The hydro-acoustic noise radiating from underwater tunnels during vehicle passage may be harmful to aquatic fauna, and this is a particular concern for endangered species. Therefore, the effects of underwater noise radiation and propagation on aquatic biodiversity must be investigated. In this study, the dynamic response of the sediment and tunnel structure in the Yangtze River in China was explored by conducting a field test, and the associated noise radiation from the tunnel was recorded and investigated. A three-dimensional numerical model was then developed to simulate the vibration of the tunnel-sediment coupling system induced by random traffic-flow models. Next, a modal acoustic transfer vector-based method was used to predict underwater noise radiation by use of a three-dimensional finite-element acoustic model. Finally, the accuracy of the simulated results was verified by comparison with measurements. The results showed that the noise radiation induced by passing vehicles was approximately 14 dB greater than the background noise, with a main frequency range of 12–25 Hz. The random traffic-flow model had obvious influence of the simulated noise level above 20 Hz. Vehicle-induced underwater noise may thus have a direct effect on fish species that can perceive low-frequency sound pressure. The proposed method can be used for further investigation of methods to reduce the effect of underwater noise on aquatic fauna, especially endangered species.

Among the noisiest man-made activities in the seas, emitting very high acoustic energy are the underwater explosions of various objects and ship shock trials. Sound energy emitted by high explosives can be predicted or measured at sea. Sometimes, it can be convenient to apply empirical formulas and scaling laws to approximate the energy of underwater explosions. In addition, at some instances the determination of the spectral properties of the explosions is useful, i.e. when possible animal exposure to impulsive noise has to be evaluated. This paper presents an example of an application of freely available scaling laws and equations for prediction of noise levels of underwater explosions of historical ordnance in the shallow sea environments.Main findings of the study: An available scaling laws applied to model underwater explosion properties; spatial extent of explosion mapped; arising issues of modelling of underwater explosions in the shallow marine areas discussed.

Underwater radiated noise from shipping is globally pervasive and can cause deleterious effects on marine life, ranging from behavioural responses to physiological effects. Acoustic modelling makes it possible to map this noise over large areas and long timescales, and to test mitigation scenarios such as ship speed reduction or spatial restrictions. However, such maps must be validated against measurements to ensure confidence in their predictions. This study carried out a multi-site validation of the monthly and annual shipping noise maps for 2019 produced as part of the Joint Monitoring of Ambient Noise in the North Sea (JOMOPANS) programme. Spectral, spatial, and temporal differences between predictions and measurements were analysed, with differences linked to uncertainty in model input data and additional sources of anthropogenic noise in the measurements. Validating shipping noise models in this way ensures they can be applied with confidence in future management decisions to address shipping noise pollution.

Loud sound emitted during offshore industrial activities can impact marine mammals. Regulations typically prescribe marine mammal monitoring before and/or during these activities to implement mitigation measures that minimise potential acoustic impacts. Using seismic surveys under low visibility conditions as a case study, we review which monitoring methods are suitable and compare their relative strengths and weaknesses. Passive acoustic monitoring has been implemented as either a complementary or alternative method to visual monitoring in low visibility conditions. Other methods such as RADAR, active sonar and thermal infrared have also been tested, but are rarely recommended by regulatory bodies. The efficiency of the monitoring method(s) will depend on the animal behaviour and environmental conditions, however, using a combination of complementary systems generally improves the overall detection performance. We recommend that the performance of monitoring systems, over a range of conditions, is explored in a modelling framework for a variety of species.

Canadian Arctic and Subarctic regions experience a rapid decrease of sea ice accompanied with increasing shipping traffic. The resulting time-space changes in shipping noise are studied for four key regions of this pristine environment, for 2013 traffic conditions and a hypothetical tenfold traffic increase. A probabilistic modeling and mapping framework, called Ramdam, which integrates the intrinsic variability and uncertainties of shipping noise and its effects on marine habitats, is developed and applied. A substantial transformation of soundscapes is observed in areas where shipping noise changes from present occasional-transient contributor to a dominant noise source. Examination of impacts on low-frequency mammals within ecologically and biologically significant areas reveals that shipping noise has the potential to trigger behavioral responses and masking in the future, although no risk of temporary or permanent hearing threshold shifts is noted. Such probabilistic modeling and mapping is strategic in marine spatial planning of this emerging noise issues.

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 218dB re 1μPa2s @1m thus posing a risk to the migrating fish.

Motorized vessels are a major source of anthropogenic noise and can have adverse effects on species relying on sound for communication and feeding. Monitoring noise levels received by endangered southern resident killer whales (SRKWs) requires knowing the number, distance, and speed of surrounding vessels, including small boats that do not have Automatic Identification Systems (AIS). A method for estimating their speed is required to predict received noise levels and compliance with vessel regulations. We compared theodolite and photogrammetry methods to estimate the number, distance, and speed of vessels in SRKW Salish Sea summertime critical habitat. By treating AIS as “truth”, we found photogrammetry-derived ranges and speeds were more variable than theodolite estimates. Error in photogrammetry-derived speeds increased with range. Overall, we found time saved in the field using photogrammetry was more than offset by long analysis time. Theodolite data were relatively easy to collect, and produced accurate and precise results.