Article

Underwater Sound Sources and Ambient Noise in Fowlers Bay, South Australia, during the Austral Winter

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Abstract

Passive acoustic recordings made in Fowlers Bay, South Australia, during the austral winter of 2013–2017 revealed the presence of several sources of underwater sound. Sound sources of biological origin include baleen and toothed whales, fish and shrimp. Physical sources of underwater sound include wind- and rain-driven noises, and underwater sounds of anthropogenic origin were primarily from boats and occasionally from an aircraft. Biological sound sources were commonly recorded within the frequency range of around 25 Hz to nearly 17 kHz, with baleen whales within the range of ~ 25 Hz to 6 kHz, and dolphins at higher frequencies of approximately 2.5–17 kHz. Broadband sounds from physical and anthropogenic sound sources were noticeable at frequencies above ~ 50 Hz. The ambient noise level in Fowlers Bay at frequencies below 100 Hz was relatively low (around 75 dB re 1 µPa²/Hz for the 95% percentile) due to an insignificant contribution of noise from distant shipping. At higher frequencies, the noise level was governed primarily by noise from wind and varied by nearly 30 dB re 1 µPa²/Hz depending on weather conditions, up to around 80 dB re 1 µPa²/Hz for the 95% percentile during periods of strong winds and intense rainfall.

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... Chapter 2 was published in Acoustics Australia (Ward et al. 2019). The chapter is presented in a style consistent with the rest of the thesis. ...
... Additionally, the PC is recognised as an important feeding stopover for PBW on their northbound migration (McCauley et al. 2004, Rennie et al. 2009). In the PC, the spot call is detected during June to November , Ward 2019. ...
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Concerns about the impact of noise of shipping on marine life, has led to the recent publication by the International Maritime Organisation of guidelines for the reduction of noise from commercial shipping. This paper puts the noise from shipping in context with other sounds in the ocean, addresses the potential impact of noise from shipping, the difficulties of assessing the impact and the likely effectiveness of mitigation measures. It draws on underwater noise studies around Australia that included areas of low shipping densities, allowing reliable characterisation of natural ambient noise at frequencies of shipping noise. This low frequency ambient noise has been difficult to determine in the high shipping areas where most ambient noise studies have been made. The paper also draws on studies of the effects of noise on marine mammals. Noise from many distant ships across an ocean basin produces a general nondescript background noise known as "traffic noise" where the contribution of any single ship is not detectable. Noise from a nearby ship reaches higher levels than traffic noise but is present for short times and close distances. Noise from a close ship can be positive if it causes an animal to move away and avoid collision.
Article
Opportunistic sightings and museum specimens of humpback whales (Megaptera novaeangliae) in South Australia (n = 116) were collated to the year 2003. Records were made in all months of the year, with 57% during June and July. Timing of this peak and the presence of neonates presumably related to the northward migration from high latitudes to breeding grounds in the tropics. Sightings and beach-washed carcasses were widely distributed, from Head of Bight to the Victorian border, with apparent concentrations in eastern Gulf St Vincent, Kangaroo Island and Victor Harbor regions, and to a lesser extent in the south-east of the State and southern Eyre Peninsula. Most sightings involved single whales or groups of two (range 1-4). All five carcasses were neonates or juveniles with total lengths of 3.88 m to approx. 10 m. Estimated lengths (5-15 m) were available for 17 live whales. The geological age of one museum specimen is uncertain but may predate European settlement. This and whaling records from Fowler Bay during 1840 indicate that humpback whales have been present, and may not have been uncommon, in South Australia since at least the early 19th century. Research is needed to determine the relationship of South Australian humpback whales to populations migrating off the western and eastern coasts of Australia.
Article
Studies of ambient noise south of Australia show higher levels at low frequencies in the deep water off the continental shelf compared with locations on the shelf. The difference arises because of differences in transmission loss. Marine animals would experience significantly different noise levels and directionality in the two regions and while crossing the boundary, provide positional information. Opportunities for long-range, low-frequency communication by animals would be significantly limited by the higher background noise in the open ocean. Measures of long-term sea noise trends highlight the influence of biological sources and the importance of local sound transmission regimens.
Article
This study summarizes 660 events involving captured, live-stranded and dead cetaceans in South Australia between 1881 and 2000. Emphasis is placed on records (n = 361) during 1985-2000 when an active necropsy programme was underway. Average number of events per year was 30.4 and the most common species were the short-beaked common dolphin (Delphinus delphis) and Indo-Pacific bottlenose dolphin (Tursiops aduncus). Records were assigned to nine categories of circumstance/cause of death. Summarizing the total database, 60% were unknown circumstance, 22% not obviously anthropogenic, 13% unintentional human-related and 5% intentional human-related. In the data set of records for 1985-2000, 50% were unknown, 25% were not obviously anthropogenic, 20% were unintentional humanrelated and 5% were intentional killings. Non-anthropogenic circumstances included neonatal deaths, live strandings, significant diseases, shark attacks and choking. Cornynebacterium ulcerans is recorded for the first time in a cetacean. Unintentional circumstances included entanglement in fishing and aquaculture equipment (17% of necropsied carcasses from 1985-2000) and boat strikes. Intentional human-related circumstances were captures for live display and illegal killing. Five percent of the necropsied carcasses during 1985-2000 were attributed to shootings or stabbings/spearings. There is need for a formal reporting procedure for marine mammal deaths and human interaction involving injury and for steps to be taken to reduce human impacts.
Article
Mysticete (baleen) whales produce a variety of vocalizations and sounds, but relatively few of these have been well described with accompanying behavior. This review concentrates on the vocalizations consistently associated with behavioral interactions or acoustic exchanges between or among conspecifics. These communication “signals” have been categorized for this review as contact calls of single animals outside of the breeding season (including cow-calf pairs), vocalizations reported during the breeding season (often designated as “songs”), and calls produced by active groups of whales that may or may not have a reproductive function. While much remains unknown, the data obtained thus far indicate that the social vocalizations of baleen whales have structural/functional similarities with those of other mammals and birds.
Article
Ocean ambient noise results from both anthropogenic and natural sources. Different noise sources are dominant in each of 3 frequency bands: low (10 to 500 Hz), medium (500 Hz to 25 kHz) and high (>25 kHz). The low-frequency band is dominated by anthropogenic sources: primarily, commercial shipping and, secondarily, seismic exploration. Shipping and seismic sources contribute to ambient noise across ocean basins, since low-frequency sound experiences little attenuation, allowing for long-range propagation. Over the past few decades the shipping contribution to ambient noise has increased by as much as 12 dB, coincident with a significant increase in the number and size of vessels comprising the world's commercial shipping fleet. During this time, oil exploration and construction activities along continental margins have moved into deeper water, and the long-range propagation of seismic signals has increased. Medium frequency sound cannot propagate over long ranges, owing to greater attenuation, and only local or regional (10s of km distant) sound sources contribute to the ambient noise field. Ambient noise in the mid-frequency band is primarily due to sea-surface agitation: breaking waves, spray, bubble formation and collapse, and rainfall. Various sonars (e.g. military and mapping), as well as small vessels, contribute anthropogenic noise at mid-frequencies. At high frequencies, acoustic attenuation becomes extreme so that all noise sources are confined to an area close to the receiver. Thermal noise, the result of Brownian motion of water molecules near the hydrophone, is the dominant noise source above about 60 kHz.
Article
Little is known of ambient noise in the ocean at frequencies above 50 kHz and there are few measurements above 20 kHz. The results of this study indicate that the sustained ambient noise at frequencies up to 200 kHz in temperature and tropical waters of depths less than about 60 m is characterized by the numerous sharp transient sounds of snapping shrimps. These transients have pulse widths of typically 3 to 8 micros (at one-third the peak voltage)and their bandwidth extends to well in excess of 200 kHz. Large variations in shrimp noise are to be expected over relatively short distances (hundreds of metres) as habitats change and hence shrimp numbers vary. Highest noise levels are to be expected near the bottom and where there ire coral or rock outcrops, shells, sponges or debris to provide shelter for shrimps. Noise measured under these conditions exceeded a peak level of 140 dB re 1 microPa2 at an average of about 20 pulses per second and exceeded 150 dB re 1 microPa2 at an average of 3 to 4 pulses a second. Lowest noise levels have been observed over uncluttered mud or sand. Shrimp noise shows little diurnal or seasonal variation.
Article
Some 1274 southern right whale sounds were randomly selected and each sound was described by 10 acoustic variables. Two hundred and fifty of these sounds were also ‘labelled’ by the activity, size and sexual composition o the group producing them. Principal components analysis was performed on all the sounds' variables (1274×10) and on the variables for a subset of 823 sounds referred to as calls. Results of the principal components analyses indicate that the sounds can be divided into three major classes: blow sounds, slaps, and calls; and that the repertoire of calls is a continuum with certain types more common than others. The distribution of the ‘labelled’ sounds in the principal components analyses patterns revealed general associations between whale activities and the types of sounds produced.
Spatial Ecology of Eubalaena australis: Habitat Selection at Multiple Scales
  • R Pirzl
Pirzl, R.: Spatial Ecology of Eubalaena australis: Habitat Selection at Multiple Scales. PhD Thesis, Deakin University, Melbourne (2008)
Notes on nineteenth century catches of southern right whales (Eubalaena australis) off the southern coasts of Western Australia
  • J L Bannister
  • JL Bannister
Bannister, J.L.: Notes on nineteenth century catches of southern right whales (Eubalaena australis) off the southern coasts of Western Australia. Rep. Int. Whal. Comm. 10(Special Issue), 255-259 (1986)
Benthic Protected Zone of the Great Australian Bight Marine Park: 2. Monitoring Sustainable-Use. Report to National Parks and Wildlife South Australia (NPWS) and the Department of Environment and Heritage (DEH)
  • T M Ward
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Ward, T.M., McLeay, L.J., Rogers, P.L.: Benthic Protected Zone of the Great Australian Bight Marine Park: 2. Monitoring Sustainable-Use. Report to National Parks and Wildlife South Australia (NPWS) and the Department of Environment and Heritage (DEH). South Australian Research and Development Institute (SARDI), Australia (2003)
Southern right whale remains from 19th century whaling at Fowler Bay
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  • CM Kemper
Kemper, C.M., Samson, C.R.: Southern right whale remains from 19th century whaling at Fowler Bay, South Australia. Rec. S. Aust. Mus. 32(2), 155-172 (1999)
Right whales caught in waters around south eastern Australia and New Zealand during the nineteenth and early twentieth centuries
  • W H Dawbin
  • WH Dawbin
Dawbin, W.H.: Right whales caught in waters around south eastern Australia and New Zealand during the nineteenth and early twentieth centuries. Int. Whal. Comm. Doc. 10(Special Issue), 261-267 (1986)
A history of recording underwater sound around Australia and the Curtin Underwater Sound Recorder hardware: a researchers’ perspective
  • R D Mccauley
  • F Thomas
  • A N Gavrilov
  • A J Duncan
  • D Cato
  • M Parsons
  • I M Parnum
  • C Salgado-Kent
  • C Erbe
  • RD McCauley
McCauley, R.D., Thomas, F., Gavrilov, A.N., Duncan, A.J., Cato, D., Parsons, M., Parnum, I.M., Salgado-Kent, C., Erbe, C.: A history of recording underwater sound around Australia and the Curtin Underwater Sound Recorder hardware: a researchers' perspective. Acoust. Aust. 45(2), 301-311 (2017). https://doi.org/ 10.1007/s40857-017-0113-8
Southern Right Whale Research and Monitoring in the Great Australian Bight
  • C M Charlton
  • R Ward
Charlton, C.M., Ward. R.: Southern Right Whale Research and Monitoring in the Great Australian Bight, South Australia 2017 Field Report. Curtin University, Western Australia (2018)
Shipping Noise Impacts on Marine Life. Paper presented at the Inter-noise Conference
  • D H Cato
Cato, D.H.: Shipping Noise Impacts on Marine Life. Paper presented at the Inter-noise Conference 2014, Melbourne, Australia 16-19 November (2014)