Presented here is a broadly applicable, transparent, repeatable analytical framework for assessing relative risk of anthropogenic disturbances on marine vertebrates, with the emphasis on the sound generating aspects of the activity. The objectives are to provide managers and action-proponents tools with which to objectively evaluate drivers of potential biological risk, to identify data gaps that limit assessment, and to identify actionable measures to reduce risk. Current regulatory assessments of how human activities (particularly those that produce sound) influence the likelihood of marine mammal behavioral responses and potential injury, rely principally on generalized characterizations of exposure and effect using simple, threshold-based criteria. While this is relatively straightforward in regulatory applications, this approach fails to adequately address realistic site and seasonal scenarios, other potential stressors, and scalable outcome probabilities. The risk assessment presented here is primarily based on a common and broad understanding of the spatial-temporal-spectral intersections of animals and anthropogenic activities, and specific examples of its application to hypothetical offshore wind farms are given. The resulting species- and activity-specific framework parses risk into two discrete factors: a population’s innate ‘vulnerability’ (potential degree of susceptibility to disturbance) and an ‘exposure index’ (magnitude-duration severity resulting from exposure to an activity). The classic intersection of these factors and their multi-dimensional components provides a relativistic risk assessment process for realistic evaluation of specified activity contexts, sites, and schedules, convolved with species-specific seasonal presence, behavioral-ecological context, and natural history. This process is inherently scalable, allowing a relativistic means of assessing potential disturbance scenarios, tunable to animal distribution, region, context, and degrees of spatial-temporal-spectral resolution.

sources, exposure criteria are given in frequencyweighted sound exposure level (SEL, given in This article evaluates Southall et al. (2007) in light units relative to 1 μPa-s or (20 μPa)-s for water of subsequent scientific findings and proposes and air, respectively). Dual exposure metrics are revised noise exposure criteria to predict the onset provided for impulsive noise criteria, including of auditory effects in marine mammals. Estimated frequency-weighted SEL and unweighted peak audiograms, weighting functions, and underwater sound pressure level (SPL, given in units relative noise exposure criteria for temporary and permato 1 μPa or 20 μPa for water and air, respectively). nent auditory effects of noise are presented for six Exposures exceeding the specified respective crispecies groupings, including all marine mammal teria level for any exposure metric are interpreted species. In-air criteria are also provided for as resulting in predicted temporary threshold shift amphibious species. Earlier marine mammal hear(TTS) or permanent threshold shift (PTS) onset. ing groupings were reviewed and modified based Scientific findings in the last decade provide subon phylogenetic relationships and a comprehensive stantial new insight but also underscore remaining review of studies on hearing, auditory anatomy, and challenges in deriving simple, broadly applicable sound production. Auditory weighting functions quantitative exposure criteria for such diverse taxa. are derived for each group; those proposed here These criteria should be considered with regard to are less flattened and closer to audiograms than the relevant caveats, recommended research, and with Southall et al. M-weightings. As in Southall et al., the expectation of subsequent revision. noise sources are categorized as either impulsive or non-impulsive, and criteria use multiple expo

Acoustic masking from anthropogenic noise is increasingly being considered as a threat to marine mammals, particularly low-frequency specialists such as baleen whales. Low-frequency ocean noise has increased in recent decades, often in habitats with seasonally resident populations of marine mammals, raising concerns that noise chronically influences life histories of individuals and populations. In contrast to physical harm from intense anthropogenic sources, which can have acute impacts on individuals, masking from chronic noise sources has been difficult to quantify at individual or population levels, and resulting effects have been even more difficult to assess. This paper presents an analytical paradigm to quantify changes in an animal's acoustic communication space as a result of spatial, spectral, and temporal changes in background noise, providing a functional definition of communication masking for free-ranging animals and a metric to quantify the potential for communication masking. We use the sonar equation, a combination of modeling and analytical techniques, and measurements from empirical data to calculate time-varying spatial maps of potential communication space for singing fin (Balaenoptera physalus), singing humpback (Megoptera novaeangliae), and calling right (Eubalaena glacialis) whales. These illustrate how the measured loss of communication space as a result of differing levels of noise is converted into a time-varying measure of communication masking. The proposed paradigm and mechanisms for measuring levels of communication masking can be applied to different species, contexts, acoustic habitats and ocean noise scenes to estimate the potential impacts of masking at the individual and population levels.

Potential responses of marine mammals to anthropogenic underwater sound are usually assessed by researchers and regulators on the basis of exposure to a single, relatively loud sound source. However, marine mammals typically receive sounds from multiple, dynamic sources. We developed a method to aggregate modeled sounds from multiple sources and estimate the sound levels received by individuals. To illustrate the method, we modeled the sound fields of 9 sources associated with oil development and estimated the sound received over 47 d by a population of 10000 simulated bowhead whales Balaena mysticetus on their annual migration through the Alaskan Beaufort Sea. Empirical data were sufficient to parameterize simulations of the distribution of individual whales over time and their range of movement patterns. We ran 2 simulations to estimate the sound exposure history and distances traveled by bowhead whales: one in which they could change their movement paths (avert) in response to set levels of sound and one in which they could not avert. When animals could not avert, about 2% of the simulated population was exposed to root mean square (rms) sound pressure levels (SPL) ≥180 dB re 1 µPa, a level that regulators in the U.S. often associate with injury. When animals could avert from sound levels that regulators often associate with behavioral disturbance (rms SPL >160 dB re 1 µPa), <1% of the simulated population was exposed to levels associated with injury. Nevertheless, many simulated bowhead whales received sound levels considerably above ambient throughout their migration. Our method enables estimates of the aggregated level of sound to which populations are exposed over extensive areas and time periods.

Predictions of animal exposure to anthropogenic acoustic sources have become increasingly sophisticated through simulating animal behavior. A long-standing issue has been the question of how many exposures occur during an activity and how those exposures are distributed over individual animals. A sensitivity study evaluated the effects of simulation duration, source movement, animal movement and group size. Two airgun array survey patterns (2D and 3D) were modeled, each with a one-month duration. During each simulation, animal movement was modeled for low-frequency, shallow and deep diving mid-frequency, and high-frequency cetaceans. The unweighted 160 dB RMS exposure threshold for behavior was used to evaluate the effect of different modeling parameters. Results found that simulating animals in groups does not alter the predicted level of exposure, but it does increase its variance. Examining the full 30 day exposure records found that deeper divers had a greater number of exposures. The more wide-ranging 2D survey pattern exposed more individual animals and animals had fewer multiple exposures than the 3D survey pattern. Species with higher residencies had a greater number of multiple exposures. Finally the long-duration modeling provides an explicit ability to predict the number of exposed individuals rather than just the number of exposure events.

The effect of anthropogenic sounds on marine wildlife is typically assessed by convolving the spatial, temporal, and spectral properties of a modeled sound field with a representation of animal distribution within the field. Both components benefit from stochastic modeling techniques based on field observations. Recent studies have also highlighted the effect of context on the probability and severity of the animal behavioral response to sound. This paper extends the stochastic approach to three modeling scenarios, including key contextual variables in aversion from a given level of sound and as a means of evaluating the effectiveness of passive acoustic monitoring.

Soundscapes emphasize the way in which the acoustic environment is perceived by an individual or species. Anthropogenic sounds have the potential to cause behavioral responses or even injury in marine mammals. Exposure criteria include sound pressure level (SPL) and sound exposure level (SEL) thresholds that, when exceeded, have the potential to cause auditory injury to marine mammals. While there is a general understanding of the hearing capabilities in representative marine species, the behavioral responses of these animals are not well understood. These responses are thought to be strongly affected by the context of exposure (animal activity at time of exposure, habituation/sensitization to the sound, etc.) in addition to acoustic metrics, such as received level (RL). To investigate the complexity of sound exposure, a user-friendly, interactive tool has been developed that utilizes a holistic and multi-dimensional approach to the exposure scenario in order to address the spatial relationships among noise environment, animal hearing and behavior, and anthropogenic sound sources.

There are no standards for assessment of the cumulative effects of underwater sound. Quantitative assessments typically consider a single source, whereas qualitative assessments may include multiple sources but rarely identify response variables. As a step toward understanding the cumulative effects of underwater sound, we assessed the aggregated sounds of multiple sources received by migrating bowhead whales (Balaena mysticetus). The quantitative method models the sound field from multiple sources and simulates movement of a population through it. The qualitative method uses experts to assess the responses of individuals and populations to sound sources and identify the potential mechanisms. These methods increase the transparency of assessments.

Chapters cannot be read stand-alone. Please see complete SpringerBrief at: http://link.springer.com/book/10.1007/978-3-319-06659-2 .

This Technical Report presents the outcome of a Working Group that was established to determine broadly applicable sound exposure guidelines for fishes and sea turtles. After consideration of the dive

We show that humpback-whale vocalization behavior is synchronous with peak annual Atlantic herring spawning processes in the Gulf of Maine. With a passive, wide-aperture, densely-sampled, coherent hydrophone array towed north of Georges Bank in a Fall 2006 Ocean Acoustic Waveguide Remote Sensing (OAWRS) experiment, vocalizing whales could be instantaneously detected and localized over most of the Gulf of Maine ecosystem in a roughly 400-km diameter area by introducing array gain, of 18 dB, orders of magnitude higher than previously available in acoustic whale sensing. With humpback-whale vocalizations consistently recorded at roughly 2000/day, we show that vocalizing humpbacks (i) were overwhelmingly distributed along the northern flank of Georges Bank, coinciding with the peak spawning time and location of Atlantic herring, and (ii) their overall vocalization behavior was strongly diurnal, synchronous with the formation of large nocturnal herring shoals, with a call rate roughly ten-times higher at night than during the day. Humpback-whale vocalizations were comprised of (1) highly diurnal non-song calls, suited to hunting and feeding behavior, and (2) songs, which had constant occurrence rate over a diurnal cycle, invariant to diurnal herring shoaling. Before and during OAWRS survey transmissions: (a) no vocalizing whales were found at Stellwagen Bank, which had negligible herring populations, and (b) a constant humpback-whale song occurrence rate indicates the transmissions had no effect on humpback song. These measurements contradict the conclusions of Risch et al. Our analysis indicates that (a) the song occurrence variation reported in Risch et al. is consistent with natural causes other than sonar, (b) the reducing change in song reported in Risch et al. occurred days before the sonar survey began, and (c) the Risch et al. method lacks the statistical significance to draw the conclusions of Risch et al. because it has a 98-100% false-positive rate and lacks any true-positive confirmation.

Potential effects of anthropogenic underwater sounds on marine mammals are usually assessed on the basis of exposure to one sound source. Recently published research modeling underwater noise exposure and assessing its impact on marine life has extended the typical single source/single species absolute received level approach to defining exposure in a variety of ways including: relative levels of exposure, such as loudness, signal to noise ratio, and sensation level; metrics for evaluating chronic elevation in background noise; cumulative exposure to multiple and dissimilar sound sources, as well as the potential for animals to selectively avoid a particular source and other behavioral changes. New approaches to managing the overall acoustic scene that account for these issues requires a more holistic and multi-dimensional approach that addresses the relationships among the noise environment, animal hearing and behavior, and anthropogenic sound sources. We present a layered acoustic scene concept that considers each facet of the extended problem. Our exemplar is a seismic survey in the Gulf of Mexico with layers for ambient oceanographic and meteorological noise, shipping, and distant anthropogenic sources in which the exposure is filtered by the animal’s hearing filter, sensation level, and nominal loudness of the signal.

Chapters cannot be read stand-alone. Please see complete SpringerBrief at: http://link.springer.com/book/10.1007/978-3-319-06659-2 .

Marine vibroseis (MarVib), if effective for geophysical purposes, might (relative to airguns) have reduced effects on marine animals. With Joint Industry Programme sponsorship, we prepared an Environmental Assessment (EA) of this possibility. Given the near-absence of specific data on biological effects of MarVib, most conclusions were based on indirect evidence. This presentation focuses on marine mammals, but the EA also addressed fish, turtles and invertebrates. With MarVib, higher frequency sound components (e.g., >100 Hz) should be reduced, benefitting species sensitive to sounds >100 Hz. Signal duration would be longer than for airguns, which could achieve similar source energy with lower peak pressures, thus reducing auditory and perhaps disturbance effects. Signal processing techniques applicable to MarVib might allow lower source energy per "shotpoint". There may also be more flexibility in the depth in the water column where a MarVib system could be operated. However, the higher duty cycle with MarVib may cause increased acoustic masking in species that rely on low-frequency sound. Also, with respect to behavioral disturbance, the higher duty cycle with MarVib may partly offset the benefits of the lower source level. Overall, use of MarVib rather than airguns would probably result in a reduction in some (but not all) types of impacts; controlled testing is needed. No extended abstract available.

The effect of underwater anthropogenic sound on marine mammals is of increasing concern. Here we show that humpback whale (Megaptera novaeangliae) song in the Stellwagen Bank National Marine Sanctuary (SBNMS) was reduced, concurrent with transmissions of an Ocean Acoustic Waveguide Remote Sensing (OAWRS) experiment approximately 200 km away. We detected the OAWRS experiment in SBNMS during an 11 day period in autumn 2006. We compared the occurrence of song for 11 days before, during and after the experiment with song over the same 33 calendar days in two later years. Using a quasi-Poisson generalized linear model (GLM), we demonstrate a significant difference in the number of minutes with detected song between periods and years. The lack of humpback whale song during the OAWRS experiment was the most substantial signal in the data. Our findings demonstrate the greatest published distance over which anthropogenic sound has been shown to affect vocalizing baleen whales, and the first time that active acoustic fisheries technology has been shown to have this effect. The suitability of Ocean Acoustic Waveguide Remote Sensing technology for in-situ, long term monitoring of marine ecosystems should be considered, bearing in mind its possible effects on non-target species, in particular protected species.