ࡱ > ` t jbjb $ |c |c i x x x x x x x 0 . . . . . l 0 {D D/ D/ D/ D/ D/ D/ D/ D/ C C C C C C C , E R QH C i x D/ D/ D/ D/ D/ C C x x D/ D/ 5D C C C D/ Z x D/ x D/ C C d @ x x x x D/ C C C x x C 8/ @ . 6 C C KD 0 {D C QI C QI C C x 0 0 ' ) 0 0 ) p20 15/05/2006 Noise impacts Mitigation measures to reduce acoustic injury and mortality in naval ship shock tests Ship shock tests involve detonations of explosives (e.g., 10,000 lb bombs) in close proximity to naval vessels to assess the structural integrity of new ship designs to combat conditions. Researchers conducted a review of mitigation measures (to protect marine mammals) actually employed during a series of ship shock tests. Various mitigation measures were used, including the establishment of safety and buffer zones, aerial surveys, and observers on board the vessel to be tested. In addition, a nearby vessel had a marine mammal observer and veterinarian on board, in case animals were injured. Detonations were delayed on three days due to marine mammal or turtle sightings, and completely postponed on one day due to numerous sightings. Detonations were also cancelled on two days due to weather conditions that would have made sighting cetaceans difficult. The large numbers of sightings in the test area suggest that had mitigation measures not been employed there would have been numerous animal deaths and injuries. It was considered that the mitigation measures were effective since no dead or injured [animals] were detected after the detonations (p. 48). In evaluating the programme it was emphasised that [e]xperienced and trained observers are crucial for detecting and tracking marine mammals (p. 49). In terms of improving and increasing the effectiveness of mitigation measures, it was suggested that: (i) passive acoustic monitoring was largely ineffective, as it was both expensive and no animals were detected; (2) two survey planes be used instead of one to improve survey coverage; (3) the additional boat (with the veterinarian) should be better equipped, with additional observers and 25x binoculars, with a more active role in tracking and monitoring marine mammals; (4) post-detonation monitoring should be increased; and (5) surveys to assess possible test areas (to identify areas with the lowest density of marine mammals and turtles) should be conducted during the same season as future tests, using similar methodologies. They note that the expense of dedicated surveys to determine a time and location of minimum marine mammal abundance is ultimately worthwhile, as it not only reduces potential impacts, but also reduces the number of extremely costly test delays. The mitigation measures examined in this study could serve as an example of appropriate measures that could be used for other high intensity noise-producing activities. (SOURCE: Clarke, J.T. and Norman, S.A. 2005. Results and evaluation of US Navy shock trial environmental mitigation of marine mammals and sea turtles. J. Cet. Res. Manage. 7: 43-50) p 21 Sound causes gas bubble formation in supersaturated blood, liver, and kidney This study placed samples of bovine blood, liver, and kidney under pressure (equivalent to 40-70m in diving depth) and exposed them to low frequency sound pulses. Bovine tissues effectively supersaturated with gases (e.g., having high levels of dissolved nitrogen) all clearly showed presence of bubbles or gas lesions after ensonification. This provides further evidence to suggest that high intensity sound sources such as sonar can cause gas emboli syndrome in stranded cetaceans. (SOURCE: Crum, L.A., Bailey, M.R., Guan, J., Hilmo, P.R., Kargl, S.G., Matula, T.J. and Sapozhnikov, O.A. 2005. Monitoring bubble growth in supersaturated blood and tissue ex vivo and the relevance to marine mammal bioeffects. Acoust. Re. Lett. Online 6: 214-220) Two new whale strandings possibly linked with sonar In January 2006, four beaked whales were reported to have stranded on the southern coast of Spain. These animals had gas emboli in their tissues, as has been found in sonar-associated strandings. Mid- frequency sonar was suspected to be a cause of the strandings, a hypothesis subsequently reinforced when the United Kingdoms Royal Navy reported that it had been using mid-frequency sonar systems during a training exercise near Gibraltar, adjacent to the stranding site. A second suspect stranding, of 45 pilot whales, occurred in March 2006, on the western coast of Sulawesi, Indonesia. This second stranding occurred coincident with a joint US/Indonesian naval exercise in the Macassar Strait. (SOURCE: Dalton, R. 2006. More whale strandings are linked to sonar. Nature 440: 593) The potential effects of pile-driving noise on cetaceans Pile driving is an activity associated with many forms of coastal development, including raising structures such as wind farms. It was noted that the sound produced by pile driving can be substantial (e.g., 135 dB re 1 P a u p t o 1 k m f r o m a s i t e ) . I n a n a n a l y s i s c o n c e n t r a t i n g o n b o t t l e n o s e d o l p h i n s , i t w a s e s t i m a t e d t h a t p i l e - d r i v i n g n o i s e c o u l d m a s k s t r o n g d o l p h i n a c o u s t i c c o m m u n i c a t i o n s w i t h i n 1 0 t o 1 5 k m a n d w e a k c o m m u n i c a t i o n s u p t o 4 0 k m . R a d i u s o f m a s k i n g e f f e c t s w a s frequency dependent, with examples being given of a masking radius of 1.2km at 115 kHz and 6km at 50kHz. (SOURCE: David, J.A. 2006. Likely sensitivity of bottlenose dolphins to pile-driving noise. Water Environ. Jour. 20: 48-54) New syndrome associated with sonar-related strandings One Gervais, one Blainvilles, and eight Cuviers beaked whales were stranded in the Canary Islands in September 2002 coincident with an international naval exercise. Examination of stranded animals found congestion and bleeding within the ears, brain, jaw fat and kidneys and unusual gas bubble lesions and fat emboli in several organs, including the liver. It was noted that [g]as and fat emboli can cause nervous and cardiovascular dysfunctions, respiratory distress, pain, and disorientation (p. 453). It was suggested that these lesions resulted from sonar exposure, eliciting changes in whale diving behaviour, e.g., forcing animals to the surface, which could lead to formation of nitrogen bubbles in a manner similar to decompression sickness or the bends. An alternative hypothesis was that the physical properties of sonar pulses actually caused bubbles to form in the tissues of the whales, as these tissues may hold higher than normal levels of (be supersaturated with) dissolved nitrogen gas. In either case, the gas lesions and fat emboli syndrome are apparently induced by exposure to mid- frequency sonar signals and particularly affect...deep, long-duration, repetition-diving species like [beaked whales] (p. 446). The researchers emphasised the need to investigate the behavioural and physiological effects of sonar and the means by which it causes these effects. (SOURCE: Fernndez, A., Edwards, J.F., Rodrguez, F., Espinosa del los Monteros, A., Herrez, P., Castro, P., Jaber, J.R., Martn, V. and Arbelo, M. 2005. Gas and fat embolic syndrome involving a mass stranding of beaked whales (family Ziphiidae) exposed to anthropogenic sonar signals. Vet. Pathol. 42: 446-457) Antibiotic treatment causes hearing loss in beluga whale Hearing tests on captive beluga whales demonstrated a severe (90 dB) hearing loss in one beluga whale. Comparing differences between two individual animals, the only major difference in environmental exposures in the two animals was that one animal had been treated with antibiotics. It is possible that this drug treatment led to damage of sensitive cells in the ears of the whale. This study demonstrates a risk of possible hearing damage when cetaceans are administered certain drugs. Also, it highlights a new problem in using captive animals in auditory studies; any animals treated with certain p22 antibiotics may have hearing damage, and using these animals as proxies for the hearing abilities of wild cetaceans could produce erroneous results. (SOURCE: Finneran, J.J., Carder, D.A., Dear, R., Belting, T., McBain, J., Dalton, L., Ridgway, S.H. 2005. Pure tone audiograms and possible aminoglycoside-induced hearing loss in belugas (Delphinapterus leucas). J. Acoust. Soc. Am. 117: 3936-3943) Report on North Carolina stranding event inconclusive On 15 and 16 January 2005, 33 short-finned pilot whales, two dwarf sperm whales and one northern minke whale stranded near Oregon Inlet and Cape Hatteras in North Carolina, USA. Coincident with this stranding event, naval activities were being conducted and concern was raised that this stranding event may have been caused by sonar exposure. A report on this stranding event published by the US National Marine Fisheries Service described necropsies conducted on the majority of the stranded animals. The minke whale appeared emaciated and the cause of its stranding may have been unrelated to the others. The other stranded animals had a variety of conditions, including cranial infections and cardiovascular problems. Gas emboli, which have been associated with sonar related strandings in beaked whales, were not found. Within the heads of animals there was some reddening of fats in the jaw, which might have been the result of haemorrhaging, but it might also have been an artefact of freezing samples. One animal had a subdural haemorrhage, i.e., bleeding between the inner and outer membranes of brain, which is typically associated with severe brain injury following trauma. This was considered likely [to have] occurred from thrashing on the beach post-stranding, although its occurrence prior to stranding cannot be excluded (p. iii). Coincident with the stranding event, the US Navy was using mid-frequency sonar in the general region of the event and the report notes the association between the naval sonar activity and the location and timing of the event could be a causal rather than a coincidental relationship (p. iv). The report does not rule out the possibility that the strandings, and thus the subsequent mortality, were the result of cetaceans exhibiting a behavorial avoidance of noise exposure (p. iv). In conclusion, disease may have been a factor in the stranding of some of the whales, and due to a lack of definitive lesions, sonar could not be definitively attributed as a cause of the stranding, but given the multiple species involved and the proximity of a naval exercise, sonar could not be ruled out as a contributor, possibly in addition to other factors, to the event. (SOURCE: Hohn, A.A, Rotstein, D.S., Harms, C.A. and Southall, B.L. 2006. Report on marine mammal unusual mortality event UMESE0505Sp: Multi-species mass stranding of pilot whales (Globicephala macrorhynchus), minke whale (Balaenoptera acutorostrata), and dwarf sperm whales (Kogia sima) in North Carolina on 15-16 January 2005. NOAA Technical Memorandum NMFS- SEFSC-537. Southeast Fisheries Science Center, Beaufort, North Carolina. Available from: http://www.sefsc.noaa.gov/PDFdocs/Report_on_UMESE0501sp.pdf) ICES ad hoc report on cetaceans considers sonar impacts a minor issue An ad hoc special panel commissioned by the International Council on the Exploration of the Seas (ICES) reviewed the issue of acoustic impacts on marine mammals and fish. Some of the conclusions of the panel were that [t]he use of high-intensity mid frequency sonar has led to the deaths of a number of cetaceans in some places (p. 38), noting that beaked whales appear to be the most affected. The report identified 40 definitive sonar-related beaked whale deaths over a 9-year period, and compared this to 35 known beaked whale by-catches in US fisheries over a 6-year period. Several mid- frequency sonar stranding case studies were reviewed; for low frequency sonar, there was less information. The report stated that knowledge of sub-lethal and behavioural effects of sonar is poor and emphasised overall the major uncertainties and unknowns with respect to sonar and cetaceans and also the lack of research on the impacts of sonar on fish. The report noted that noise levels in the ocean are increasing and that impacts of noise on communication may affect the life history of cetaceans (including reproduction), stating that long-term impacts on populations could be worse than direct killing (p. 39). However, a main conclusion of the report was that it appears that sonar is not a major current threat to marine mammal populations generally, nor will it ever be likely to form a major part of ocean noise. Sonar can place individual whales at risk, and has affected the local abundance of beaked whales (p. 39). The report nevertheless pointed out that sonar deployment would probably increase in future and thus there was a need to continue to search for effective mitigation measures. (SOURCE: International Council for the Exploration of the Sea. 2005. Report of the ad-hoc group on impacts of sonar on cetaceans and fish (AGISC) (2nd Edition). CM 2006/ACE. ICES, Copenhagen, Denmark) 23 Gas lesions reported in UK cetaceans Pathological examinations found gas emboli, which have previously been associated with sonar-related strandings, in the livers of four Rissos dolphins, three short-beaked common dolphins, one harbour porpoise and one Blainvilles beaked whale. From 5 to 90% of the liver volume contained these gas lesions. Other organs found with similar lesions included the kidneys, spleen, lymph nodes and thyroid gland. Lack of bacteria associated with the lesions did not support infection as a cause. Lesions were more prevalent in deep-diving species, although lesions were found in shallower-water species as well. The veterinarians and pathologists suspected a decompression-related mechanism involving embolism of intestinal gas or de novo gas bubble (emboli) development derived from tissues supersaturated with nitrogen (p. 291) to be the cause of the lesions. This increases the number of species associated with this type of lesion, and the implications of this study are that sonar impacts are not limited to beaked whales or deep-diving species alone, and may be more widespread a problem than previously thought. (SOURCE: Jepson, P.D., Deaville, R., Patterson, I.A.P., Pocknell, A.M., Ross, H.M., Baker, J.R., Howie, F.E., Reid, R.J., Colloff, A. and Cunningham, A.A. 2005. Acute and chronic gas bubble lesions in cetaceans stranded in the United Kingdom. Vet. Pathol. 42: 291-305) Sound exposure duration increases temporary deafness in marine mammals The sound pressure levels (SPL) at which temporary hearing loss (temporary threshold shift or TTS) is inflicted are frequently used as the standard levels at which marine mammals may be injured. A controlled exposure experiment on three individual seals, of three different species, found that the degree of TTS increased substantially when the duration of noise exposure was doubled. Indeed, the degree of effect was greater than increasing the sound pressure level by 15dB. Therefore, the researchers emphasised the importance of not only considering the sound pressure level, but the duration of sound exposure when evaluating the effects of noise on marine mammals and stressed the use of sound exposure levels (SEL), which are a function of sound pressure level and duration, when assessing the effects of noise on marine mammal hearing. (SOURCE: Kastak, D., Southall, B.L., Schusterman, R.J. and Reichmuth Kastak, C. 2005. Underwater temporary threshold shift in pinnipeds: effect of noise level and duration. J. Acoust. Soc. Am. 118: 3154-3163) Differing reactions of different cetacean species to a noise source Researchers compared the reactions of a striped dolphin and a harbour porpoise to an acoustic deterrent device (ADD) or pinger (Dukan e N e t m a r k 1 0 0 0 ; 9 - 1 5 k H z ; 1 3 3 - 1 6 3 d B r e 1 P a ) . A l t h o u g h t h e p o r p o i s e s h o w e d a s i g n i f i c a n t r e a c t i o n , t h e r e w a s l i t t l e c h a n g e i n t h e b e h a v i o u r o f t h e s t r i p e d d o l p h i n . T h i s h a s s e v e r a l i m p l i c a t i o n s f o r c e t a c e a n c o n s e r v a t i o n . T h e r e a c t i o n o f o n e c e t a c e a n s pecies to a noise source is not necessarily representative of all species. Also, the efficacy or feasibility of pingers such as the type tested to reduce striped dolphin by-catch is thrown into doubt. (SOURCE: Kastelein, R.A., Jennings, N., Verboom, W.C., de Haan, D. and Schooneman, N.M. 2006. Differences in the response of a striped dolphin (Stenella coeruleoalba) and a harbour porpoise (Phocoena phocoena) to an acoustic alarm. Mar. Environ. Res. 61: 363-378) A new way to measure potential acoustic impacts on marine mammals: acoustic discomfort zone As part of an evaluation of an acoustic system to help prevent ship collisions, an environmental impact assessment (EIA) was conducted, which included evaluation of the effects on marine mammals. When determining safety zones, instead of basing them on physical impacts (e.g., temporary threshold shift, which is commonly used as a mitigation standard), they were based on behavioural impacts, e.g., avoidance and displacement. The concept of the acoustic discomfort threshold was defined as the boundary between areas that the animals generally occupy during the transmission of the sounds and the areas that they generally do not enter during transmission. The [sound pressure level in decibels] at this boundary is the discomfort threshold (p. 21). It was emphasised that this is an important measure because [i]f animals are deterred from ecologically important areas to less favourable areas, this might affect the population size. The animals in the s t u d y ( c a p t i v e h a r b o u r s e a l s ) r e a c t e d t o t h e t e s t s o u n d s o u r c e b y s w i m m i n g a w a y f r o m t h e s o u r c e i n t o l e s s - e n s o n i f i e d a r e a s o f t h e t e s t t a n k , a n d a 1 0 7 d B r e 1 P a d i s c o m f o r t t h r e s h o l d l e v e l w a s d e t e r m i n e d . T h e E n v i r o n m e n t a l I m p a c t A s s e s s m e n t f o r t h e s y s t e m h a d a s s u m e d a 1 8 0 d B ( r e 1 P a ) s a f e l e v e l f o r m a r i n e m a m m a l s ( a s t h i s w a s 1 0 d B l o w e r t h a n t h e l e v e l a t w h i c h p e r m a n e n t h e a r i n g l o s s w a s a s s u m e d t o o c c u r ) . S u c h a s a f e l e v e l w o u l d b e o v e r 1 0 m i l l i o n t i m e s l o u d e r t h a n t h e d i s c o m f o r t t h r e s h o l d d e t e r m ined in this study. The researchers noted that other sound sources would produce other discomfort thresholds and zones. This study provides a p 24 new method for assessing zones of impact on wild marine mammals that takes into account marine mammal behaviour and potential displacement from critical habitat, which perhaps can serve as a model for future noise impact assessments. (SOURCE: Kastelein, R.A., van der Heul, S., Verboom, W.C., Triesscheijn, R.J.V. and Jennings, N.V. 2006. The influence of underwater data transmission sounds on the displacement behaviour of captive harbour seals (Phoca vitulina). Mar. Environ. Res. 61: 19-39) A need to re-evaluate how to measure sound safety levels The difficulties of estimating what level of noise could prove harmful to whales are made more complex by the various differences in sound structure. An example is given of a brief, simple click by a sperm whale, which may produce a wave with amplitude similar to that of a sonar ping and so would theoretically be considered nearly equal in terms of possible impacts on cetaceans. However, the click is at peak amplitude for only a brief moment, with most of the energy of the wave contained in this brief moment. Maximum amplitude is maintained longer by a sonar ping, with energy levels being consistently high. Therefore, the total amount of energy that an animal might be exposed to is greater for the sonar ping than for the whale click. It is suggested that energy flux density should be used as a measurement when trying to assess the potential impact of sound sources, as it takes into account the amount of energy delivered per unit area, and it is concluded that current standards for safe sound source levels are unsuited as a stand-alone mitigative measure for transient noise effects on marine mammals (p. 3956). (SOURCE: Madsen, P.T. 2005. Marine mammals and noise: problems with root mean square sound pressure levels. J. Acoust. Soc. Am. 117: 3952-3957) The potential acoustic impacts of windfarms The growing number of windfarms in coastal areas may have an impact on cetaceans, in particular because of the noise associated with these facilities. The researchers considered four different zones around windfarms: the first was the area in which the noise was detected; the second the area in which the noise resulted in a behavioural or physiological reaction (i.e., disturbance or harassment); the fourth the area in which sounds cause masking and may prevent biologically important acoustic information from being transmitted; and finally a zone of injury (defined as being where animals begin to suffer temporary threshold shifts or TTS). Noise-producing activities associated with windfarms include initial pile driving during construction and actual operation. The researchers note that the calculated ranges clearly indicate that pile-driving sounds are audible to all the marine mammals treated here at very long ranges of more than 100km, and possibly up to more than a thousand kilometers (p. 289) and pile driving operations have the potential to cause disruption of normal behavior in marine mammals over a very large area at ranges of many kilometers (p. 289). They consider that acoustic injury to cetaceans may occur within a radius of 2km of pile-driving activity. For operating wind turbines, which produce lower frequency sound, and sound levels lower than that of pile driving, there is a lack of studies on effects, but it was concluded that there is no reason to believe that [bottlenose dolphins and harbour porpoises] can hear even the noisiest of the wind turbines in current use at a range of more than a few hundred meters (p. 290). However, with respect to baleen whales, which are low frequency specialists, [they] may respond to noise from operating turbines at ranges up to a few kilometers in a quiet habitat (p. 289), leading to greater effects. Although short-term displacement of cetaceans as the result of windfarm-associated noise may not be biologically significant, in some areas prolonged construction in multiple areas may have cumulative and long-term impacts. (SOURCE: Madsen, P.T., Wahlberg, M., Tougaard, J., Lucke, K. and Tyack, P. 2006. Wind turbine underwater noise and marine mammals: implications of current knowledge and data needs. Marine Ecology Progress Series 309: 279-295) Indo-Pacific bottlenose dolphins alter communications to avoid noise-induced masking The acoustic communications of three populations of Japanese Indo-Pacific bottlenose dolphins were studied in relation to levels of ambient noise in their respective environments. It was found that animals inhabiting waters with less ambient noise produced a greater range of frequencies and with more modulation of frequencies. In comparison, there was decreased frequency modulation observed in animals inhabiting environments with higher levels of ambient noise and, moreover, animals tended to produce lower frequency whistles. It was suggested that communication signals are adaptive and are selected to avoid the masking of signals and attenuation of higher frequency signals (p. 541). This adaptation of acoustic communication may have an important role in avoiding one of the problems that marine noise poses for cetaceans: masking biologically important signals. p25 (SOURCE: Morisaka, T., Shinohara, M., Nakahara, F. and Akamatsu, T. 2005. Effects of ambient noise on the whistles of Indo-Pacific bottlenose dolphin populations. J. Mammal. 86: 541-546) Infant dolphin more sensitive to sound than adult Experiments investigating hearing sensitivities of captive cetaceans have been widely used to model and predict the possible effects of anthropogenic sounds on free-ranging cetaceans. Therefore, studies investigating the efficacy of this method are important for research on, and management of, noise- related impacts. A study investigating the hearing sensitivities of a stranded infant Rissos dolphin discovered that the young animal had a greater sensitivity to sound than a previously tested adult individual, e.g., detecting 100 kHz signals at a level nearly 60dB lower than the adult. The young dolphin also detected higher frequencies than the adult, suggesting, perhaps, age-related hearing loss and probably underestimat[ing] the best hearing sensitivity for this species (p. 4187). This emphasises that acoustic sensitivity data based on older and/or captive animals may be underestimating the potential impacts of anthropogenic sound. (SOURCE: Nachtigall, P.E., Yuen, M.M.L., Mooney. T.A. and Taylor, K.A. 2005. Hearing measurements from a stranded infant Rissos dolphin, Grampus griseus. J. Experiment. Biol. 208: 4181-4188) Military sonar probable cause of Hanalei Bay milling event At approximately 0700hrs on 3 July 2004, about 150 melon-headed whales were observed in the shallow waters of Hanalei Bay, Kauai, Hawaii. These normally deep water animals were in the bay for over 28 hours in what has been termed a milling event, i.e., multiple animals crowded into shallow water near shore, but not actually stranded on land. On 4 July at 0930hrs, the animals were herded out of the bay into deeper water by volunteers. Only one animal was known to have died (a calf), which was necropsied with no evidence of trauma or disease-related lesions observed. The possible cause of death may have been separation from the mother, i.e., dehydration and starvation. An analysis of environmental conditions, including bathymetry, oceanographic fronts and weather conditions, could find no link between these factors and the event. Moreover, there were no harmful algal blooms in the vicinity. However, the event was coincident with use of mid-frequency sonar by six naval vessels prior to the start of the biennial Rim of the Pacific (RIMPAC) naval exercise (US and Japan) and the National Marine Fisheries report notes that [p]ropagation modelling suggests that transmissions from sonar use during the July 3 exercise...may have been detectable at the mouth of the Bay (p. 2). Although the report does not claim that the sonar activities were definitively the cause of the event, the compilers do state that they consider the active sonar transmissions of July 2-3, 2004, a plausible, if not likely, contributing factor (p. 2) for the event, although other factors may have also contributed. (SOURCE: Southall, B.L., Braun, R., Gulland, F.M.D., Heard, A.D., Baird, R.W., Wilkin, S.M. and Rowles, T.K. 2006. Hawaiian melon-headed whale (Peponocephala electra) mass stranding event of July 3-4, 2004. NOAA Technical Memorandum NMFS-OPR-31, Office of Protected Resources, NOAA, Silver Spring, Maryland, http://www.nmfs.gov/pr/health/mmume/event2004jul.htm) U V e f C D E W $ # $ X( ( Q3 3 ; ; $; J; @ A 4E yE VF XF I 5J >O @O BO :P