Anthropogenic Noise and Conservation - Springer Link

Chapter 14

Anthropogenic Noise and Conservation Peter K. McGregor, Andrew G. Horn, Marty L. Leonard and Frank Thomsen

Abstract Anthropogenic noise is a common but evolutionarily recent influence on communicating animals and evidence is accumulating of its adverse impacts on human health, therefore it has potential relevance to conservation. However, demonstrating that this potential is realised is not straightforward. A particular issue is the difficulty of assessing likely impacts from the limited evidence on the main factors influencing impacts—from the hearing abilities of animals of conservation concern through to the characteristics of emitted sound fields in natural environments. Further issues include the likely underestimation of behavioural effects, and a lack of knowledge of how animals trade off costs and benefits. In this chapter, we aim to highlight the main themes emerging from the growing interest in the effects of anthropogenic noise on conservation. We predominantly consider the marine environment (with examples drawn mainly from marine mammals) and the terrestrial environment (with bird examples). An important consideration that emerges from the increasing levels of anthropogenic noise and difficulties in assessing specific impacts is the need to develop interim guidance, while more detailed information is gathered and assessed.

P. K. McGregor (&) Centre for Applied Zoology, Cornwall College Newquay, Trenance Gardens, Newquay TR7 2LZ, UK e-mail: [email protected] A. G. Horn M. L. Leonard Department of Biology, Life Science Centre, Dalhousie University, 1355 Oxford Street, Halifax, NS B3H 4J1, Canada e-mail: [email protected] M. L. Leonard e-mail: [email protected] F. Thomsen DHI, Agern Alle 5, DK-2970 Hørsholm, Denmark e-mail: [email protected]

H. Brumm (ed.), Animal Communication and Noise, Animal Signals and Communication 2, DOI: 10.1007/978-3-642-41494-7_14, Springer-Verlag Berlin Heidelberg 2013

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14.1 Introduction Post-industrial revolution humans produce more and louder noise than any other species on the planet. Given that we are also ubiquitous and numerous, anthropogenic noise has become a dominating feature of most animals’ environments. Animals have evolved to communicate in the presence of natural biological and physical sources of noise, including other animals of the same and different species (see other chapters in this volume). However, most anthropogenic noise differs from natural noise in features including intensity, distribution, persistence and timescale that are likely to make an adaptive response by most species problematic. Therefore anthropogenic noise has the potential to impact conservation. Another reason to consider that anthropogenic noise will have conservation impacts in addition to being common and new (on an evolutionary time scale) is its documented adverse effects on human health. For example, a recent study in Western Europe indicated that at least one million healthy life years are lost every year from traffic-related noise. These losses are principally through stress-related effects linked to sleep disturbance and annoyance but also include ischaemic heart disease, cognitive impairment of children, tinnitus (WHO 2011) and incident diabetes (Sørensen et al. 2013). These studies and similar demonstrations in humans of the role of noise as a stressor, suggest that comparable effects could occur in other vertebrates. The WHO study (2011) also pointed out that exposure to noise in Europe is increasing whereas other stressors such as exposure to dioxins and benzene are declining. It is not clear whether this relative difference in noise v. other stressors also applies to animal populations, although it is clear that anthropogenic noise is increasing (see Sect. 14.3). Our chapter is different in content and scope from the others in this book. We aim to appraise the significance of anthropogenic noise for issues related to conservation. Mitigation of, and adaptation to, noise are fundamental processes in communication and signal detection (well demonstrated by the other chapters in this volume). However, anthropogenic noise can increase errors by signal receivers (see Chap. 2) and such errors can reduce individual fitness. Reductions in individual fitness can translate into effects at a population level and therefore become relevant to conservation. However, demonstrating that the potential impact of noise on conservation is realised, particularly through effects on communication, is not straightforward. We will discuss anthropogenic noise in terrestrial and marine environments with a taxonomic coverage largely limited to birds and marine mammals because these are the groups with which we are most familiar. This chapter is not intended as an exhaustive review of the importance of noise to animal communication and conservation, rather we highlight what we see as the main themes emerging from the growth in this field. Several recent reviews provide more details and other emphases (e.g. Pepper et al. 2003; Warren et al. 2006; Nowacek et al. 2007; Slabbekoorn and Ripmeester 2007; Southall et al. 2007; Barber et al. 2009a, b; Popper and Hastings 2009b; OSPAR 2009b; Goodwin and Shriver 2010; Tasker et al. 2010; Kociolek 2011; Ortega 2012; Slabbekoorn 2013).

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As this book amply demonstrates, noise is a common problem for all modalities of animal communication—acoustic, visual, chemical, tactile or electrical (for acoustic see Chaps. 3–10, visual see Chap. 11, electrical see Chap. 12 and chemical see Chap. 13) and includes intrinsic noise in the reception system of receivers (e.g. noise of receptor cells, see Chaps. 3 and 12). We will focus on extrinsic acoustic noise because this is likely to be the only context in which noise will be familiar to those with conservation interests. However, we believe that it would be productive to apply the approach we develop in this chapter to other communication modalities. Consider, for example, noise in the chemical modality. Anthropogenic chemicals have long been included in legal definitions of pollutants and many have, or mimic, biological signalling functions. Therefore, pollution by such chemicals can also be considered as noise in chemical communication systems. A specific example in freshwater habitats is the widespread presence of anthropogenic sex hormone mimicking chemicals and other endocrine disrupters, which have demonstrable behavioural and physiological effects with potential conservation implications (e.g. Tyler and Jobling 2008). We begin this chapter by characterising terrestrial and marine environments with respect to the potential for anthropogenic noise to have consequences for conservation through communication effects, including differences in sources of noise. We then consider how noise impacts in general have been assessed. The Sect. 14.2 discusses potential and demonstrated conservation impacts of noise through effects on communication. It is subdivided into evidence for proximate costs (with effects at population level inferred) and evidence for population level effects where proximate causes are inferred. In Sect. 14.2 we look at management of anthropogenic noise and mitigation measures; dealing with terrestrial and marine environments separately because we believe that, unlike previous sections, an integrated approach yields fewer additional insights. We conclude by identifying where further work is necessary and interim approaches that can be applied now.

14.2 Characteristics of Terrestrial and Marine Environments There are several characteristics of marine and terrestrial environments that affect both the potential for anthropogenic noise to impact communication and the implications for conservation. These range from the physics of sound transmission to the ease of observing impacts and will be considered individually before looking at their combined effects.

14.2.1 Sound Transmission The speed of sound in salt water is approximately 1,500 ms-1 whereas in air it is about four and a half times slower at approximately 330 ms-1. Sound is also attenuated less in seawater, especially at lower frequencies and can thus travel

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considerable distances (Urick 1983; Richardson et al. 1995; Ainslie 2010). In consequence, the active space of acoustic signals is much larger underwater than it is in air. For example, bottlenose dolphin Tursiops truncatus whistles have an estimated active space of up to 25 km (Janik 2000); and fin whales Balaenoptera physalus could communicate over ranges of up to 100 km, depending on conditions (Stafford et al. 2007). By contrast, the active space of a bird’s song would be measured in tens of metres (Lohr et al. 2003; Nemeth and Brumm 2010). As a result, the area over which a given noise might be of concern is much larger underwater than on land; noise from a shipping lane may interfere with communication across a wide area of sea, whereas noise from a highway is likely to interfere with signalling only in the bird territories within a few road-widths of the road.

14.2.2 Frequencies Used in Communication The wide range of frequencies emitted by animals is illustrated in this section by marine taxa. At the lower end of the frequency scale are calls in the region of 20 Hz by baleen whales such as fin whales which are presumed to be reproductive displays (Watkins et al. 1987). The higher end of the scale are clicks of more than 300 kHz produced by odontocetes such as whitebeaked dolphins Lagenorhynchus albirostris (Mitson and Morris 1988, see also Rasmussen and Miller 2002) which are used for navigation (echolocation). Consequently, the hearing of most marine mammals investigated to date spans a very wide bandwidth (see Chap. 10). Southall et al. (2007) divided marine mammals into four functional hearing groups. The three families of pinnipeds were placed in one category with a designated hearing range of 75 Hz–75 kHz. Cetaceans were placed in three functional groups (1) low-frequency cetaceans, e.g. fin whale (7 Hz–22 kHz); (2) mid-frequency cetaceans, e.g. bottlenose dolphin (150 Hz–160 kHz); (3) high-frequency cetaceans, e.g. harbour porpoise Phocoena phocoena 200 Hz–180 kHz. This designation of species into functional groups is preliminary as hearing studies with published audiograms are available for *20 of the 128 species and subspecies of marine mammals. For the species in which hearing has yet to be measured (and this includes all species of baleen whales), hearing range has been derived from the acoustic properties of the emitted signals and anatomical features (see Ketten 1997). Fish show a more restricted bandwidth of emitted sounds than marine mammals. Most fish signals are well below 1 kHz, albeit with exceptions (Zelick et al. 1999; Popper et al. 2003; Ladich 2008, see Chap. 4). Hearing ability is diverse and dependent on anatomical features. Taxa with no swim bladder, for example sharks and flatfish, are only sensitive to particle motion. Species such as cod Gadus morrhua have swim bladders but no apparent connection between swim bladder and ear. Such species are sensitive to particle motion and pressure. Species such as herring Clupea harengus have tight connections between pressure receptors and inner ear and exhibit high sensitivity and a wide bandwidth extending to frequencies well above 1 kHz (see Popper and Fay 2011). Hearing has been

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investigated in fewer than 200 of the 30,000 species of fish, so our knowledge of the fish hearing spectrum (see review by Popper and Hastings 2009a) is more limited than of cetaceans (see previous paragraph). In addition to fish and marine mammals, invertebrates such as decapod crustaceans have been described as being sensitive to sound, i.e. the particle motion component (Popper et al. 2001) and the shore crab Carcinus maenas responds physiologically to playback of ship noise (Wale et al. 2013). Cephalopods are sensitive to frequencies below 20 Hz (Packard et al. 1990; Mooney et al. 2012). Sea turtles have shown hearing capabilities in the lower frequency band (Bartol et al. 1999; Dow Piniak et al. 2012; Lavender et al. 2012). If and to what extent underwater sound is used by marine birds and how sensitive they are to sound is unknown (Dooling and Therrien 2012) although attempts are underway to document underwater hearing in some species (Johansen et al. 2013).

14.2.3 Use of Sound Animals use sound for a range of activities including detecting predators and prey, communication, navigation and foraging. Echolocation is well characterised in marine mammals (e.g. Au 1993) and bats (e.g. Jones and Teeling 2006). The use of sound for navigation and orientation is less well characterised in other groups, although it is possible that fish use the surrounding acoustic environment (acoustic scene information) for orientation (Fay and Popper 2000; Montgomery et al. 2006) and infrasound may provide navigation cues for some birds (e.g. Bingman and Cheng 2005). As a general rule, however, on land sound is primarily a tool for communication, while in marine environments it serves a broader range of functions.

14.2.4 Habitat Biases Terrestrial habitats differ from underwater habitats in the visibility of effects. One consequence of this difference is that more is known about the immediate effects of noise on land animals than those living underwater, because it is easier to observe (and conduct) experiments with most terrestrial animals, including assessing their hearing ability. A second consequence is that the habitat destruction associated with noise production is more visible on land than underwater and this has contributed to a difference in the perceived relative importance of noise and habitat destruction in the two habitats. On land it is considered that the conservation consequences of habitat destruction around noise sources (e.g. the cleared area around a gas well) are more important than the effects of noise per se (e.g. interference with communication). Underwater, the reverse is often the case as the difficulty of observing habitat destruction associated with noise production may

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result in such potentially significant conservation effects being overlooked and attention being concentrated on noise alone. Anthropocentric biases are different; terrestrial noise is readily appreciated to affect humans, whereas marine noise is viewed mainly in terms of its effects on animals. This effect is enhanced if the marine species have iconographic status (e.g. humpback Megaptera novaeangliae, blue Balaenoptera musculus and killer whales Orcinus orca), with the result that the well-being of such species is widely considered.

14.2.5 Intentional v. Incidental Noise production Most anthropogenic noise is a by-product of activities such as travel (road, shipping and aircraft noise), construction (e.g. pile driving), extraction (e.g. blasting), industrial activity and wind farms (Blickley and Patricelli 2010). Noise resulting from sound that is intentionally introduced is much more common in the marine environment through sonar and geophysical surveys (e.g. airguns), with terrestrial examples limited to alarm and warning sounds. Clearly, the scope for mitigation is greater when anthropogenic noise is an incidental by-product than when it is vital for the outcome of the activity.

14.2.6 Summary It will be clear from the rest of this chapter that anthropogenic noise has received far less attention in relation to its impacts on, and conservation implications for, terrestrial animals than marine animals. This is likely a combination of a failure to consider the impact of noise on terrestrial animals due to anthropocentric bias and the presumed greater effects of visible habitat destruction. This bias is also despite the relative ease of observation and measurement of impacts on land. However, as much terrestrial noise is an incidental by-product of our activities (cf. for example the essential role of sound in marine seismic surveys) there may be more scope for mitigation on land.

14.3 Sources of Noise At first consideration, anthropogenic noise would seem to differ in several characteristics from natural sources of noise, such as wind, other species, waterfalls, waves and thermal energy (marine environment reviewed by Hildebrand 2009; Ainslie 2010). The first difference is that anthropogenic sounds are often more intense than natural noises (exceptions include large waterfalls, storms, undersea earthquakes, sea floor volcanic eruptions and sperm whale Physeter macrocephalus

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echolocation clicks, all of which are relatively localised in space and time.) A second difference is that most anthropogenic sounds contain more low frequencies than natural noises (exceptions are high-frequency sounds produced by some machinery and the hiss of tyres on road surfaces). A third difference is the relative commonness of high-intensity impulse sounds produced by anthropogenic sources (naturally occurring exceptions are lightning strikes and echolocation clicks of most odontocetes). Intense impulse sounds such as airgun firing, blasting charges, pile strikes and sonar pings are more likely to have acute impacts including temporary or permanent injury to auditory systems. By contrast, continuous noise including road, ship and aircraft traffic noise, drilling, construction, industrial activities, lowand mid-frequency sonar systems (see Southall et al. 2007; Tasker et al. 2010) and acoustic harassment/deterrent devices are more likely to produce chronic effects such as masking and stress. Some of the key acoustic characteristics of marine anthropogenic noise are summarised in Table 14.1. The source levels of sounds can provide a first impression of their potential impacts; however, inferring impact from source levels is complicated by two things. First, source levels are usually determined by measuring sound levels in the acoustic far-field and extrapolating back to determine the level at 1 m from the source (see Ainslie 2010). In many cases a simple Xlog (R/1 m) scaling is used and not an actual propagation loss correction. The resulting source level is therefore not independent of the environment in which the measurements were taken and it is difficult to compare results obtained in different studies. Second, effects on living animals are dependent on many other acoustic characteristics in addition to the sound level at the receiver (for a discussion of these in the marine environment, see Southall et al. 2007). Finally, as there is at least one biological source of naturally occurring high-intensity impulse sounds (odontocete echolocation clicks, see previous paragraph), it is possible that marine animals may be adapted to deal with high-intensity impulse sounds. Anthropogenic sources of noise are increasing in their distribution and abundance. In the US, for example, road traffic nearly tripled between 1970 and 2007 and aircraft traffic, by some measures, more than tripled between 1980 and 2007 (Barber et al. 2009a). Unfortunately, this increase significantly offsets the reduction in intensity of many sound sources (e.g. sound levels from US aircraft engines dropped 20 dB(A) in the past three decades, Bronzaft and Hagler 2010) that resulted from a growing awareness of noise pollution and consequent regulations (discussed below). In the seas, ambient noise levels have increased in several regions over the past decades due to increased ship traffic (e.g. Ross 1993; Andrew et al. 2011).

14.4 Assessing Noise Impacts Anthropogenic noise can have many different impacts on individual fitness that can translate into conservation consequences, such as permanent or temporary threshold shifts, flight reactions and disruption of activities such as foraging and

TNT (1–100 lbs) Pile driving (4–4.7 m ø pile) Airgun array Echo sounders Military sonar mid-frequency Military sonar low- frequency Large vessels Trailer Suction Hopper Dredger Small boats and ships Drilling (Drillship and drilling operation) Wind turbine in operation Acoustic deterrent/harassment devices

272–287Peak 243–257Peak-to-Peak 260–262 Peak-to-Peak 230–245 223–235Peak 214–240Peak 180–190 168–186 160–180 145–190 142–151 132–200Peak

2–1000 6–21 20–100,000 100–500 50–100,000 10–120 10,500–100,000 Various 2,600–8,200 Various 100–500 Various 6 to [ 30,000 \200 30 to [ 20,000 100–500 20 to [ 10,000 \1000 10–10,000 \100 16–20,000 30–200 1,800–30,000 Various

0.001–0.01 0.05 0.03–0.06 0.00001–0.002 0.5–2 6–100 Continuous Continuous Continuous Continuous Continuous 0.015–0.6

Omni Omni Vertical Vertical Horizontal Horizontal Omni Omni Omni Omni Omni Omni

Table 14.1 Acoustic characteristics of some marine anthropogenic sounds (Adapted from Hildebrand 2009; OSPAR 2009a; CEDA 2011; Thomsen et al. 2011) Sound source Source level (dB re 1lPa-1 m) Bandwidth (Hz) Major amplitude (Hz) Duration (ms) Source direction

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migration. We detail three approaches that have been formalised to assess effects of noise on animal populations. These have mainly been applied in the marine environment, but we discuss their actual and potential application to terrestrial environments.

14.4.1 Zone of Influence Model This approach to assessing noise impacts is based, at least partly, on the distance between the source and the receiver; the rationale is that sound intensity falls with increasing distance from the source and therefore impacts are likely to lessen, or at least to change, with distance. Richardson et al. (1995) defined a nested series of zones of influence centred on the source (Fig. 14.1): • The zone of audibility is the most extensive and is defined by the receiver’s ability to detect noise. • The zone of responsiveness is the area within which the receiver reacts behaviourally or physiologically to the sound. (For examples of behavioural disruption in a terrestrial environment see Kaseloo and Tyson 2004). • The zone of masking is the area where noise interferes with the detection of biologically relevant signals such as echolocation clicks or social signals. It is highly variable. • The zone closest to the source is where the received sound level is high enough to cause hearing loss, discomfort or injury. In air, continuous noise[110 dB(A) causes permanent threshold shifts in birds, noise [93 dB(A) causes temporary threshold shifts (Dooling and Popper 2007). The physiological effects of noise noise inaudible