ArticlePDF Available

A validation of the dBht as a measure of the behavioural and auditory effects of underwater noise

Authors:

Abstract and Figures

Underwater piling was undertaken in 2003 in Southampton Water on the South Coast of England. Monitoring was simultaneously undertaken of the waterborne sound from impact and vibropiling and its effects on brown trout in cages at increasing distances from the piling. Brown trout Salmo trutta were used as a model for salmon Salmo salar, which were the species of interest but were not readily available. No obvious signs of trauma that could be attributed to sound exposure were found in any fish examined, from any of the cages. No increase in activity or startle response was seen to vibropiling. Analysis using the dB ht metric indicated that the noise at the nearest cages during impact piling reached levels at which salmon were expected to react strongly. However, the brown trout showed little reaction. An audiogram of the brown trout was measured by the Auditory Brainstem Response method, which indicated that the hearing of the brown trout was less sensitive than that of the salmon. Further analysis indicated that this accounted for the relative lack of reaction, and demonstrated the importance of using the correct species of fish as a model when assessing the effect of noise.
Content may be subject to copyright.
An investigation into the effects of underwater piling noise
on salmonids
Jeremy R. Nedwell
Subacoustech Ltd., Chase Mill, Winchester Road, Bishop’s Waltham, Hampshire SO32 1AH,
United Kingdom
Andrew W. H. Turnpenny
Jacobs Babtie Aquatic, Fawley, Southampton, Hampshire SO45 1TW, United Kingdom
Jonathan M. Lovell
University of Plymouth, Drake Circus, Plymouth PL4 8AA, United Kingdom
Bryan Edwards
Subacoustech Ltd., Chase Mill, Winchester Road, Bishop’s Waltham, Hampshire SO32 1AH,
United Kingdom
Received 16 August 2005; revised 5 July 2006; accepted 17 July 2006
Underwater piling was undertaken in 2003 in Southampton Water on the South Coast of England.
Monitoring was simultaneously undertaken of the waterborne sound from impact and vibropiling
and its effects on brown trout in cages at increasing distances from the piling. Brown trout Salmo
trutta were used as a model for salmon Salmo salar, which were the species of interest but were
not readily available. No obvious signs of trauma that could be attributed to sound exposure were
found in any fish examined, from any of the cages. No increase in activity or startle response was
seen to vibropiling. Analysis using the dB
ht
metric indicated that the noise at the nearest cages
during impact piling reached levels at which salmon were expected to react strongly. However, the
brown trout showed little reaction. An audiogram of the brown trout was measured by the Auditory
Brainstem Response method, which indicated that the hearing of the brown trout was less sensitive
than that of the salmon. Further analysis indicated that this accounted for the relative lack of
reaction, and demonstrated the importance of using the correct species of fish as a model when
assessing the effect of noise. © 2006 Acoustical Society of America. DOI: 10.1121/1.2335573
PACS numbers: 43.30.Nb, 43.80.Nd WWA Pages: 2550–2554
I. INTRODUCTION
It has been documented that the driving of piles in water
causes high levels of underwater noise. Measurements made
of piling using piles of 0.7 m diameter on the River Arun in
southern England indicated a peak-to-peak Source Level of
191 dB re1
Pa@1 m Nedwell et al., 2002. Measure-
ments made of the noise from piling using piles of 4.3 m
diameter during the construction of offshore windfarms in
the UK indicated a peak-to-peak Source Level of
260 dB re1
Pa@1 m for 5 m depth, and
262 dB re1
Pa@1 m at 10 m depth, associated with a
Transmission Loss given by 22 logR, where R is the range
Nedwell et al., 2003b. Such levels of sound may have an
effect on marine species. A report for Caltrans on piling in
San Francisco Bay indicated mortality to several species of
fish at ranges of up to 50 m Abbott, 2005. Intense sound
from piling may also have an effect on hearing. McCauley et
al. 2003 reported damage to the ears of a pink snapper
caused by the impulsive noise of an airgun having a peak-to-
peak Source Level of 222.6 dB re1
Pa@1 m and deployed
at a range of 400–800 m from the caged fish. Enger 1981
reported damage to the ciliary bundles on the sensory cells of
the inner ear of cod caused by sound at frequencies of 50 to
400 Hz at a level of 180 dB.
In September 2003, piling was undertaken in Southamp-
ton Water, a shallow inlet on the South Coast of England,
adjacent to the quayside of a ferry terminal. There was con-
cern that the construction work might adversely impact local
fish populations, and, in particular, the migration of salmon
up Southampton Water into the River Test, a Special Area of
Conservation SAC. A limit of 90 dB
ht
Salmo salar at half-
channel width was set as a noise limit by the regulator the
UK Environment Agency, with the intent of leaving half of
the channel open for migration; the dB
ht
metric is discussed
in Sec. III B. Consequently, monitoring was undertaken of
the waterborne sound generated by the piling operations. Si-
multaneously, the opportunity was taken to monitor the ef-
fects of the noise on fish in cages at increasing distances
from the piling.
II. FIELD WORK
A. Location of measurements
The piling was carried out adjacent to a quay, in other-
wise open water conditions. A total of ten piles, four 914 mm
in diameter and six 508 mm in diameter, were driven. Vibro-
driving was used for driving the piles, the duration being
approximately 20 min per pile. At the end of the operation 3
of the 10 piles were driven to final depth by impact driving
2550 J. Acoust. Soc. Am. 120 5, November 2006 © 2006 Acoustical Society of America0001-4966/2006/1205/2550/5/$22.50
Redistribution subject to ASA license or copyright; see http://acousticalsociety.org/content/terms. Download to IP: 192.129.2.17 On: Tue, 17 Feb 2015 13:02:46
for dynamic test purposes, the duration of each test being
between one and three minutes, with approximately 20 blows
during the period.
B. Fish response monitoring
Hydrophones and fish cages for reaction monitoring
were located at 30, 54, 96, 234, and 417 m from the piling.
The cages were 1 m cubes, made from a mild steel angle and
covered with plastic mesh of 25 mm square aperture and
suspended 2.5 m below the water surface. A closed circuit
television camera was placed in each cage. A control cage
was suspended in a dock 6 km from the site of the piling,
where the piling noise had fallen below background levels.
Although the species of interest was salmon Salmo
salar, suitable fish were not available and instead farmed
brown trout Salmo trutta were substituted as a close rela-
tive, which it was thought would react similarly. As is noted
in Sec. III B, this assumption proved to be invalid.
C. Fish behavioral reactions
The video recordings were reviewed to identify any
changes in behavior that might have resulted from the piling
noise. These data were reviewed “blind,” with the reviewer
unaware of the condition of exposure. Two types of behavior
were investigated.
i Startle reactions, which are here defined as sudden
C-shaped flexure of the fish’s body, described by Blaxter and
Hoss 1981. The analysis of the startle reactions was based
on a frame-by-frame inspection of the video at the start-up
instant of each vibropiling session and for the next 5 s;
ii Fish activity level; captive fish that are exposed to
irritating stimuli commonly show “milling behavior,” in
which the fish swim faster and make random turns. These
were measured by counting the number of times fish entered
the camera’s field of view within a two-minute observation
period.
Due to the fish being caged avoidance reaction i.e.,
fleeing the noise could not be directly observed, and the
activity level was used as a measure of the behavioral effect.
It may be commented, however, that human experience
would indicate that the avoidance of noise may well occur at
lower levels of noise than an increase in activity, and startle
probably occurs at relatively high levels of noise. Since the
caged fish could not flee, the experiment was imperfect in
that it probably did not demonstrate the lowest level of sound
at which avoidance of the piling noise occurred.
1. Reactions during vibropiling
No startle response was seen for any of the piles driven
by vibropiling.
Table I gives the activity level observations for the
2 min period prior to piling and then for the first 2 min dur-
ing vibropiling; they are seen to have remained similar be-
fore and after the start of piling. The control and event ac-
tivity levels were compared using the nonparametric Mann-
Whitney U-test Campbell, 1974 with the null hypothesis
that activity levels were not significantly different at the
P= 0.05 level; it was found that there was no significant dif-
ference in activity level following the commencement of vi-
bropiling P = 0.001.
2. Reactions during impact piling
One pile of 914 mm diameter and two of 508 mm were
impact driven. No startle reactions were observed at any of
the five locations.
Activity levels recorded before and during the impact
piling sessions are given in Table II. Fish activity is seen to
have remained similar in most cases before and after the start
of impact piling. The Mann-Whitney U test shows that there
was no significant difference in activity level following the
commencement of pile driving P = 0.001 in cages at 30, 96,
234, and 417 m; a 36% increase in fish activity level was,
however, observed in the cage at 54 m, which was significant
at the P = 0.05 level.
III. LABORATORY STUDIES
A. Electron microscope examination of the inner ear
of the trout Salmo trutta
The fish were initially examined under an optical micro-
scope after the end of the piling operation for any evidence
of swim bladder rupture, eye haemorrhage, or eye embolism
as a result of exposure to the sound from the piling; none
was found. The saccule, the primary auditory region of the
fish ear Popper and Fay, 1993, was investigated for evi-
dence of trauma to the inner ear ultrastructure. Five fish from
each of the cages were examined for ultrastructural damage
to the hearing organs; the examiner was unaware of which
fish came from which cage. A typical Scanning Electron Mi-
crograph SEM of saccular hair cells from S. trutta is pre-
sented in Fig. 1, which is from a central region of the
macula. The image shows apical hair cell bundles with an
anterior positioned kinocilia, surrounded by approximately
40 cilia arranged in 4 to 5 consecutively shorter rows in a
format common to many fish species e.g., Platt and Popper,
1981; Lovell et al., 2005. Each hair cell is separated from
TABLE I. Fish activity statistics No. of movements per 2 min period for
vibropiling.
Mann-Whitney U test
Range m Before During UZ P
30 147.5 152.5 69.5 0.1443 0.8852
54 150.5 149.5 71.5 −0.028 0.9769
TABLE II. Fish activity statistics No. of movements per 2 min period for
impact piling.
Mann-Whitney U test
Distance Before After UZ P
30 m 9 12 3 −0.654 0.513
54 m 6 15 0 −1.96 0.0495
96 m 12 9 3 0.654 0.512
234 m 6.5 3.5 0.5 1.16 0.245
417 m 12 9 3 0.654 0.512
J. Acoust. Soc. Am., Vol. 120, No. 5, November 2006 Nedwell et al.: Effects on fish of piling noise 2551
Redistribution subject to ASA license or copyright; see http://acousticalsociety.org/content/terms. Download to IP: 192.129.2.17 On: Tue, 17 Feb 2015 13:02:46
neighboring cells by an area of epithelium bearing short
1
m microvilli. No obvious signs of trauma that could
be attributed to sound exposure were found in any fish ex-
amined, from any of the cages.
B. Fish audiograms
1. Quantifying the effects of noise on species
The response of marine animals to a given sound is de-
pendent on the species since these vary greatly in hearing
sensitivity and frequencies range. A metric has been de-
scribed Nedwell et al., 2003a, Nedwell et al., 2004
termed the dB
ht
Species scale, which may be regarded as a
generalization of the dBA metric used for the rating of the
behavioral effects of noise on humans and hence that is in-
dicative of how much a species will be affected by that
sound. It is an estimate of the level that the sound is above
the hearing threshold of the species and hence is an indica-
tion of the likely perception by, or “loudness” of the sound
to, that species. Initial research with fish Nedwell, in prepa-
ration indicates that at levels of 90 dB or more above the
species’ threshold of hearing i.e., of 90 dB
ht
Species or
more strong avoidance of sound occurs.
2. Inadequacies of brown trout as a model for salmon
At the time of the experimental measurements, it was
noted that, despite the piling reaching levels of noise at
which salmon, S. salar, were expected to react i.e., in excess
of 90 dB
ht
S. salar兲兴, the brown trout, S. trutta, were show-
ing no obvious signs of reaction. It was suspected that this
was a result of the hearing of the latter being less sensitive.
Since there was no audiogram available for the brown trout,
this was determined by the Auditory Brainstem Response
ABR method, and compared with previous published au-
diograms of salmon Hawkins and Johnstone, 1978, in order
to attempt to explain this unexpected observation. It should
be noted, however, that the latter audiogram was obtained by
the behavioral method, which in humans has been noted to
yield slightly different results from ABR audiograms.
3. The ABR method
The ABR method was similar to that described by
Kenyon et al. 1998. Fish were held in a cradle in a water
tank and a pair of electrodes placed cutaneously on the cra-
nium such that they spanned the VIIIth nerve, recording the
evoked auditory response to sound. The sound stimulus of
several periods of a sine wave at a given frequency was
generated by two underwater projectors within a water tank.
Responses were averaged over 2000 presentations. The level
of the stimulus was reduced until the stimulus trace was no
longer discernible in the response trace. The sound level at
which the stimulus trace was just discernible was taken as
the threshold level for that frequency. The procedure was
carried out using four fish at all of the frequencies tested, and
24 fish at frequencies between 300 and 1000 Hz.
Figure 2 shows the resulting S. trutta audiogram, as well
as that for S. salar from Hawkins and Johnstone 1978.
First, it should be noted that the latter audiogram was ob-
tained by the behavioral method, which may give slightly
different results from the ABR method. Nevertheless, it may
be seen that, despite being a close relative with morphologi-
cally similar hearing, the audiogram of the brown trout is
significantly different from that of the salmon. It is less sen-
sitive, and broader and flatter in frequency response, with
effective hearing from 30 Hz to above 1 kHz. It was con-
cluded that the common assumption that closely related spe-
cies will have similar hearing abilities is not reliable. Conse-
quently, the data recorded during the piling were reprocessed
using the brown trout audiogram to yield dB
ht
S. trutta val-
ues in addition to the dB
ht
S. salar values recorded on-site at
the time of the noise measurements; these data are presented
in Sec. IV.
IV. ANALYSIS OF NOISE MEASUREMENTS
A. Introduction
The piling was recorded using Brüel & Kjær hydro-
phones calibrated to International Standards, and conditioned
by Brüel & Kjær charge amplifiers, before being digitized,
FIG. 1. Scanning Electron Micrograph SEM of saccular hair cells from S.
trutta, from a central region of the macula. Fish from cage number 1. k.
kinocilia, c. cilia, mv. microvilli.
FIG. 2. Audiograms for the brown trout Salmo trutta and the salmon
Salmo salar. Salmon audiogram from Hawkins and Johnstone 1978.
2552 J. Acoust. Soc. Am., Vol. 120, No. 5, November 2006 Nedwell et al.: Effects on fish of piling noise
Redistribution subject to ASA license or copyright; see http://acousticalsociety.org/content/terms. Download to IP: 192.129.2.17 On: Tue, 17 Feb 2015 13:02:46
archived, and analyzed using a program written in the Na-
tional Instruments LabVIEW environment that calculated
one second dB
ht
Species values.
B. Results
It was found that the unweighted Source Level of the
impact piling of the 508 mm diameter pile was
193 dB re1
Pa@1 m, with a linear Transmission Loss rate
of 0.13 dB per meter, and for the 914 mm diameter pile the
Source Level was 201 dB re1
Pa@1 m and the Transmis-
sion Loss 0.13 dB per meter.
Figure 3 presents the dB
ht
levels of the impact piling as
a function of range. The levels recorded at each of the mea-
surement positions are indicated on the figure; for each of the
two pile diameters driven the values of the noise in
dB
ht
Species units for both species have been plotted. It will
be noted that the levels are different for the same data for the
two different species since they have different hearing ability
and frequency range of hearing. The figure may therefore be
interpreted as indicating “loudness” for the two species as a
function of range. Also illustrated in the figure is the
90 dB
ht
Species limit at which it is believed noise becomes
intolerable.
For each set of results a least squares best fit of the data
has been calculated, the results being
SPL = 85 0.12R dB
ht
S . salar and SPL = 62
0.09R dB
ht
S . trutta, 1
for the 914 mm diameter pile, and
SPL = 85.4 0.16R dB
ht
S . salar and SPL = 70.7
0.17R dB
ht
S . trutta, 2
for the 508 mm diameter pile.
In general, the dB
ht
S. salar levels are higher than the
dB
ht
S. trutta levels. This is to be expected, as the hearing of
the salmon is more sensitive than that of the brown trout. It is
noticeable that there is a significant difference in Transmis-
sion Loss for the case of S. trutta for the two pile diameter
cases. It is thought likely that this might have been due to the
fit of Source Level and Transmission Loss to the data being
poor in the case of the 914 mm diameter pile.
In respect of the results for S. trutta, it may be seen that
both the measured and the estimated levels near to the piling
are well below the level at which a mild reaction would be
expected to occur. In other words, no reaction would be ex-
pected by S. trutta at any range from the piling. By compari-
son, the results for S. salar would indicate that a mild reac-
tion would be expected at a range of about 60–80 m, and an
increasingly stronger reaction as this range was reduced.
These results may explain the relative lack of a reaction to
the piling from the brown trout S. trutta, and indicate the
importance of using the correct species of fish as a model
when assessing the effect of noise.
V. CONCLUSION
In summary we have the following.
1 Observations were made of caged brown trout S.
trutta during vibropiling of four 914 mm and six 508 mm
diameter piles. The brown trout was used as a model for
salmon S. salar, which were not readily available.
2 No reaction to vibropiling was noted at any of the
cages. No startle reactions were observed for the impact driv-
ing. However, there was a 36% increase in the fish activity
level observed in the cage at 54 m, which was significant at
the P =0.05 level, although in the two cages nearest to the
piling at 30 and 54 m, no significant difference in activity
level was detected.
3 Despite the noise from the piling at the nearest cages
reaching levels at which salmon, S. salar, were expected to
react strongly, the brown trout, S. trutta, showed little reac-
tion. An audiogram of the brown trout measured by the Au-
ditory Brainstem Response method indicated that the hearing
of the brown trout was less sensitive than that of the salmon.
Analysis using the dB
ht
metric indicated that this could ac-
count for the relative lack of reaction, and indicated the im-
portance of using the correct species of fish as a model when
assessing the effect of noise.
Abbott, R. 2005. “Fisheries and hydroacoustic monitoring program com-
pliance report addendum.” San Francisco Oakland Bay Bridge East Span
Seismic Safety Project. May 2005, Office of Biological Sciences and Per-
mits, Caltrans District 4.
Blaxter, J. H. S., and Hoss, D. E. 1981. “Startle responses in herring: the
effect of sound stimulus frequency, size of fish and selective interference
with the acousto-lateralis system,” J. Mar. Biol. Assoc. 61, 871–879.
Campbell, R. C. 1974. Statistics for Biologists Cambridge University
Press, Cambridge.
Enger, P. S. 1981. “Frequency discrimination in teleosts—central or pe-
ripheral?,” in Hearing and Sound Communication in Fishes, edited by W.
N. Tavolga, A. N. Popper, and R. R. Fay. Springer, New York,pp.
FIG. 3. The average peak-to-peak sound pressure level as a function of
range, for the impact piling case, in dB
ht
Species units, for two diameters of
pile.
J. Acoust. Soc. Am., Vol. 120, No. 5, November 2006 Nedwell et al.: Effects on fish of piling noise 2553
Redistribution subject to ASA license or copyright; see http://acousticalsociety.org/content/terms. Download to IP: 192.129.2.17 On: Tue, 17 Feb 2015 13:02:46
243–255.
Hawkins, A. D., and Johnstone, A. D. F. 1978. “The hearing of the Atlantic
salmon, Salmo salar,” J. Fish Biol. 13, 655–673.
Kenyon, T. N., Ladich, F., and Yan, H. Y. 1998. “A comparative study of
hearing ability in fishes: the auditory brainstem response approach,” J.
Comp. Physiol., A 182, 307–318.
Lovell, J. M., Findlay, M. M., Moate, R. M., and Pilgrim, D. A. 2005.
“The polarization of inner ear ciliary bundles from a scorpaeniform fish,”
J. Fish Biol. 66, 836846.
McCauley, R. D., Fewtrell, J., and Popper, A. N. 2003. “High intensity
anthropogenic sound damages fish ears,” J. Acoust. Soc. Am. 113, 638
642.
Nedwell, J. R. in preparation.
Nedwell, J. R., Turnpenny, A. W. H., and Edwards, B. 2002. “Piling on the
River Arun; implications for salmon migration,” American Fisheries So-
ciety 132nd Annual Meeting, 18–22 August 2002, Hyatt Regency Hotel,
Baltimore, MD.
Nedwell, J. R., Turnpenny, A. W. H., and Lambert, D. R. 2003a. “Objec-
tive design of acoustic fish deflection systems,” Proceedings of the US
EPA Symposium on Cooling Water Intake Technologies to Protect Aquatic
Organisms, 6–7 May, 2003, Hilton Crystal City at National Airport, Ar-
lington, VA.
Nedwell, J. R., Langworthy, J., and Howell, D. 2003b. “Assessment of
sub-sea acoustic noise and vibration from offshore wind turbines and its
impact on marine wildlife; initial measurements of underwater noise dur-
ing construction of offshore windfarms, and comparison with background
noise,” Subacoustech Report No. 544 R 0424 for the Crown Estate,May
2003.
Nedwell, J. R., Langworthy, J., and Howell, D. 2004.“ThedB
ht
; a meth-
odology for evaluating the behavioral effects of underwater noise and
some examples of its use,” Proceedings of the Symposium on Bio-Sonar
Systems and Bio-Acoustics, Institute of Acoustics, 16 September 2004,
Loughborough University, UK.
Platt, C., and Popper, A. N. 1981. “Fine structure and function of the ear,”
in Hearing and Sound Communication in Fishes, edited by W. N. Tavolga,
A. A. Popper, and R. R. Fay Springer-Verlag, New York, pp. 3–36.
Popper, A. N., and Fay, R. R. 1993. “Sound detection and processing by
fish: critical review and major research questions,” Brain Behav. Evol. 41,
14–38.
2554 J. Acoust. Soc. Am., Vol. 120, No. 5, November 2006 Nedwell et al.: Effects on fish of piling noise
Redistribution subject to ASA license or copyright; see http://acousticalsociety.org/content/terms. Download to IP: 192.129.2.17 On: Tue, 17 Feb 2015 13:02:46
... The Swedish review does not propose noise levels for flight behaviour or a temporary threshold shift (TTS) in fish because, unlike damage to internal organs, both flight behaviour and hearing damage are linked to the species' specific sensitivity to frequency and sound intensity. And using the existing literature, it is not possible to assess whether flight behaviour negatively affects the species at the population level or whether the effect is related to the area and period of time.In the UK,Nedwell et al. (2007) proposed a set of guidelines for behavioural responses utilising what they referred to as the dB ht (species) concept.Nedwell et al. (2007) suggested that specific dB ht levels above the hearing threshold of a fish elicited particular responses. The dB ht is based on a frequency weighting approach since animals do not hear equally well at all frequencies within their hearing range. ...
... g the existing literature, it is not possible to assess whether flight behaviour negatively affects the species at the population level or whether the effect is related to the area and period of time.In the UK,Nedwell et al. (2007) proposed a set of guidelines for behavioural responses utilising what they referred to as the dB ht (species) concept.Nedwell et al. (2007) suggested that specific dB ht levels above the hearing threshold of a fish elicited particular responses. The dB ht is based on a frequency weighting approach since animals do not hear equally well at all frequencies within their hearing range. Frequency weighting is therefore often applied in assessing the effects of sounds upon partic ...
... However, the dB ht approach has very serious flaws that make it totally unacceptable. This is suggested sinceNedwell et al. (2007) concluded that strong avoidance responses by fishes start at a level about 90 dB above the dB ht ...
Article
Full-text available
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.
... No criteria exist for invertebrates. To tackle this lack of information and estimate behavioral impact for all target species equally, we used the weighted scale proposed by Nedwell et al. (2007) and referred to as dB ht . This set of criteria "allows the likelihood of behavioural effects and damage to hearing to be assessed for a wide range of species". ...
... For dB ht < 50, the behavioral disturbance is described as non-existent (dB ht under 0) or as "mild reaction in minority of individuals, probably not sustained". Consequently, within the target species studied, we looked for the species with a dB ht > 50, namely species having a "stronger reaction by majority of individuals, but habituation may limit effect" (Nedwell et al., 2007). These species where considered as significantly behaviorally disturbed. ...
... For example, the minimal duration a harbor porpoise would have to stay continuously at 10 m from the turbine to be temporarily or permanently injured varied between 2 days 17 h up to 84 years ( Table 2). The frequency weighted dB ht scale (Nedwell et al., 2007) was used to define the zones of behavioral disturbance. Estimates of the dB ht noise levels for the target species suggest that strong behavioral disturbance likely occurs up to a distance of 250 m for the bottlenose dolphin (max dB ht = 62.5), 300 m for the grey seal (max dB ht = 70.8) ...
... The model assumed vessel noise production and reception are omnidirectional, and did not take into account the more dynamic nature of SRKW calling, in terms of directionality, beam width, call strength or inter-pulse-interval modification in the presence of noise sources (Miller, 2006;Lammers et al., 2004;Madsen et al., 2005;Morisaka et al., 2011;Jensen et al., 2018;Wellard et al., 2020). In addition, no compensatory calling or masking release mechanisms were considered, nor were the intensity of noise and animal hearing sensitivity evaluated (Nedwell et al., 2007;Barber et al., 2010;Pine et al., 2018Pine et al., , 2020. The amplitude of noise by frequency was unweighted for hearing sensitivity (Szymanski et al., 1999;Southall et al., 2007;Branstetter et al., 2017). ...
Technical Report
Full-text available
Primary threats to the endangered Southern Resident Killer Whale (SRKW) population are reduced prey availability, acoustic and physical disturbance, contaminants, and vessel strike. Successful threat mitigation is contingent on knowledge of spatiotemporal overlap of whale presence with areas of elevated risk. A co-occurrence framework was used to illustrate areas within the critical habitat where SRKW are at higher risk for physical and acoustic disturbance and strike from vessels from May to October. The SRKW sightings data analyses indicate that the locations with the highest SRKW frequency of occurrence are Swiftsure Bank, Haro Strait, the Fraser River estuary. Individual and group follow data were used to add behavioural context to sightings data and identify Swiftsure Bank and Haro Strait as key foraging locations, while Juan de Fuca Strait is mainly used for travel. Collision risk was determined using a combination of Automatic Information System (AIS) vessel data to assess presence of large commercial ships, and aerial surveys adding to records of the presence of smaller or recreational vessels. The acoustic implications of vessel presence were explored by examining the noise additions in frequency ranges used for SRKW communication (500 Hz to 15 kHz) and echolocation (15-100 kHz). A reference level of ‘minimum ambient’ noise was derived from the 1% quietest conditions obtained from acoustic mooring recordings in the study area. The ranges at which calls and clicks could travel in minimum ambient conditions were then calculated. Loss of communication and echolocation ranges were expressed as percent reductions from minimum ambient. Noise from AIS Class A vessels resulted in significant loss of both echolocation and communication range in SRKW critical habitat. Echolocation range loss of greater than 50% was identified in key foraging locations, and range loss increased with foraging depth. Echolocation range loss from small vessels was also observed, with increased impacts occurring on weekends. These analyses will inform recovery measures to reduce acoustic impacts on SRKW in critical habitat, and provide a framework for future investigations on threats to recovery. Moving forward, inclusion of prey and contaminants data into the co-occurrence analysis will inform our understanding of cumulative effects, and will support management actions for the survival and recovery of the population.
... These thresholds have been used for many years by NMFS and other agencies around the world to assess behavioral impacts from various sound-producing offshore projects (seismic or other). Alternative methods to these simplistic thresholds that are based on observations of mysticetes alone [16][17][18][19], have been proposed (e.g., [14,20]). Alternative criteria used in this study include frequency-weighted SPL step functions proposed by Wood et al. [21] for impulsive sounds, and frequency-weighted SPL values adopted by the US Department of the Navy (DoN) [22] for non-impulsive sounds. ...
Article
Full-text available
Concerns about the potential environmental impacts of geophysical surveys using air gun sources, coupled with advances in geophysical surveying technology and data processing, are driving research and development of commercially viable alternative technologies such as marine vibroseis (MV). MV systems produce controllable acoustic signals through volume displacement of water using a vibrating plate or shell. MV sources generally produce lower acoustic pressure and reduced bandwidth (spectral content) compared to air gun sources, but to be effective sources for geophysical surveys they typically produce longer duration signals with short inter-signal periods. Few studies have evaluated the potential effects of MV system use on marine fauna. In this desktop study, potential acoustic exposure of marine mammals was estimated for MV and air gun arrays by modeling the source signal, sound propagation, and animal movement in representative survey scenarios. In the scenarios, few marine mammals could be expected to be exposed to potentially injurious sound levels for either source type, but fewer were predicted for MV arrays than air gun arrays. The estimated number of marine mammals exposed to sound levels associated with behavioral disturbance depended on the selection of evaluation criteria. More behavioral disturbance was predicted for MV arrays compared to air gun arrays using a single threshold sound pressure level (SPL), while the opposite result was found when using frequency-weighted sound fields and a multiple-step, probabilistic, threshold function.
Book
Full-text available
A guide to recommendations for limiting the impact of anthropogenic noise emissions on marine fauna, written under the patronage of the French Ministry of Ecological Transition, this work aims to (1) provide an overview of the acoustic emissions generated by industrial activities at sea and the knowledge related to these emissions; (2) to summarise the state of knowledge on the impacts of noise on marine fauna (from invertebrates to marine mammals) and to identify the research axis to be developed; (3) to list the existing measures to avoid or reduce impacts and their degree of maturity; (4) to propose summary sheets for each activity, cross-referencing the various information mentioned in the previous points. These different points are largely illustrated and summarised in the form of summary tables. This guide is intended for government departments, marine area managers, NGOs, consultancy firms and any other structure requiring information on noise and marine fauna interactions. An introduction to the basics of underwater acoustics is also provided for non-specialists.
Book
Full-text available
Guide de préconisations pour limiter l'impact des émissions acoustiques d'origine anthropique sur la faune marine, rédigé sous l'égide du Ministère français de la Transition Ecologique, ce rapport a pour objectif (1) de faire un état des lieux des émissions acoustiques générées par les activités industrielles en mer et des connaissances liées à ces émissions ; (2) de résumer l'état des connaissances sur les impacts du bruit sur la faune marine (des invertébrés aux mammifères marins) et d'identifier les axes à développer ; (3) de lister les mesures existantes pour éviter ou réduire les impacts et leurs degrés de maturité ; (4) de proposer des fiches synthétiques par activités recoupant les différentes informations mentionnées dans les points précédents. Ces différents points sont largement illustrés et résumés sous forme de tableaux récapitulatifs. Ce guide s'adresse aux services de l'Etat, gestionnaire d'aire marine, ONG, bureaux d'études ou tout autre structure ayant besoin d'informations sur les interactions bruit et faune marine. Une introduction aux notions élémentaires d'acoustique sous marine est également proposée pour les non spécialistes. Ce guide est disponible en français uniquement pour le moment, une version anglaise est en cours de rédaction.
Thesis
Full-text available
Les activités humaines font peser sur l’écosystème marin de multiples pressions délétères. Pollution chimique, changement climatique, risque d’acidification, débris de plastique et déchets radioactifs ont des impacts sans précèdent. Une pollution de plus en plus reconnu comme majeur est la pollution sonore. La prospection sismique, le battage de pieux et le trafic maritime génèrent des niveaux sonores qui peuvent être extrêmement forts, modifiant fondamentalement le paysage acoustique sous-marin. On sait que de nombreux mammifères marins et poissons entendent le bruit généré par ces activités et que cela altère leur physiologie et leur éthologie. Par contre, chez les invertébrés marins très peu d’études avaient évalué leur capacité à entendre et l’impact de cette pollution sur eux reste à déterminer. Nous avons abordé le problème par une étude de la capacité de perception du son chez l'huître creuse Magallana gigas en utilisant une approche comportementale et physiologique. Nous avons montré que M. gigas entend dans la gamme de fréquences entre 10 et 1000 Hz. Cette analyse nous a permis de caractériser les sources de sons qui contribuent à leur environnement auditif. Au laboratoire, dans un milieu contaminé (i) au cadmium, un métal que nous avons considéré à la fois comme une substance toxique et un marqueur indirect de l'activité ventilatoire, et (ii), par des bruits de cargo, nous montrons un effet répresseur du bruit caractérisé par une diminution de l'activité valvaire, de l'activité ventilatoire et du taux de croissance. Nous rapportons également une diminution de la bioaccumulation du Cd dans les branchies et une modulation de l'expression de certains gènes. Nous avons enfin étudié sur un enregistrement de 2 ans dans le port commercial de Santander, le comportement (incluant les pontes et la croissance) de 3 groupes d’huitres exposés à une forte pollution sonore et à une « qualité de l’eau » considérée dans la littérature comme bonne à très bonne pour une masse d’eau fortement modifiée. Nous avons retrouvé dans notre analyse différents effets que nous avions provoqués ou prédits à partir du travail de laboratoire où nous avions manipulé le bruit seul. Nous concluons que la pollution sonore au sein du port doit diminuer le fitness des huîtres en modifiant leur activité valvaire, la hiérarchie de leurs rythmes biologiques et la croissance. Nos résultats suggèrent que la pollution sonore peut avoir des conséquences importantes sur les invertébrés et présente un risque fort en termes de productivité de l'écosystème.
Technical Report
Full-text available
The distribution of harbour porpoises in EU waters is poorly understood, and modelled predictions of their distributions could inform the strategic spatial planning of future exploitation of the marine environment to avoid potential conflicts. We analysed satellite telemetry data from 39 harbour porpoises Phocoena phocoena in inner Danish waters using a modelling tool rooted in maximum entropy: Maxent. Maxent does not require absence data and has been shown to be effective for data characterised by small sample size, sampling bias and locational errors. For each season we used an iterative bootstrapping procedure to randomly select among the most precise records from each of the 39 tagged individuals, and ran Maxent on pooled records based on explanatory environmental variables hypothesised to serve as good proxies for harbour porpoise prey abundance. Among our environmental variables, distance to coast and bottom salinity had the most explanatory power, and their response shapes were relatively consistent across most seasons. The predictive power of the models (assessed by ROC-AUC) ranged from 0.70 to 0.86 within seasons. The southern Kattegat, the Belt Seas, most western part of the Baltic Sea and the Sound were predicted to have relatively high probabilities of occurrence across seasons. In contrast, the central part of Kattegat and the Baltic Sea south and east of Limhamn and Darss Ridge consistently showed low probabilities of occurrence. Areas with the lowest probabilities of occurrence were generally characterised by high predictive uncertainty. Our methods have implications for the analyses of satellite tagged animals in terrestrial and marine environments. By coupling a bootstrapping procedure with Maxent we circumvented some of the statistical challenges presented by satellite telemetry data to generate spatial predictions within the inner Danish waters.
Article
Full-text available
Background Many attempts have been made to use sound to reduce the conflict between mammals and human activities in the marine environment. AHD-s (Acoustic Harassment Devices) produce a sound intense enough to cause discomfort and avoidance and are used extensively in aquaculture. Some trials have also been made in fisheries operations (Mate and Harvey 1986, Jefferson and Curry 1996) with the aim of avoiding by-catch of marine mammals and of stopping damage to gear and catch. Generally, limited quantitative data have been presented on the long term mitigating effect of AHD-s. In order to obtain such data, a series of field trials were carried out at set traps for salmonids in the northern part of the Baltic Sea. This fishery is subject to heavy disturbance by grey seals (Westerberg et al. 2000, Fjälling 2005), and mitigation methods are under development (Lunneryd et al. 2003). Technical specifications The AHD tested generates groups of pulses, with a frequency of approximately 15 kHz. Modifications were made to the device to make it difficult for seals to anticipate the arrival of a pulse train (by randomization of pulses and delay time) and to reduce energy consumption (decreased pulse length and number of pulses). Several power supply systems were tried (mains, solar panels, wind generators, replacement battery packs). The source level was measured to 191 dB re 1 µPa, 1m p-p. This should not be enough to harm the seals, but should be high enough to cause discomfort and avoidance at a distance of the order of 100 m, according to the manufacturer (LofiTech A/S). The cost of each AHD is approximately €3,000. The fish traps used were variations on a Scottish salmon trap. Methods Commercial fishers were enrolled to test the AHD-s in their regular fishing operations. Their commitment included the maintenance of equipment and the keeping of detailed records of catches and seal damage to both fish and gear. The catches of salmon, sea-trout and whitefish were summed per lifting of nets. Up to nine AHD-s were deployed during the period from 1997 to 2002. For each test trap with an AHD there was a control trap. In some instances the AHD unit was moved back and forth between two traps to allow for a more detailed analysis of data. The total number of unit efforts (trap*days) during trials was around 5000. Several problems occurred, both technical, logistic and weather-related. Some fishermen did not meet the minimum standards for maintenance of the AHD-s, or the guidelines for fishing, or record keeping.
Article
Full-text available
The polarization of ultrastructural ciliary bundles from hair cells in the inner ear of the sea scorpion Taurulus bubalis was studied using a scanning electron microscope, revealing arrays of ciliary bundles with diverse orientations on each of the sensory epithelia. Members of this order are known to produce sound, though results of this study show no significant variation from the standard receptor patterns found in the hearing system of many silent marine teleosts. This is the first time that the ultrastructure of T. bubalis has been studied, and this work presents a new set of polarization patterns, which provide anatomical information important in understanding electrophysiological aspects of fish hearing from an ecological perspective.
Chapter
Pitch discrimination in fish is well established although the number of behavioral studies concerned with the topic is fairly limited. Table 12-1 lists some species investigated and the results obtained, including the value for Cottus scorpius which will be reported here. In such studies it is important to be aware of the complicated and unpredictable acoustics of small tanks (Parvulescu 1967). For example, when changing the frequency of the sound producing equipment, great fluctuations in sound pressure and particle displacement amplitude will occur as well. Moreover, the relation between sound pressure and particle displacement is not predictable, as it would be in a large body of water, like the open sea. It is generally agreed that particle displacement is the relevant stimulus for the auditory receptor cells. For a fish with a swimbladder, sound pressure is a relevant stimulus as well, since the swimbladder is then acting as a pressure to displacement transformer. This secondary displacement will be transmitted through the surrounding tissues to the inner ear, there stimulating the sensory hair cells. In the ostariophysine species, all of which have a bony connection between the swimbladder and the inner ear, the sense of hearing is particularly good. In nonostariophysine species there seems to be a relation between threshold and hearing range on the one hand, and the anatomical configuration of the peripheral auditory system and the swimbladder on the other (Coombs and Popper 1979).
Chapter
In evoked potential work the action of the inner ear is too often ignored and seen only as the necessary mechanism for obtaining responses to auditory stimuli. In discussions this cochlear action is furthermore reduced to only the action of the basal part of the cochlea, since popular belief is that click evoked potentials (EP) are only mediated by the high frequency fibers emanating from this part of the cochlea. Subsequently the opinion is heard that no matter what stimulus is used, one can only test the integrity of this basal part of the cochlea. This of course is not the case and introduction dedicated to those aspects of cochlear and auditory nervous system physiology appears necessary for the interpretation of auditory brainstem responses (ABR). We will observe that the application in neurology is straightforward when one is only concerned with the distinction normal vs abnormal brainstem. The difficulties arise when false positives (i.e. diagnosing an abnormality of the brainstem when in fact it is normal) resulting from cochlear abnormalities, have to be eliminated. For this important purpose alone an understanding of cochlear action and its influence on the generation and the interpretation of the ABR is indicated.
Chapter
One of the most striking features in the auditory system of fishes is the extensive structural diversity in the inner ear and its peripheral accessories. In this chapter we will summarize this diversity in the ear, from the gross structure to the ultrastructure of the sensory epithelia, and suggest some of the possible functional meanings for these structural differences. We hope that this discussion will stimulate interest in pursuing direct experimentation on the function of the fish ear in order to fill in the gaps in our understanding of peripheral auditory mechanisms. Two major points will be stressed throughout this chapter. First, we feel that dividing up of auditory and vestibular functions between the different otolithic organs of the ear may not be as absolute as has been often implied, so it may be necessary to reconsider some of the basic “classical” assumptions of auditory organ functions, at least with regard to the teleost ear. Second, we suggest that the notion of a functionally or structurally “typical teleost ear” is no longer tenable, since the breadth of interspecific structural variation in teleost ears may imply significant functional variation.
Article
A microcomputer-controlled positive reward operant conditioning paradigm was developed to measure auditory sensitivity of goldfish (Carassius auratus) and oscar (Astronotus ocellatus). Past studies of hearing in fish have proved challenging in part because of difficulties in precise measurement of the sound field and in part because their range of behavior seems so limited. Here a new positive reinforcement procedure is described which solves some of these problems. The audiogram obtained from this paradigm is in close agreement with thresholds obtained with instrumental avoidance and classical conditioning procedures involving aversive conditioning. The major advantages of the present paradigm are: (1) there is minimal stress to the fish, and (2) the versatility of the system allows easy modification for a variety of experimental needs.
Article
1. ABSTRACT Traditionally the study of fish hearing is achieved either by psychophysical method (e.g., behavioral training) or invasive electrophysiological recording (e.g., microphonics, single unit recording). A non-invasive, the auditory brainstem response (ABR) recording method is developed to study fish hearing. With the use of the ABR method and the removal of gas from various gas holding structures, it is proved that the mechanically coupled or directly linked gas holding devices are used by fish to enhanced hearing.