Impact Of Underwater Noise Research Articles

Developing and testing systems for the attenuation of ships' machinery noise

With ships operating in areas including important marine biodiversity, it is crucial to understand the sources and characteristics of underwater noise and develop effective measures to mitigate underwater noise's impact on the environment. The underwater noise signature from a ship is usually dominated by machinery noise and propulsion engines at low speeds. Given the importance of onboard electrical power, diesel generators might continuously function (i.e., even when a ship is docked) and generate low-frequency underwater noise. Université de Sherbrooke (Sherbrooke, Canada) and Innovation Maritime (Rimouski, Canada) lead a collaborative work focusing on the means and methods for attenuating machinery noise. Two main research axes are considered. The first concerns the setup and validation of a small-scale platform that can be used to test noise reduction methods in a controlled water basin environment. The second research axis investigates passive, tunable, and possibly multi-resonant vibroacoustic solutions to attenuate machinery noise. These solutions mostly come as 3D-printed folded quarter-wave resonators following spiral or cantilever resonators. Acoustic resonators can also be embedded into a layer of sound-absorbing material to improve soundproofing properties at specific frequencies. The applications and scope of this work are finally put into perspective.

On the equivalence of scalar-pressure and vector-based acoustic dosage measures as derived from time-limited signal waveformsa).

The dynamic (acoustic pressure) and kinematic (acoustic acceleration and velocity) properties of time-limited signals are studied in terms of acoustic dose metrics as might be used to assess the impact of underwater noise on marine life. The work is relevant for the study of anthropogenic transient acoustic signals, such as airguns, pile driving, and underwater explosive sources, as well as more generic transient signals from sonar systems. Dose metrics are first derived from numerical simulations of sound propagation from a seismic airgun source as specified in a Joint Industry Programme benchmark problem. Similar analyses are carried out based on at-sea acoustic measurements on the continental shelf, made with a vector sensor positioned 1.45 m off the seabed. These measurements are on transient time-limited signals from multiple underwater explosive sources at differing ranges, and from a towed, sonar source. The study demonstrates, both numerically and experimentally, that under many realistic scenarios, kinematic based acoustic dosage metrics within the water column can be evaluated using acoustic pressure measurements.

Minimal chemical pollution, increased offshore wind farms and energy production sustainability

Minimal chemical pollution, increased offshore wind farms and energy production sustainability Coordinator of the Anemoi project, Bavo De Witte (ILVO), discusses the path to minimal chemical pollution and increasing the sustainability of offshore wind energy. Offshore wind energy production is a relatively sustainable yet fast-growing industry, contributing to the UN development goals on green energy and climate actions. Europe’s total offshore wind power capacity as of September 2023 is 32 GW (1), only 20% of the European target to produce >150 GW by 2030. The vast increase in offshore energy production urged different European countries to monitor the potential effects of offshore wind farms (OWFs) on the marine ecosystem, including the impact of underwater noise, the introduction of novel habitats, and the exclusion of fisheries. However, the potential risk of chemical emissions by OWF structures remains largely unknown though estimated to be small.

Measurements of underwater noise genenrated during wind turbine operation in Korea Southwest Offshore Wind Farm

Offshore wind power generation, a representative eco-friendly energy generation, is known as one of the promising solutions for sustainable development. However, the potential negative impact of underwater noise emitted from wind turbine operation on the marine ecosystem may limit development. Measurements of underwater noise generated from the operation of a 3-MW offshore wind turbine in the Korea Southwest Offshore Wind Farm located off the southwest coast of Korea were made twice in late February to early March and November 2021, and the acoustic characteristics of operational noise with wind speed, rotor speed, and tower vibration were investigated. As a result, the tonal frequencies of the underwater noise and tower vibration acceleration signal coincided, and their changes showed high correlations with the wind speed and rotor speed. Our results may be used as a reference to evaluate the impact of underwater operational noise of offshore wind turbines on the marine environment.

Underwater noise impact assessment of a wave energy converter in the northern Atlantic (Spain)

As most nations around the world commit to decarbonize their economies, the electrification of many sectors is an ongoing trend that will only strengthen in the next years. The energy demands for this transition are considerable, and renewable energies are being pushed to substitute fossil-fuel technologies with great urge.While marine renewable energy (MRE) is still not as developed as wind, hydraulic or photovoltaic energies, it constitutes a promising and mostly untapped resource. MRE may complement quite well the production curves of both wind and solar power, and can provide non-fossil energy to coastal populations, or those located in islands where land is precious, so its development is important to many countries, given that most of the population is located near the coast.Even though MRE does not produce CO2 emissions, their possible impacts on the marine environment are already well theorized, such as encounters with moorings/cables, collisions, underwater pollution (among others) there are still uncertainties in the actual impacts of real WECs on their surrounding ecosystem.This is one of the reasons behind the European research project SafeWAVE - Streamlining the assessment of environmental effects of wave energy (2020-2023), - as well as its predecessor WESE – Wave Energy in Southern Europe (2018-2021)-, which is dedicated to research on the non-technological barriers to the development of the wave energy sector. A fundamental work package of SafeWAVE is the monitoring and modelling of possible relevant impacts of wave energy converters (WEC), including electromagnetic fields, underwater noise, or seabed integrity, using as test cases four different WECs deployed in corresponding test sites, located in Basque Country (Spain), Nantes (France) and Aguçadoura (Portugal).The aim of the present work is to report the results obtained from monitoring, processing, and modelling of underwater noise around one of the wave energy converters (WEC) studied in the context of this project. The monitoring activities consisted of two campaigns, one before and during installation of the device, and another one during its operation and eventual decommissioning. Each one covered a duration of about 45 days, using one and three moored hydrophones surrounding the WEC, respectively. Acquired data was processed and analysed to obtain Sound Pressure Levels (SPL) in 1/3 octave bands ranging from 20 Hz to 20 kHz for different sea states, operational status, and activity (deployment, decommission, etc.). Lastly, underwater transmission losses were modelled using a full range dependent computational model allowing to assess the extent of acoustic disturbance that could be caused by the WEC, and furthermore, by a hypothetical array of several WECs.Initial results evidence differences between the SPL distributions before and after the deployment of moorings, as well as during operation (with respect to background levels), at the location of the hydrophones.

Understanding the Impact of Underwater Noise to Preserve Marine Ecosystems and Manage Anthropogenic Activities

Policy makers require a knowledge-based support to identify effective interventions for the socio-economic sustainability of human activities at sea. When dealing with anthropogenic impacts on marine ecosystems, we deal with a complex and faceted system which has high variability in terms of environment, regulation, governance, industrial activities, and geo-political scenarios. We analyzed the conceptual scientific framework adopted to address underwater noise as a polluting component of the marine environment. We identified the scientific paths that can provide useful contributions towards comprehending the impacts on the native ecosystem. In order to furnish relevant clues towards the properties of the interconnection of signals, we briefly reviewed an example from a different discipline (helioseismology). We describe a new approach on how acoustic energy in the sea could be detected and analyzed to understand its role in the functioning of the ecosystem. We propose a change of perspective in the observation strategy of underwater noise, promoting a knowledge transfer from other disciplines, which in turn will enable a better understanding of the system. This will allow researchers and policy-makers to identify feasible and effective solutions to tackle the negative impacts of underwater noise and the conservation of the marine ecosystem.

Controllable acoustic deterrent based on the warning signals generated by nonel detonators

Acoustic deterrents are a practical strategy to mitigate the impact of underwater noise on marine mammals. However, their safety and effectiveness are still debatable. This study proposes a controllable acoustic deterrence method to protect marine mammals threatened by underwater blasting noise. The method creates strong-randomness warning signals using nonel detonators and establishes an escape time for animals protected. Combining the BELLHOP ray-based acoustic model with the marine environmental parameters and animals' auditory characteristics, we built a prediction model to establish a link between the acoustic fields and the adjustable source parameters, and provide a Risk zone and Deterrent zone for animals. The simulation and experimental results demonstrated that the root mean squared error between the simulated and measured sound pressure spectral density levels did not exceed 4.5 dB and the coefficient of determination remained at approximately 0.8, indicating that the new deterrent is an effective method with good controllable performances.

A real-time passive acoustic monitoring system to detect Yangtze finless porpoise clicks in Ganjiang River, China

Phocoenidae live in fresh, coastal waters where they often share a significant portion of their habitat with humans. As a result, local activities (e.g., coastal fisheries and shipments) cause underwater noise pollution and threaten their ecosystem. To better conserve the habitat of porpoises, we aimed to study their activities in these waters by recording their echolocation clicks using a passive acoustic monitoring (PAM) system. However, because the off-line PAM instruments were often used in the past that need to be periodically deployed and recovered, data acquisition is typically obtained and analyzed in batches, rather than in real-time. A real-time PAM detection system would help minimize the impact of underwater noise on approaching porpoises. Furthermore, issues of bad quality data–with gaps due to loss or damage of the off-line PAM instruments–could be avoided with a real-time detection system. Therefore, in this study, we developed the Real-time Porpoise Click Detector-II (RPCD-II), equipped with a digital hydrophone, main memory (2 TB storage), a central processing unit, and a wireless transmission module. We deployed the RPCD-II under a docked fishing vessel at the Ganjiang River in Yangzi Zhou Town Fisheries Village, Nanchang City (8–9 December 2021), where it recorded signals of Yangtze finless porpoise and produced a real-time report. To validate the results of RPCD-II, another underwater sound recorder, the SoundTrap 300HF (ST), was also set up (as a control device) under the docked fishing vessel. Both devices recorded consistent results of 9330 clicks, further demonstrating RPCD-II’s ability for the real-time detection of Yangtze finless porpoise in the field.

Impacts of Sand Mining Activities on the Wetland Ecosystem of Poyang Lake (China)

Increasing anthropogenic activities are threatening freshwater ecosystems worldwide. Sand mining in Poyang Lake has significantly impacted the wetland ecosystem over the past 20 years, yet a quantitative analysis of these impacts remains insufficient. Here, we used 63 Landsat images taken from 2000 to 2020 along with the support vector machine (SVM) method and a retrieval model of suspended sediment concentration (SSC) to identify sand mining vessels and areas affected by sand mining. Then, we analyzed the changes in landscape patterns in the areas affected by sand mining. The potential impact of underwater noise generated by sand mining vessels on Yangtze finless porpoises was analyzed by a sound propagation model. The number of sand mining vessels in Poyang Lake during the flood, normal, and dry seasons increased from 2000 to 2016 but rapidly decreased from 2017 to 2020. Sand mining vessels were mainly distributed in the northern channel from 2000 to 2006, moved toward the center of the lake from 2007 to 2010, then moved northward in 2017. Within the areas affected by sand mining, water and mudflats declined, grassland and sandbars increased, and the landscape discontinuity increased. The habitat of the Yangtze finless porpoise affected by underwater noise from sand mining vessels in all seasons has significantly increased overtime. The mean area of the affected habitats was 70.65% (dry), 64.48% (normal), and 63.30% (flood) of the total habitat areas. The porpoise habitats in the northern channel and the west branch of the Ganjiang River are more seriously affected by the underwater noise of sand mining vessels than the southern lake. The impact of sand mining activities on wetland landscape and aquatic species demands systematic investigation in the future.

Environmental Impact of Underwater Noise

The description of sound as a form of energetic pollutant is very complex as is also its impact on aquatic life. Human activities causing continuous and implosive underwater noise, such as marine traffic, maintenance of ships, coastal tourism, marine research, military, offshore energy platforms, generation of ocean energies and construction operations are expected to increase. The paper analyses current approach to minimise the impact of underwater noise and limit its emissions, examines regulatory approach and discusses the possibilities to control this type of pollution in order to ensure the preservation of natural underwater soundscape. The timely implementation and further development of the European Marine Strategy Framework Directive and its provisions related to underwater noise is of exceptional importance for the Adriatic Sea, which is facing increasing pressure from various industries generating underwater noise.

Underwater noise impact of a ferry route on dive patterns of transiting Baltic ringed seals

Underwater noise impact of a ferry route on dive patterns of transiting Baltic ringed seals

Review of the marine environmental impact assessment reports regarding offshore wind farm

The energy production of offshore wind farms plays an important role in expanding renewable energy. However, the development of offshore wind farms faces many challenges due to its incompatibility with marine environments and its social acceptability among the local community. In this study, we reviewed the marine environmental impact assessment status of offshore wind farm development projects for 2012–2019 in South Korea. A total of nine projects were selected for this study, all of which experienced considerable conflict with local fisheries resources. To appropriately respond to the underlying challenges faced by offshore wind farm development and in order to better support decision-making for future impact assessment, our findings identified: i) a need for adequate preliminary investigation and technical examination of fisheries resources; ii) a need to assess and estimate the impact of underwater noise, vibration, and electromagnetic waves on fisheries resources during wind farm construction and operation; and iii) a need for a bottom-up approach that allows for communication with local stakeholders and policy-makers to guarantee the local acceptability of the development.

Impact of underwater noise on the growth, physiology and behavior of Micropterus salmoides in industrial recirculating aquaculture systems

The operation of the equipment in industrial recirculating aquaculture systems (RAS) affects the underwater soundscape of aquaculture tanks where fishes live. This study evaluated the influence of commercial industrial RAS noise on the growth, physiology, and behavior of juvenile largemouth bass (Micropterus salmoides). In this study, two experimental groups, the RAS noise group (115 dB re 1 μPa RMS) and the ambient group (69 dB re 1 μPa RMS), were studied. The water quality and feeding regime for each group were kept the same during the 60-day experiment. Results showed that there was no significant difference in the average daily feed intake of the fish between the two treatments, while the rate of weight gain of the ambient group (755.27 ± 65.62%) was significantly higher than that of the noise group (337.66 ± 88.01%). In addition, the RAS environmental noise also had an adverse effect on the anti-oxidation and immune systems of the fish based on results of analysis of blood, liver, and intestinal samples. Moreover, environmental noise affected the swimming behavior of the fish school. The mean angle and distance between the focal fish and its nearest neighbor fish in RAS noise group were 33.3° and 92.1 mm, respectively, which were larger than those of the ambient group with 24.4° and 89.5 mm, respectively. From the above results, RAS noise did influence the welfare of largemouth bass, and the soundscape in RAS hence should be managed in real production.

Potential effects of underwater noise from wind turbines on the marbled rockfish (Sebasticus marmoratus)

Environmental assessments of underwater noise on marine species must be based on species-specific hearing abilities. This study was to assess the potential impact of underwater noise from the East China Sea Bridge wind farm on the acoustic communication of the marbled rockfish. Here, the 1/3 octave frequency band of underwater noise was 125 Hz with the level range of 78–96 dB re 1 μPa, recorded at distances between 15-20m from the foundation at wind speed of 3–5 m/s. Auditory evoked potential (AEP) and passive acoustic techniques were used to determine the hearing abilities and sound production of the fish. The resultes showed the lowest auditory threshold of Sebastiscus marmoratus was 70 dB at 150 Hz matching the disturbance sound ranging 140–180 Hz, which indicating the acoustic communication used in this species. However, the frequency and level of turbine underwater noise overlapped the auditory sensitivity and vocalization of Sebastiscus marmoratus. The wind turbine noise could be detected by fish and may have a masking effect on their acoustic communication. This result can be applied for further to the assessent of fish species released into offshore wind farm marine ranch.

Environmental Impact of Underwater Noise Generated from Offshore Wind Power on Marine Organisms

Environmental Impact of Underwater Noise Generated from Offshore Wind Power on Marine Organisms

Metadata-Driven Universal Real-Time Ocean Sound Measurement Architecture

Underwater sound in the oceans has been significantly rising in the past decades due to an increase in human activities, adversely affecting the marine environment. In order to assess and limit the impact of underwater noise, the European Commission’s Marine Strategy Framework Directive (MSFD) included the long-term monitoring of low-frequency underwater sound as a relevant indicator to achieve a good environmental status. There is a wide range of commercial hydrophones and observing platforms able to perform such measurements. However, heterogeneity and lack of standardization in both hydrophones and observing platforms makes the integration and data management tasks time-consuming and error-prone. Moreover, their power and communications constraints need to be addressed to make them suitable for long-term ocean sound monitoring. Measured underwater sound levels are challenging to compare because different measurement methodologies are used, leading to a risk of misunderstandings and data misinterpretation. Furthermore, the exact methodology applied is not always public or accessible, significantly reducing ocean sound data re-usability. Within this work, a universal architecture for ocean sound measurement is presented, addressing hydrophone integration, real-time in situ processing and data management challenges. Emphasis is placed on generic and re-usable components, so it can be seamlessly replicated and deployed in new scenarios regardless of the underlying hardware and software constraints (hydrophone model, observing platform, operating system, etc.). Within the proposed architecture, a generic implementation of an underwater sound algorithm based on underwater noise measurement best practices is provided. Standardized and coherent metadata with emphasis on strong semantics is discussed, providing the building blocks for FAIR (Findable, Accessible, Interoperable, Reusable) ocean sound data management.

In Design of an Ocean Bottom Seismometer Sensor: Minimize Vibration Experienced by Underwater Low-Frequency Noise

Ocean Bottom Seismometers (OBS) placed on the seafloor surface are utilized for measuring the ocean bottom seismic waves. The vibration of OBS excited by underwater noise on its surface may interfere with its measured results of seismic waves. In this particular study, an OBS was placed on the seabed, while ray acoustic theory was used to deduce the sound field distribution around the OBS. Then using this information, the analytical expression for the OBS vibration velocity was obtained in order to find various factors affecting its amplitude. The finite element computing software COMSOL Multiphysics® (COMSOL) was used to obtain the vibration response model of the OBS which was exposed to underwater noise. The vibration velocity for the OBS calculated by COMSOL agreed with the theoretical result. Moreover, the vibration velocity of OBS with different densities, shapes, and characters were investigated as well. An OBS with hemispherical shape, consistent average density as that of the seafloor, and a physical structure of double tank has displayed minimum amplitude of vibration velocity. The proposed COMSOL model predicted the impact of underwater noise while detecting the ocean bottom seismic waves with the OBS. In addition, it provides significant help for the design and optimization of an appropriate OBS.

Assessing risk of underwater noise impact on marine mammals throughout a new methodology

Shipping noise has been identified as a threat on underwater ecosystems. In particular, several impacts have been documented on cetaceans, e.g., communication’s masking and stress increasing. To assess the risk related to such anthropogenic noise requires both quantifying the noise levels and estimating the distribution of the cetaceans’ population. However, current methods evaluating the risks related to anthropogenic pressures generally rely on strong expert priors, which may be difficult to define. This presentation aims at introducing a new framework for the comparison of anthropogenic pressure levels maps and cetaceans’ distribution in order to infer the risk of impact and provide management solutions. The methodology, combining simple statistical analyses and a theoretical representation tool was applied to the Bay of Biscay using shipping noise model and fin whale observation from regular surveys for the years 2012 and 2016. Relationships between cetaceans’ distribution and noise levels were investigated and linked to mammals theoretical responses to pressure. A trend analysis between 2012 and 2016 was also proposed to identify the noise hotspots. The results were interpreted in both terms of ecological meaning for fin whale and conservation measures for shipping noise, according to marine policies requirements.

Noise affects porpoise click detections – the magnitude of the effect depends on logger type and detection filter settings

Automatic click detectors and full-bandwidth sound recorders are widely used in passive acoustic monitoring of small cetaceans. Detection of these signals depends on a variety of factors, including signal to noise ratio. Passive acoustic monitoring is often used to study impact of underwater noise on small cetaceans, but as detection probability is affected by changes in signal to noise ratio, variable noise levels may affect conclusions drawn from these experiments. Therefore, we examine how different detectors and filters perform in varying ocean noise conditions. C-PODs and full-bandwidth recorders (Wildlife Acoustics, SM2M+) were deployed at two stations in an environment with fluctuating ambient noise for 42 days. Noise level and harbour porpoise (Phocoena phocoena) click trains simultaneously recorded on both loggers were compared. Overall, we found that porpoise click detections by the algorithm used to analyse full-band recorder data (Pamguard) paralleled detections by the C-POD. However, Pamguard detected significantly more clicks than the C-POD. A decrease in detections was seen for both loggers with increasing noise in the band 20 –160 kHz, in particular for levels above 100 dB re 1μPa rms. We also found that the Pamguard detection function changed the least over varying noise conditions when compared to the C-POD detectors. This study sheds light on the fact that inference of animal presence/absence or density that are based on echolocation cues (here, Porpoise Positive Minutes) shall account for the acoustic environments where probability of detecting signals may be affected by variability in ambient noise levels.

Guiding principles for assessing the impact of underwater noise

Guiding principles for assessing the impact of underwater noise