Underwater noise modelling for environmental impact assessment

Underwater noise from human activities appears to be rising, with ramifications for acoustically sensitive marine organisms and the functioning of marine ecosystems. Policymakers are beginning to address the risk of ecological impact, but are constrained by a lack of data on current and historic noise levels. Here, we present the first nationally coordinated effort to quantify underwater noise levels, in support of UK policy objectives under the EU Marine Strategy Framework Directive (MSFD). Field measurements were made during 2013–2014 at twelve sites around the UK. Median noise levels ranged from 81.5–95.5 dB re 1 μPa for one-third octave bands from 63–500 Hz. Noise exposure varied considerably, with little anthropogenic influence at the Celtic Sea site, to several North Sea sites with persistent vessel noise. Comparison of acoustic metrics found that the RMS level (conventionally used to represent the mean) was highly skewed by outliers, exceeding the 97 th percentile at some frequencies. We conclude that environmental indicators of anthropogenic noise should instead use percentiles, to ensure statistical robustness. Power analysis indicated that at least three decades of continuous monitoring would be required to detect trends of similar magnitude to historic rises in noise levels observed in the Northeast Pacific. Underwater noise pollution can have adverse effects on marine organisms 1–4 and appears to be correlated with global economic growth 5. Sources of noise such as shipping 6 , pile driving 7 , geophysical seismic surveys 8,9 , and naval sonar operations 10 have each been linked to detrimental effects on marine fauna. Long-term measurements from deep-water sites in the Northeast Pacific have shown that low-frequency (<~50 Hz) noise levels in that ocean basin increased markedly (by ~10 dB) between the 1960 s and mid-1990 s 11,12. Since then, this trend has largely levelled off or begun to decline 13 , and data from the past decade suggest that more recent trends in noise levels for other ocean basins may also be mixed 14. The extent to which these open-ocean trends apply to the shallower continental shelf seas where human activity is concentrated is unclear 15 , since long-term datasets for these regions are lacking. Sources of anthropogenic noise can be categorised as impulsive or continuous 16. Each type is associated with particular effects on marine fauna, and each requires a bespoke management approach to mitigate potential impact 17. Impulsive noise consists of brief, discrete sounds with a sudden onset, such as acoustic pulses from explosions, pile driving, or seismic airguns. Such sources can elicit acute effects on animals including permanent or temporary auditory damage 16 , physiological stress, and antipredator responses (e.g. displacement 18). For example, short-term displacement of harbour porpoise has been reported in response to pile driving 7 and seismic surveys 19 , and in situ exposure of European seabass to pile driving has been observed to induce physiological stress 20. Such noise sources are associated with activities that are typically subject to a regulatory consenting process , and can therefore be managed through licence conditions required by these regulatory processes. Continuous anthropogenic noise is primarily generated by shipping. Since shipping routinely crosses international boundaries, management of shipping noise requires a coordinated international response (e.g. through the International Maritime Organisation). The widespread increase in noise levels caused by continuous sources has been associated with acoustic masking of biologically important cues 18,21 , disruption to foraging 22 , increased physiological stress 2,6 , and developmental deficiencies 23 in aquatic species. Although continuous noise sources are typically less intense than impulsive sources, the pervasive presence of continuous noise from shipping could lead to more significant and widespread effects 2,24. This is of particular concern given that vessel noise can affect species that mediate important ecosystem functions 25 , as well as altering predator-prey dynamics 26 .

Marine Pollution Bulletin, 2011

Recent observations of cetacean mass strandings, coincident with anthropogenic sounds emissions, have raised concerns on the potential environmental impact of underwater noise. Cuvier’s beaked whale (Ziphius cavirostris) was reported in all the cited stranding events. Within the NATO Marine Mammal Risk Mitigation project (MMRM), multiple interdisciplinary sea trials have been conducted in the Mediterranean Sea with the objective of developing tools and procedures to mitigate the impact of underwater sound emissions. During these cruises, visual observations, passive acoustic detections and environmental data were collected. The aim of this study was to evaluate “a priori” predictions of Cuvier’s beaked whale presence in the Alboran Sea, using models developed in the Ligurian Sea that employ bathymetric and chlorophyll features as predictors. The accuracy of these predictions was found adequate and elements are given to account for the uncertainties associated to the use of models developed in areas different from their calibration site.► Bathymetry and chlorophyll can be predictors of Cuvier’s beaked whale habitat. ► The transferability of models calibrated in different areas was proven. ► Uncertainty factors can be employed for model-based risk mapping of unsurveyed areas.

Marine Pollution Bulletin, 2013

The effects of anthropogenic underwater noise on marine life is of growing concern and assessment of impacts on marine life is often carried out using predictive underwater noise models to map zones of influence for marine species. However, these models do not predict how a species may react to that noise. In this paper, the results from a modified predictive underwater noise model and a hydrodynamic model are used in an individual based model (IBM) to predict the impacts on cod (Gadhus moruha) from noise generated during a pile driving event at an offshore wind farm in Liverpool Bay, UK. The model included cod which were sensitive to noise and those which were insensitive ('deaf'). Fish movement was from the outer bay into the Dee Estuary, a known feeding ground. The IBM indicated that the cod which could hear took up to 7 days longer to reach their destination than the cod which were deaf. This technique could be used during the consenting process for offshore projects to better understand the potential impact on marine species.

Handbook on Marine Environment Protection, 2017

Over the last decade the issue of underwater noise pollution has received increased attention from scientific bodies, the media, NGOs, and institutions at the national, supranational and international levels. This in turn, has led to the development of several regulatory initiatives that seek to mitigate the negative impact of this source of pollution. This article outlines and analyses existing legislation and management regimes that govern marine activities that generate noise. Best practices and specific mitigation measures are also addressed and assessed. Underwater noise pollution • Anthropogenic noise input • Underwater sound • Sonar • Pile driving • Whale watching • Seismic surveys • Air guns • Shipping • Off-shore constructions • Offshore infrastructures • Precautionary approach • Marine environment • Marine mammals • Marine life Management? In recent times, the issue of anthropogenic noise input to the marine environment, or "underwater noise", has received increased attention from scientific bodies (

2015

Underwater sound is important for the underwater creatures. It is useful for the navigation, food finding, mating, and also predator detection. The natural phenomenons in the marine environment that produce noise include waves, wind, surf, lightning, precipitation, animals’ sound and also the earthquakes. The frequency of the natural sound was usually below 100 Hz, but rain and waves sounds dominate higher frequencies. However, some human activities can cause the underwater noise pollution such as the sound produced by the ships, sonar, pile driving, dredging, oil and gas explorations and also military activities. The effect of man-made noise is a main threat to marine animals. Fish, in particular, was less attractive with the noisy environments and avoid areas where man-made noise levels are high.The presence of noise also could keep fish changes their way, behavior and reproduction. Our analysis has determined the cause, occurrence and the effect of the underwater noise pollution ...

2019 International Congress on Ultrasonics

The Effects of Noise on Aquatic Life took place in Den Haag, the Netherlands, in July 2019. The potential effects on animals ranging from plankton, shrimps, crabs, and lobsters, to fishes, seals, dolphins, and whales were discussed. Reported effects include behavioral responses, auditory masking, cardiac rate changes, stress, a temporary loss of hearing, and perhaps more serious tissue and organ damage. Shortterm and long-term, individual and population-level effects were portrayed. Several studies also looked at the fundamentals of animal sound production and perception. One session dealt with the regulation and management of underwater noise. Another integral part of the meeting focused on the sounds and sound sources that might affect aquatic life. As a consequence, underwater noise from pile driving, seismic surveying, shipping, and sonars, as well as from non-anthropogenic sources such as wind and waves was examined. The social program was intended to encourage more leisurely discussions amongst conference participants in order to facilitate networking and the strengthening of relationships. The feedback from conference delegates (submitted via an online survey after the meeting) was very positive.

Establishing noise exposure criteria for marine mammals has proven to be a difficult and contentious issue. Over the last decade, several attempts have been made to provide scientifically-based exposure criteria. While representing the " best available science " on the issue, these criteria, and the assumptions underpinning them, have led to considerable discussion among both scientists and policy-makers. However, one area where there has been little or no debate is around the use of appropriate statistical and other numerical procedures in the various criteria-establishing methodologies. A common issue, arising from a desire to include as much data as possible, is pseudoreplication. Examples from acoustic criteria are the use of many data points from a single animal to establish a value for one species and the use of several points from one species to set values for a functional hearing group. Less fundamental, but equally problematic for the application of the criteria to policy, is the failure to adequately represent uncertainty around proposed criteria through the use of confidence intervals. Other issues include the uneven treatment of different data in terms of transformation protocols and extrapolation, and the determination of which " outliers " to discard. Each of these errors introduces bias into the resulting criteria. Thus, despite the paucity of relevant data, we need to meet such statistical standards to truly provide objective advice that rises to the level of the " best available science. "

Over the last two decades, marine noise pollution has become increasingly recognized as an issue of major significance. The issue has become a primary focus of marine mammal research, but is also of concern to the public and policy makers. The result has been efforts involving a variety of disciplines, and relevant legislation and associated guidance are now in place in many parts of the world. Most current mitigation efforts are directed at reducing the risk of injury from exposure to intense noise, although the effectiveness of such mitigation measures in terms of risk reduction has rarely been quantified. Longer-term chronic impacts of noise including disturbance or masking of sounds critical for feeding and reproduction have received substantially less attention in management. New technologies are being developed for a number of activities which can substantially reduce noise inputs into the marine environment. As with other forms of pollution, reducing input at source is likely...

Marine Environmental Research, 2011

Concern about the impact of sound on marine mammals has increased over the last decade, causing governments to take a more rigorous look at the potential impact of activities that introduce sound into the ocean. Environmental Impact Statements (EIS's) can be prepared using differing analysis methods to estimate the impact on marine mammals. To assess consistency in assessment methods, differences in the base assumptions were investigated; in particular, differences that arise between assumptions of dynamic marine mammals (animat method) and static distributions of marine mammals (static distribution method). Using several ocean environment scenarios and species, it is demonstrated that differences consistently arise between the two methods. The static distribution method underestimates the number of behavioral harassments compared with the animat method. Repeating many simulations with the animat method provides a robust risk assessment, provides a measure of variability, and allows the probability of "spurious events" to be estimated.

Anthropogenically driven environmental changes affect our planet at an unprecedented scale and are considered to be a key threat to biodiversity. According to the World Health Organization, anthropogenic noise is one of the most hazardous forms of anthropogenically driven environmental change and is recognized as a major global pollutant. However, crucial advances in the rapidly emerging research on noise pollution focus exclusively on single aspects of noise pollution, e.g. on behaviour, physiology, terrestrial ecosystems, or on certain taxa. Given that more than two-thirds of our planet is covered with water, there is a pressing need to get a holistic understanding of the effects of anthropogenic noise in aquatic ecosystems. We found experimental evidence for negative effects of anthropogenic noise on an individual's development, physiology, and/or behaviour in both invertebrates and vertebrates. We also found that species differ in their response to noise, and highlight the potential underlying mechanisms for these differences. Finally, we point out challenges in the study of aquatic noise pollution and provide directions for future research, which will enhance our understanding of this globally present pollutant.