Impacts of ship noise on the nighttime foraging behaviors of the North Atlantic humpback whale (Megaptera novaeangliae)

The humpback whale (Megaptera novaeangliae) is an endangered baleen whale species with a cosmopolitan distribution. The coastal habitat of this species result in significant exposure to anthropogenic noise from human activities. Previous research in the well-studied Pacific populations has demonstrated changes in calling behavior in response to noise, but noise impacts on other critical behaviors such as foraging have not yet been investigated. This study examines the impacts of ship noise on the nighttime bottom foraging behavior of humpback whales in the North Atlantic – a region with substantial human activity including high levels of noise from commercial shipping traffic. Data were collected from 2006 to 2009 in the Stellwagen Bank National Marine Sanctuary in the southern Gulf of Maine during June and July. Data included underwater behaviors and acoustic recordings of surrounding environmental noise collected using an archival tag attached to nine individual whales. Here I use series of linear mixed models to assess the effects of ship noise on eight metrics of nighttime feeding behaviors. Fixed effects included the presence versus absence of ship noise, received level of ship noise, and the before, during, or after ship noise exposure period. These variables had significant influence on three metrics: dive descent rate, ascent rate, and number of rolls indicative of feeding events. Descent rate decreased as noise level increased, while ascent rate was significantly faster in the during or after period when compared to the before period. The number of rolls significantly increased in the after exposure period, but at the greatest received levels, feeding rolls were completely absent during dives. These findings indicate that humpback whales on Stellwagen Bank show small, but significant, changes in foraging activity when exposed to ship noise. This study supports the hypothesis that environmental noise has an impact on the nighttime foraging activities of this species

Consequences of ship noise for camouflage, anti-predation, and movement in crabs.

The marine environment is becoming increasingly polluted, with unprecedented levels of anthropogenic noise changing the marine soundscape. Mounting evidence shows that exposure to this noise can cause numerous adverse effects across taxa. However, invertebrates, juveniles, and behaviours not dependent on acoustics have received relatively little attention. Furthermore, research into how individuals may cope with these pressures is lacking. I address these knowledge gaps through a series of laboratory-based playback experiments focussed on juvenile shore crabs (Carcinus maenas), using three noise treatments: ship noise, ambient underwater sounds (control), and ambient underwater sounds played at the same amplitude as the ship treatment (loud control). In chapter 2, I examined the effects of ship noise on brightness change; a strategy employed by juvenile shore crabs to increase their level of camouflage and reduce predation risk. Individuals were repeatedly exposed to one of the aforementioned noise treatments for 8 weeks. Photographs of individuals, taken regularly throughout, were analysed using a predator vision model to determine the level of brightness change and camouflage in an ecologically relevant context. Ship noise reduced the overall brightness change and camouflage, though it did not affect the change in brightness per moult. The level of growth per moult was reduced by ship noise however, and the timing of moulting events was delayed. In chapter 3 I investigated the effects of noise on antipredator behaviour (using the response to a simulated predator) and locomotion, including the frequency of pausing and directionality of movement. By comparing the effects between individuals with varying levels of previous noise exposure, I also tested for signs of acclimatisation. Ship noise reduced the likelihood of individuals responding to a predator and increased their latency of response. Locomotion was not disrupted, but individuals moved away from ship noise, positioning themselves in quieter areas. These findings were consistent for all individuals, regardless of their previous level of noise exposure. The negative consequences of anthropogenic noise in the marine environment are clearly not constrained to species or behaviours reliant on acoustics, as juvenile shore crabs exposed to ship noise suffered decreased levels of camouflage and reduced growth. Individuals also displayed maladaptive behavioural responses to a simulated predator when exposed to ship noise. There is no evidence that acclimatisation occurred, but individuals did attempt to physically avoid noisy areas. Loud natural sounds did not affect any behaviours studied, suggesting the type of noise is important in determining how individuals may be affected. Overall, this thesis shows that juvenile shore crabs suffer multiple negative effects from noise pollution, including the disruption of critical behaviours that are pervasive in the marine environment, with potential implications for survival

Close range ship noise cross correlations with a vector sensor in view of geoacoustic inversion

Distant ship noise has been utilized for geoacoustic inversion and ocean monitoring for many years. In a shallow water experiment, Makai 2005, a 4-element acoustic vector sensor array was deployed at the stern of the research vessel R/V Kilo Moana. The recorded engine noise of R/V Kilo Moana during its dynamic positioning was analyzed by the DEMON (Detection of Envelope Modulation on Noise) method. The strongest modulation frequency band of the ship noise was found by a group of band-pass filters for further data processing. Multipath arrivals in the vertical particle velocity have higher signal-to-noise ratios than those in the horizontal particle velocities because of steep arrival directions. By exploiting this advantage, the cross-correlation of broadband ship noise between the pressure and the vertical particle velocity can be used for multipath information exploration. Since ship noise is often characterized as continuous broadband noise plus strong tonal noise, the cross-correlation of tonal noise would dominate that of broadband noise, and consequently cover the multipath arrival pattern. Therefore, spectral weighting functions are applied in order to reduce the noise contamination and ensure sharp multipath peaks in the cross-correlation. For engine noise emitted by the dynamically positioned ship, a short correlation time of 0.4s was used in order to keep the time delay fluctuation details of multipath arrivals. Clear multiple arrivals are seen in the cross-correlation of different arrivals, and verified by the ray tracing program TRACEO. The results demonstrate the potential of only one acoustic vector sensor in applications of source localization and geoacoustic inversion

Vessel noise affects routine swimming and escape response of a coral reef fish

An increasing number of studies have shown that anthropogenic noise can negatively affect aspects of the anti-predator behaviour of reef fishes, potentially affecting fitness and survival. However, it has been suggested that effects could differ among noise sources. The present study compared two common sources of anthropogenic noise and investigated its effects on behavioural traits critical for fish survival. In a tank-based experiment we examined the effects of noise from 4-stroke motorboats and ships (bulk carriers > 50,000 tonnes) on the routine swimming and escape response of a coral reef fish, the whitetail damselfish (Pomacentrus chrysurus). Both 4-stroke boat and ship noise playbacks affected the fast-start response and routine swimming of whitetail damselfish, however the magnitude of the effects differed. Fish exposed to ship noise moved shorter distances and responded more slowly (higher response latency) to the startle stimulus compared to individuals under the 4-stroke noise treatment. Our study suggests that 4-stroke and ship noise can affect activity and escape response of individuals to a simulated predation threat, potentially compromising their anti-predator behaviour

Holistic control of ship noise emissions

The sustainability of anthropogenic activities at sea is recently gaining more and more attention. As regards shipping, emissions from ships into the environment of various nature (engine exhaust gases, anti-fouling paints leaching, ballast exchange, releases at sea of oil and other noxious liquid or solid cargoes, of sewage and of garbage) have been recognized as sources of pollution and therefore controlled and limited since a long time. The subject of noise emission has been identified only recently. To study the problem, the EU has funded, among others, the FP7 SILENV (Ship Innovative soLutions to rEduce Noise and Vibrations) project that run from 2010 to 2012. In the present work, the holistic approach followed within the project to characterize and control the ship as a source of noise is presented. Three types of noise emissions (in air, in water and inside the ship) are analyzed highlighting peculiarities and different strategies adopted to characterize the source, the impact on the receiver and the possible solutions to set limits to the ship emissions. The project outcome included a socalled “Green Label”: a set of new prenormative requirements defined for the three main areas mentioned above

Several specific and nonspecific responses of the human and animal body to ship noise

The effect of noise on cargo boats on a long voyage differs considerably from the effect of noise in factories and in service industries. The peculiarities of the effect of round-the-clock noises at sea at 55 to 85 decibels, typical for cargo boats, were studied in white rats in the laboratory and aboard ship (each of the experiments lasted three months) and in young naval cadets and experienced seamen on voyages lasting one, two, and three months. The findings helped to derive health standards for maximum admissible noise level at sea

An experimental demonstration of blind ocean acoustic tomography

Despite the advantages clearly demonstrated by ocean acoustic tomography OAT when compared to other ocean monitoring techniques, it suffers from several technical-related drawbacks. One is the requirement for rather expensive equipment to be maintained and operated at several locations in order to obtain sufficient source–receiver propagation paths to cover a given ocean volume. This paper presents the preliminary feasibility tests of a concept that uses ships of opportunity as sound sources for OAT. The approach adopted in this paper views the tomographic problem as a global inversion that includes determining both the emitted signal and the environmental parameters, which is a similar problem to that seen in blind channel identification and was therefore termed blind ocean acoustic tomography BOAT . BOAT was tested on a data set acquired in October 2000 in a shallow-water area off the west coast of Portugal, including both active and passive ship noise data. Successful results show that BOAT is able to estimate detailed water column temperature profiles coherent with independent measurements in intervals where the uncontrolled source signal ship noise presents a sufficient bandwidth and signal-to-noise ratio, which clearly define the limitations of the presented method.FCT; CN

Quantifying the contribution of ship noise to the underwater sound field

Author Posting. © Acoustical Society of America, 2020. This article is posted here by permission of Acoustical Society of America for personal use, not for redistribution. The definitive version was published in Journal of the Acoustical Society of America 148(6), (2020): 3863-3872, https://doi.org/10.1121/10.0002922.The ambient sound field in the ocean can be decomposed into a linear combination of two independent fields attributable to wind-generated wave action at the surface and noise radiated by ships. The vertical coherence (the cross-spectrum normalized by the power spectra) and normalized directionality of wind-generated noise in the ocean are stationary in time, do not vary with source strength and spectral characteristics, and depend primarily on the local sound speed and the geoacoustic properties which define the propagation environment. The contribution to the noise coherence due to passing vessels depends on the range between the source and receiver, the propagation environment, and the effective bandwidth of the characteristic source spectrum. Using noise coherence models for both types of the sources, an inversion scheme is developed for the relative and absolute contribution of frequency dependent ship noise to the total sound field. A month-long continuous ambient sound recording collected on a pair of vertically aligned hydrophones near Alvin Canyon at the New England shelf break is decomposed into time-dependent ship noise and wind-driven noise power spectra. The processing technique can be used to quantify the impact of human activity on the sound field above the natural dynamic background noise, or to eliminate ship noise from a passive acoustic monitoring data set.The work was funded by Office of Naval Research, Code 32 (Grant No. N00014-17-1-2692 for Y.T. Lin), and the Canada Research Chair program and the Natural Science and Engineering Research Council Discovery program. N. S. would like to thank Transatlantic Ocean System Science and Technology (TOSST) for his graduate fellowship.2021-06-2

It often howls more than it chugs: Wind versus ship noise under water in Australia’s maritime regions

Marine soundscapes consist of cumulative contributions by diverse sources of sound grouped into: physical (e.g., wind), biological (e.g., fish), and anthropogenic (e.g., shipping)—each with unique spatial, temporal, and frequency characteristics. In terms of anthropophony, shipping has been found to be the greatest (ubiquitous and continuous) contributor of low-frequency underwater noise in several northern hemisphere soundscapes. Our aim was to develop a model for ship noise in Australian waters, which could be used by industry and government to manage marine zones, their usage, stressors, and potential impacts. We also modelled wind noise under water to provide context to the contribution of ship noise. The models were validated with underwater recordings from 25 sites. As expected, there was good congruence when shipping or wind were the dominant sources. However, there was less agreement when other anthropogenic or biological sources were present (i.e., primarily marine seismic surveying and whales). Off Australia, pristine marine soundscapes (based on the dominance of natural, biological and physical sound) remain, in particular, near offshore reefs and islands. Strong wind noise dominates along the southern Australian coast. Underwater shipping noise dominates only in certain areas, along the eastern seaboard and on the northwest shelf, close to shipping lanes

Ship noise inhibits colour change, camouflage, and anti-predator behaviour in shore crabs

This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this record.Ship noise is a prominent source of underwater sound pollution. Carter et al. demonstrate that ship noise has multiple negative effects on animal traits that do not primary rely on acoustics. In shore crabs, colour change to improve camouflage, and predator escape responses are adversely affected by ship noise but not by equally loud ambient noise