortality in invertebrates (Andr e et al., 2011;Day et al., 2019;McCauley et al., 2017;Sol e et al., 2016), which can be used to investigate possible influence of kurtosis on risk of injury or long-term hearing impairment. ...
... However, ethical considerations preclude investigation of the empirical relation between exposure metrics (sound exposure, peak sound pressure, kurtosis) and long-term hearing impairment, or loss of hair cells in aquatic mammals. On the other hand, experimental studies have demonstrated TTS Halvorsen et al., 2012;Popper et al., 2005a;Popper et al., 2005b), injury, and mortality (Casper et al., 2013;Halvorsen et al., 2011;Halvorsen et al., 2012) in fishes, and suggested injury and mortality in invertebrates (Andr e et al., 2011;Day et al., 2019;McCauley et al., 2017;Sol e et al., 2016), which can be used to investigate possible influence of kurtosis on risk of injury or long-term hearing impairment. ...
Regulations for underwater anthropogenic noise are typically formulated in terms of peak sound pressure, root-mean-square sound pressure, and (weighted or unweighted) sound exposure. Sound effect studies on humans and other terrestrial mammals suggest that in addition to these metrics, the impulsiveness of sound (often quantified by its kurtosis β) is also related to the risk of hearing impairment. Kurtosis is often used to distinguish between ambient noise and transients, such as echolocation clicks and dolphin whistles. A lack of standardization of the integration interval leads to ambiguous kurtosis values, especially for transient signals. In the current research, kurtosis is applied to transient signals typical for high-power underwater noise. For integration time ( t 2 − t 1 ), the quantity ( t 2 − t 1 ) / β is shown to be a robust measure of signal duration, closely related to the effective signal duration, τ eff for sounds from airguns, pile driving, and explosions. This research provides practical formulas for kurtosis of impulsive sounds and compares kurtosis between measurements of transient sounds from different sources.
... For example, of five species exposed to high intensity simulated pile driving signals (Casper et al., 2013a;Halvorsen et al., 2012b;Halvorsen et al., 2012c), only the hogchoker Trinectes maculatus (Bloch & Schneider 1801), a flatfish without a swim bladder, showed no tissue damage (Halvorsen et al., 2012b). At the same time, exposure to very high intensity continuous signals that did not contain any impulsive components showed no tissue damage in five different species (Halvorsen et al., 2012d;Halvorsen et al., 2013;Kane et al., 2010;Popper et al., 2007). ...
... A few of these, described below, are perhaps the most ubiquitous sounds potentially affecting fishes over the widest geographic areas. Sonar systems, while used very widely, generally operate within frequency ranges that are not detectable by fishes(Halvorsen et al., 2012d;Popper et al., 2007). ...
Fishes use a variety of sensory systems to learn about their environments and to communicate. Of the various senses, hearing plays a particularly important role for fishes in providing information, often from great distances, from all around these animals. This information is in all three spatial dimensions, often overcoming the limitations of other senses such as vision, touch, taste and smell. Sound is used for communication between fishes, mating behaviour, the detection of prey and predators, orientation and migration and habitat selection. Thus, anything that interferes with the ability of a fish to detect and respond to biologically relevant sounds can decrease survival and fitness of individuals and populations.
Since the onset of the Industrial Revolution, there has been a growing increase in the noise that humans put into the water. These anthropogenic sounds are from a wide range of sources that include shipping, sonars, construction activities (e.g., wind farms, harbours), trawling, dredging and exploration for oil and gas. Anthropogenic sounds may be sufficiently intense to result in death or mortal injury. However, anthropogenic sounds at lower levels may result in temporary hearing impairment, physiological changes including stress effects, changes in behaviour or the masking of biologically important sounds.
The intent of this paper is to review the potential effects of anthropogenic sounds upon fishes, the potential consequences for populations and ecosystems and the need to develop sound exposure criteria and relevant regulations. However, assuming that many readers may not have a background in fish bioacoustics, the paper first provides information on underwater acoustics, with a focus on introducing the very important concept of particle motion, the primary acoustic stimulus for all fishes, including elasmobranchs. The paper then provides background material on fish hearing, sound production and acoustic behaviour. This is followed by an overview of what is known about effects of anthropogenic sounds on fishes and considers the current guidelines and criteria being used world‐wide to assess potential effects on fishes.
Most importantly, the paper provides the most complete summary of the effects of anthropogenic noise on fishes to date. It is also made clear that there are currently so many information gaps that it is almost impossible to reach clear conclusions on the nature and levels of anthropogenic sounds that have potential to cause changes in animal behaviour, or even result in physical harm. Further research is required on the responses of a range of fish species to different sound sources, under different conditions. There is a need both to examine the immediate effects of sound exposure and the longer‐term effects, in terms of fitness and likely impacts upon populations.
... org) and tens of thousands of species of marine invertebrates. This diversity, particularly in body type and physiology, is likely to result in substantial interspecific differences in how sound affects different species, as has been shown for studies of effects of naval sonars (Popper et al., 2007;Halvorsen et al., 2012b) and seismic airguns on fishes (McCauley et al., 2003;Popper et al., 2005). ...
... AEPs only reflect the responses to sound at the level of the hair cells of the ear, or the responses of particular groups of auditory nerve fibers, or in some cases the summed responses of cells within the central nervous system. Such physiological measures are very useful for comparing hearing mechanisms, or for determining differences before and after some intervention, such as exposure to loud sounds (e.g., Popper et al., 2005;Halvorsen et al., 2012b). But they are much less useful for determining the hearing capabilities of a particular species, or comparing the behavioral responses of different species. ...
... The TTS was more pronounced in one group of rainbow trout studied (group 1) than in another group (group 2) at 400 Hz (Figs. 51a, b). Halvorsen et al. (2012) studied the effects of exposure to mid-frequency active sonar (MFA-a military sonar) in rainbow trout and the channel catfish Ictalurus punctatus (family Ictaluridae) at SPLs of 210 dB between 2.8 and 3.6 kHz. The exposure level did not affect the hearing sensitivity of rainbow trout, a species whose hearing range is lower than the MFA frequencies, and is sensitive to particle acceleration. ...
... The average of two groups is shown. AfterHalvorsen et al. (2012). MFA mid- ...
A recent survey lists more than 100 papers utilizing the auditory evoked potential (AEP) recording technique for studying hearing in fishes. More than 95 % of these AEP-studies were published after Kenyon et al. introduced a non-invasive electrophysiological approach in 1998 allowing rapid evaluation of hearing and repeated testing of animals. First, our review compares AEP hearing thresholds to behaviorally gained thresholds. Second, baseline hearing abilities are described and compared in 111 fish species out of 51 families. Following this, studies investigating the functional significance of various accessory hearing structures (Weberian ossicles, swim bladder, otic bladders) by eliminating these morphological structures in various ways are dealt with. Furthermore, studies on the ontogenetic development of hearing are summarized. The AEP-technique was frequently used to study the effects of high sound/noise levels on hearing in particular by measuring the temporary threshold shifts after exposure to various noise types (white noise, pure tones and anthropogenic noises). In addition, the hearing thresholds were determined in the presence of noise (white, ambient, ship noise) in several studies, a phenomenon termed masking. Various ecological (e.g., temperature, cave dwelling), genetic (e.g., albinism), methodical (e.g., ototoxic drugs, threshold criteria, speaker choice) and behavioral (e.g., dominance, reproductive status) factors potentially influencing hearing were investigated. Finally, the technique was successfully utilized to study acoustic communication by comparing hearing curves with sound spectra either under quiet conditions or in the presence of noise, by analyzing the temporal resolution ability of the auditory system and the detection of temporal, spectral and amplitude characteristics of conspecific vocalizations.
... As these sonars operate at large ranges the signals can be very intense. Investigations using low and mid-frequency naval sonars have shown no tissue damage in fishes, although there is the potential for temporary hearing loss in some specimens of some species (Popper et al. 2007;Kane et al. 2010;Halvorsen et al. 2012c). ...
... Studies to determine sensitivity of fishes to substrate vibrations Studies on the ability of fishes to discriminate between sounds of differing quality coming from different directions and distances and how man-made sounds affect these abilities 123 juveniles may be damaged by exposure to low frequency naval sonars (Jorgensen et al. 2005) but other investigations of the effects of impulsive pile driving on larvae showed no effect (Bolle et al. 2012). Additionally, exposure of fishes to very high intensity sonars operating at frequencies below 1 kHz and from 2 to 4 kHz showed no mortality (Popper et al. 2007;Halvorsen et al. 2012c). The greater likelihood is that fishes and invertebrates will be injured by high intensity impulsive sounds with rapid rise times, and that some of these injuries could result in fatalities over the short term or over a longer term if animal fitness is compromised (Halvorsen et al. 2011Casper et al. 2012aCasper et al. , b, 2013a. ...
Mitigating measures may be needed to protect animals and humans that are exposed to sound from man-made sources. In this context, the levels of man-made sound that will disrupt behavior or physically harm the receiver should drive the degree of mitigation that is needed. If a particular sound does not affect an animal adversely, then there is no need for mitigation! The problem then is to know the sound levels that can affect the receiving animal. For most marine animals, there are relatively few data to develop guidelines that can help formulate the levels at which mitigation is needed. In this talk, we will review recent guidelines for fishes and turtles. Since so much remains to be determined in order to make guidelines more useful, it is important that priorities be set for future research. The most critical data, with broadest implications for marine life, should be obtained first. This paper will also consider the most critical gaps and present recommendations for future research.
... Given that intense noise can cause hearing loss, it is unsurprising that several studies have examined the effect of anthropogenic noiseincluding sounds from aquaculture operationson fish ear structure and function (Wysocki et al. 2007;Halvorsen et al. 2012;Casper et al. 2013;Popper and Hawkins 2019;Sapozhnikova et al. 2020). This section briefly discusses a few studies (of many) as part of our broader survey of the impacts of aquaculture noise on fishes. ...
... Furthermore, mid-frequency active sonar (MFAS) consisting of frequency sweeps from 2.8 to 3.8 kHz lasting for 2 s repeated five times at a sound exposure level of 220 dB re 1 μPa 2 s did not affect hearing sensitivity in rainbow trout and only in some catfish. Only one cohort of channel catfish showed a hearing loss of 4-6 dB at 2.3 kHz, but not at lower frequencies (Halvorsen et al., 2012). Thus, LFAS and MFAS had only minimal impact on a hearing specialist, the channel catfish, but none on species lacking auxiliary hearing structures. ...
Ernst Weber stated in 1819, based on dissections, that the swimbladder in the European wels ( Silurus glanis , Siluridae) and related cyprinids serves as an eardrum and that the ossicles connecting it to the inner ear function as hearing ossicles similar to mammals. In the early 20th century, K. von Frisch showed experimentally that catfishes and cyprinids (otophysines) indeed hear excellently compared to fish taxa lacking auxiliary hearing structures (ossicles, eardrums). Knowledge on hearing in catfishes progressed in particular in the 21st century. Currently, hearing abilities (audiograms) are known in 28 species out of 13 families. Recent ontogenetic and comparative studies revealed that the ability to detect sounds of low‐level and high frequencies (4–6 kHz) depends on the development of Weberian ossicles. Species with a higher number of ossicles and larger bladders hear better at higher frequencies (>1 kHz). Hearing sensitivities are furthermore affected by ecological factors. Rising temperatures increase, whereas various noise regimes decrease hearing. Exposure to high‐noise levels (>150 dB) for hours result in temporary thresholds shifts (TTS) and recovery of hearing after several days. Low‐noise levels reduce hearing abilities due to masking without a TTS. Furthermore, auditory evoked potential (AEP) experiments reveal that the temporal patterns of fish‐produced pulsed stridulation and drumming sounds are represented in their auditory pathways, indicating that catfishes are able to extract important information for acoustic communication. Further research should concentrate on inner ears to determine whether the diversity in swimbladders and ossicles is paralleled in the inner ear fine structure.
... The most common monitoring methods are based on the analysis of video images, while newer ones target sound/acoustic signals [8][9][10]. However, the sensors themselves may influence an animal's behaviour; for instance, acoustic telemetry requires tagging [9,11], sonar affects a fish's hearing [12], and the presence of robots or divers' videorecording also alter fishes' behaviour [13,14]. Fixed sensors interfere the least, but they can only record fish within a certain region. ...
In a non-linear system, such as a biological system, the change of the output (e.g., behaviour) is not proportional to the change of the input (e.g., exposure to stressors). In addition, biological systems also change over time, i.e., they are dynamic. Non-linear dynamical analyses of biological systems have revealed hidden structures and patterns of behaviour that are not discernible by classical methods. Entropy analyses can quantify their degree of predictability and the directionality of individual interactions, while fractal dimension (FD) analyses can expose patterns of behaviour within apparently random ones. The incorporation of these techniques into the architecture of precision fish farming (PFF) and intelligent aquaculture (IA) is becoming increasingly necessary to understand and predict the evolution of the status of farmed fish. This review summarizes recent works on the application of entropy and FD techniques to selected individual and collective fish behaviours influenced by the number of fish, tagging, pain, preying/feed search, fear/anxiety (and its modulation) and positive emotional contagion (the social contagion of positive emotions). Furthermore, it presents an investigation of collective and individual interactions in shoals, an exposure of the dynamics of inter-individual relationships and hierarchies, and the identification of individuals in groups. While most of the works have been carried out using model species, we believe that they have clear applications in PFF. The review ends by describing some of the major challenges in the field, two of which are, unsurprisingly, the acquisition of high-quality, reliable raw data and the construction of large, reliable databases of non-linear behavioural data for different species and farming conditions.
... Experiments performed in open water allow for the establishment of simple, well-controlled sound fields (Schuijf and Buwalda 1975;Hawkins 2014;Gray et al. 2016;Hawkins and Chapman 2020), and offer the best insights into natural behavioral responses from free-ranging species, despite the obvious logistical and financial constraints. Studies performed on caged animals (McCauley et al. 2003;Popper et al. 2007;Halvorsen et al. 2012Halvorsen et al. , 2013Bruintjes et al. 2016) are useful to explore inner ear damage in a controlled sound field in open water, but less so for behavioral measurements, as it is unlikely that these animals will exhibit complex and context-dependent behaviors when they are confined. ...
Cartilaginous fishes (Chondrichthyes), including sharks, skates, rays, elephant fishes and chimaeras, have been in existence for over 400 million years and represent early stages of the evolution of extant jawed vertebrates. The sensory systems of cartilaginous fishes, including their hearing apparatus, have adapted to a diverse range of ecosystems, from the deep ocean to freshwater rivers, revealing high levels of morphological diversity. Since sound travels such long distances underwater, this environmental cue may represent an important signal in the behavior and survival of this group of fishes but there are still many gaps in our understanding of their hearing system. Based on current knowledge, cartilaginous fishes are most sensitive to low frequency sounds (< 1500 Hz) and there is abundant support that their inner ears use only particle displacement detection rather than the detection of sound pressure, but further studies are needed to corroborate the observations of long distance detection of sound sources that might be based on the detection of pressure oscillations. This review investigates the diversity and functional significance of the inner ear of chondrichthyans from a range of habitats and explores what is known about their hearing capabilities. How underwater sounds are processed by the central nervous system, the impacts of sound on acoustic ecology and behavior , and the potential effects of anthropogenic sound are also examined. Some suggestions for future work are presented to fill the large gaps in our knowledge of the hearing abilities of this important group of vertebrates.
... Freshwater fishes show commonalities with marine species in regard to the importance of acoustic perception and the impact noise has upon it, although the sources of noise often differ. While anthropogenic noise in marine habitats is produced by shipping vessels (Wysocki et al., 2006), navyoperated sonar systems (Halvorsen et al., 2012) and pile driving (Mueller-Blenkle et al., 2010), noise in streams is primarily generated by roads (Riitters and Wickham, 2003;Ware et al., 2015;Castaneda et al., 2020). Additionally, different bridge structures vary in the types of noise they emit. ...
While the expansion of anthropogenic noise studies in aquatic habitats has produced conservation-based results for a range of taxa, relatively little attention has been paid to the potential impacts on stream fishes. Recent work has shown responses to road noise in single species of stream fish; however, assemblage-wide effects of anthropogenic noise pollution have not yet been investigated. By examining five metrics of disturbance across four ecologically and evolutionarily disparate species of stream fishes, a series of laboratory experiments aimed to describe the effects of and species susceptibility to anthropogenic noise playback. Each species studied represented a unique combination of hearing sensitivity and water column position. Physiological and behavioral metrics were compared across the presence and absence of rail-noise noise playback in four target species. Through repeated subsampling, the temporal dynamics of cortisol secretion in response to noise in two target species were additionally described. Rail-noise playback had no statistically significant effect on blood glucose or water-borne cortisol levels, with the exception of decreased cortisol in noise-exposed largescale stoneroller (Campostoma oligolepis). Time-course cortisol experiments revealed rapid secretion and showed minimal effects of noise at most observation points. The presence of noise produced significant changes in ventilation rate and swimming parameters in a portion of the four species observed representing the most conserved responses. Overall, effects of noise were observed in species contrary to what would be hypothesized based on theoretical hearing sensitivity and water column position demonstrating that predicting susceptibility to this type of stressor cannot be accomplished based off these course considerations alone. More importantly, we show that anthropogenic noise can disrupt a variety of behavioral and physiological processes in certain taxa and should be further investigated via measures of fitness in the wild.
... This work resulted in a number of papers showing that the sonars, at the intense sound levels we used, did not have long-lasting impact on the species we studied (e.g. Popper et al., 2007;Halvorsen et al., 2012b). ...
Collaboration is integral to most scientific research today, and it has certainly been important in my career and for my career path. However, not all collaborations are “equal”. Most, in fact, are short term or transient, with collaborators working on one project and then moving on to other projects and perhaps other collaborations. There are, however, a few collaborations, such as the three I describe here, that are long term and that not only resulted in a large number of collaborative projects but that also strongly influenced career paths. Indeed, these three collaborations resulted in all of us undertaking new paths that we were not likely to have taken alone or without the stimulation of working with someone we know well and have learned to trust.
... Effects of underwater noise on marine life are wide ranging: it can cause species to avoid areas with significant anthropogenic sound, possibly disrupting feeding, breeding or migratory behaviour (Bracciali et al., 2012;Gill et al., 2012 and references therein ;Sara et al., 2007); cause permanent or temporary damage to marine organisms (Casper et al., 2012;Kastak et al., 1999;Southall et al., 2008), mask communications (Clark et al., 2009;Gutscher et al., 2011;Halvorsen et al., 2012b;Wood, 2011) or even cause death of an individual (Halvorsen et al., 2012a;Madsen et al., 2006;Southall et al., 2008). This study did not set out to investigate the impacts of underwater noise on marine life, however an understanding of the response of marine species to anthropogenic noise and the effects the noise could have on them was essential to creating the ecological response model. ...
The effects of anthropogenic underwater noise on marine life is of growing concern and assessment of impacts on marine life is often carried out using predictive underwater noise models to map zones of influence for marine species. However, these models do not predict how a species may react to that noise. In this paper, the results from a modified predictive underwater noise model and a hydrodynamic model are used in an individual based model (IBM) to predict the impacts on cod (Gadhus moruha) from noise generated during a pile driving event at an offshore wind farm in Liverpool Bay, UK. The model included cod which were sensitive to noise and those which were insensitive ('deaf'). Fish movement was from the outer bay into the Dee Estuary, a known feeding ground. The IBM indicated that the cod which could hear took up to 7 days longer to reach their destination than the cod which were deaf. This technique could be used during the consenting process for offshore projects to better understand the potential impact on marine species.
... Given its widespread use for marine and civilian purposes, high-frequency (HF) sound is considered ubiquitous and can impact greatly on sessile species that are unable to move away at speed from a noisy area. Physical and physiological effects were observed in marine mammals (Wright et al., 2007;Fern andez et al., 2005;Ketten et al., 1993;Rolland et al., 2012) and fish (Halvorsen et al., 2012;Cox et al., 2018) as a result of both low and high acoustic frequencies. ...
Underwater sounds generated by anthropogenic activity can cause behavior changes, temporary loss of hearing, damage to parts of the body, or death in a number of marine organisms and can also affect healing and survival. In this study, the authors examined the effects of high-frequency acoustic stimulations on a number of biochemical parameters in the Mediterranean mussel, Mytilus galloprovincialis. During the experiment, animals were placed in a test tank and exposed to acoustic signals [a linear sweep ranging from 100 to 200 kHz and lasting 1 s, with a sound pressure level range of between 145 and 160 dBrms (re 1μParms)] for 3 h. Total haemocyte count was assessed and glucose levels, cytotoxic activity and enzyme activity (alkaline phosphatase, esterase and peroxidase) in the digestive gland were measured. For the first time, this study suggests that high-frequency noise pollution has a negative impact on biochemical parameters in the digestive gland.
... Such ultrasonic sources are detected by some fish species (Mann et al. 2001). In addition, there are some high-power, low-and midfrequency naval sonars that use signals from several hundred to several thousand hertz, within the hearing range of fishes Halvorsen et al. 2012c). ...
Sound provides animals with a means of rapid, directional, and long-distance communication. It also provides animals with a “gestalt” view of their environment by giving an acoustic image of the world that often extends far beyond what is available from other senses. Thus, sound is highly relevant for fishes, and any interference with the ability to detect sound has potential consequences for the fitness and survival of individuals, populations, and species. There is a growing body of evidence that the addition of man-made sound in the aquatic environment has the potential to affect the ability of fishes to detect and use the biologically relevant sounds that are important for their survival. Moreover, there is also evidence that especially intense sounds not only affect sound detection and behavior but also have the potential to have physiological and physical effects on fish that could result in greatly reduced fitness and, in some cases, directly to death. This chapter examines the potential effects of man-made sound on fishes. It considers the sources of such sounds, the current data on potential effects and impacts, and implications for regulation of such sounds so that the potential impact is mitigated.
... The magnitude of the impact will depend on species, individual sensitivity, physiological and behavioural state, age, nature of the sound source (impulsive vs continuous), prior experience, resource availability and individual and group activity. Very high noise levels, for instance, originating from pile driving or seismic measurements, can cause tissue damage, damage of the inner ear and lateral lines of fish (Halvorsen et al., 2012a;Casper et al., 2013), although not all marine species have shown such effects and the levels at which injuries occur appeared to vary Popper and Hastings, 2009a,b;Casper et al., 2012Casper et al., , 2013Bolle et al., 2012;Halvorsen et al., 2012b). ...
This review is one of the objectives of the project carried out as an MRE Knowledge exchange NERC Fellowship (NE/L014335/1) Developing and testing models of fish behaviour around tidal turbines. The overarching aim of this project was to provide an evidence-based tool to forecast the effects of anthropogenic noise on marine fish for Environmental Impact Assessments (EIA). The project was run in collaboration with the tidal turbine developer Sustainable Marine Energy (SME), the marine modelling consultant HR Wallingford (HRW) and University of Exeter.
The review was asked by Natural England with the specific aims of presenting the projects that used sound propagation modelling in Environmental Impact Assessments. The review has found that there are a number of numerical models available for the calculation of the sound propagation in ocean. These include ray tracing, normal mode and parabolic equation models. Each model has its own strengths and weaknesses. Some are best suited to shallow water, others to deep water; some can deal with complex bathymetry profiles, others require a fixed water depth; some can deal with shear waves, others cannot. It follows that the choice of the propagation model depends on the circumstances found in the environment considered. The collection of accurate oceanographic data such as sound speed profiles, sea floor properties, and bathymetry as well as ambient noise data for computational modelling presents several constrains and this has consequences on the outcome of an ocean acoustics propagation model.
... Underwater hearing experiments have been conducted within water volumes varying in extent from small "tabletop" tanks (Fay and Passow 1982 ;Anderson and Mann 2011 ) to essentially semi-infi nite water bodies (Chapman and Hawkins 1973 ;Halvorsen et al. 2012 ). Some of the complexities of the sound fi elds in the former were addressed by Parvulescu ( 1967 ) and are further investigated in a companion paper (see Chapter 115 by Rogers et al. ...
In this paper, we discuss the issues encountered when trying to perform hearing experiments in water-filled tanks that are several meters in lateral extent, typically large in terms of the size of the animals under study but not necessarily so with respect to the wavelengths of interest. This paper presents measurements of pressure and particle motion fields in these "large" tanks. The observed characteristics and complexities are discussed in reference to their potential impact on the planning and interpretation of hearing experiments.
... Threshold shifts were evident for the channel catfi sh, but not for the bass or perch. Mid-frequency active (MFA) sonar, at a cumulative SEL of 220 dB re 1 μPa 2 s, did not cause a hearing threshold shift in rainbow trout, but channel catfi sh exhibited a 4-6 dB threshold shift at 2300 Hz, which recovered within 24 h (Halvorsen et al. 2012c ). In summary, the effects of sonar on fi sh hearing depend upon the sensitivity and bandwidth of the species and the frequency range of the sonar. ...
Sensory hair cells are the mechanotransductive receptors that detect gravity, sound, and vibration in all vertebrates. Damage to these sensitive receptors often results in deficits in vestibular function and hearing. There are currently two main reasons for studying the process of hair cell loss in fishes. First, fishes, like other non-mammalian vertebrates, have the ability to regenerate hair cells that have been damaged or lost via exposure to ototoxic chemicals or acoustic overstimulation. Thus, they are used as a biomedical model to understand the process of hair cell death and regeneration and find therapeutics that treat or prevent human hearing loss. Secondly, scientists and governmental natural resource managers are concerned about the potential effects of intense anthropogenic sounds on aquatic organisms, including fishes. Dr. Arthur N. Popper and his students, postdocs and research associates have performed pioneering experiments in both of these lines of fish hearing research. This review will discuss the current knowledge regarding the causes and consequences of both lateral line and inner ear hair cell damage in teleost fishes.
... Threshold shifts were evident for the channel catfi sh, but not for the bass or perch. Mid-frequency active (MFA) sonar, at a cumulative SEL of 220 dB re 1 μPa 2 s, did not cause a hearing threshold shift in rainbow trout, but channel catfi sh exhibited a 4-6 dB threshold shift at 2300 Hz, which recovered within 24 h (Halvorsen et al. 2012c ). In summary, the effects of sonar on fi sh hearing depend upon the sensitivity and bandwidth of the species and the frequency range of the sonar. ...
Sensory hair cells are the mechanotransductive receptors that detect gravity, sound, and vibration in all vertebrates. Damage to these sensitive receptors often results in deficits in vestibular function and hearing. There are currently two main reasons for studying the process of hair cell loss in fishes. First, fishes, like other non-mammalian vertebrates, have the ability to regenerate hair cells that have been damaged or lost via exposure to ototoxic chemicals or acoustic overstimulation. Thus, they are used as a biomedical model to understand the process of hair cell death and regeneration and find therapeutics that treat or prevent human hearing loss. Secondly, scientists and governmental natural resource managers are concerned about the potential effects of intense anthropogenic sounds on aquatic organisms, including fishes. Dr. Arthur N. Popper and his students, postdocs and research associates have performed pioneering experiments in both of these lines of fish hearing research. This review will discuss the current knowledge regarding the causes and consequences of both lateral line and inner ear hair cell damage in teleost fishes.
... Startle responses depend on the species-specific sound level threshold, which in turn depends on species-specific hearing sensitivity [49]. Hearing sensitivity of a generalist hearing species (e.g., Oncorhynchus mykiss) such as C. chromis [13], [50], was altered at low frequency exposure, showing a shift in the hearing threshold [51], but not at high frequencies, that instead affected hearing abilities of a specialist hearing species (Ictalurus punctatus) [52]. Boat noise was already known to reduce the auditory sensitivity in C. chromis [8] relative to the perception of conspecific vocalizations, but no studies have been conducted to date that determine their sound threshold for startle responses. ...
Anthropogenic noise is becoming a major underwater pollutant due to rapidly increasing boat traffic worldwide. But its impact on aquatic organisms remains largely unknown. Previous studies have focused mainly on high-frequency and impulsive noises (i.e. sonar), however, boat noise is more pervasive, continuous, and its highest intensity and component frequencies overlap the auditory bandwidth of most fishes. We assessed the impacts of boat noise on saccular sensory hair cell density and hearing thresholds of a soniferous species, Atlantic Croaker (Micropogonias undulatus). In two laboratory experiments, individuals were subjected to simulated boat noise: a single 15-minute exposure and three days of intermittent noise (simulating passing vessels). Immediately after both experiments, fish were either 1) tested for hearing sensitivity with auditory evoked potential (AEP) tests or 2) sacrificed for fluorescent phalloidin and TUNEL labeling for hair cell density counts. Relative to controls, no differences were observed in auditory thresholds nor hair cell density between individuals subjected to a single 15-minute noise exposure. However, fish from the three-day experiment showed decreased sensory hair cell density, increased apoptotic cells, and hearing thresholds were higher than control fish at 300, 800, and 1000 Hz. Our results demonstrate that impacts from boat noise depend upon the duration and frequency of exposure. For a species reliant on vocalization for communication, these impacts may hinder spawning success, increase predation risks, and significantly alter the ecosystem.
This thesis investigates the potential for insonified bubble curtains that use the resonant properties of bubbles to be used as behavioural deterrents for fish. This can help mitigate the ecological impacts of river and estuarine infrastructure such as hydropower technologies. To this end, in a series of four flume experiments, the following was tested: (1) the reactions of fish to a low air flow bubble curtain; (2) the effect of deconvoluting visual cues from stimuli generated by the bubble curtain; (3) the effectiveness of resonant versus non-resonant insonified bubble curtains to deter passage, determining the stimuli responsible for eliciting deterrence; (4) the question of whether regions with different levels of particle motion or acoustic pressure influence fish behaviour. Models of the extinction cross-section for each bubble population were used to explain the acoustical effects, confirming bubble resonance. Results of this fundamental study showed that bubble clouds with a higher proportion of resonant bubbles were better at deterring fish passage and this was likely influenced by multimodal cues, specifically, particle displacement, and sound pressure within a body length of the fish. All insonified bubble curtains were less effective in the presence of visual cues, likely because when available these are given greater importance by fish over mechanosensory cues. The benefits of energy-efficient, resonance-based acoustic behavioural deterrents examined by this thesis may be explored further for field-based applications. Finally, the importance of avoiding certain historical pitfalls when characterising acoustically active bubble curtains is discussed.
The stocks of the Atlantic salmon (Salmo salar) in many rivers in North America and Europe have declined in recent years and are experiencing a crisis. Despite their high degree of legal protection, the quality of their aquatic environments within rivers and in the sea, including local coastal waters, appears to be deteriorating. Salmon survival, has declined both within the sea and within rivers. The status of the Atlantic salmon stocks is considered here, together with the adverse effects of different sources, and those steps that may need to be taken to improve the condition of the salmon. This paper is intended to assist management bodies in taking steps to resolve the problems that exist for salmon, both within rivers and in the sea. It makes particular use of information available on the River Dee in Scotland.
Rising levels of anthropogenic underwater sound may have negative consequences on freshwater ecosystems. Additionally, the biological relevance of sound to fish and observed responses to human-generated noise promote the use of acoustics in behavioural guidance technologies that are deployed to control the movement of fish. For instance, acoustic stimuli may be used to prevent the spread of invasive fishes or facilitate the passage of vulnerable native species at man-made obstructions. However, a strong understanding of fish response to acoustics is needed for it to be effectively deployed as a fisheries management tool, but such information is lacking. Therefore, this thesis investigated the group behavioural responses of cyprinids to acoustic stimuli. A quantitative meta-analysis and experimental studies conducted in a small-tank or large open-channel flume were used to address key knowledge gaps that are necessary to improve the sustainability of acoustic deterrent technologies, and assist in conservation efforts to reduce the negative impacts of anthropogenic noise.
Current understanding on the impact of anthropogenic noise on fishes (marine, freshwater and euryhaline species) was quantified. The impact of man-made sound is greatest for fish experiencing anatomical damage, for adult and juveniles compared to earlier life-stages, and for fish occupying freshwater environments. These findings suggest a review of the current legislation covering aquatic noise mitigation which commonly focus on marine-centric strategies, thereby undervaluing the susceptibility of freshwater fish to the rising levels of anthropogenic sound. Limitations and knowledge gaps within the literature were also identified, including: 1) group behavioural responses to sound, 2) the response of fish to different fundamental acoustic properties of sound, 3) system longevity (e.g. habituation to a repeated sound exposure), and 4) site-specific constraints.
Fish movement and space use were quantified using fine-scale behavioural metrics (e.g. swimming speed, shoal distribution, cohesion, orientation, rate of tolerance and signal detection theory) and their collective response to acoustics assessed using two approaches. First, a still-water small tank set-up allowed for the careful control of confounding factors while investigating cyprinid group response to fundamental acoustic properties of sound (e.g. complexity, pulse repetition rate, signal-to-noise ratio). Second, a large open-channel flume enabled the ability of a shoal to detect and respond to acoustic signals to be quantified under different water velocities.
Shoals of European minnow (Phoxinus phoxinus), common carp (Cyprinus carpio) and roach (Rutilus rutilus) altered their swimming behaviour (e.g. increased group cohesion) in response to a simple low frequency tonal stimulus. The pulse repetition rate of a signal was observed to influence the long-term behavioural recovery of minnow to an acoustic stimulus. Furthermore, signal detection theory was deployed to quantify the impact of background masking noise on the group behavioural response of carp to a tonal stimulus, and investigate how higher water velocities commonly experienced by fish in the wild may influence the response of roach to an acoustic stimulus. Fine-scale behavioural responses were observed the higher the signal-to-noise ratio, and discriminability of an acoustic signal and the efficacy at which fish were deterred from an insonified channel was greatest under higher water velocities.
The information presented in this thesis significantly enhances our understanding of fish group responses to man-made underwater sound, and has direct applications in freshwater conservation, fish passage and invasive species management.<br/
In teleost fishes, the evolution of hearing enhancement and corresponding auditory structures remains largely elusive. We know little about the selective pressures acting on the evolution of improved hearing. Cichlids are marked by great species diversity; they have adapted to a variety of ecological niches, including different ecoacoustical conditions such as ambient noise levels or frequency spectra. This makes cichlids a perfect model for comparative approaches to investigate the relationship between ecological factors, acoustical behavior, and functional morphology of hearing in teleost fishes and to approach questions about the evolution of improved hearing. Functional acoustical studies show that cichlids evolved a considerable diversity in ancillary auditory structures and hearing abilities. This review summarizes what is known about the morphology of inner ears and swimbladders in cichlids and about their auditory abilities. The focus is on recent comparative studies designed to shed light on the functional morphology of hearing. These studies, however, still widely lack ecological and phylogenetic perspectives. We therefore suggest that future acoustical studies in cichlids should be embedded in a phylogenetic framework including ecological data. This would help gain insight into how hearing enhancement and auditory structures evolved in this group and potentially in other teleosts as well.
The stocks of the Atlantic salmon (Salmo salar) have declined in the sea and in many rivers in North America and Europe in recent years and are experiencing a crisis. Despite their high degree of legal protection, the quality of their aquatic environments within rivers and in the sea, including local coastal waters, appears to be deteriorating. Salmon survival, has declined both within the sea and within rivers. The status of the Atlantic salmon stocks is considered here, together with the adverse effects of different sources, and those steps that may need to be taken to improve the condition of the salmon. This paper is intended to assist management bodies in taking steps to resolve the problems that exist for salmon, both within rivers and in the sea. It makes particular use of information available from the River Dee in Scotland.
Many sensory systems are more commonly known than others, but all are critical for survival. These include those senses typically described by Aristotle around 300–400 Before the Common Era (BCE), such as sight (vision), hearing (audition), touch (somatosensation), smell (olfaction), and taste (gustation). However, many years of scientific endeavor have shown that these five senses represent only a part of the sensory abilities that are now known throughout the aquatic animal kingdom. The extended repertoire of senses includes the ability for vestibular control (equilibrioception), the sensation of temperature (thermoreception), postural awareness (proprioception), the monitoring of pain (nociception), the use of sonar (echolocation), and the detection of weak electric (electroreception) and magnetic (magnetoreception) fields. The papers presented in this Research Topic were greatly welcomed and consist of a collection of exciting and well-received articles that incorporated new knowledge on almost all of the known senses in a range of aquatic vertebrates, such as the sarcopterygian lungfishes, both freshwater and marine teleosts, elasmobranchs, marine reptiles, and cetaceans (marine mammals). The papers target many of the known senses in aquatic vertebrates, but are biased toward vision, which reflects the number of active research programs that concentrate on this sensory modality.
In assessing the impact of sound on aquatic life, or its potential to guide fauna away from hazards, there is reliance on decades of human audiology, for example by adapting tests such as behavioral audiograms and Auditory Evoked Potentials.
However, now that human audiology has translated over decades from research laboratories to the high-street hearing-aid dispenser, we might forget the underlying challenges that human audiology overcame, and which face its aquatic analogue because it is still in its infancy.
A major challenge of researching effects of sound on fish comes from sparsity of data. One aspect of human audiology that shares this characteristic is the effect of Very High Frequency sound/ultrasound in air on humans. Their similarities will be discussed in terms of the difficulties associated with: lack of appreciation of the complexities of the sound field; lack of recognized calibrations and measurement procedures; reliance on the concept of a ‘typical’ subject based on an average; reliance on data from too few subjects; insufficient appreciation of group effects; reliance on a tacit assumption of an assumed mapping between threshold for hearing and threshold for behavioral/adverse effects; the tension between field and laboratory observations; and confusion caused by inexpert reporting.
Sensory input to the central nervous system is the primary means by which animals respond to variation in their physical and biological environments. It is well established that key threats such as habitat destruction, the introduction of non-native species, and climate change are imposing significant pressures on natural ecosystems, yet surprisingly few studies have examined how these threats impact the senses or determine species' responses to environmental change. This review focuses on how anthropogenic impacts on aquatic ecosystems can have a detrimental effect on the sensory systems of aquatic organisms and how these modalities can act to influence genetic and non-genetic (e.g., developmental) responses to environmental change, which in turn can cause knock-on effects in a range of other biological systems. Species often exhibit unique sensory specializations that are suited to their behavioral requirements; at present it is unclear whether and how sensory systems have the capacity to respond to environmental change through genetic adaptation and/or sensory plasticity, and on what timescale this might occur. Sensory systems lie at the forefront of how various species respond to environmental perturbation. As such, determining the important role they play in determining fitness is critical for understanding the effects of external processes such as habitat degradation and climate change. Given the current consensus that human impacts and environmental changes are potentially highly detrimental to the delicate balance of the biome, knowing how organisms respond, and to what degree adaptation is physiologically and behaviorally limited, warrants urgent attention.
The aquatic environment is increasingly bombarded by a wide variety of noise pollutants, whose range and intensity are increasing with each passing decade. Yet little is known about how aquatic noise affects marine communities. To determine the implications that changes to the soundscape may have on fishes, a meta-analysis was conducted focusing on the ramifications of noise on fish behavior and physiology. Our meta-analysis identified 42 studies that produced 2,354 data points, which in turn indicated that anthropogenic noise negatively affects fish behavior and physiology. The most predominate responses occurred within foraging ability, predation risk, and reproductive success. Additionally, anthropogenic noise was shown to increase the hearing thresholds and cortisol levels of numerous species while tones, biological, and environmental noise were most likely to affect complex movements and swimming abilities. These findings suggest that the majority of fish species are sensitive to changes in the aquatic soundscape, and depending on the noise source, species responses may have extreme and negative fitness consequences. As such this global synthesis should serve as a warning of the potentially dire consequences facing marine ecosystems if alterations to aquatic soundscapes continue on their current trajectory. This article is protected by copyright. All rights reserved.
Aquatic noise has the potential to travel extreme distances and as such many marine species rely on the soundscape for auditory information regarding habitat selection, predator or prey locations, and communication. These species not only take advantage of the prevailing sounds but also contribute to the soundscape through their own vocalizations. Certain sounds have the potential to negatively effect marine species resulting in unbalanced predator-prey interactions and disrupted communication. In an attempt to determine the implications that changes to the soundscape may have on fishes, we conducted a meta-analysis focusing on how anthropogenic and biological noises may alter fish behavior and physiology. We reviewed 3,174 potentially relevant papers of which 44 met our criteria and were used in the analysis. Results indicated that anthropogenic noise has an adverse effect on marine and freshwater fish behavior and physiology. Alternatively biological and environmental noises did not significantly alter fish behavior and physiology. These findings suggest that although certain species may be more susceptible to anthropogenic noise than others, the vast majority of fish have the potential to be negatively affected by noise pollution, while biological noises may not have the same negative consequences for fish behavior and physiology.
Due to the extreme distance that sounds can travel through water, many marine species rely on the soundscape for auditory information regarding predator or prey locations, communication, and habitat selection. These species not only take advantage of the prevailing sounds but also contribute to the soundscape through their own vocalizations. Certain sounds have been shown to have negative effects on marine species, resulting in disrupted communication and unbalanced predator-prey interactions. Unfortunately, the vast majority of soundscape studies are biased towards marine mammals, and only recently has attention been directed towards the potential repercussions for fishes. In an attempt to determine the implications that changes to the soundscape may have on the fishes, a meta-analysis was conducted focusing primarily on the role that anthropogenic noises may play in altering fish behavior and physiology. The review identified 3,174 potentially relevant papers of which were 27 used. The analysis indicates that anthropogenic noise has an adverse effect on marine and freshwater fish behavior and physiology. These findings suggest that although certain species may be more susceptible to anthropogenic noise than others, the vast majority of fish have the potential to be negatively affected by noise pollution.
Light detection not only forms the basis of vision (via visual retinal photoreceptors), but can also occur in other parts of the body, including many non-rod/non-cone ocular cells, the pineal complex, the deep brain, and the skin. Indeed, many of the photopigments (an opsin linked to a light-sensitive 11-cis retinal chromophore) that mediate color vision in the eyes of vertebrates are also present in the skin of animals such as reptiles, amphibians, crustaceans and fishes (with related photoreceptive molecules present in cephalopods), providing a localized mechanism for light detection across the surface of the body. This form of non-visual photosensitivity may be particularly important for animals that can change their coloration by altering the dispersion of pigments within the chromatophores (pigment containing cells) of the skin. Thus, skin coloration may be directly color matched or “tuned” to both the luminance and spectral properties of the local background environment, thereby facilitating behavioral functions such as camouflage, thermoregulation, and social signaling. This review examines the diversity and sensitivity of opsin-based photopigments present in the skin and considers their putative functional roles in mediating animal behavior. Furthermore, it discusses the potential underlying biochemical and molecular pathways that link shifts in environmental light to both photopigment expression and chromatophore photoresponses. Although photoreception that occurs independently of image formation remains poorly understood, this review highlights the important role of non-visual light detection in facilitating the multiple functions of animal coloration.
FOI är en huvudsakligen uppdragsfi nansierad myndighet under Försvarsdepartementet. Kärnverksamheten är forskning, metod-och teknikutveckling till nytta för försvar och säkerhet. Organisationen har cirka 1000 anställda varav ungefär 800 är forskare. Detta gör organisationen till Sveriges största forskningsinstitut. FOI ger kunderna tillgång till ledande expertis inom ett stort antal tillämpningsområden såsom säkerhetspolitiska studier och analyser inom försvar och säkerhet, bedömning av olika typer av hot, system för ledning och hantering av kriser, skydd mot och hantering av farliga ämnen, IT-säkerhet och nya sensorers möjligheter.
A recent survey lists more than 100 papers utilizing the auditory evoked potential (AEP) recording technique for studying hearing in fishes. More than 95 % of these AEP-studies were published after Kenyon et al. introduced a non-invasive electrophysiological approach in 1998 allowing rapid evaluation of hearing and repeated testing of animals. First, our review compares AEP hearing thresholds to behaviorally gained thresholds. Second, baseline hearing abilities are described and compared in 111 fish species out of 51 families. Following this, studies investigating the functional significance of various accessory hearing structures (Weberian ossicles, swim bladder, otic bladders) by eliminating these morphological structures in various ways are dealt with. Furthermore, studies on the ontogenetic development of hearing are summarized. The AEP-technique was frequently used to study the effects of high sound/noise levels on hearing in particular by measuring the temporary threshold shifts after exposure to various noise types (white noise, pure tones and anthropogenic noises). In addition, the hearing thresholds were determined in the presence of noise (white, ambient, ship noise) in several studies, a phenomenon termed masking. Various ecological (e.g., temperature, cave dwelling), genetic (e.g., albinism), methodical (e.g., ototoxic drugs, threshold criteria, speaker choice) and behavioral (e.g., dominance, reproductive status) factors potentially influencing hearing were investigated. Finally, the technique was successfully utilized to study acoustic communication by comparing hearing curves with sound spectra either under quiet conditions or in the presence of noise, by analyzing the temporal resolution ability of the auditory system and the detection of temporal, spectral and amplitude characteristics of conspecific vocalizations.
The hearing abilities of three age-groups (which correspond to size-classes) of walleye pollock Theragra chalcogramma were determined from auditory evoked potentials. Walleye pollock had the best hearing sensitivity from 100 to 200 Hz, with thresholds around 75 dB re: 1 μPa. Hearing sensitivity decreased with increasing frequency up to 450 Hz. There was no significant difference in hearing sensitivity between the age-groups, although there was a significant interaction between frequency and age as well as a trend in which the older fish had slightly lower mean thresholds. At the same time, there was a substantial increase in the size of the saccular otolith and associated sensory epithelia of the inner ear, suggesting that a large increase in ear size does not lead to a large change in hearing sensitivity. In addition, there was an effect of water temperature on the hearing thresholds at 350 Hz, whereby each degree of temperature (°C) increase resulted in an 8.3-dB decrease in hearing threshold. The results suggest that the hearing thresholds of walleye pollock are generally similar to those of other gadid fishes. This knowledge can be used to evaluate the potential impact, in terms of behavioral responses or physiological effects, that various human-generated sounds (e.g., seismic survey and underwater radiated vessel noise) may have on this species.
The hearing of the salmon, Salmo salar L., was studied by means of a cardiac conditioning technique. Fish were trained to show a slowing of the heart, on hearing a sound, in anticipation of a mild electric shock applied later. The minimum sound level to which the fish would respond was determined for a range of pure tones, both in the sea, and in the laboratory. The fish responded only to low frequency tones (below 380 Hz), and particle motion, rather than sound pressure, proved to be the relevant stimulus. The sensitivity of the fish to sound was not affected by the level of sea noise under natural conditions but hearing is likely to be masked by ambient noise in a turbulent river. Sound measurements made in the River Dee, near Aberdeen, lead to the conclusion that salmon are unlikely to detect sounds originating in air, but that they are sensitive to substrate borne sounds. Compared with the carp and cod the hearing of the salmon is poor, and more like that of the perch and plaice.
To avoid mortality caused by passage through dam turbines and spillways, juvenile Chinook salmon Oncorhynchus tshawytscha are annually transported downstream by barge through the federal hydropower system on the Snake and Columbia rivers. Survival of transported fish is higher than that of in-river migrants; however, transported fish experience higher rates of postrelease mortality. Increased mortality could result from a decrease in the ability to detect or avoid predators due to stressors associated with the barge environment. This study examined the effects of barging on juvenile Chinook salmon olfaction and auditory function, two sensory systems involved in predator detection. We focused on dissolved metals known to be toxic to the salmon olfactory system and on the level of noise from the barge, which could impair the auditory system. Experimental groups included animals collected (1) before barge loading (control group), (2) at the Bonneville Dam bypass system (migrant fish), (3) immediately after barge transport, and (4) within 7 d postbarging and at or after 7 d postbarging. Measured concentrations of dissolved metals from the water within the barge were below established water quality criteria for the protection of aquatic life. Moreover, ultrastructural examination of the olfactory epithelium surface showed no evidence of injury to olfactory sensory neurons. Noise in the barge holding tanks had levels up to 136 dB referenced to 1 mu Pa (root mean square) with primary energy below 400 Hz. Auditory sensitivity was measured using the auditory-evoked potentials (AEP) technique. We found a small but statistically significant threshold shift for fish collected within 7 d postbarging, while in the 7-d-and-later postbarging group the AEP thresholds were similar to the control. Our findings indicate that the olfactory systems of transported Chinook salmon are intact and probably functional, while the auditory sensitivities are compromised with probable recovery.
Intensive aquaculture production often utilizes equipment (e.g., aerators, air and water pumps, harvesters, blowers, filtration systems, and maintenance machinery) that increases noise levels in fish culture tanks. Consequently, chronic exposure to elevated noise levels in tanks could negatively impact cultured species. Possible effects include impairment of the auditory system, increased stress, and reduced growth rates. The objective of this study was to evaluate the long-term effects of sound exposure on the hearing sensitivity, growth, and survival of cultured rainbow trout (Oncorhynchus mykiss). Two cohorts of rainbow trout were cultured for 8 months in replicated tanks consisting of three sound treatments: 115, 130, or 150 decibels referenced at 1 micropascal (dB re 1 μPa root mean square [RMS]) levels. Auditory evoked potential (AEP) recordings revealed no significant differences in hearing thresholds resulting from exposure to increased ambient sound levels. Although there was no evident noise-induced hearing loss, there were significant differences in hearing thresholds between the two fish cohorts examined. No statistical effect of sound treatment was found for growth rate and mortality within each fish cohort. There was no significant difference in mortality between sound treatments when fish were exposed to the pathogen Yersinia ruckeri, but there was significantly different mortality between cohorts. This study indicated that rainbow trout hearing sensitivity, growth, survival, stress, and disease susceptibility were not negatively impacted by noise levels common to recirculating aquaculture systems. These findings should not be generalized to all cultured fish species, however, because many species, including catfish and cyprinids, have much greater hearing sensitivity than rainbow trout and could be affected differently by noise.
Sound production and hearing sensitivity of ectothermic animals are affected by the ambient temperature. This is the first study investigating the influence of temperature on both sound production and on hearing abilities in a fish species, namely the neotropical Striped Raphael catfish Platydoras armatulus.
Doradid catfishes produce stridulation sounds by rubbing the pectoral spines in the shoulder girdle and drumming sounds by an elastic spring mechanism which vibrates the swimbladder. Eight fish were acclimated for at least three weeks to 22°, then to 30° and again to 22°C. Sounds were recorded in distress situations when fish were hand-held. The stridulation sounds became shorter at the higher temperature, whereas pulse number, maximum pulse period and sound pressure level did not change with temperature. The dominant frequency increased when the temperature was raised to 30°C and the minimum pulse period became longer when the temperature decreased again. The fundamental frequency of drumming sounds increased at the higher temperature. Using the auditory evoked potential (AEP) recording technique, the hearing thresholds were tested at six different frequencies from 0.1 to 4 kHz. The temporal resolution was determined by analyzing the minimum resolvable click period (0.3-5 ms). The hearing sensitivity was higher at the higher temperature and differences were more pronounced at higher frequencies. In general, latencies of AEPs in response to single clicks became shorter at the higher temperature, whereas temporal resolution in response to double-clicks did not change.
These data indicate that sound characteristics as well as hearing abilities are affected by temperatures in fishes. Constraints imposed on hearing sensitivity at different temperatures cannot be compensated even by longer acclimation periods. These changes in sound production and detection suggest that acoustic orientation and communication are affected by temperature changes in the neotropical catfish P. armatulus.
Auditory brainstem response (ABR) techniques, an electrophysiological far-field recording method widely used in clinical evaluation of human hearing, were adapted for fishes to overcome the major limitations of traditional behavioral and electrophysiological methods (e.g., invasive surgery, lengthy training of fishes, etc.) used for fish hearing research. Responses to clicks and tone bursts of different frequencies and amplitudes were recorded with cutaneous electrodes. To evaluate the effectiveness of this method, the auditory sensitivity of a hearing specialist (goldfish, Carassius auratus) and a hearing generalist (oscar, Astronotus ocellatus) was investigated and compared to audiograms obtained through psychophysical methods. The ABRs could be obtained between 100 Hz and 2000 Hz (oscar), and up to 5000 Hz (goldfish). The ABR audiograms are similar to those obtained by behavioral methods in both species. The ABR audiogram of curarized (i.e., Flaxedil-treated) goldfish did not differ significantly from two previously published behavioral curves but was lower than that obtained from uncurarized fish. In the oscar, ABR audiometry resulted in lower thresholds and a larger bandwidth than observed in behavioral tests. Comparison between methods revealed the advantages of this technique: rapid evaluation of hearing in untrained fishes, and no limitations on repeated testing of animals.
It has previously been shown that at least one species of fish (the American shad) in the order clupeiforms (herrings, shads, and relatives) is able to detectsounds up to 180 kHz. However, it has not been clear whether other members of this order are also able to detectultrasound. It is now demonstrated, using auditory brainstem response (ABR), that at least one additional species, the gulf menhaden (Brevoortia patronus), is able to detectultrasound, while several other species including the bay anchovy (Anchoa mitchilli), scaled sardine (Harengula jaguana), and Spanish sardine (Sardinella aurita) only detectsounds to about 4 kHz. ABR is used to confirm ultrasonichearing in the American shad. The results suggest that ultrasounddetection may be limited to one subfamily of clupeiforms, the Alosinae. It is suggested that ultrasounddetection involves the utricle of the inner ear and speculate as to why, despite having similar ear structures, only one group may detectultrasound.
Being ectothermic, fish body temperature generally depends on ambient water temperature. Thus, ambient temperature might affect various sensory systems, including hearing, as a result of metabolic and physiological processes. However, the maintenance of sensory functions in a changing environment may be crucial for an animal's survival. Many fish species rely on hearing for acoustic orientation and communication. In order to investigate the influence of temperature on the auditory system, channel catfish Ictalurus punctatus was chosen as a model for a eurytherm species and the tropical catfish Pimelodus pictus as a model for a stenotherm fish. Hearing sensitivity was measured with animals acclimated or unacclimated to different water temperatures. Ambient water temperature significantly influenced hearing thresholds and the shape of auditory evoked potentials, especially at higher frequencies in I. punctatus. Hearing sensitivity of I. punctatus was lowest at 10 degrees C and increased by up to 36 dB between 10 degrees C and 26 degrees C. Significant differences were also revealed between acclimated and unacclimated animals after an increase in water temperature but not a decrease. By contrast, differences in hearing thresholds were smaller in P. pictus, even if a similar temperature difference (8 degrees C) was considered. However, P. pictus showed a similar trend as I. punctatus in exhibiting higher hearing sensitivity at the highest tested temperature, especially at the highest frequency tested. The results therefore suggest that the functional temperature dependence of sensory systems may differ depending upon whether a species is physiologically adapted to tolerate a wide or narrow temperature range.
The ability of a fish to interpret acoustic information in its environment is crucial for its survival. Thus, it is important to understand how underwater noise affects fish hearing. In this study, the fathead minnow (Pimephales promelas) was used to examine: (1) the immediate effects of white noise exposure (0.3-4.0 kHz, 142 dB re: 1 microPa) on auditory thresholds and (2) recovery after exposure. Audiograms were measured using the auditory brainstem response protocol and compared to baseline audiograms of fathead minnows not exposed to noise. Immediately after exposure to 24 h of white noise, five out of the eight frequencies tested showed a significantly higher threshold compared to the baseline fish. Recovery was found to depend on both duration of noise exposure and auditory frequency. These results support the hypothesis that the auditory threshold of the fathead minnow can be altered by white noise, especially in its most sensitive hearing range (0.8-2.0 kHz), and provide evidence that these effects can be long term (>14 days).
It has previously been shown that at least one species of fish (the American shad) in the order clupeiforms (herrings, shads, and relatives) is able to detect sounds up to 180 kHz. However, it has not been clear whether other members of this order are also able to detect ultrasound. It is now demonstrated, using auditory brainstem response (ABR), that at least one additional species, the gulf menhaden (Brevoortia patronus), is able to detect ultrasound, while several other species including the bay anchovy (Anchoa mitchilli), scaled sardine (Harengula jaguana), and Spanish sardine (Sardinella aurita) only detect sounds to about 4 kHz. ABR is used to confirm ultrasonic hearing in the American shad. The results suggest that ultrasound detection may be limited to one subfamily of clupeiforms, the Alosinae. It is suggested that ultrasound detection involves the utricle of the inner ear and speculate as to why, despite having similar ear structures, only one group may detect ultrasound.
The auditory brainstem response (ABR) was recorded in adult budgerigars (Melopsittacus undulatus) in response to clicks and tones. The typical budgerigar ABR waveform showed two prominent peaks occurring within 4 ms of the stimulus onset. As sound-pressure levels increased, ABR peak latency decreased, and peak amplitude increased for all waves while interwave interval remained relatively constant. While ABR thresholds were about 30 dB higher than behavioral thresholds, the shape of the budgerigar audiogram derived from the ABR closely paralleled that of the behavioral audiogram. Based on the ABR, budgerigars hear best between 1000 and 5700 Hz with best sensitivity at 2860 Hz-the frequency corresponding to the peak frequency in budgerigar vocalizations. The latency of ABR peaks increased and amplitude decreased with increasing repetition rate. This rate-dependent latency increase is greater for wave 2 as indicated by the latency increase in the interwave interval. Generally, changes in the ABR to stimulation intensity, frequency, and repetition rate are comparable to what has been found in other vertebrates.
Fishes are often exposed to environmental sounds such as those associated with shipping, seismic experiments, sonar and/or aquaculture pump systems. While efforts have been made to document the effects of such anthropogenic (human-generated) sounds on marine mammals, the effects of excess noise on fishes are poorly understood. We examined the short- and long-term effects of increased ambient sound on the stress and hearing of goldfish (Carassius auratus; a hearing specialist). We reared fish under either quiet (110-125 dB re 1 microPa) or noisy (white noise, 160-170 dB re 1 microPa) conditions and examined animals after specific durations of noise exposure. We assessed noise-induced alterations in physiological stress by measuring plasma cortisol and glucose levels and in hearing capabilities by using auditory brainstem responses. Noise exposure did not produce long-term physiological stress responses in goldfish, but a transient spike in plasma cortisol did occur within 10 min of the noise onset. Goldfish had significant threshold shifts in hearing after only 10 min of noise exposure, and these shifts increased linearly up to approximately 28 dB after 24 h of noise exposure. Further noise exposure did not increase threshold shifts, suggesting an asymptote of maximal hearing loss within 24 h. After 21 days of noise exposure, it took goldfish 14 days to fully recover to control hearing levels. This study shows that hearing-specialist fishes may be susceptible to noise-induced stress and hearing loss.
For seasonally breeding vertebrates, reproductive cycling is often coupled with changes in vocalizations that function in courtship and territoriality. Less is known about changes in auditory sensitivity to those vocalizations. Here, we show that nonreproductive female midshipman fish treated with either testosterone or 17beta-estradiol exhibit an increase in the degree of temporal encoding of the frequency content of male vocalizations by the inner ear that mimics the reproductive female's auditory phenotype. This sensory plasticity provides an adaptable mechanism that enhances coupling between sender and receiver in vocal communication.
Mammals exposed to loud aerial sounds exhibit temporary threshold shifts (TTS) that are linearly related to increases of sound pressure above baseline hearing levels. It was unknown if this relationship held true for aquatic ectotherms such as fishes. To test this linear threshold shift hypothesis (LINTS) in fishes, we examined the effects of increased ambient sound on hearing of two species differing in hearing capabilities: goldfish (Carassius auratus; a hearing specialist) and tilapia (Oreochromis niloticus; a hearing generalist). Fish were exposed to 1-28 days of either quiet (110 dB re 1 microPa) or continuous white noise. First, we examined the effect of noise sound pressure level (SPL; 130, 140, 160 or 170 dB re 1 microPa) on goldfish hearing thresholds after 24 h of noise exposure. Second, in a long-term experiment using 170 dB re 1 microPa white noise, we continuously exposed goldfish and tilapia for either 7 or 21-28 days. In both experiments, we measured alterations in hearing capabilities (using auditory brainstem responses) of noise-exposed fish. While tilapia exposed to noise for 28 days showed little or no hearing loss, goldfish exhibited considerable threshold shifts that reached an asymptote of up to 25 dB after only 24 h of exposure. There was a positive linear relationship between noise-induced TTS and the sound pressure difference between the noise and the baseline hearing thresholds in goldfish but not in tilapia. A similar relationship was found for published noise-induced threshold shifts in birds and mammals, but the slope of the linear relationship was greater in these groups than for fish. The linear threshold shift relationship provides insights into differential susceptibility of hearing specialist and generalist fishes to noise-induced hearing loss for a given SPL and provides a framework for future research on noise-induced threshold shifts in fishes and other animals.
This study investigated the effects on rainbow trout (Oncorhynchus mykiss) of exposure to high-intensity, low-frequency sonar using an element of the standard Surveillance Towed Array Sensor System Low Frequency Active (LFA) sonar source array. Effects of the LFA sonar on hearing were tested using auditory brainstem responses. Effects were also examined on inner ear morphology using scanning electron microscopy and on nonauditory tissues using general pathology and histopathology. Animals were exposed to a maximum received rms sound pressure level of 193 dB re 1 microPa(2) for 324 or 648 s, an exposure that is far in excess of any exposure a fish would normally encounter in the wild. The most significant effect was a 20-dB auditory threshold shift at 400 Hz. However, the results varied with different groups of trout, suggesting developmental and/or genetic impacts on how sound exposure affects hearing. There was no fish mortality during or after exposure. Sensory tissue of the inner ears did not show morphological damage even several days post-sound exposure. Similarly, gross- and histopathology observations demonstrated no effects on nonauditory tissues.
Studies investigated the effects of exposure to low‐frequency active (LFA) sonar on rainbow trout, channel catfish, and pumpkinseed sunfish using an element of the SURTASS LFA. Animals were exposed to sounds that had a received peak level of 193 dB re: 1 uPa (rms) (188.5 dB re: 1 uPa² s SEL). Measurements were made of hearing sensitivity using auditory brainstem response and of behavioral responses. Additional studies were done on pathology of the ear and other organ systems. Trout and catfish both showed temporary threshold shifts immediately after sound exposure, while sunfish showed no threshold shift. However, the amount of threshold shift and frequencies concerned varied. In addition, trout and catfish showed immediate behavioral responses to the sound onsets and in relative distribution during sound presentation. Details of the responses differed between species. There was no mortality in any species attributable to sound exposure during or after experiments. SEM examination of hair cell ciliary bundles of the inner ears did not show any damage. Similarly, there were no effects on the swim bladder or nonauditory tissues. Overall, the effects of LFA on fish depend upon species and appear to be temporary and relatively modest. [Work supported by Chief of Naval Operations.]
Attention has been drawn to the subject of how ocean noise affects marine mammals by a series of marine mammal strandings, lawsuits, and legislative hearings, and most recently, the report from the U.S. Commission on Ocean Policy. One way to assess the impact of ocean noise is to consider whether it causes changes in animal behavior that are "biologically significant," that is, those that affect an animal's ability to grow, survive, and reproduce. This report offers a conceptual model designed to clarify which marine mammal behaviors are biologically significant for conservation purposes. The report is intended to help scientists and policymakers interpret provisions of the federal Marine Mammal Protection Act. © 2005 by the National Academy of Sciences. All rights reserved.
Humans generate sounds in the ocean intentionally (e.g., sonar) and as a consequence of other activities (e.g., shipping). These sounds increase the noise level in the acoustic spectrum which one or more species of marine mammals utilize. Different marine mammal species are sensitive to sound at frequencies between 10 Hz and 180 kHz and thus all human-generated sounds have the potential to impact some marine mammals. Any sound that rises to the level of detectability has the potential to alter behavior. Louder sounds can interfere with acoustic communication or detection of relevant acoustic cues from the environment. Still louder sounds can lead to physiological changes such as temporary or permanent threshold shifts in hearing sensitivity with extremely loud sounds at very close range causing acoustic trauma. Continued exposure to noise causes stress reactions in humans and other terrestrial species studied and is likely to cause stress reactions in marine mammals. Determining the significance of any of these effects of human-generated sounds on marine mammal populations is exceedingly difficult.
The effect of man‐made sound on marine mammals has been surrounded by controversy over the past decade. Much of this controversy stems from our lack of knowledge of the effects of noise on marine life. Ocean
sound is produced during activities of great benefit to humans: commerce, exploration for energy reserves, national defense, and the study of the ocean environment itself. However, some recent strandings of marine mammals have been associated with the occurrence of human‐generated sound. The documented increase of man‐made sound in the ocean suggests the potential for more extensive though subtler effects than those observed in the mass strandings. The purpose of this tutorial is to present the scientific issues pertaining to ocean
noise and marine mammals. Basic physics of sound in the ocean and long term trends of ocean
sound will be presented. The biology of marine mammals, particularly their production, reception and use of sound in monitoring their environment, social interactions, and echolocation, will be reviewed. This background information sets the stage for understanding the effects of man‐made sound on marine mammals. The extensive gaps in current knowledge with respect to marine mammal distribution and behavioral and physiological responses to sound will highlight research needs.
Für den Zwergwels (Amiurus nebulosus) werden die absoluten Hörschwellen im Frequenzbereich von 60–10000 Hz bestimmt. Die in der Arbeit angegebene Methode gestattet nur Messungen, deren Fehler etwa auf ±10 db geschätzt werden muß.
Das Gehörorgan der Zwergwelse ist ein Schalldruckempfänger, so daß die Hörschwellen in Schalldruckeinheiten (μbar = dyn/cm2) angegeben werden können.
Im Bereich von 60–1600 Hz ist der Schwellenschalldruck annähernd konstant; oberhalb von 1600 Hz steigt er steil mit der Frequenz an (s. Abb. 7).
Nach beidseitiger Exstirpation des Malleus ist die Empfindlichkeit auf 1/30–1/100 (um 30–40 db) abgesunken, die Form der Hörschwellenkurve bleibt jedoch erhalten (s. Abb. 8).
Versuche, die Schwimmblase auszuschalten, waren erfolglos.
Eigenfrequenz und Dämpfung der Pulsationsschwingungen der isolierten Camera aerea (vordere Schwimmblasenkammer) der Elritze wurden gemessen. Die Eigenfrequenz der Schwimmblase ist ihrem mittleren Durchmesser umgekehrt proportional. Das logarithmische Dekrement der Schwingungen beträgt im Mittel 0,25. Es ist anzunehmen, daß die Dämpfung im Fischkörper größer ist.
Die Form der Schwellenschalldruckkurve läßt sich aus den akustischen Eigenschaften des Weberschen Apparates verstehen, wenn man annimmt, daß für die Schwellenerregung der Sinneszellen eine frequenzunabhängige Mindestamplitude der Endolymphschwingungen im Labyrinth erforderlich ist.
Ein Vergleich der Schwingungsamplituden einer kugelförmigen Luftblase in Wasser und der Teilchen in einem Wasserschallfeld mit fortschreitenden Wellen bei gleichem Schalldruck zeigt den Vorteil, den die Transformation des Schalldrucks in Bewegungen der Schwimmblasenwand für das Hörvermögen der Ostariophysen bietet.
Die Schallempfindlichkeit der Zwergwelse (dargestellt durch die Schwellen-Energiedichte eines ungestörten Schallfeldes) ist im optimalen Frequenzbereich (etwa 800 Hz) gleich der des Menschen und des Vogels (Dompfaff) in ihren optimalen Frequenzbereichen (etwa 3200 Hz); dagegen ist die Schallempfindlichkeit des Zwergwelses bei tiefen Frequenzen (z. B. 60 Hz) wesentlich größer, bei hohen Frequenzen (z. B. 10000 Hz) jedoch wesentlich kleiner als die von Mensch und Vogel (s. Abb. 13). Die berechneten Schwellenamplituden der Schwimmblasenwand sind nur wenig größer als die des Trommelfells von Mensch und Vogel.
Barotrauma-injuries sustained following rapid decompression occur in many different fisheries applications. Previous attempts to quantify barotrauma in fish have been limited by the functionality of hypo/hyperbaric systems. Further, field studies often are confounded by covariates. The mobile aquatic barotrauma laboratory (MABL) was designed to address these limitations. Specifically, this testing facility allows the user to evaluate similar complex pressure scenarios to which migrating juvenile salmonids are exposed following turbine or spillway passage. In this paper, we describe the MABL and present a case study in which negative and neutrally buoyant juvenile Chinook salmon were exposed to simulated hydro-turbine passage (STP). The severity of the decompression profile and the fish's ability to gain neutral buoyancy were used as predictor variables. We determined that following STP, fish that achieved neutral buoyancy during a 16-h acclimation period had a greater risk of mortality and injury (gill emboli, swim bladder rupture, and internal hemorrhaging) than negatively buoyant conspecifics. This research solidifies the need to allow fish to become neutrally buoyant when assessing barotrauma and mortality in field and laboratory applications. Future research examining injury and mortality of turbine-passed fish needs to consider the fish's buoyancy to more appropriately evaluate these endpoints.
There is increasing concern about the effects of pile driving and other anthropogenic (human-generated) sound on fishes. Although there is a growing body of reports examining this issue, little of the work is found in the peer-reviewed literature. This review critically examines both the peer-reviewed and 'grey' literature, with the goal of determining what is known and not known about effects on fish. A companion piece provides an analysis of the available data and applies it to estimate noise exposure criteria for pile driving and other impulsive sounds. The critical literature review concludes that very little is known about effects of pile driving and other anthropogenic sounds on fishes, and that it is not yet possible to extrapolate from one experiment to other signal parameters of the same sound, to other types of sounds, to other effects, or to other species.
This study investigated immediate effects of intense sound exposure associated with low-frequency (170-320 Hz) or with mid-frequency (2.8-3.8 kHz) sonars on caged rainbow trout Oncorhynchus mykiss, channel catfish Ictalurus punctatus and hybrid sunfish Lepomis sp. in Seneca Lake, New York, U.S.A. This study focused on potential effects on inner ear tissues using scanning electron microscopy and on non-auditory tissues using gross and histopathology. Fishes were exposed to low-frequency sounds for 324 or 628 s with a received peak signal level of 193 dB re 1 microPa (root mean square, rms) or to mid-frequency sounds for 15 s with a received peak signal level of 210 dB re 1 microPa (rms). Although a variety of clinical observations from various tissues and organ systems were described, no exposure-related pathologies were observed. This study represents the first investigation of the effects of high-intensity sonar on fish tissues in vivo. Data from this study indicate that exposure to low and midfrequency sonars, as described in this report, might not have acute effects on fish tissues.
There is significant concern that high-intensity sounds can impact fish physiology and behavior. Important sources of such sounds are commercial and military sonars. A recent publication reports that exposure to low-frequency active (LFA) sonar might result in hearing loss in some fish species, but did not damage any tissues [Popper et al. (2007). J. Acoust. Soc. Am. 122, 623-635]. We have extended our studies to include U.S. Navy mid-frequency sonar. Fish were exposed to a 3-s-long signal that consisted of a 2-s 2.8-3.8-kHz frequency sweep, immediately followed by a 1-s 3.3-kHz tone). The stimulus was repeated five times with a 25-s interval. Fish were subsequently tested for hearing sensitivity and examined both grossly and microscopically for tissue damage. Some temporary hearing loss was found in catfish, species known to hear sounds above 1000 Hz, whereas there was no effect in fish which do not hear above about 1 kHz. There was no gross damage to any tissue, and microscopic examination showed no effect on any tissues. [Work supported by Office of the U.S. Chief of Naval Operations.].
The ulstrastructure of the saccular and lagenar maculae were studied in 15 species of teleost fishes, using the scanning electron microscope. Particular attention was paid to hair cell orientation patterns, composition of the ciliary bundles on the hair cells, hair cell distributions, and supporting cell types. The hair cells on both otolithic organs are divided into several groups with all of the hair cells in each group oriented in the same direction. The posterior region of the saccular macula in all species had dorsally oriented hair cells on the dorsal half of the macula and ventrally oriented hair cells on the ventral half. The cells on the anterior end of the macula were oriented anteriorly and posteriorly, with the posterior group, in most species, being on the dorsal half of the anterior region of the macula. There was considerable inter-specific variation upon this basic pattern.
Inter-specific variation on the lagenar macula was considerably less than on the saccular macula. The basic pattern in all of the species includes one dorsal cell group and one ventral cell group.
There are four more-or-less discrete ciliary bundles, each varying in the relative size of the kinocilia and stereocilia. Intermediary forms were also observed, making it difficult to differentiate ciliary bundles in some instances. It was apparent, however, that several of the ciliary bundles were found in particular macular regions.
An expert panel reviewed the expanding literature on marine mammal (cetacean and pinniped) auditory and behavioral responses to sound exposure to develop comprehensive, scientifically based noise exposure criteria [Aquatic Mammals 33(4)]. They used precautionary extrapolation procedures to predict exposure levels above which adverse effects (both physical and behavioral) could be expected. Due to the paucity of data on long-term exposures, criteria were developed for single exposure events only. Marine mammals were broken into functional hearing groups. Exposure types were lumped into three broad classes (single pulses, multiple pulses, and nonpulses). Levels estimated to induce permanent noise-induced hearing loss were determined for each of 15 sound typeanimal group combinations. For example, injury criteria for pinnipeds in water exposed to multiple pulses were 186 dB re 1 muPa(2) -s (weighted SEL) and 218 dB(pk) re 1 muPa (unweighted peak SPL). Discrete behavioral disturbance thresholds could only be determined for exposure to single pulses. For other exposures, available data on behavioral responses were ranked by severity and significance. This severity scaling and the resulting conclusions will be described. New research required to improve criteria and to assess cumulative and ecosystem-level effects will also be considered, along with current policy andor regulatory applications.
In representative elasmobranchs, osteichthyans, amphibians, reptiles and birds, average evoked potentials in response to acoustic clicks and tone bursts were recorded intracranially, but outside the brain, or extracranially. Controls against artifacts and tests after transections show that these potentials conform to criteria for auditory brain stem responses (ABRs). Brief waves in a 10-15 msec sequence originate successively in the eighth nerve, medulla and midbrain; there is little contribution to the latter waves from the lower levels. This response pattern appears to be consistent within each species and is similar to that extensively studied in mammals. Some of its features are remarkably alike in all the vertebrate classes tested, implying a generality in the existence of a subset of auditory neurons at several brain levels that are highly synchronous in activity, even after several synapses, and geometrically oriented to add their macroscopic, open, dipole fields. The intensity, repetition rate and the power spectrum of the click stimuli have little effect on the ABR pattern, except when the peak energy is in the low frequency range. In the range below ca. 700 Hz frequency content has a considerable effect; lower frequencies broaden certain waves. Cooling has marked and differential effects on component processes. Reversing click phase, e.g. from initial compression to initial rarefaction, can show no effect or any of several effects, depending on the species. Tone bursts evoke onset ABRs and in some cases after a transitional period a sustained frequency following response. The ABR resembles a click evoked potential even when stimulus rise time is slow. Background tones of particular frequency are most efficient in masking click evoked ABRs; white noise is less efficient. The ABR should be useful in neuroethology since it can be studied without invading the brain. It can tell that the brain is sensitive to a sound. In an immobilized animal it can be recorded in a single sweep, or it can be averaged from an awake tethered animal. It shows good sensitivity and at least some correspondence with behavioral measures of hearing.
Auditory and vestibular nerve fibers of the goldfish are strongly directionally sensitive to whole-body acceleration at audio frequencies. The three-dimensional pattern of sensitivity shows that input from a receptor ensemble (hair cells) is essentially equivalent to that expected from a single hair cell having a given three-dimensional orientation of best sensitivity. Fibers from the sacculus, lagena, and utriculus differ with respect to distributions of directional orientation, but are similar in best threshold (less than 1 nanometer, root mean square, at 140 hertz). In combination with other mechanisms for detection of sound pressure, this directionality is a likely basis for directional hearing in fishes, and it could allow the determination of underwater acoustic intensity.
Fish (Astronotus ocellatus, the oscar) were subject to pure tones in order to determine the effects of sound at levels typical of man-made sources on the sensory epithelia of the ear and the lateral line. Sounds varied in frequency (60 or 300 Hz), duty cycle (20% or continuous), and intensity (100, 140, or 180 dB re: 1 muPa). Fish were allowed to survive for 1 or 4 days posttreatment. Tissue was then evaluated using scanning electron microscopy to assess the presence or absence of ciliary bundles on the sensory hair cells on each of the otic endorgans and the lateral line. The only damage that was observed was in four of five fish stimulated with 300-Hz continuous tones at 180 dB re: 1 muPa and allowed to survive for 4 days. Damage was limited to small regions of the striola of the utricle and lagena. There was no damage in any other endorgan, and the size and location of the damage varied between specimens. No damage was observed in fish that had been allowed to survive for 1 day poststimulation, suggesting that damage may develop slowly after exposure.
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