to be aware of this, so as not to change behavior by their presence ). speeds of 10 knots produced dramatic reductions in communication range, even at 100 and 200 meters, though the researchers note more uncertainty about these results. in the tagging experiments, the pilot whales experienced often extreme masking noise levels within pilot whale whistle frequencies, up to 55db above the levels that would begin to obscure communication ; which the authors note that this " suggest ( s ) that vessel noise may be an important factor in determining range of communication signals in this deep - water environment with significant whale - watching and commercial marine traffic activities. " in addition, whale watching boats shift shift gears quite often in order to remain in proximity of the dolphins or whales they are observing ( as often as 2 or 3 times a minute ) ; this study found that gear shifting creates pulses of much louder sound ( up to 200db re 1 upa peak - peak ) containing a much broader range of frequencies, especially higher frequencies. since such unpredictable bursts of sound tend to elicit more powerful short - term behavioral responses, " steps taken to lessen the erratic movement and number of gear shifts of vessels … would lessen the impact. " finally, the authors note that this study only addresses communications masking, and that, while not investigated here, some higher frequency noises created by cavitation ( especially at higher speeds ) " has the potential to impact foraging toothed whales by masking weak echoes from their echolocation signals. " acknowledging differing underlying values as a key to breakthroughs in conservation conflicts raphael d. sangarin and larry b. crowder. breaking through the crisis in marine conservation management : insights from the philosophies of ed ricketts. conservation biology, volume 23, no. 1, 24 - 30. [ download ] this short paper is well worth a read by all who have been frustrated by the lack of constructive progress in moving beyond contentious conflict in addressing environmental challenges. here, two contemporary researchers ( one with a focus on policy, and the other on marine conservation ) sketch the three - part approach of ed ricketts, a mid - 20th century marine ecologist ( immortalized as " doc " in steinbeck ' s cannery row ). in addition to his scientific work, ricketts articulated an approach to science and policy that drew from taoism, buddhism, and his friendships with steinbeck and joseph campbell. while the three aspects of rickett ' s approach are far more philosophical than practical, they bear consideration in light of the seeming


articulated an approach to science and policy that drew from taoism, buddhism, and his friendships with steinbeck and joseph campbell. while the three aspects of rickett ' s approach are far more philosophical than practical, they bear consideration in light of the seeming inability of the best intentions of both scientists and policy - makers to effectively turn the tide of ocean ecosystem collapse. at its heart, ricketts ' approach contains two key aspects. first, a clear and ongoing commitment to observing what is, rather than a focus on what should be – with a related emphasis on shifting relationships rather than facile attempts to assess simple cause and effect in what are always complex, holistic systems. central to this approach is a conscious intent to avoid neatly preconceived ideas about who or what is to blame for the problem under consideration. second, and most resonant for me, ricketts emphasizes that most intractable conflicts over policy are, at root, reflective of differing underlying priorities, worldviews, or " sacred values. " the key factor that drives " breakthroughs " is a shared commitment to be forthcoming about each party ' s underlying values. sharing the diverse " core needs " is, in ricketts ' view, the foundation of a constructive search for mutually favorable solutions, rather than a mutually damaging fight to chip away at two widely different, predetermined positions. the authors suggest that today ' s rapidly expanding toolbox of monitoring technologies provides us opportunities to initiate the sorts of ongoing observations that underlay ricketts ' approach, and that developments over the last generation in policy and public engagement support an attempt to be more explicit about the underlying values that are too often unspoken as competing advocates argue their sides in a fight to " win " in policy decisions which have turned unwittingly into battles, thanks to a simplistic focus on particular causes and effects within systems that are spinning out of control due to countless inter - related factors. as in his time, it is not altogether obvious how to apply ricketts ' ideas in practice, but reading this brief overview of his thoughts, along with the context provided in relation to current attempts to define and enact ecosystem based management in the oceans, is bound to spur some new perspectives among reflective policy players today. related : a key paper cited by sangarin and crowder is another short essay perspectives piece, which suggests that the repeated failure of worldwide fisheries management might be ameliorated by inverting the traditional " trophic pyramid " that places humans at the


key paper cited by sangarin and crowder is another short essay perspectives piece, which suggests that the repeated failure of worldwide fisheries management might be ameliorated by inverting the traditional " trophic pyramid " that places humans at the top, and instead using a model that puts humans at the bottom, or at the tipping point of a circle which explicitly includes consideration of three key factors : ethics, corporate responsibility, and social justice. bundy, chuenpagdee, jentoft, mahon. if science is not the answer, what is? an alternative governance model for the world ' s fisheries. front ecol environ 2008 ; 6 ( 3 ) : 152 - 155. [ download ] moderate seismic survey noise linked to increase in blue whale calling l. di lorio and c. w. clark. exposure to seismic survey alters blue whale acoustic communication. biology letters doi : 10. 1098 / rsbl. 2009. 0651 [ download ] this study found that a seismic survey in wide bay at the mouth of the st. lawrence seaway caused blue whales feeding and socializing nearby to double or triple their call rates. the calls were near - range communication signals, rather than the long, loud songs that are heard over hundreds of miles. the research was meant to simply learn more about these social calls, but during the study, their recordings began to pick up the pulses from a seismic survey. “ the whales made more calls on days when the testing was happening. it seems they are having to repeat themselves in order to not lose information, ” said lead researcher lucia di lorio. during the four days in which survey sounds were heard, the whales also increased their call rates when the sparkers were audible than when they were not, and tended to rapidly increase call rates when the sounds appeared. the results were especially surprising, since the survey in question was using a much lower - power sound source ( sparkers ) than the airguns used in most surveys. the electronic sparkers top out at only 190db, rather than the 230 - 240db of airguns. sparkers are slightly higher frequency as well, but still solidly centered in low - frequency bands of 30 - 450hz, primarily 60 - 250hz, very similar to airguns, and matching key blue whale communication frequencies. the study notes that “ our results clearly show that blue whales change their calling behaviour in response to a low - medium power technology that is presumed to have minor environmental impact. in fact


similar to airguns, and matching key blue whale communication frequencies. the study notes that “ our results clearly show that blue whales change their calling behaviour in response to a low - medium power technology that is presumed to have minor environmental impact. in fact, the mean sound pressure impinging on the ( study ) area, and thus probably on the whales present there, was relatively low, 131 db re 1 upa ( peak to peak, 30 – 500 hz ) with a mean sound exposure level ( sel ) of 114 db re 1 mpa2 s. the increase in calls was a contrast to some other studies, which have found call rates reduced near seismic surveys, perhaps in part due to animals moving away ; in some cases, animals call louder or change the pitch of their calls to cope with noise intrusions. this is the first study to find a marked increase in call rates, or repeating themselves, which di lorio suspects may be due to the key role of this area in socializing and feeding ( i. e., the communication is time - and place - dependent, and cannot easily be postponed until a quieter time ). the study concludes by noting that the st. lawrence estuary “ is an important feeding area where blue whales acquire energy and also a place where this wide - roaming, highly dispersed population congregates to engage in social interactions. reducing an individual ’ s ability to detect socially relevant signals could therefore affect biologically important processes. this study suggests careful reconsideration of the potential behavioural impacts of even low source level seismic survey sounds on large whales. this is particularly relevant when the species is at high risk of extinction as is the blue whale. ” update : a skeptical note received by email from a longtime correspondent : “ to me, given a detectable new sound, mammals tend to decrease vocalization if it induces fear, or increase vocalization if it stimulates interest. how a sparker could block communications rather eludes me, but whales responding to a pulse — be it noncoherent noise stimulates noise, or actual whale talk directed at the pulse — comes to mind …. sperm whales in the gom seemed to alter click patterns and perhaps anticipated a pulse once they got the beat. that was a casual observation by one of the acoustic team - always thought that would have been a great add - on study but we were already at overload working on acoustic tracking for tagging purposes. more at home, my grey parrot, who talks quite a bit, of course becomes completely silent when


team - always thought that would have been a great add - on study but we were already at overload working on acoustic tracking for tagging purposes. more at home, my grey parrot, who talks quite a bit, of course becomes completely silent when visitors ask ‘ if he talks? ’ - his reaction to seeing new people is silence. now, if you go into another room and play classical music, the next question is ‘ how do you stop him? ’ i think there is a complexity to animal behavior and acoustic responses and the reasons blue whales would increase calls could be many. ” what do beaked whales hear? finneran, houser, base - guthrie, ewing, lingenfelser. auditory evoked potentials in a stranded gervais ' beaked whale ( mesophlodon europaeus ). j. acous. soc. am 126 ( 1 ), july 2009. 484 - 490. this study took place with a stranded beaked whale that was euthanized after three days in captivity ; it was very ill ( organ failure due to bacterial infection ) throughout. since beaked whales seem to be more affected by naval mid - frequency active sonar, the study was designed to see whether beaked whale hearing is more sensitive than other closely related families of cetaceans. the results find a hearing sensitivity curve that is similar to those of dolphins and orcas, with no indication of greater hearing acuity. the highest frequency that could be heard was 80khz ( though this could be limited by hearing impairment in this individual, as one earlier study of this species found good sensitivity than at 80khz, and did not test higher ). highest sensitivity was found at 40khz ( i. e. the animal can hear sounds at this frequency when they are relatively faint - - higher and lower frequency sounds must be louder to be heard ) no tests were done using frequencies below 20khz ; mid - frequency active sonar ranges from 2 - 10khz. some breeding birds avoid areas within 500 - 800m of wind turbines pearce - higgins, stephen, langston, bainbridge, bullman. the distribution of breeding birds around upland wind farms. journal of applied ecology, doi : 10. 1111 / j. 1365 - 2664. 2009. 01715. x [ download ] this comprehensive survey of breeding birds in non - agricultural british uplands ( moors and grassland ) included weekly surveys during the breeding season at 12 different wind farm sites, along with comparable nearby landscapes without turbines. half


. 01715. x [ download ] this comprehensive survey of breeding birds in non - agricultural british uplands ( moors and grassland ) included weekly surveys during the breeding season at 12 different wind farm sites, along with comparable nearby landscapes without turbines. half the wind farms were from the previous generation ( way back in the ' 90s ), with hub heights of 40m and less ; the other half had hub heights of 60 - 70m. of the twelve species that were observed often enough to provide good data, five seemed relatively unaffected by turbines ( including kestrel, lapwing, grouse, skylark, and stonechat ), while 7 species were less likely to nest within 500m of turbines, with smaller ( i. e., not statistically significant ) effects extending to 800m, or roughly half a mile. for six of the species ( buzzard, hen harrier, plover, snipe, curlew, and wheatear ), numbers were reduced by 39 - 52 %. the authors note that there is a pressing need for examination of the reasons for the depressed numbers : " we do not know whether our observations of avoidance of turbines reflect a behavioural displacement, the local population consequences of collision mortality or reduced productivity, or both. the distinction is important. if there is high mortality of birds breeding close to the turbines associated with collision ( ed. note : or reduced productivity ), then a wind farm may become a population sink if repeatedly colonized by naive birds. if, however, the birds simply avoid breeding close to the turbines, then … displaced birds may settle elsewhere with little cost. " they also note that " whether wind farms result in meaningful population - level effects at a regional and national scale depends both upon the mechanisms involved, and the overlap between bird distribution and wind farm development, " and encourage new development to avoid high densities of open country species, until these factors can be more clearly understood. they note the contrast between these findings and those of devereux et al ( 2008 ), which " may suggest that species occupying remote semi - natural habitats are more sensitive to wind farm development than species occupying intensive production landscapes. " ( ed. note : the earlier study looked at wintering birds in farmland, rather than breeding birds in uplands. ) habituation often misused or wrongly assumed in impact assessments bejder, samuels, whitehead, finn, allen. impact assessment research : use and misuse of habituation, sensitization and tolerance in describing wildlife responses to anthropogenic


habituation often misused or wrongly assumed in impact assessments bejder, samuels, whitehead, finn, allen. impact assessment research : use and misuse of habituation, sensitization and tolerance in describing wildlife responses to anthropogenic stimuli. mar ecol prog ser, vol. 395 : 177 - 185, 2009. [ download ] this paper serves as an excellent review of an important line of reasoning that is skeptical of facile claims that animals readily habituate to human disturbances such as noise. while the paper may be seen by some as little more than a set of " what if " propositions designed to undermine the simple observation of animals not being affected by a disturbance ( and in this way, proposing an extreme precautionary view that supposes the worst in situations where we do not have complete information ), the underlying intent is more serious than this : when policy decisions are being made based on a simplistic assessment of the situation, then we should at least be aware of the limitations of our terms and our study designs. this paper adds clarity to these issues in important ways. the authors distinguish between true habituation ( which is a learning process that occurs over time ) and tolerance ( which can be measured instantaneously ), and suggest that most impact studies are designed in ways that can only confirm tolerance, since they do not track the responses of individual animals over time. further, they point out that even studies of tolerance can be easily distorted if the most sensitive animals leave at the first disturbance, leaving more tolerant individuals as the " study group. " another key – and often ignored – factor is that any behavioral response is influenced by many factors, not just the invasive human disruption being studied ; for example, increased human noise may be one factor in an animal ' s decision about moving away, but this decision is also dependent on other key factors, such as the quality of the site where the animal current is ( e. g. for feeding, mating, resting ), the distance to and quality of other suitable sites, the relative risk of predation or density of competitors in other sites, and any investment the individual or group has made to the site ( e. g., establishing a territory, gaining dominant status, or acquiring environmental information ). it is commonly assumed that avoidance or lack of avoidance of a human sound source is a good indicator of whether that sound has a negative impact ; the authors stress that this is an unwarranted and often incorrect assumption, and point out that the few studies that


commonly assumed that avoidance or lack of avoidance of a human sound source is a good indicator of whether that sound has a negative impact ; the authors stress that this is an unwarranted and often incorrect assumption, and point out that the few studies that have assessed both behavioral responses and physiological measures ( heart rate, stress hormones ) have often found physiological markers of a negative response even when animals exhibited little or no behavioral reaction, i. e., when they appeared to tolerate the intrusion. this paper serves as a good starting point for examining previous research that has raised similar questions about the design of behavioral response studies, and the use of these studies in making policy decisions ( in particular, previous work by ja gill and l bejder ). the core message here is that managers should be very cautious in assessing claims of habituation ( since few studies truly are designed to prove habituation ), and likewise that habituation or tolerance do not necessarily imply the lack of negative impacts on individuals or populations. as they conclude, " most studies are restricted to monitoring short - term, observable, behavioral responses, ( which ) limits the scope of conclusions that can be drawn … the conclusion is likely to be specific only to the response variable that has been monitored … ( while ) animals may become habituated in one modality but not in another …. the most effective course of action in impact studies would therefore be to complement behavioral assessment with monitoring of physical condition and physiological measures such as heart rate, body temperature and / or hormonal levels. " " worst case " wind turbine noise can occur 30 % of summer / fall nights clifford p. schneider. measuring background noise with an attended, mobile survey during nights with stable atmospheric conditions. internoise 2009. [ download paper ( pdf ) ] this well - designed study, by a retired new york state department of the environment staffer, sheds light on several key questions surrounding standard noise assessments of wind farms. most strikingly, it quantifies the extent of one of the key atmospheric components of excessive wind farm noise, finding that stable night time atmospheres may occur two - thirds of the time in the summer and fall, with wind high enough at turbine height to trigger them into action on 30 % of nights, increasing to 40 % in june and july. on these " worst case " nights, turbine noise is likely to be significantly louder than local background ambient noise from late evening until the beginning of the pre - dawn bird chorus. schneider ' s study also included a brief but useful test of whether a quick but


these " worst case " nights, turbine noise is likely to be significantly louder than local background ambient noise from late evening until the beginning of the pre - dawn bird chorus. schneider ' s study also included a brief but useful test of whether a quick but systematic mobile sound survey can be used instead of set of arbitrarily - chosen monitoring sites ( addressing questions about whether arbitrary site selection accurately measures local averages ) – he did 10 - minute recordings at 21 sites, one every mile along two rural roads, and compared the results to 5 baseline sites chosen arbitrarily around the same town. this study took place in the township of cape vincent, new york, which sits at the confluence of the st. lawrence river and lake ontario, where two wind farm proposals would place 200 turbines in town, covering the majority of its land area. local and state ordinances require sound to be within 5db of average ambient noise levels ; the wind developer ' s sound level report based their projected compliance on a day - night average of 45dba. by contrast, schneider ' s study focused in on the times when other wind farms have generated the most problematic noise impacts : nights when wind is low at ground level but high enough at hub height to trigger turbines to turn on. in these conditions, night - time background ambient sound levels are very very low, and turbine noise can dominate the nighttime soundscape. the results are striking, to say the least. night - time sound levels were at or below the lowest that the researcher ' s meters could record, 25dba, for most of the late - night hours at 4 of the 5 locations, and under 30db from 9pm - 4 : 30am at three ; one site received shore waves and dropped below 35db for just a few hours in the middle of the night. average readings along the mobile monitoring route ( which was traversed over the course of three nights ) were similar, and generally ranged from 25 - 32db, with one site at 36db. by contrast, measurements near a wind farm in the region, also measured at several ( 10 ) locations, showed the quietest times of night ( l90 ) ranged from 35 - 43db, and the average ( leq ) from 36 - 45db. bottom line : wind turbine sounds are likely to be 10 - 15db louder than background ambient sound on these " worst case " nights in cape vincent. but how often do such nights occur? in what is likely to be the section of the study with them farthest - reaching impact,


likely to be 10 - 15db louder than background ambient sound on these " worst case " nights in cape vincent. but how often do such nights occur? in what is likely to be the section of the study with them farthest - reaching impact, the results suggest that turbines could be operating ( hub height winds > 4 m / s ) on nights with very still, quite ground conditions ( ground wind < 1. 5 m / s ) for 42 % of nights in june and july, and for a total of 30 % of nights from june through october. this lines up well with the only other study that i know of that specifically addressed stable night air conditions, the van den berg study that found such conditions occur about a third of the time in the netherlands, with similar levels suspected in many temperate zones. using new york state dec standards for predicting human reaction to noise, which is based on increasing levels of industrial noise above background ambient, this study suggests that ( counter to the developer ' s prediction that no residents will experience noise more than 5db above ambient, i. e., loud enough to trigger complaints ), the vast majority of households in town will find the noise " very noticeable " ( 9 - 14db above ambient ) on these nights, with 34 % finding it " objectionable " ( 84 homes at 14 - 19db above ambient ) and a further 19 % finding it " very objectionable to intolerable " ( 48 homes at 19 - 25db above ambient ). it is important to note that these levels of audibility and possibly objectionable sleep disruption will occur on a minority of nights ; indeed, on an annual basis, probably around 15 % of nights. and, on those nights, just a portion of the population will be affected. this perspective is part of what has led to our current acceptance of relatively small setbacks from homes ( often 1000 - 1500 feet ). our social decisions about wind farm siting will need to grapple with the question of how much disturbance we consider acceptable – in this case, a third to half of the residents of cape vincent may be looking at troubling noise levels for a third to half of summer and autumn nights. to protect most residents from most of the noise intrusions ( keeping noise levels to 5 - 10db above ambient ) would require setbacks of 1km or so, which would likely mean more like 30 - 50 turbines in cape vincent, rather than the planned 200. two other results are worth mentioning. as mentioned above, the systematic mobile sound assessments matched closely with


) would require setbacks of 1km or so, which would likely mean more like 30 - 50 turbines in cape vincent, rather than the planned 200. two other results are worth mentioning. as mentioned above, the systematic mobile sound assessments matched closely with those made at arbitrary locations, suggesting that either method is reliable. the author notes that the arbitrary locations that he chose were well away from buildings, while a systematic mobile survey with a random start avoids possible problems of subjectivity in site selection. he notes : " i could have increased the measures spl ( at the arbitrary locations ) if i had located equipment closer to homes, barns, and roads, and if i had picked nights with moderate winds. " further, he notes that the attended metering used in the mobile survey allows identification and documentation of noise intrusions, some of which might be of interest in assessing either true ambient or noise conditions with turbines operating ( i. e., a site with many cars passing will show elevated sound levels, compared to one with fewer ; this increased noise could either lead to over - estimate of quiet times at these sites, or improperly suggest that turbines are the primary source elevating sound levels at a site. ) finally, this study ' s measurements of dbc ( low frequency sound ) found substantial variability at different sites, more variable than audible sound, including several sites where the difference between dba and dbc approached 20db ; this suggests that later measurements with turbines operating may not necessarily suggest that the turbines are the source of such variability. animal listening area and alerting distance reduced substantially by moderate human noise barber, crooks, fristrup. the costs of chronic noise exposure for terrestrial organisms. trends in ecology and evolution, 2010. [ article in press available here ] this is one of the most important and interesting papers published this year. it emerges from the partnership between the national park service ' s natural sounds program and researchers at colorado state university, who have been working together for several years to create metrics that are more useful for assessing the biological impacts of moderate human noise on wildlife. the assessments presented here, along with the paper ' s review of recent studies documenting changes in foraging, anti - predator behavior, reproductive success, density and community structure in response to noise, form the basis for a much more cogent assessment of noise impacts on wildlife. the focus of this research is the ways that moderate increases in background noise can affect animals. the authors note that both air and road traffic in the us has tripled in recent decades ; even in


much more cogent assessment of noise impacts on wildlife. the focus of this research is the ways that moderate increases in background noise can affect animals. the authors note that both air and road traffic in the us has tripled in recent decades ; even in national parks, noise is audible 25 % of the time in more than half of sites assessed. over 80 % of us land area is close enough to roads for some low - frequency masking to occur, with passing trucks and motorcycles increasing the sound levels at 1km to 40db ( a ). one of the new proposed metrics is the effective " listening area. " changes in listening area has impacts involving both communication and what the authors term " adventitious " sounds ( sound made largely by movement, which are important in predator / prey awareness ). for predators, the listening area is the area over which they might hear the rustling of their prey, and for prey, it is the area in which they are alerted to approaching predators, whether wingbeats or footsteps ; in each case, the most important sounds are those right at the edge of audibility. social groups rely on hearing each other ' s alarm calls or songs inviting mating ; reduced listening areas for these calls result in effectively reducing the number of individuals in any given communication network. each animal has its own auditory acuity, so can hear at different distances ; but for all animals, increasing background noise will reduce their natural listening area in predictable ways. the authors note analyses of transportation noise impacts often assert that a 3db increase in noise – a barely perceptual change – has " negligible " effects, whereas in fact this increased noise reduces the listening area of animals by 30 %. a 10db increase in background noise ( ed. note : likely within a few hundred meters of a road or as a private plane passes nearby ) reduces listening area by 90 %. throughout, the authors stress the difficulties in separating noise - related effects of traffic from other related forces, such as habitat fragmentation or threat responses ; there is also a fascinating short section citing studies showing behavioral changes in response to quiet recreation, sometimes even more dramatic than those caused by vehicles. though only a few studies have directly addressed this ambiguity, many studies cited here provide strong indications that acoustic masking is a significant factor in behavioral changes near roads. among the findings that caught my eye / ear : - masking affects not only audibility, but understanding : " thresholds for discrimination between calls of the same species were consistently higher than were detection thresholds for the same


in behavioral changes near roads. among the findings that caught my eye / ear : - masking affects not only audibility, but understanding : " thresholds for discrimination between calls of the same species were consistently higher than were detection thresholds for the same calls. " not surprising, but easy to forget : background sound often obscures the words being said, though we can still hear the voice. - bats that listen for ground movements of their prey hunt more in quiet areas than noisy ones ; similarly insect - eating birds are more likely to avoid noisy areas than other birds. masking can also make it more difficult for animals to tell what direction a call ( such as a mating call ) is coming from - pronghorn antelope showed a marked shift in proportion of time spent foraging and in vigilance ( looking around ) when closer to roads : foraging dropped from 45 % of the time to 35 %, while vigilance increased from 40 % to over 50 %. - two key studies of increased vigilance in clearly noise - triggered contexts : ground squirrels showed a marked increase in vigilance behavior when hearing squirrel alarm calls at a site in a wind farm than in a quiet site ( including a slightly less " relaxed " non - vigilance baseline state ), and a lab study with chaffinches found that the mean time spent pecking ( eating ) between times scanning the area decreased when noise was introduced. the authors conclude by stressing : " chronic noise exposure is widespread. taken individually, many of the papers cited here offer suggestive but inconclusive evidence that masking is substantially altering many ecosystems. taken collectively, the preponderance of evidence argues for immediate action to manage noise in protected natural areas …. the costs of noise must be understood in relation to other anthropogenic forces, to ensure effective mitigation and efficient realization of environmental goals. noise pollution exacerbates the problems posed by habitat fragmentation and wildlife responses to human presence ; therefore, highly fragmented or heavily visited locations are priority candidates for noise management. noise management might also offer a relatively rapid tool to improve the resilience of protected lands to some of the stresses imposed by climate change. " bias in military ( or conservation ) funded ocean noise research wade, whitehead, weilgart. conflict of interest in research on anthropogenic noise and marine mammals : does funding bias conclusions? marine policy 34 ( 2010 ) 320 - 327. ( ed. note : this lay summary includes more analysis and interpretation by aei than we generally include


conflict of interest in research on anthropogenic noise and marine mammals : does funding bias conclusions? marine policy 34 ( 2010 ) 320 - 327. ( ed. note : this lay summary includes more analysis and interpretation by aei than we generally include ; some of this commentary questions the conclusions of the paper, and some of it addresses the underlying controversies surrounding ocean noise issues. i have attempted to be clear about which statements are simple summations of the report ' s data and findings, and which are aei ' s reflections or perspectives. it is a long read, but the issues that triggered this study are important ones. though the clear - cut results reported here are difficult to take at face value, it is well worth considering the underlying forces that drive tensions between environmental groups and navy / industry actions in the seas. ) in the united states, the us navy funds about half of the research into the effects of ocean noise on wildlife. for many years, conservation groups have questioned whether this preponderance of funding is skewing research results, whether by constraining the types of questions being studied, or by leading researchers to downplay negative impacts of noise in order to continue receiving funding. this paper investigates the latter possibility, by comparing five recent reviews of the effects of ocean noise on wildlife, one funded by a leading environmental group, three that received substantial navy funding, and two funded by organizations with no particular stake in the debate. the researchers compared the number of citations in each that showed an effect of noise, or not, or that showed both an effect and lack of effect. they also attempted to identify funding sources of the primary papers cited in each of these secondary reports, and to correlate the funding source with the same three parameters ( noise shown to have an effect, noise causing no effect, or aspects of the primary research showing both effects and no effect ). using both simple citation counts and g - test statistical analysis to test for a null hypothesis of random connection between funding sources and outcomes, the authors report a significant correlation between funding source and proportion of citations reporting " no effect " of noise. the five review papers certainly show a trend, though it appears to aei that three papers that form the anchors of that trend each may be somewhat shaped by its original intention. reviews : proportion of citations of each stance the authors recognize that the one conservation - funded paper ( " oceans of noise ", wdcs ) drew almost only on studies that did show an effect of noise, and re - analyzed the trend with that


reviews : proportion of citations of each stance the authors recognize that the one conservation - funded paper ( " oceans of noise ", wdcs ) drew almost only on studies that did show an effect of noise, and re - analyzed the trend with that one excluded ; a significant effect remained, though it was half as strong. however, one of the " independent " papers, a chapter in a book on the ocean environment ( hildebrand ), was perhaps similarly constrained by its purpose ; it was titled " impacts of anthropogenic noise, " and was not necessarily intended as a comprehensive assessment of what does and does not cause an effect. on the other end of the spectrum of the five surveys, the only navy - funded survey that diverged notably from the other independent paper ( from ices ), was the third national research council report, which addressed the difficulties in determining when repeated behavioral disruptions of a portion of a population accumulates to the point of becoming " biologically significant. " thus, this survey could be expected to include more papers that were exploring the edges of impacts, and so it is not surprising that to do so, more citations would appear that show no effect. given these underlying intentions of the two reports showing the fewest " no effect " citations, and the one showing the most " no effect " citations, it appears that the five papers being compared are not quite on the same playing field. the other three papers ( ices and the first two nrc reports on noise and marine mammals ) showed no marked differences in balance between citations, with the navy - funded reports actually having a lower proportion of " no effect " papers and higher proportion of " effect " papers than the ices survey. primary papers : funding sources and results reported turning to the primary papers, the situation is not muddied by the variable intentions of the reviews. here, there is a clearer trend of increasing conclusions of " no effect " as funding moves from conservation to no - agenda to industry and military funding. again, the 19 conservation - funded papers nearly all reported an effect, with just one showing both effect and no effect to separate questions being investigated. the 67 military - funded papers, by contrast, were far more likely ( 2. 3 times as likely ) to come to a no - effect conclusion than papers funded by other ( non - conservation and non - industry ) sources. however, and significantly, less than 30 % of military - funded papers came to that conclusion, while about 50 % did report an effect of noise, and


- effect conclusion than papers funded by other ( non - conservation and non - industry ) sources. however, and significantly, less than 30 % of military - funded papers came to that conclusion, while about 50 % did report an effect of noise, and 20 % showed both effects and lack of effects. likewise, in the first two nrc reviews, about 20 % of citations showed " no effect, " while over 60 % showed an effect ; even the most " extreme " review had more citations showing an effect than not. of special note is that the authors did not find any strong trend toward bias of results reported by independent, academic researchers receiving navy funding for research studies - these studies showed a similar proportion of effect and no effect results as studies funded by neither the military nor conservation groups ( though when comparing military - funded studies with all the others, including consevation - funded, a non - statisticially significant trend of 1. 64 times more " no effect " findings was observed ). as the authors stress in consideration of the possible bias of conservation - funded primary studies, conflicts of interest would be dangerous if scientists " orient ( ed ) their goals, methods, analysis or interpretation towards the perceived interests of the …. community that funded them. " the authors conclude that " much of the bias in military - funded research was in work carried out at military institutions, rather than in studies funded by the military but carried out at universities and other institutions. " this seems to suggest that the concern about bias in funding alone is negligible, thus diffusing concerns that cash - strapped academic researchers are " cooking the books " to retain navy funding. research coming directly out of military offices is likely to remain less reliable as representing " the whole picture, " as may research entirely funded by conservation groups. still, by integrating and considering the full range of studies reported in all of these reviews, the public can get a pretty decent picture of current state of our understanding of the effects of ocean noise. of note, though, is that the proportion of " no effect " to " effect " findings is slightly lower in military - funded studies. in addition, military - funded studies are more likely to report both effects and lack of effects in a single paper ; this could indicate either a more careful assessment of the margins where effects are just noticeable, or a tendency to split the difference in order to either underplay the effects or accentuate the non - effects to assuage funders. overall, at both layers of analysis, it seems clear to ae


the margins where effects are just noticeable, or a tendency to split the difference in order to either underplay the effects or accentuate the non - effects to assuage funders. overall, at both layers of analysis, it seems clear to aei that the conservation - funded papers and survey report showed the most obvious " bias. " however, this is not necessarily problematic ( unless used as a baseline to suggest bias in others ). as the authors note, " conservation groups do not fund research unless they have previously identified a potentially damaging effect, " and since conservation groups ' focus on precautionary approaches, and their mandate to " publicize activities that are potentially damaging to the environment " is quite transparent, it " should not be problematic unless threats are ' hyped ' where there are none. " ( note : while non - existent threats are rarely hyped by conservation groups, a more difficult question arises when moderate or minor threats are presented to the public as more dramatic than they may be. ) the authors note that while these results could suggest that conservation funding may be considered problematic, " the argument can be made that their role as a preventative authority is necessary. " indeed, while primary research and even survey reviews funded by the military are evidently not overly biased toward finding no effect ( since in both cases, they include far more results showing effects than not ), it also appears to aei that in practical terms, the eis ' s generated by the navy and the mitigation measures imposed by regulators on both military and oil and gas activities are largely grounded in the belief – and regulatory determination – that any effects of these activities are " negligible, " to use the formal term. thus the focus of the conservation community on funding research and publishing overviews that emphasize credible studies outlining observed negative effects is understandable, given these groups ' role in raising public awareness and balancing the singular interpretation of the more nuanced research by the military and industry. it might be more fruitful to explore ways that the " balance " of navy - funded studies and reviews serve as a fig leaf for actions that nearly always presume no harm. another key question not yet considered with the rigor brought to this study is whether navy - funded research is oriented toward studies that, by the questions being asked, may be more likely to come up with " no effect " findings, as apparently the investigations that conservationists tend to fund ask questions that lean toward those that are likely to show an effect. similarly, the questions being asked


by the questions being asked, may be more likely to come up with " no effect " findings, as apparently the investigations that conservationists tend to fund ask questions that lean toward those that are likely to show an effect. similarly, the questions being asked can color the perceived importance of changing our ways of using sound in the sea. for example, a study might seek to identify " recoverable thresholds " of exposure ( the maximum sound can an animal experience, causing temporary hearing shifts, but with their hearing returning to normal after a few minutes or hours ), while another study may be looking for " behavioral thresholds " ( the sound exposure that triggers behavioral changes ). implicit in the first question is the thought that as long as the effect is not permanent, it ' s acceptable ; conversely, the second question implies a desire to minimize disturbance of animals. indeed, the first question seeks the maximum sound level we can feel comfortable imposing, while the second inquires as to the minimal sound that the animal might be affected by. more to the point, though, many or most of the studies that do show effects are somewhat ambiguous ( e. g., only a proportion of the population shows the effect, or the practical import of the change or effect is difficult or impossible to determine ), while a finding of " no effect " is more clear - cut. it is not outlandish on the face of it for the navy to say, as it does, that their actions are not likely to cause any major disruption of animal life : the only clear - cut evidence we have is that extremely loud sounds at very close range ( tens of meters ) can injure animals, while the rest of the research really is shades of grey. nearly all of the controversy over military and oil and gas noise today boils down to differing interpretations of how important moderate behavioral changes are, and whether they should be avoided or not. and science is nearly incapable of shedding any definitive light on how important behavioral changes are, thus leaving the two sides largely reliant on their divergent faith : the navy and oil industry ' s faith that the behavioral changes are transient and negligible, and environmentalists ' faith that chronic behavioral disruption by human noise is bound to have negative consequences. meanwhile, ethical questions about humanity ' s relationship to the natural world are outside the bounds of discussion on one side, and central to the whole discussion, on the other. in the end, studies like this – and indeed, reviews such as those considered here – are largely diligent


s relationship to the natural world are outside the bounds of discussion on one side, and central to the whole discussion, on the other. in the end, studies like this – and indeed, reviews such as those considered here – are largely diligent exercises in quantifying an issue that has become, for all practical purposes, an exercise in divergent world views talking at and past each other. two pinger studies : harbour porpoise bycatch reduced, common dolphins show little response palka, d. l., m. c. rossman, a. s. vanatten, and c. d. orphanides. 2008. effect of pingers on harbour porpoise ( phocoena phocoena ) bycatch in the us northeast gillnet fishery. journal of cetacean research and management 10 ( 3 ) : 217 - 226. berrow, s., r. cosgrove, r. h. leeney, j. o ' brien, d. mcgrath, j. dalgard, and y. le gall. 2008. effect of acoustic deterrents on the behaviour of common dolphins ( delphinus delphis ). journal of cetacean research and management 10 ( 3 ) : 227 - 233. two studies of the use of pingers on gillnets came up with starkly different results for two key species of dolphins. the first, a long - term study of actual by - catch off the northeast coast of the us from 1999 - 2007, found that harbour porpoise bycatch was reduced 50 - 70 % in fisheries that used pingers, with no bycatch at all in nets using 15cm mesh. most importantly, there were no long - term increases in by - catch, which offers strong evidence that the porpoises are not habituating to the pinger sounds. however, the second study found that pingers that caused evasive responses in bottlenose dolphins had no effect on common dolphin behavior. a pinger source that allowed several types of signals to be tested also elicited no response in the common dolphins ; the researchers conclude that “ pinger, at their current state of development, may not provide a consistently effective deterrent signal for common dolphins. ” treefrogs call more when human noise intrudes kaiser, k & jl hammers ( 2009 ) the effect of anthropogenic noise on male advertisement call rate in the neotropical treefrog, dendropsophus triangulum. behaviour


of sound. clownfish were found to detect sound from 75hz to 1. 8khz, and to be most sensitive to sounds below 200hz. it ’ s long been known that the sounds made by fish are closely related to their size, with lower frequency sounds made by larger fish. interestingly, younger ( i. e. smaller ) fish have best hearing sensitivity at frequencies lower than the sounds they make, but close to the dominant frequencies of larger fish calls. it is suggested that this allows juvenile fish to hear and localize the position of adults, which may be useful as juveniles return to their home reefs. offshore wind farms : impact area on porpoises is small during operation, but potentially over 20km during construction these two papers, from related research teams, assessed the impacts of construction and operation of wind farms in europe on local populations of harbor porposeis and harbor seals. tougaard, henriksen, miller. underwater noise from three types of offshore wind turbines : estimation of impact zones for harbor porpoises and harbor seals. j. acoust. soc. am. 125 ( 6 ), june 2009. 3766 - 3773. underwater noise was recorded from three different types of wind turbines in denmark and sweden. the authors note that virtually all airborne noise from the turbine blades is reflected off the surface of the water, while vibrations from the machinery are transmitted through the tower and into the foundation, from where it radiates out into the water column and seabed. in general, turbine noise was only measurable above ambient noise at frequencies below 500hz, with total spls of 109 - 127db re 1upa rms, measured at 14 - 20m from the turbines ’ foundations. by comparing measured sound levels with audiograms of harbor seals and harbor porpoises, the researchers determined that the sounds were only slightly audible for the porpoises at ranges of 20 - 70m, whereas harbor seals may hear the sounds at ranges of 100m to several kilometers. as a bottom line, researchers suggest that behavioral changes are very unlikely in harbor porpoises except at very close ranges, while seals may have some behavioral reaction out to a few hundred meters. for both species, masking is predicted here to be low to non - existent ( due to differences between vocalization frequency patterns and the predominantly low - frequency turbine noise ), and the sound is too low to cause physical injury, no matter how close the animals are. tougaard, carstensen, teilmann


existent ( due to differences between vocalization frequency patterns and the predominantly low - frequency turbine noise ), and the sound is too low to cause physical injury, no matter how close the animals are. tougaard, carstensen, teilmann, skov, rasmussun. pile driving zone of responsiveness extends beyond 20km for harbor porpoises ( phocoena phocoena ( l. ) ) ( l ). j. acous. soc. am. 126 ( 1 ), july 2009. 11 - 14. this study took place during construction of an offshore wind farm in the north sea. acoustic t - pods were placed in the wind farm and in two locations outside the wind farm, at 7 and 20km away. during pile driving operations, which generate high - intensity impulsive sounds ( 235db peak - peak ), detections of harbour porpoises declined at all listening stations. ( the baseline was detections during construction, but without pile driving activity taking place ) the declines were not dramatic ( within the 95 % confidence bars in most cases, barely beyond them in some cases ), but were consistently found. there was no clear difference in detection rates at 7 and 20km, which implies that the displacement effect extends well beyond 20km. the differences inside the wind farm were minimal when pile driving was occurring, though total detections were lower inside the farm than outside at all times, suggesting that animals inside the construction zone were individuals who were more acclimated or tolerant of the ongoing construction noise. a summary of recent studies of wind farm noise annoyance and possible health effects the take - away from these new reports appears to be that while significant proportions of the population are affected by moderate wind farm noise, neither increasing wind farm noise nor even annoyance to it lead inevitably to health effects. there is an entire separate body of research investigating various attitudinal aspects related to stress and health, which only muddy the waters as we try to interpret these direct studies on wind farm noise. some studies indicate that attitudes toward a noise source can affect both annoyance and stress responses, and that a subjective sense of being threatened can likewise increase physiological responses to noise ; however, once again, these correlations are far from universal, so they cannot be used to " explain away " either annoyance or health impacts that do take place, any more than annoyance can be used as a clear indication of eventual health effects. there is far more gray than black and white in these reports. still, they provide a concrete picture of annoyance and sleep


either annoyance or health impacts that do take place, any more than annoyance can be used as a clear indication of eventual health effects. there is far more gray than black and white in these reports. still, they provide a concrete picture of annoyance and sleep deprivation increasing as turbine noise increases, along with a better sense of the proportion of affected neighbors who will experience these impacts at various distances and received sound levels. clearly, 35 - 45db is a range at which impacts on neighbors become far more widespread. the social question that will need to addressed is what proportion of nearby neighbors we will accept causing sleep deprivation or annoyance in : 10 %? 20 %? where will we draw the line, beyond which we consider turbine placement too close? minnesota dept of health minnesota department of health, environmental health division. public health impacts of wind turbines. may 2009. [ download report here ] this state agency report provides a good overview of the current state of knowledge regarding wind farm noise propagation, with particular attention given to possible low frequency noise impacts. the report makes no dramatic recommendations, though the data presented suggests that audible and low - frequency noise could affect neighbors within a half mile to mile. among the key pieces of information contained in this report, gleaned from previous research studies : - a reminder that the 2007 report on wind farms and human health from the national academies of science concluded that " noise produced by wind farms is generally not a major concern beyond a half mile " ( i. e., under a half mile can be problematic ). - some individuals have extraordinary sensitivity to low frequency sound, up to 25db more sensitive than presumed ( average ) thresholds at some frequencies - some people can dismiss and ignore repetitive but low intensity noise, while for others, the signal will grow and become more apparent and unpleasant over time. these reactions may have little relationship to will or intent, and more to do with previous exposure history and personality. - the difference, in db, between soft ( acceptable ) and loud ( annoying ) noise is much less at low frequencies, due to the our perceptual compression of the full audible range. - compiled data from two recent swedish studies ( summarized below ) suggest that wind farm noise levels of over 40db ( a ) lead to annoyance in about half the population, while slightly lower sound levels of 35 - 40db ( a ) leads to annoyance in about a quarter of the population. - a surprising study from new zealand found that over half of household 2 - 2. 5km and 5 - 9. 5km from wind farms


sound levels of 35 - 40db ( a ) leads to annoyance in about a quarter of the population. - a surprising study from new zealand found that over half of household 2 - 2. 5km and 5 - 9. 5km from wind farms could hear them at times ( fewer in between heard them ) ; these wind farms were in mountainous terrain, which likely explains the great distances at which they could be heard. - two charts from a 2006 report by the uk department of transport and industry suggest that low frequency noise ( lfn ) from wind turbines can be well above audible levels, and above the uk ' s night noise lfn criterion, at frequencies of 50 - 200hz. summary of three european studies eja pederson. effects of wind turbine noise on humans. third international meeting on wind turbine noise, aalborg, denmark, june 2009. this review by one of the leading researchers of wind turbine noise, annoyance, and health, compiles data from three studies, two in sweden and one in holland. the results, while indicating clear thresholds for annoyance and sleep disruption at sound levels often experienced by wind farm neighbors, also illustrate the subtleties inherent in making generalizations based on ambiguous data. the author makes a key introductory point : that wind farms " often are placed in rural settings considered places with low exposure ( to ) environmental stressors …. in such a setting, even when the levels are comparably low, ( wind farm noise could ) be perceived as a potential health risk. " the heart of the studies shows a correlation between increasing noise levels and annoyance. this effect was clearly stronger in the two flat, rural areas, than in a study that took place in a more suburban, rolling landscape that had more other noises present. a dramatic increase in proportion of people annoyed by turbine noise took place when the noise was over 40db ( a ) ; here, 25 - 45 % reported annoyance in rural settings, and 10 % in the suburban area. at 35 - 40db, annoyance ranged from 16 - 20 % in rural settings but was only 5 % in suburban ; at 30 - 35db, annoyance hovered around 10 % in rural areas. the studies showed no direct correlation between noise levels and health effects related to stress ( including headaches, tiredness, tenseness, and irritability ) ; this is not surprising, since at all noise levels, a majority of the population was not annoyed, so also not likely to be stressed. among those experiencing annoyance, there was a correlation with


tiredness, tenseness, and irritability ) ; this is not surprising, since at all noise levels, a majority of the population was not annoyed, so also not likely to be stressed. among those experiencing annoyance, there was a correlation with stress effects, but it was far from universal ( correlations generally in the 1. 25 range ). sleep disruption from any source was reported by 15 - 20 % of rural respondents even at sound levels under 30db ; some may interpret this as evidence of impact from wind turbines at very low sound levels, but it could as well be considered a baseline of sleep disturbance from non - wind farm causes. at sound levels of 30 - 40db, 5 - 8 % more rural residents reported sleep disruption, and as levels rose above 40db, a total of 30 - 40 % of rural residents reported being awakened. more insight into noise perception and annoyance kerstin persson waye. perception and environmental impact of wind turbine noise. presentation at inter - noise 2009. this is another paper that re - analyzes results from the several previous studies, including the swedish and dutch ones cited above ( waye and pederson were co - authors of one of these earlier studies ), and adds several interesting and important points to the discussion. first, she cites studies that suggest that the swishing nature of turbine noise is especially problematic, leading to a much higher correlation with annoyance than simple db level measurements. indeed, even at sound levels of only 35 - 40db ( a ), when swishing was present, 45 % of respondents reported being " rather " or " very " annoyed ; over 20 % were similarly annoyed at 30 - 35db. waye delves too - briefly into studies addressing the connection between seeing turbines and being annoyed by them. this is an especially difficult question, but she cites studies suggesting very high correlations between visibility and annoyance, much higher than the related correlation between visibility and audibility. this ties into other studies suggesting that those who don ' t like seeing turbines, also don ' t like hearing them ; again, though, it ' s important to remember that even these strong correlations are not universal, and many who experience noise issues are content to see turbines, if they are far enough away to not create audible disruptions to their recreational, work, and sleep life. in parsing the data from the three studies also addressed by pederson, above, waye adds two key pieces of information : first, all these wind farms consist of relatively small turbines, by current


their recreational, work, and sleep life. in parsing the data from the three studies also addressed by pederson, above, waye adds two key pieces of information : first, all these wind farms consist of relatively small turbines, by current standards : 500 - 800kw. second, our consideration of annoyance thresholds at various db levels is greatly enhanced by also including a graph showing that, in addition to those annoyed at each sound level, another 40 - 70 % of the population could hear the turbines, but did not report annoyance. for example, at 30 - 35db, over half of rural residents reported hearing the turbines, while only 8 - 12 % were annoyed ; at 35 - 40db ( within most global regulatory limits ), 85 % heard them, while just under 20 % were annoyed ; and at 40 - 45db ( within common us regulatory limits ), 95 % heard them, while 45 % were annoyed. finally, waye addresses a commonly reported finding : that annoyance levels are higher for wind turbines than for noise from less dynamic industrial sources, such as factories. she cites a study that shows that annoyance when indoors is pretty much the same, but that outdoors in rural settings, annoyance is significantly higher at sound levels above 35db ( annoyance at the one suburban wind farm was nearly identical to that from factory noise, again suggesting that expectations in rural setting plays a key role ). waye suggests that in rural settings, recreational and " restorative " aspects of outdoor experiences are impinged upon by wind farm noise. a final fascinating tidbit in her paper is that people who move from cities to the country are significantly more sensitive to noise than people who had always lived in the country ; that is, those who actively chose to relocate to the country are more attached to the quiet nature of the landscape, while those who grew up there are more accepting of changes. ( ed. note : as with so many statistics in these studies, though, this should not be over - emphasized ; surely many long - time locals also struggle with noise impacts. indeed, the difference in sensitivity to noise, while an interesting finding, is just 15 % ) low - frequency active sonar annual report to nmfs annual report no. 1 : operation of the surveillance towed array sensor system low frequency active ( surtass lfa ) sonar aboard the r / v cory chouest and usns impeccable ( t - agos 23 ) under the national marine fisheries service letters of authorization of 15 august 2007. department of the navy


frequency active ( surtass lfa ) sonar aboard the r / v cory chouest and usns impeccable ( t - agos 23 ) under the national marine fisheries service letters of authorization of 15 august 2007. department of the navy, chief of naval operations, september 2008. [ download ( pdf ) ] this report details the actual operations of the us navy ' s two lfas - equipped ships, from mid - august 2007 to mid - august 2008. both ships remained close to the asian pacific coast, near china, the philippines, and japan. the letter of authorization issued by nmfs, allows the navy to use lfas for up to 432 hours per vessel each year. during this year, the cory chouest used the system for 25 days, totaling 71 hours of transmissions, and the impeccable used it on 24 days for a total of 65 hours of transmissions. during these missions, both passive acoustic detection and an active " whale - finder " high frequency sonar were used to supplement visual marine mammal observers ; no whales were heard via passive listening, one group of whales was spotted visually, and on 19 occasions, whales or turtles were spotted by the whale - finder sonar. operations were suspended 43 times, including the 20 encounters just noted, and 23 times when the whale - finder sonar was not working correctly. such shut - downs occur when whales may move within 1km of the ship ; the whale - finder sonar reliably detects whales out to 2km away. based on current population studies of whales in the region, the report estimates that lfas operations injured no animals, and created possible behavioral reactions ( received levels of 120db or more ) in less than 1 % of most cetacean species, with no more than 3 % of any species affected. the report notes that the lfas source transmitter send out sound in a full 360 degrees, at a source level of 215db or less, using a variety of signal types at 100 - 500hz. the document provides a good overview of the navy ' s eis process since it began in 1996, along with court challenges and rulings from 2002 - 2008. safety thresholds for ocean noise should address character of signal, not just loudness michael stocker. the importance of incorporating signal characteristics in the evaluation of noise exposure impacts on marine life. acoustical society of america presentation, may 2009. this paper is a literature review that presents evidence suggesting that our current reliance on simple amplitude ( db level )


injury ; he proposes evaluation of the following signal characteristics : - rise time of impulse signals - periodicity of intermittent signals - kurtosis, evaluated three ways : fft of spectral distribution, amplitude variability, and spectral variability. measuring air gun propagation from new nsf research ship r / v langseth tolstoy, diebold, doermann, nooner, webb, bohnenstiehl, crone, holmes. broadband calibration of the r / v marcus g. langseth four - string seismic sources. geochemistry geophysics geosysytems, vol. 10, number 8. august 2009. [ download ( pdf ) ] this study marks the primary calibration of the new seismic survey vessel managed by columbia university ' s lamont - doherty earth observatory ( ldeo ) and often chartered by the national science foundation for academic surveys. the langseth ' s air gun arrays are different than those on the previous vessel, the r / v ewing, as it uses four identical 9 - gun linear arrays of somewhat smaller air guns, rather than up to 20 separately towed and larger air guns. tests were run in a deep water site and a shallow water site, since sound propagation varies considerably with depth. sound levels were calculated using both 90 % rms ( re 1upa ) and sel ( re : 1upa2s ). the resulting exposure radii ( safety zones to prevent exposure at the given level ) are as follows : | db threshold rms | db threshold sel interestingly, actual received levels at distances over 3km at the deep site were below the slope of the statistical " line " the data created at closer ranges ; thus the very distant exposure radii are likely over - estimates. as has been widely noted in recent years, sound energy was concentrated in the 10 - 300hz range ( 120 - 150db energy spectral density at 1km ), but continued to have significant energy up to 1khz ( 100 - 120db shallow, 90 - 110db deep ) and 20khz ( 60 - 80db shallow, 20 - 60 esl deep ). of special note in this study is the further clarification that, contrary to previous assumptions, differences between rms and sel are not consistent, but rather vary greatly with water depth. reverberations in shallow environments create a smaller difference ( about 8db ) than in deep water ( about 14db ). fin whales seem to avoid seismic survey castellote, clark, esteban. mediterranean


rather vary greatly with water depth. reverberations in shallow environments create a smaller difference ( about 8db ) than in deep water ( about 14db ). fin whales seem to avoid seismic survey castellote, clark, esteban. mediterranean fin whale migration movements altered by seismic exploration noise. presentation at acoustical society of america, may 2009. this study took place in the western mediterranean, off the coasts of spain, france, and northwestern italy ; its main purpose was to simply identify seasonal patterns of fin whales and better understand their migratory movements, using the now - common cornell marine autonomous recording units ( maru ), which are deployed for weeks or months, and then " pop up " for recovery. by chance, an medium - sized academic seismic survey took place in the vicinity of the recorders for ten days, from 8 - 17 december 2006, using 5 typical air guns and 4 small " sleeve " guns, totaling 1555 cubic inches. the resulting changes and in fin whale call rates strongly suggest that they shifted their migratory path, though given the limited " perspective " offered by two marus deployed near each other, and the fact that understanding of normal migratory pattern is limited, the study is not conclusive. during the ten days before the survey began, whale calls were heard fairly regularly ; during the first three days of the survey, it appears that whales vocalized more, while moving to a different position relative to the recorders. the call rate was most dramatically higher on the 2nd day of the survey : whale calls were heard for over 20 hours, rather than the 6 - 8 hours that was more typical before and after the survey ( some non - survey days peaked at 12 - 14 hours ). the researchers note a dramatic change in bearing ( angle at which most of the calls came from ) during this peak early in the survey, which was followed by a dramatic drop in calls, to zero on the 4th day of the survey, and continuing at zero or close to it for two weeks after the survey was completed ; presumably the whales moved out of range of the recorders ( the peak in call rates may represent more whales being temporarily closer as their route shifted ). by the beginning of january, whale calls sporadically rose again to near the levels before the survey, and, by january 7th, became more consistent, and back to the bearing that had been noted before. the researchers cite a few other studies that have shown displacement or changed vocalizing patterns near surveys, to bolster their sense that this study should be added to that emerging


7th, became more consistent, and back to the bearing that had been noted before. the researchers cite a few other studies that have shown displacement or changed vocalizing patterns near surveys, to bolster their sense that this study should be added to that emerging body of research suggesting behavioral effects that are not fully accepted yet by the scientific and industrial communities. ocean acidification not likely to increase ambient background noise reeder, chiu. ocean acidification and its impact on ocean noise level : an analysis using empirical and physical models of acoustic transmission loss. presented at asa october 2009 meeting. udovydchenkov, duda. ocean noise level change in response to ocean acidification. presented at asa october 2009. these two papers take a closer look at the widely - noted ocean noise implications of increasing ocean acidification ( a combination of factors related to global warming is triggering a steady increase in the ocean ’ s ph, which decreases sound absorption ). when the acidification results were first released there was much speculation that shipping noise would propagate farther, resulting in cumulative ambient noise increases throughout the oceans. these two papers, presented at this fall ’ s acoustical society of america meeting, both come to the same conclusion : low frequency noise will not be significantly increased due to ocean acidification ; rather, the primary changes will occur at mid - frequencies. this calms concerns about shipping noise, but may ( over time ) lead to slightly larger areas being impacted by mid - frequency active sonar, some acoustic harassment devices used by fish farms, noise from recreational boating, and other mid - frequency noise. rather than simply looking at the effects of sound absorption, both papers assessed the combined effects of many factors in sound propagation : seabed attenuation and boundary effects, waveguide physics, and the distribution of ph and absorption through different depths of water. the first paper looked at shallow water, a surface duct, and deep ocean, and found that the maximum change in noise transmission occurs at about 2khz, with no significant change below 800hz. the second paper notes that at low frequency, little sound is absorbed anyway, so ph - related absorption effects are much smaller than all the other effects, and that at high frequencies, sound does not propagate very far, also minimizing effects of decreased absorption ; the authors note that effects can be sizable at middle frequencies. ( ed. note : for both papers, pre - conference abstracts do not quantify the mid - frequency effects ; details will follow after the presentations and with later publication of results. )


; the authors note that effects can be sizable at middle frequencies. ( ed. note : for both papers, pre - conference abstracts do not quantify the mid - frequency effects ; details will follow after the presentations and with later publication of results. ) sleep " arousal " and awakening could be cause of wind farm health woes christopher hanning. sleep disturbance and wind turbine noise. june 2009 [ download report ] ( ed. note : this is not a peer - reviewed paper ; it was written for an anti - wind group in swinford, uk. however, dr. hanning, unlike some other physicians wading into industrial wind noise issues, is not writing outside his area of expertise. he ' s a renowned sleep disturbance expert : his school hospital named their sleep lab after him. ) this report by a uk md whose specialty is sleep disorders takes a comprehensive look at factors affecting sleep disturbance caused by nearby wind farms, and is highly recommended reading for anyone working to develop regulations at the local or state level. hanning ’ s primary point is that external noise need not wake a sleeper to cause problems, and the repeated “ arousals ” can break the most restful periods of sleep. he notes that “ the sleep, because it is broken, is unrefreshing, resulting in sleepiness, fatigue, headaches and poor memory and concentration. ” these are precisely the symptoms often reported by people living near wind farms. he stresses that arousals are also associated with “ physiological changes, an increase in heart rate and blood pressure, which are thought to be responsible for the increase in cardiovascular risk. arousals occur naturally during sleep and increase with age ( boselli 1998 ) which may make the elderly more vulnerable to wind turbine noise. arousals may be caused by sound events as low as 32 dba and awakenings with events of 42dba ( muzet and miedema 2005 ), well within the measured noise levels of current wind farms ” and the levels permitted by most jurisdictions. the report also summarizes other studies suggesting that night - time noise levels are often higher than sound models predict, as well as one that suggests that wind farms cause high levels of annoyance at lower sound levels than other common noise sources. he concludes that “ while it may be possible to produce a reasonable acoustically based theoretical approach to calculating set back distances ( kamperman and james 2008b ), it makes more sense to rely on recommendations from observations of the effects on real people at established wind farms. ” some birds choose noisy areas for


a reasonable acoustically based theoretical approach to calculating set back distances ( kamperman and james 2008b ), it makes more sense to rely on recommendations from observations of the effects on real people at established wind farms. ” some birds choose noisy areas for nests francis, c. d., ortega, c. p., and a. cruz. 2009. noise pollution changes avian communities and species interactions. current biology doi : 10. 1016 / j. cub. 2009. 06. 052 a new study surveyed nesting birds in new mexico woodlands with oil and gas compressors, and came up with a surprising result. while, as expected, most birds were more numerous in areas farther from the compressors, two species seemed to prefer these areas. black - chinned hummingbirds and house finches had more than 90 percent of their nests at the noisy sites. the researchers dug a bit deeper, and found that nests in the quiet areas were more likely to be attacked by predators, with predator birds significantly less abundant around noisy sites. it is suggested that the noise may mask their calls or make it harder for them to find their prey. increase in noise levels leads to more annoyance than similar noise in steady state brown, kamp. response to a change in transport noise exposure : competing explanations of change effects. j. acoust. soc. am. 125 ( 2 ), february 2009 this literature review addresses an interesting question, and one that may be relevant to concerns about noise from wind farms. a long history of studies of human annoyance responses to traffic noise seems to suggest that a change in noise levels ( for example, traffic noise increasing from 50db to 60db ) triggers more annoyance than occurs when exposure is steady at the higher level ( in this case, a steady 60db ). this paper reviews many proposed explanations for this affect ; while no single explanation is identified as most likely, several common ones are shown to be unlikely, and a set of plausible explanations remains. among the explanations that are rejected is the common assumption that the annoyance after an increase is transient, and over time will dissipate as people adapt to the new noise level ; in fact, evidence suggests that annoyance remains for years after a change. also of note is that the one study that looked closely at whether attitudes toward a noise source is related to annoyance after an increase in noise found that neither prior attitude nor changes in attitude could account for the increased annoyance. this paper, and its many citations, are highly recommended for anyone addressing community responses to new or increased noise sources


a noise source is related to annoyance after an increase in noise found that neither prior attitude nor changes in attitude could account for the increased annoyance. this paper, and its many citations, are highly recommended for anyone addressing community responses to new or increased noise sources. harbor porpoise tts, behavioral response at moderate noise levels in lab tests lucke, seibert, lepper, blanchet. temporary shift in masked hearing thresholds in a harbor porpoise ( phocoena phocoena ) after exposure to seismic airgun stimuli. j. acoust. soc. am. 125 ( 6 ), june 2009. field researchers have observed for years that harbor porpoises appear more sensitive to noise than most other cetacean species, moving away from noise sources at greater distances than typically considered problematic ( belugas and bowhead whale mothers are also more behaviorally sensitive to noise ). this study was the first that measured harbor porpoise auditory sensitivity in the lab, using auditory evoked potential measurements ( brain - wave scanners that note auditory brain activity ), and the results confirm that this species ' avoidance behavior occurs at relatively low sound levels, and may be linked to a similarly low threshold of tts ( temporary hearing loss ). the test animal was a wild - born ten - year old porpoise who has lived in captivity in denmark for most of his life ; the testing facility is open to the sea, so background noise ( ranging roughly from 60 - 80db pressure spectral density ) is dominated by local shipping sounds. a single small ( 20 cubic inches ) airgun was used as the sound source, gradually moving closer until a tts was observed at one of the 3 tested hearing frequencies ( 4, 32, and 100khz ). the airgun source sound was, as is typical, loudest at low frequencies ( max of 150db spl at 300hz ), but had significant energy at higher frequencies as well ( 100 - 110db spl from 2khz to 5khz ), at the relatively close range used in this test ( 14 - 150m ). the key finding was that the airgun sounds caused tts in the 4khz hearing range at received levels of 165. 5db sel ( 202. 1db peak to peak ) ; perhaps more importantly, recovery was quite slow, with reduced sensitivity ( i. e., sound had to be louder than normal to be heard ) still measured at 29 hours post - exposure. based on the pattern of recovery


tts ; temporary decline in hearing sensitivity ) after exposure to loud noise in dolphins, calls into question one of the key advantages of the sound exposure level metric. sel measurements are designed to measure total sound exposure over a given period of time ; simply stated, sel remains constant when sound intensity increases while duration decreases ( e. g., twice as loud for half as long should result in " equal energy ", or the same sel ). the assumption was that sel offered an " equal energy " metric that could allow biologists and ocean regulators to set a sel threshold that would apply to many types of noise exposure. however, this study indicates that a given sel db level ( arrived at via a mathematical equation combining sound energy from many noise pulses over time ) did not seem to induce tts in the single captive dolphin used in this study. as with other metrics, higher sels were required to induce tts with shorter duration sounds. by extension, the hypothesis that tts is caused by a given level of sound energy ( the " equal energy " hypothesis ) is called into question. the relationship appears to be logarithmic, rather than linear. in this study, the sound source was short ( 20ms ) digitally generated tone bursts. related : mid - frequency sonar must be very loud / close to trigger tts mooney, nachtigall, vlachos. sonar - induced temporary hearing loss in dolphins. biology letters, doi : 10. 1098 / rsbl. 2009. 0099 the same team more recently found the same difficulty with using sel to predict tts when using a recording of a us naval mid - frequency active sonar ; short duration mfa " pings " had to be ramped up to a sel of 214db ( equivalent to 203db spl rms ) to induce a modest tts of 6db, which faded rapidly back to normal hearing levels in 20 - 40 minutes, a higher sel than had induced tts using longer duration sounds in the above study. this was the first hearing test on dolphins to use actual mid - frequency active sonar signals ; previous studies had used sonar simulations or tones at similar frequencies. ed. note : the usual caveats are in order here, as a long - time captive dolphin may not hear as well as his wild relatives ; it is often assumed that captive dolphins are less sensitive both physiologically ( hearing loss from living in noisy pens ) and behaviorally ( habituated to noise, and given food to remain in the


captive dolphin may not hear as well as his wild relatives ; it is often assumed that captive dolphins are less sensitive both physiologically ( hearing loss from living in noisy pens ) and behaviorally ( habituated to noise, and given food to remain in the test area ), though the relative lack of clear studies on wild animals makes this assumption difficult to confirm. wind turbines do not seem to displace wintering farmland birds devereaux, denny, whittingham. minimal effects of wind turbines on the distribution of wintering farmland birds. journal of applied ecology 2008, 45, 1689 - 1694. in what be the first study examining whether wind farms displace birds, this team studied bird distributions around two small wind farms in england ( each had 8 2mw 60m hub - height turbines in two rows ). birds of four different functional groups ( seed - eaters, corvids, gamebirds, and skylarks ) were counted at five distances ( multiples of 150m, out to 750m ). after controlling for crop types and boundary effects, there was no overall significant difference in distribution by distance. one species was an exception to the overall findings : the largest and least maneuverable bird, the common pheasant, was more common as distance increased. two other species not included in the overall study of functional groups were also less abundant within 150m : the mallard and the wood pigeon, also both less maneuverable than most of the other birds in the area ( the authors note that counts were low enough for these that the pattern may have been skewed by a few large flocks ). in some cases ( skylarks and corvids ), the data showed statistically significant increases in bird numbers closer to the turbines. the authors make a point of noting that this winter study needs to be complemented by similar investigations of distribution during the breeding season, when birds may be affected differently. this study did not study noise, but just the presence of the turbines. related : compressor station noise can reduce forest bird abundance bayne, habib, boutin. impacts of chronic anthropogenic noise form energy - sector activity on abundance of songbirds in the boreal forest. conservation biology, volume 22, no. 5, 1186 - 1193, 2008. this study used an innovative study design to separate the effect of noise from the also - important effects of habitat disruption and edge effects caused by energy development. the authors compared bird distributions around ( quiet ) well pads and ( constantly noise


1193, 2008. this study used an innovative study design to separate the effect of noise from the also - important effects of habitat disruption and edge effects caused by energy development. the authors compared bird distributions around ( quiet ) well pads and ( constantly noise - producing ) coalbed methane compressor stations in the forest of alberta. they found that areas near well pads had a passerine density of 1. 5 times higher than areas near compressor stations ; one - third of the species studied showed this affect. the noise levels produced by the compressor stations is typically 75 - 95 db ( a ) at the source, sometimes reaching 105db ( a ) at large facilities ; compressor noise is commonly heard at distances of well over 1km in the boreal forest ; with 5000 compressor stations in boreal alberta, the question of noise - related displacement is potentially significant. in addition to the overall tendency for passerines to be found in greater numbers near quiet energy installations than noisy ones ( with three species especially affected ), seven other species showed less dramatic but still noticeable differences, while eleven other species showed no difference. red - eyed vireos, white - throated sparrows, and yellow - rumped warblers were particularly affected, with chickadees, jays, and wrens showing little effect. right whales experience dramatic variations in noise during annual movements along north american coast parks, urazghildiiev, clark. variability in ambient noise levels and call parameters of north atlantic right whales in three habitat areas. j. acous. soc. am. 125 ( 2 ), february 2009. this study used pop - up recorders to examine ambient noise conditions and right whale calls in three of the species ' annual habitats : the bay of fundy, cape cod bay, and the coast of georgia. while the variability of calls was subtle, there was some indication that louder call patterns were in response to the peak sound in an area, rather than the overall noise level. however, the seasonal variability of noise experienced by this population is the key finding here. overall sound levels were highest during the summer season spent in the bay of fundy, and lowest in the winter off georgia. likewise, the percentage of time that the habitat was " loud " ( ambient noise over 105db re 1upa in the 50 - 350hz frequency range of right whale contact calls ) varied dramatically : in the bay of fundy, it was loud 85 - 95 % of the time, in cape cod bay it was loud 53 - 63 % of the time, and


50 - 350hz frequency range of right whale contact calls ) varied dramatically : in the bay of fundy, it was loud 85 - 95 % of the time, in cape cod bay it was loud 53 - 63 % of the time, and off georgia it was loud only 20 - 30 % of the time. while the quiet is surely appreciated during calving time in georgia, the high proportion of noisy times in the bay of fundy could impede summer social interaction, perhaps including mating. the population of north atlantic right whales is precarious, and slowly decreasing ; the researchers conclude with the urgent observation that " locating the mating grounds for right whales and quantifying the noise occurring in their breeding areas may be crucial in understanding how increases in ambient noise may limit the range of communication signals that are vital for successful reproduction. " orcas increase volume of calls in synch with increasing boat noise holt, noren, v. veirs, emmons, s. veirs. speaking up : killer whales ( orcinus orca ) increase their call amplitude in response to vessel noise. j. acous. soc. am. 125 ( 1 ), january 2009. this study found that southern resident killer whales, who are nearly always within earshot of boat traffic, increase their call amplitude by 1db for every 1db increase in background noise levels. call amplitudes ranged from 133 - 174db re 1upa ( mean 155db ), while background noise ( measured in the 1 - 40khz band ) ranged from 98 - 123db ( mean 110db ), as nearby boat counts ranged from 1 - 46. of course, source levels of calls vary, based on the type of call ; still, there was a significant correlation between call source level and background noise for all call types. the detailed analysis was restricted to the one call type with the largest sample size. it appeared that call amplitude was relatively unaffected until background noise reached 105db, though the researchers note a small sample size below that level, and suggest further investigation to see whether there is a threshold at some point. above 105db, calls increased 1db for each 1db of increased boat noise. interestingly, they found no increase in duration of calls ; an earlier study had found that calls were longer in noisy conditions. the researchers suggest that this difference may be due to differences in study design, or due to the fact that the current study site did not provide any " no boat noise " conditions ( i. e., perhaps call duration increases at the


noisy conditions. the researchers suggest that this difference may be due to differences in study design, or due to the fact that the current study site did not provide any " no boat noise " conditions ( i. e., perhaps call duration increases at the first appearance of background noise, with call amplitude increasing with the noise ). boats reduce foraging time in orcas lusseau, bain, williams, smith. vessel traffic disrupts the foraging behavior of southern resident killer whales orcinus orca. endangered species research, vol. 6 : 211 - 221, 2009. this recent paper continues a line of research undertaken by this team throughout this decade, which investigates the ways that boat traffic changes orca behavior, with a special focus on foraging activity ( a 2004 paper by these researchers suggests that reduced foraging is the most significant impact on an animals ' energy budget ; ie, the extra energy used in, e. g., avoidance is much less significant than the much larger decrease in energy received when foraging is reduced ). as in their study of the northern orcas of bc, and in line with studies by others of delphinid species in other parts of the world, this study found that orcas around san juan island reduced their time spent foraging by about 21 % when boats were within 400m ( from 76 % of the time to 60 % of the time ). they had hoped to identify behavior patterns when 100m, 400m, and 1000m or more from boats ; unfortunately, in the san juan islands, boat traffic is nearly constant, and there were very few opportunities to observe orcas with boats more than 1000m away. in the end, the authors show a clear affect with boats within 100m and 400m, as well as an apparently smaller affect when boats were within 1000m. the authors note that it is possible that the 400m affect is mainly caused by boats not far beyond 100m ( a study with finer spatial analysis would be needed to clarify this ). nonetheless, they show that the current whale watching standard of remaining 100m away is not sufficient to avoid disrupting the key foraging behaviors of orcas. related : number of vessels may play larger role than proximity of vessels williams, bain, smith, lusseau. effects of vessels on behavior patterns of individual southern resident killer whales orcinus orca. endangered species research, vol. 6 : 199 - 209, 2009. this companion paper by the same research team does not address foraging, but rather looks at overall behavioral effects of the same boat traffic measured in


resident killer whales orcinus orca. endangered species research, vol. 6 : 199 - 209, 2009. this companion paper by the same research team does not address foraging, but rather looks at overall behavioral effects of the same boat traffic measured in the above study. they find that behavioral changes such as swimming speed and directness of travel path changed slightly in response to boats, and in general, they found that changes were more correlated to the number of boats within 400 yards than by the proximity of the boats, whereas current whale watching standards address only how close each boat is, rather than total numbers of boats. they also note that, given the difficulties in finding clear patterns within this noisy environment, it may be hard for managers to feel that the data is solid enough to warrant additional protections. however, the authors conclude with the observation that it appears that this population is food - limited ( many researchers consider declining salmon runs to be a primary factor in population stagnation and sometimes dips ), and suggest that reducing the ambient noise levels would improve the whales ' ability to find the limited food that remains in the region. ed. note : this paper ' s focus on numbers of vessels corresponds well with the holt paper directly above, which finds overall ambient noise is closely tied to the number of boats in the vicinity. soundscapes, acoustic daylight, and fish hearing richard fay. soundscapes and the sense of hearing in fishes. integrative zoology 2009 ; 4 : 26 - 32. this fascinating review offers a wide - ranging consideration of the implications of a simple observation : goldfish have an acute sense of hearing, though they do not vocalize or engage in any known sound communication. what are they listening to? fay introduces several key lines of research into fish hearing, some dating from the 80s, and some from the past decade. his own research, along with that of several others, has demonstrated that fish can isolate multiple sound sources ( though studies cited are limited to two distinct sounds, rather than much more complex mixes of sound ). from there, fay suggests that fishes ' sensitivity to particle motion in water, via their lateral lines, provides them the ability to engage in what in human perception is termed " auditory scene analysis, " or the perception of a complex environment by distinguishing the many sound sources and their motion through the soundscape. the most intriguing suggestion in the paper is less solidly fleshed out : that fish make use of reflections of ambient sound to build this " auditory scene. " that is, ambient noise can act as "


sources and their motion through the soundscape. the most intriguing suggestion in the paper is less solidly fleshed out : that fish make use of reflections of ambient sound to build this " auditory scene. " that is, ambient noise can act as " acoustic daylight, " with subtle differences in the echoes of the overall ambient sound bouncing off specific objects being a source of perception ( as light reflects off objects to create visual perception ). fay mentions one study in which goldfish were shown to be able to perceive a single point source of delayed ( as if echoed ) signal in a noise field ; this was apparently done with artificial noise sources, though the researchers ( and fay ) propose that it represents an ability of goldfish to perceive the fish bladder of another fish re - radiating ambient noise. this may well be true, though this ( and one other related study that showed fish using echoes from self - produced sound ) do not yet cross the chasm of showing that fish process complex acoustic scenes by using reflections of ambient noise. yet the point of this review is not to " make a case " for these higher order perceptual abilities, but rather to open our minds to the likely fact that fish listen to much more than simply communication signals, which have been overlooked due to our " profound ignorance of the other possible sounds and sources that probably have biological significance to fish, " and to suggest that " environmental soundscapes ( are ) most probably important sources of information. " this more modest first step is clearly successful here, opening the way to future studies of the undoubtedly subtle and complex sensory world of fishes. iucn report highlights noise impact of shipping in mediterranean, calls for mpas to provide " acoustic comfort " ameer abdulla, olof london ( editors ). 2008. maritime traffic effects on biodiversity in the mediterranean sea : review of impacts, priority areas and mitigation measures. malaga, spain : iucn centre for mediterranean cooperation. 184 pp. [ download ( pdf ) ] [ website ] this comprehensive look at mediterranean shipping, from the international union for the conservation of nature and natural resources, includes a long section in the early pages on noise impacts. due to the concentration of shipping in the mediterranean, ambient noise is 40db higher than in relatively shipping - free seas such as the sea of cortez. among the recommendations made in regards to noise are that " much effort should be devoted to developing a legal framework within which underwater noise is recognized and regulated as a threat, " and the advocacy of mpas that are designed to provide acoustic protection to