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This paper proposes a new method that makes the direct volume integration of the Lighthill stress term in FWH acoustic analogy affordable in terms of both computational time and disk storage requirement. The method is based on a dual mesh concept, i.e. while a fine mesh is used in CFD, a relatively coarse mesh is used for the acoustic calculation. The terms being independent of the observer positions in the integral formula of FWH acoustic analogy are calculated on the CFD mesh and mapped onto the acoustic mesh during the simulation. These sound source terms are used for the on-the-fly acoustic computation or saved for later use in the post-processing. A formulation of the Lighthill stress tensor in cavitating flow is also derived. The method is verified with the acoustic assessment of an inclined marine propeller case. A reduction of the calculation time by 98% and disk storage by 99% is achieved while maintaining small acoustic error.

Acoustic deterrent devices (ADDs) are used in attempts to mitigate pinniped depredation on aquaculture sites through the emission of loud and pervasive noise. This study quantified spatio-temporal changes in underwater ADD noise detections along western Scotland over 11 years. Acoustic point data (‘listening events’) collected during cetacean line-transect surveys were used to map ADD presence between 2006 and 2016. A total of 19,601 listening events occurred along the Scottish west coast, and ADD presence was recorded during 1371 listening events. Results indicated a steady increase in ADD detections from 2006 (0.05%) to 2016 (6.8%), with the highest number of detections in 2013 (12.6%), as well as substantial geographic expansion. This study demonstrates that ADDs are a significant and chronic source of underwater noise on the Scottish west coast with potential adverse impacts on target (pinniped) and non-target (e.g. cetaceans) species, which requires further study and improved monitoring and regulatory strategies.

This is the accepted manuscript of the paper "Underwater noise assessment outside harbor areas: The case of Port of Civitavecchia, northern Tyrrhenian Sea, Italy", published as final paper in "Marine Pollution Bulletin 08/2018, 133, 865 –871;https://doi.org/10.1016/j.marpolbul.2018.06.058" Cafaro V, Piazzolla D, Melchiorri C, Burgio C, Fersini G, Conversano F, Piermattei V, Marcelli M. (2018). Underwater noise assessment outside harbor areas: The case of Port of Civitavecchia, northern Tyrrhenian Sea, Italy. Marine Pollution Bulletin 08/2018, 133, 865 – 871. https://doi.org/10.1016/j.marpolbul.2018.06.058 Underwater noise assessment is particularly important in coastal areas where a wide range of natural and anthropogenic sounds generate complex and variable soundscapes. In the last century, the number and size of noise sources has increased significantly, thereby increasing the ocean's background noise. Shipping is the main source of lower-frequency underwater noises (< 500 Hz). This research aimed to provide an initial assessment of underwater noise levels in a coastal area of the northern Tyrrhenian Sea (Italy) using short-term recordings. Spatial and temporal variations in the noise level, and the type and number of ships sailing through the port were recorded. A significant correlation was found between ferry boats and sound pressure levels, indicating their role as a prevalent source of low frequency underwater noise in the project area. This research could provide the baseline for implementation of distribution and point-source underwater noise models that are required for sustainable coastal management.

The prediction of the noise scattered by a submarine subject to the propeller tonal noise is here addressed through a non-standard frequency-domain formulation that extends the use of the acoustic analogy to scattering problems. A boundary element method yields the scattered pressure upon the hull surface by the solution of a boundary integral equation, whereas the noise radiated in the fluid domain is evaluated by the corresponding boundary integral representation. Propeller-induced incident pressure field on the scatterer is detected by combining an unsteady three-dimensional panel method with the Bernoulli equation. For each frequency of interest, numerical results concern with sound pressure levels upon the hull and in the flowfleld. The validity of the results is established by a comparison with a time-marching hydrodynamic panel method that solves propeller and hull jointly. Within the framework of potential-flow hydrodynamics, it is found out that the scattering formulation herein proposed is appropriate to successfully capture noise magnitude and directivity both on the hull surface and in the flowfleld, yielding a computationally efficient solution procedure that may be useful in preliminary design/multidisciplinary optimization applications. (C) 2018 Elsevier Ltd. All rights reserved.

Underwater noise pollution from shipping is a significant ecological concern. Acoustic propagation models are essential to predict noise levels and inform management activities to safeguard ecosystems. However, these models can be computationally expensive to execute. To increase computational efficiency, ships are spatially partitioned using grids but the cell size is often arbitrary. This work presents an adaptive grid where cell size varies with distance from the receiver to increase computational efficiency and accuracy. For a case study in the Celtic Sea, the adaptive grid represented a 2 to 5 fold increase in computational efficiency in August and December respectively, compared to a high resolution 1 km grid. A 5 km grid increased computational efficiency 5 fold again. However, over the first 25 km, the 5 km grid produced errors up to 13.8 dB compared to the 1 km grid, whereas, the adaptive grid generated errors of less than 0.5 dB.

The Yangtze River exhibits a high biodiversity and plays an important role in global biodiversity conservation. As the world's busiest inland river in regard to shipping, little attention has been paid to underwater noise pollution. In 2017, the underwater noise level in 25 riverside locations along the middle and lower reaches of the Yangtze River mainly at night time were investigated by using passive acoustic monitoring method. Approximately 88% and 40% of the sampled sites exhibit noise levels exceeding the underwater acoustic thresholds of causing responsiveness and temporary threshold shift, respectively, in cetacean. Noise pollution may impose a high impact on fish with physostomous swim bladders and Weberian ossicles, such as silver carp, bighead carp, goldfish and common carp, whereas it may affect fish with physoclistous swim bladders and without Weberian ossicles, such as lake sturgeon and paddlefish, to a lesser extent. Noise levels reductions of approximately 10 and 20 dB were observed in the middle and lower reaches, respectively, of the Yangtze River over the 2012 level. The green development mode of the ongoing construction of green shipping in the Yangtze River Economic Belt, including the development of green shipping lanes, ports, ships and transportation organizations, may account for the alleviated underwater noise pollution. Follow-up noise mitigation endeavors, such as the extension of ship speed restrictions and the study and implementation of the optimal navigation speed in ecologically important areas, are required to further reduce the noise level in the Yangtze River to protect local porpoises and fish.

We proposed a machine learning-based underwater noise classification method that extracts five underwater noise features (the 1/3 octave noise spectrum level (NL), time–frequency spectrum, power spectral density (PSD), Mel-frequency cepstral coefficient, and Mel filter bank energy) from three domains (the frequency, time–frequency and Mel transform domains). We classified underwater noise using the support vector machine (SVM) and convolutional neural networks (CNN) methods and verified the results using the original data from five classes of typical underwater noise and noise-added data with different signal-to-noise ratios (SNRs). The results show that under different SNR conditions, the classification performance were better with the input features of NL and PSD; when the SNR was −10 dB, the corresponding classification accuracies were 98.95% and 97.65%, respectively. The CNN method outperformed the SVM method for classifying underwater noise, and when the SNR was above −20 dB, the mean classification accuracies of the SVM and CNN methods were 87.8% and 95.6%, respectively.

Passive acoustic monitoring is a valuable tool for non-intrusive monitoring of marine environments, also allowing the assessment of underwater noise that can negatively affect marine organisms. Here we provide for the first time, an assessment of noise levels and temporal soundscape patterns for a European estuary. We used several eco-acoustics methodologies to characterize the data collected over six weeks within May 2016 - July 2017 from Tagus estuary. Biophony was the major contributor dominated by fish vocalizations and the main driver for seasonal patterns. Maritime traffic was the major source of anthropogenic noise, with daily patterns monitored using 1584 Hz third-octave band level. This indicator avoided biophony and geophony, unlike other indicators proposed for the EU Marine Strategy Framework Directive. Furthermore, the frequency overlap between anthropophony and biophony demands precautionary actions and calls for further research. This study provides an assessment that will be useful for future monitoring and management strategies. Fundação para a Ciência e Tecnologia - FCT info:eu-repo/semantics/publishedVersion

One of the newly emerging environmental issues is underwater noise pollution. It has both negative environmental and socio-economic impacts and threatens sustainable shipping. While other types of shipping pollutants have been regulated and societal awareness has been raised, due to the intangible characteristics of underwater noise pollution, there is neither societal awareness nor an international legally binding instrument to mitigate underwater noise pollution. This paper aims to raise awareness of ship owners regarding UWN pollution by introducing the sources of UWN pollution, as well as proposing a transdisciplinary policy for shipping companies to mitigate UWN pollution from their ships. The proposed policy is aligned with IMO's initial GHG strategy, especially the Energy Efficiency Design Index, Energy Efficiency Existing Ship Index, and Enhanced Ship Energy Efficiency Management Plan. This multi-dimensional approach will make stakeholders more enthusiastic to tackle underwater noise pollution while enhancing the efficient use of capacities and resources.

Until now, physiological stress assessment of large whales has predominantly focused on adrenal glucocorticoid (GC) measures. Elevated GC concentrations in feces (fGC) are known to reflect stressful disturbances, such as fishing gear entanglement and human-generated underwater noise, in North Atlantic right whales (Eubalaena glacialis). However, there can be considerable variation in GC production as a function of sex and life history stage, which may confound the interpretation of fGC levels. Additionally, GC antibodies used in immunoassays can cross-react with other fecal metabolites (i.e., non-target steroids), potentially influencing fGC data. Here, aldosterone concentrations (fALD; aldosterone and related metabolites) were measured in fecal samples from right whales (total n=315 samples), including samples from identified individuals of known life history (n=82 individual whales), to evaluate its utility as a complementary biomarker to fGC for identifying adrenal activation. Concentrations of fALD were positively correlated with fGCs in right whales (r=0.59, P0.001), suggesting concurrent secretion of these hormones by the adrenal gland. However, fALD levels were less influenced by concentrations of reproductive steroids in feces, minimizing the potential confounder of assay cross-reactivity in samples with highly skewed hormone ratios. Across different life history states for right whales, fALD concentrations showed similar patterns to those reported for fGC, with higher levels in pregnant females (35.9±7.6ng/g) followed by reproductively mature males (9.5±0.9ng/g) (P0.05), providing further evidence of elevated adrenal activation in these groups of whales. The addition of fALD measurement as a biomarker of adrenal activation may help distinguish between intrinsic and external causes of stress hormone elevations in large whales, as well as other free-living wildlife species, providing a more comprehensive approach for associating adrenal activation with specific natural and anthropogenic stressors.

Underwater acoustic metasurface is rising in recent years for its capability of low-frequency acoustic blocking and isolating underwater acoustic signals. Inspired by the superhydrophobic systems in nature, a laser textured superhydrophobic cavity structure acoustic metasurface is proposed for enhancing the underwater sound insulation performance. Two laser texturing prepared overlay and substrate aluminum alloy plates are seamlessly bonded together to form the laser textured overlay cavity structured acoustic surface (LTOCS). The acoustic characteristics testing results showed excellent sound insulation effect of the LTOCS in the designed response frequency range (50–60 kHz). The underwater sound transmission coefficient is reduced by up to 81%. This study provides a technical scheme for effective control of underwater low-frequency acoustic waves which can be used to suppress underwater noise propagation, acoustic stealth, underwater detection, etc.

The extraction, time–frequency (TF) tracking and enhancement of whistle signals play an important role in biological research or non-biological research about whistle signals of cetaceans. Underwater noise is a major hurdle in the automated extraction of whistle from sound recording files. Another major hurdle is that some whistle signals that overlap each other need to be separated automatically. This paper proposes a whistle signal processing algorithm based on time–frequency spectrum (TFS) image and morphology processing, which can extract whistle signals from noisy background noise and achieve TF tracking and enhancement of whistle signals. This algorithm has revealed perform well during dealing with the above-mentioned challenging problem. Experiments show that, under low signal-to-noise ratio (SNR) conditions, the algorithm can still accurately extract, and track, and enhance the whistle signals. In addition, the algorithm can also separate whistle signals which overlap each other.

Greater demands for underwater sound absorption materials have been growing due to the concern about underwater noise control in water. Among the range of existing materials, polymer-based materials are increasingly being utilized as underwater sound absorption materials. In this paper, different kinds of polymer-based materials for underwater sound absorption with regards to key factors associated with sound absorption properties, measurements, applications, and mechanisms are reviewed and summarized. Commonly used polymers for underwater sound comprise, in general, interpenetrating polymer networks (IPN), polymer foams, and gradient polymers. To further improve underwater sound absorption performance, different types of inclusions that are introduced into the polymer matrix to transform the polymers as underwater sound absorption materials via air voids, solid inclusions, nanofillers, and phononic crystals are discussed. Challenges for further development of better polymer-based acoustic materials to meet requirements of current and future underwater applications are also presented.

This paper argues the need for consideration of both animal welfare and conservation when making management decisions regarding human activities that affect marine mammals. Population level effects may take a long time to be determined, whereas animal welfare metrics can be observed in the short term, enabling problems to be addressed more rapidly. In addition, implementing current legislation in many countries related to the management of impacts on marine mammals requires animal welfare to be taken into account. Such legislation reflects societal values and public concern for individual animals. Two case studies are discussed. These are: management measures related to incidental killing in commercial fisheries, and injury or disturbance from intense sources of underwater noise from seismic surveys. Both of these threats have welfare and conservation implications for marine mammals. An increased focus on welfare would better reflect societal values including requirements under various legal regimes and could also enable more targeted and effective conservation actions.

This study focused on whistles produced by Guiana dolphin under different noise conditions in Guanabara Bay, southeastern Brazil. Recording sessions were performed with a fully calibrated recording system. Whistles and underwater noise levels registered during two behavioral states were compared separately between two areas. Noise levels differed between the two areas across all frequencies. Whistle duration differed between areas and was negatively correlated with noise levels. Whistling rate was positively correlated with noise levels, showing that whistling rate was higher in noisier conditions. Results demonstrated that underwater noise influenced Guiana dolphin acoustic behavior.

Free-ranging individual fish were observed using a baited remote underwater video (BRUV) system during sound playback experiments. This paper reports on test trials exploring BRUV design parameters, image analysis and practical experimental designs. Three marine species were exposed to playback noise, provided as examples of behavioural responses to impulsive sound at 163–171 dB re 1 μPa (peak-to-peak SPL) and continuous sound of 142.7 dB re 1 μPa (RMS, SPL), exhibiting directional changes and accelerations. The methods described here indicate the efficacy of BRUV to examine behaviour of free-ranging species to noise playback, rather than using confinement. Given the increasing concern about the effects of water-borne noise, for example its inclusion within the EU Marine Strategy Framework Directive, and the lack of empirical evidence in setting thresholds, this paper discusses the use of BRUV, and short term behavioural changes, in supporting population level marine noise management.

Anthropogenic underwater noise levels have generally increased as industrial activities in the ocean have become more prevalent. Because of the central nature of sound in the lives of many marine animals, and the known and potential adverse impacts of noise, it is also gaining increased international recognition as an important global conservation issue. Here, a current compilation and synthesis of official documents, reports, and strategic plans from various intergovernmental, governmental, and international organizations, and noise-related projects and programs, demonstrate increasing efforts to understand anthropogenic underwater noise, and the mitigation and management measures that are being considered to reduce noise. While some entities aim to better understand and quantify underwater noise and its impacts, others have recommended explicit mitigation measures including spatio-temporal approaches to managing noise sources, and vessel quieting technologies. New approaches also include the development of certification or voluntary noise-reduction programs and agreements. We highlight four considerations that will better link the potential impacts of noise with corresponding mitigation and noise reducing efforts: 1) collaboration to address the transboundary and cumulative nature of underwater noise; 2) differing countries’ implementation capabilities for addressing noise; 3) time and intensity tradeoffs (e.g., louder noise for a shorter time period versus quieter but for longer); and 4) variable noise impacts depending on specific life history stages and life functions. Our review affirms the international consensus that anthropogenic underwater noise is a currently pervasive yet relatively transient form of pollution, the effects of which can be significantly reduced through effective mitigation and regulatory action.

Mitigation of shipping noise is a topical issue in marine engineering because of the dramatic increase in the levels of anthropogenic underwater noise and its impact on marine life. In recent years, hydro-acoustic research has focussed on the development of reliable methods for predicting underwater radiated noise (URN) due to cavitation, which is known to be the dominant contribution to the overall radiated noise spectrum of ships above the cavitation inception threshold. Model-scale measurements are currently considered the most reliable approach to study URN problems in marine engineering and are crucial for the verification and validation of numerical methods. However, their reliability is affected by several uncertainty sources for which suitable test procedures and post-processing techniques are needed. As a means to better understand the accuracy and reliability of underwater radiated noise measurements, a round-robin (RR) test programme for an open water propeller setup was organized within the Community-of-Practice “Noise” of the HydroTesting Forum, with the aim of comparing results among several institutes (i.e. University of Genova UNIGE, University of Newcastle UNEW, NMRI, SSPA, KRISO, CNR-INM and MARIN). This paper reports an overview of the RR programme and compares the different approaches and results.

The effect of shaft inclination can induce important unsteady hydrodynamic phenomenon usually associated with small and high-speed craft. This paper presents systematic cavitation tunnel tests with a 214 mm diameter model propeller of a catamaran research vessel. The propeller is subjected to uniform and inclined flow conditions, to investigate its efficiency, cavitation and underwater radiated noise characteristics. The experiments were conducted in the Emerson Cavitation Tunnel of Newcastle University based on the starboard 5 -bladed right-hand propeller of the University׳s research vessel, The Princess Royal . In the paper the details of the tests and significant findings for the effect of the shaft inclination on the propeller efficiency, cavitation and underwater radiated noise characteristics are presented. A better understanding is sought in relation to the noise signatures of different types of cavitation. The systematic tests presented in the paper also have a long-term objective, being the first of an organised round robin test campaign that is being currently undertaken by the members of the Underwater Noise Community of Practice (CoP) of Hydro-Testing Forum (HTF). This long-term objective is to repeat similar tests in the different facilities of all CoP members to reveal the relative merits of their testing facilities for underwater noise investigations.

Offshore wind power comprises a relatively new challenge for the international wind industry with a demonstration history of around twenty years and a ten-year commercial history for large, utility-scale projects. By comparison to other forms of electric power generation, offshore wind energy is generally considered to have relatively benign effects on the marine environment. However, offshore projects include platforms, turbines, cables, substations, grids, interconnection and shipping, dredging and associated construction activity. The Operation & Maintenance (OM mainly the underwater noise and the impacts on the fauna. Based on the fact that in many of the aforementioned issues there are still serious environmental uncertainties, contradictive views and emerging research, the present work intents to provide a thorough literature review on the environmental and social impacts of offshore wind energy projects in comparison with the onshore counterparts.

The standard propeller has been investigated in model scale, using medium size cavitation tunnel. The hydroacoustic characteristics of propellers under different loading conditions have been investigated. Additionally the presented experimental results have been used for the verification of applied numerical approach. During both numerical and experimental analyses non-uniform inflow propeller’s conditions have been adapted. Good correlations of both kinds of results have been noticed and highlighted.

Assessment of underwater noise is increasingly required by regulators of development projects in marine and freshwater habitats, and noise pollution can be a constraining factor in the consenting process. Noise levels arising from the proposed activity are modelled and the potential impact on species of interest within the affected area is then evaluated. Although there is considerable uncertainty in the relationship between noise levels and impacts on aquatic species, the science underlying noise modelling is well understood. Nevertheless, many environmental impact assessments (EIAs) do not reflect best practice, and stakeholders and decision makers in the EIA process are often unfamiliar with the concepts and terminology that are integral to interpreting noise exposure predictions. In this paper, we review the process of underwater noise modelling and explore the factors affecting predictions of noise exposure. Finally, we illustrate the consequences of errors and uncertainties in noise modelling, and discuss future research needs to reduce uncertainty in noise assessments.

In EU FP7 project SONIC, partners set out in October 2012 to study the underwater radiated noise of ships and shipping. The objectives of the project were (1) to study the numerical and experimental techniques to determine the underwater noise; (2) to develop methods for mapping the noise of ships and shipping; and (3) to determine mitigation measures to reduce the underwater radiated noise. Numerical methods focused on determination of the cavitation extent and dynamics on propellers which is the main source of noise of commercial shipping. Research also focused on methods to determine the underwater radiated noise from machinery. Experimental methods in model test facilities have been studied and validated against dedicated full scale measurements. The ship noise source levels obtained from these numerical and experimental methods provide input to shipping noise mapping tools to determine the overall underwater noise in a certain sea area. Based on the experience gained in the SONIC project, a set of guidelines for regulators concerned with underwater radiated noise of ships were developed together with the AQUO project. These guidelines discuss the definitions, numerical and experimental methods and mitigation solutions for underwater radiated noise. This paper gives an overview of the work done by all partners in the SONIC project.

Measurements of underwater noise radiated under ship normal operations are presented. The acoustic data, from the cabled ocean observatory, are analyzed under each identified ship passage, which was obtained by the Automatic Identification System. Under each passage, sound pressure level is calculated to observe local noise variations due to shipping noise. This paper emphasizes the study of noise variations at the observatory, presents the noise measurements under identified ship passages in the last several years, and provides references for predictive models of underwater noise pollution from commercial ship traffic. From the passages of one ship to the passages of 26 ships, the measurements reveal similar variation patterns when the ships traveled at similar courses, but different patterns when they traveled at different courses. When evaluating the noise variations due to ship traffics, it is important to consider the shipping noise propagation as well as ship movement.

The Lithuanian sea space belongs to the smallest sea areas in Europe. The sea space incorporates multiple marine ecosystem services (MES) that support human-wellbeing and sustain maritime economies, but is also subjected to intensive anthropogenic activities that can affect its vulnerable ecological components. We present a flexible geospatial methodology to assess MES richness (MESR) and to analyse areas of exposure of MES to human impacts using a MES exposure index (MESEx). Source of anthropogenic threats to MES were firstly derived from the Marine Strategy Framework Directive and include marine litter (from ports and shipping), underwater noise (from offshore pile driving and shipping) and hazardous substances (from oil extraction platforms). Results were presented for the three main planning areas in Lithuania, the Lithuanian Coastal Stripe, territorial waters and EEZ. In detail, areas of highest MESR are located in the coastal areas of the Lithuanian Mainland Coast that are particularly rich in ecosystem services such as nursery function from for Baltic Herring and cultural services related to valuable recreational resorts, landscape aesthetic values and natural heritage sites. Modelled pressure exposure on selected MES show that cultural ecosystem services in proximity of Klaipėda Port can be particularly affected by marine litter accumulation phenomena, while transboundary effects of potential oil spills from D6-Platform (Kaliningrad Region) can affect valuable fish provisioning areas and coastal cultural values in the Curonian Spit. Results were discussed for the relevance in MES assessment for marine spatial planning in small sea areas and the methodological outlook of the application of geospatial techniques on cumulative impacts assessment within this region of the Baltic Sea.

Development of human activities in the Klaipėda strait generates a wide spectrum of underwater noise. In the fall of 2013, at the liquid natural gas terminal construction site in the shallow Curonian Lagoon area, an assessment of possible negative impacts on migrating salmon fish caused by pile driving noise was made. It is well known that impact hammer pile driving generates pulses with extremely high underwater noise levels. The obtained results proved that the pile hammering into the lagoon bottom generated pulses with a sound exposure level of 218 dB re 1 μPa2 s @1 m thus posing a risk to the migrating fish.

This paper describes the interpretations of underwater noise spectra of rainfall on water bodies. It uses a simple methodology of measurement of bubbles of various sizes up to 10 mm in diameter and the comparison of resonating frequencies of the above bubbles with theoretical calculations. The underwater noise of rainfall is a combined effect of drop impacts and bubble bursting. The rain drop size during actual rainfall varies between 0.8 and 5 mm in diameter and the underwater bubble sizes can vary from 0.5 mm to 10 mm in diameter. The detailed description of the experimental results of the underwater spectrum of natural light rain and artificially generated rain are presented. By analyzing the resonating frequencies of underwater bubbles for different type of rainfall, it is plausible to interpret the underwater noise spectrum of rainfall on water bodies and then predict the amount of rainfall.

The impact of underwater noise on marine life calls for identification of exposure criteria to inform mitigation. Here we review recent experimental evidence with focus on the high-frequency cetaceans and discuss scientifically-based initial exposure criteria. A range of new TTS experiments suggest that harbour and finless porpoises are more sensitive to sound than expected from extrapolations based on results from bottlenose dolphins. Furthermore, the results from TTS experiments and field studies of behavioural reactions to noise, suggest that response thresholds and TTS critically depend on stimulus frequency. Sound exposure levels for pure tones that induce TTS are reasonably consistent at about 100 dB above the hearing threshold for pure tones and sound pressure thresholds for avoidance reactions are in the range of 40–50 dB above the hearing threshold. We propose that frequency weighting with a filter function approximating the inversed audiogram might be appropriate when assessing impact.

Human activities in and around waters generate a substantial amount of underwater noise, which may negatively affect aquatic life including fish. In order to better predict and assess the consequences of the variety of anthropogenic sounds, it is essential to examine what sound features contribute to an impact. In this study, we tested if sounds with different temporal structure resulted in different behavioural changes in European seabass. Groups of four fish were exposed in an outdoor basin to a series of four sound treatments, which were either continuous or intermittent, with either consistent or fluctuating amplitude. The behavioural changes of the fish were analyzed by a video-tracking system. All sound treatments elicited similar behavioural changes, including startle responses, increased swimming speed, increased group cohesion and bottom diving. However, with all other sound conditions being the same, intermittent exposure resulted in significantly slower behavioural recovery to pre-exposure levels compared to continuous exposure. Our findings imply that the temporal structure of sound is highly relevant in noise impact assessments: intermittent sounds, such as from pile driving, may have a stronger behavioural impact on fish than continuous sounds, such as from drilling, even though the latter may have higher total accumulated energy. This study urges regulatory authorities and developers to pay more attention to the influence of temporal structure when assessing noise impacts. However, more studies are needed to examine other sound parameters and to determine the generality of our observations in other species and in other outdoor water bodies.

Acoustic noise has the potential to cause stress, to distract and to mask important sounds, and thus to affect behaviour. Human activities have added considerable noise to both terrestrial and aquatic habitats, and there is growing evidence that anthropogenic noise affects communication and movement patterns in a variety of species. However, there has been relatively little work considering the effect on behaviours that are fundamental to survival, and thus have direct fitness consequences. We conducted a series of controlled tank-based experiments to consider how playback of ship noise, the most common source of underwater noise, affects foraging and antipredator behaviour in the shore crab, Carcinus maenas. Ship noise playback was more likely than ambient-noise playback to disrupt feeding, although crabs experiencing the two sound treatments did not differ in their likelihood of, or speed at, finding a food source in the first place. While crabs exposed to ship noise playback were just as likely as ambient-noise controls to detect and respond to a simulated predatory attack, they were slower to retreat to shelter. Ship noise playback also resulted in crabs that had been turned on their backs righting themselves faster than those experiencing ambient-noise playback; remaining immobile may reduce the likelihood of further predatory attention. Our findings therefore suggest that anthropogenic noise has the potential to increase the risks of starvation and predation, and showcases that the behaviour of invertebrates, and not just vertebrates, is susceptible to the impact of this pervasive global pollutant.

Responding to the increasing number, size, and speed of commercial ships, the underwater noise is also increasing which could result in a possible adverse impact on marine lives. For clarifying this possible concern, a method for measurement of ship noise and marine lives is required, especially for marine mammals which are sensitive for the frequency range of ship noise. In order to enable to observe marine mammal's behavior and the ship noise simultaneously, this study developed an algorithm to detect ship noise, added to a conventional dolphin detection algorithm. The ship noise is obtained by eliminating some nature sounds and the dolphin's sonar sound. Both dolphin's sounds and ship noises can be separated efficiently so that the noise can be identified using sample data. Further improvement of monitoring system and algorithm are future tasks.

Marine mammal management traditionally focuses on lethal takes, but non-lethal (or not immediately lethal) impacts of human disturbance, such as prolonged or repeated activation of the stress response, can also have serious conservation implications. The physiological stress response is a life-saving combination of systems and events that maximises the ability of an animal to kill or avoid being killed. However, “chronic stress” is linked to numerous conditions in humans, including coronary disease and infertility. Through examples, including beaked whales and sonar exposure, we discuss increasing human disturbance, mal-adaptive stress responses and chronic stress. Deep-diving and coastal species, and those targeted by whalewatching, may be particularly vulnerable. The various conditions linked with chronic stress in humans would have troubling implications for conservation efforts in endangered species, demands management attention, and may partly explain why some species have not recovered after protective measures (e.g., smaller protected areas) have been put into place.

The study of the organ of Corti is essential to assess the impact of underwater noise on cetaceans. While classical histology techniques (including EDTA decalcification) have been previously considered, the process is time consuming. Independently from the histological technique, one of the challenging steps after extraction and fixation of the samples is to decalcify the bone envelope to access the cochlea without damaging the soft tissues. Here, we propose to use a fast commercial decalcifier (RDO®). 93 ears from 11 different odontocetes species stranded in the Mediterranean, Spanish North Atlantic and North Sea were used to precisely determine the decalcification time. Depending on the tympanic–periotic volume of the species, the decalcification time ranged from several hours to a few days, allowing a subsequently faster observation of the cochlear structures through routine microscope techniques.

Feature selection of noise sources is important for noise sources detection and classification. In this paper, a new rough set based feature selection method has been given. Based on the method, a noise sources automatic classification system (NSACS) has been designed and validated. The key idea of the method is that most effective features can distinguish the most number of samples belonging to different classes of noise sources, if they are used for classification. This new approach has been applied into the system NSACS to select relevant features for artificial datasets and real-world datasets and the results have shown that this approach can correctly select all the relevant features of artificial datasets and at the same time it can drastically reduce the number of features. From the experiments, it can be found that to consider all the five datasets, the number of classification features after selection drops to 35% and the accurate classification rate increases about 14%. For the underwater noise sources dataset the number of features drops to 1/5 and the accurate classification rate increases about 6% after feature selection.

Reports of the effects of man-made noise on the behavior and related processes of marine animals are widely scattered among a variety of literature sources. This report brings much of this literature together and attempts a synthesis by a comparative analysis of the results obtained from taxonomically diverse species. Mammals and fishes are emphasized since little is known about the subject in other groups. Field studies have shown aversion by various baleen and toothed whales to the noise accompanying offshore petroleum exploration and production. Variation in response involves: level of source-noise to that of the ambient, degree of naivete of the animals to the source-noise, on-going activity at the time of exposure and, to an uncertain degree, the species involved. Although seals and their relatives have not been adequately examined regarding their response to underwater noise, individuals have been shown to be clearly susceptible (anatomically based) to high levels of such noise. Studies have also shown the deleterious effects of even moderate noise levels on hearing in fishes. Aversion to various types of man-made noise has been noted several times, with associated levels being similar to those noted when similar responses were recorded by whales. Finally, several studies have documented abnormal growth and reproductive processes in several species of fin- and shellfish due to high levels of man-made noise. Such findings should be of concern to the field of aquaculture, since it is dependent on such fundamental processes.

Maps based on predictions of underwater noise pollution could give whales much-needed peace and quiet

Behaviour near actual and simulated activities associated with offshore oil exploration was compared with ‘presumably undisturbed’ behaviour. Underwater noise was monitored. Reactions to an approaching fixedwing aircraft were frequent if it was at ≤305 m above sea level, infrequent at 457 m, and not detected at 610 m. When boats closed to within 1–4 km, surface/dive cycles became shorter and the whales swam rapidly away. Fleeing ceased when the vessel was a few kilometres beyond the whales, but scattering persisted longer. Bowheads did not move away from seismic vessels ≥ 6 km away, but subtle effects on behaviour sometimes were suspected. We found bowheads as close as 4 km from drillships and