Antarctic marine mammals and ocean acoustics

Marine mammals rely on sound and hearing as their primary means of communication and sensing their world. Concerns that anthropogenic sound in the ocean could infer their sensing, cause stress or even damage their hearing physically rose a controversial discussion and triggered a worldwide boost in marine bioacoustic research. Innovative acoustic technologies and field methods are required to provide a basis for carefully designed and technically challenging research projects on free-ranging marine mammals, especially under the harsh environmental conditions of polar regions. The Ocean Acoustics group within the Marine Observing Systems section endeavors multidisciplinary research of environmental scientists, geophysicists, oceanographers, physicists, physiologists, and biologists to investigate the need and scope of mitigation measures for the effects of man-generated sound in the ocean, develop acoustic census techniques, explore marine mammal responses to various anthropogenic sounds, and study the vocal behaviour and hearing physiology of Antarctic marine mammals

Acoustic ecology of marine mammals in polar oceans

In polar habitats, research on marine mammals including studies of the possible ecological consequences of anthropogenic impact is hampered by adverse climate conditions restricting human access to these regions. Marine mammals are known to produce sound in various behavioural contexts, rendering (hydro-)acoustic recording techniques, which are quasi-omnidirectional and independent of light and weather conditions, an apt tool for year round monitoring of marine mammal presence and behaviour in polar habitats. Acoustic behaviour is shaped by the species-specific behavioural ecology, as well as by abiotic, biotic and anthropogenic factors of the animal's living environment, a concept known as acoustic ecology. Acoustic ecology thereby describes the interaction between an animal and its environment as mediated through sound. An understanding of the acoustic ecology is important when interpreting acoustic data, as the acoustic ecology of a species determines if physical presence results in acoustic presence, on which temporal scale acoustic activity occurs and over which spatial scales acoustic presence can be detected. This thesis comprises ten manuscripts/papers, which are based on acoustic data collected in the Southern and Arctic Oceans. All provide examples of how aspects of the acoustic ecology of the species shape acoustic behaviour. In addition, the majority of manuscripts/papers also illustrate how acoustic monitoring can provide information of physical presence of marine mammals in areas where prolonged visual observations are not possible. Acoustic ecology forms the overarching concept that braces these publications. Given the relatively sparse literature on this concept with respect to marine mammals, this synopsis includes a first detailed conceptual description of acoustic ecology for polar habitats. Particular emphasis thereby is given to the specific environmental conditions in polar habitats and the looming threats of climatic change and other anthropogenic influences

Underwater Noise from Arctic Shipping: Impacts, Regulations and Recommendations

Marine mammals, including whales, walrus, and seals, rely heavily on sounds for survival. The Arctic soundscape has long been shaped by their clicks and calls. The rapid loss of summer sea ice that's been observed in recent years is opening this once largely inaccessible region to ship traffic. The low-frequency sounds that ships generate propagate efficiently and travel vast distances in deep water marine environments. This means that the Arctic is becoming noisier, which could have a profound impact on marine mammals

Noise levels and sources in the Stellwagen Bank National Marine Sanctuary and the St. Lawrence River Estuary

Although ambient (background) noise in the ocean is a topic that has been widely studied since pre-World War II, the effects of noise on marine organisms has only been a focus of concern for the last 25 years. The main point of concern has been the potential of noise to affect the health and behavior of marine mammals. The Stellwagen Bank National Marine Sanctuary (SBNMS) is a site where the degradation of habitat due to increasing noise levels is a concern because it is a feeding ground and summer haven for numerous species of marine mammals. Ambient noise in the ocean is defined as “the part of the total noise background observed with an omnidirectional hydrophone.” It is an inherent characteristic of the medium having no specific point source. Ambient noise is comprised of a number of components that contribute to the “noise level” in varying degrees depending on where the noise is being measured. This report describes the current understanding of ambient noise and existing levels in the Stellwagen Bank National Marine Sanctuary. (PDF contains 32 pages.

Novel Bio-Logging Tool for Studying Fine-Scale Behaviors of Marine Turtles in Response to Sound

Increases in the spatial scale and intensity of activities that produce marine anthropogenic sound highlight the importance of understanding the impacts and effects of sound on threatened species such as marine turtles. Marine turtles detect and behaviorally respond to low-frequency sounds, however few studies have directly examined their behavioral responses to specific types or intensities of anthropogenic or natural sounds. Recent advances in the development of bio-logging tools, which combine acoustic and fine-scale movement measurements, have allowed for evaluations of animal responses to sound. Here, we describe these tools and present a case study demonstrating the potential application of a newly developed technology (ROTAG, Loggerhead Instruments, Inc.) to examine behavioral responses of freely swimming marine turtles to sound. The ROTAG incorporates a three-axis accelerometer, gyroscope, and magnetometer to record the turtle\u27s pitch, roll, and heading; a pressure sensor to record turtle depth; a hydrophone to record the turtle\u27s received underwater acoustic sound field; a temperature gauge; and two VHF radio telemetry transmitters and antennas for tag and turtle tracking. Tags can be programmed to automatically release via a timed corrodible link several hours or days after deployment. We describe an example of the data collected with these tags and present a case study of a successful ROTAG deployment on a juvenile green turtle (Chelonia mydas) in the Paranaguá Estuary Complex, Brazil. The tag was deployed for 221 min, during which several vessels passed closely (\u3c2 km) by the turtle. The concurrent movement and acoustic data collected by the ROTAG were examined during these times to determine if the turtle responded to these anthropogenic sound sources. While fine-scale behavioral responses were not apparent (second-by-second), the turtle did appear to perform dives during which it remained still on or near the sea floor during several of the vessel passes. This case study provides proof of concept that ROTAGs can successfully be applied to free-ranging marine turtles to examine their behavioral response to sound. Finally, we discuss the broad applications that these tools have to study the fine-scale behaviors of marine turtles and highlight their use to aid in marine turtle conservation and management

Shipping Through Sea Ice: Impacts on Marine Habitats and Best Practices

As the result of Arctic climate change and an increase in shipping season length, there is a growing interest in Arctic shipping operations. Sea ice serves as an important habitat for marine mammals, therefore, shipping through sea ice could lead to increased negative interactions with ice-bound marine mammals. The following literature review discusses the impacts of icebreaking on marine mammals and habitats. These impacts include: avoidance of areas where icebreaking is occurring, behavioral and physiological impacts of increased anthropogenic noise, entrapment, habitat destruction and fragmentation, and oil spills

Pollution in the open oceans: 2009-2013

This review of pollution in the open oceans updates a report on this topic prepared by GESAMP five years previously (Reports and Studies No. 79, GESAMP, 2009). The latter report, the first from GESAMP focusing specifically on the oceans beyond the 200 m depth contour, was prepared for purposes of the Assessment of Assessments, the preparatory phase of a regular process for assessing the state of the marine environment, led jointly by the United Nations Environment Programme (UNEP) and the Intergovernmental Oceanographic Commission (UNESCO-IOC)

Short-term disturbance by a commercial two-dimensional seismic survey does not lead to long-term displacement of harbour porpoises

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