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To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.anbehav.2004.06.020 Byline: Damon P. Gannon, Nelio B. Barros, Douglas P. Nowacek, Andrew J. Read, Danielle M. Waples, Randall S. Wells Abstract: Bottlenose dolphins possess a sophisticated echolocation system, but evidence suggests that they use this sensory modality sparingly in the wild. Several authors have noted that soniferous fish are prevalent in the diet of bottlenose dolphins, leading to the hypothesis that these predators detect their prey by passive listening. We tested this hypothesis by performing controlled acoustic playback experiments with free-ranging dolphins in Sarasota Bay, Florida. We used recorded calls of prey fish and sounds of snapping shrimp as experimental and control treatments, respectively, and measured the dolphins' direction of travel and rate of echolocation as response variables. Dolphins changed their direction of travel significantly, turning towards the sound source when fish sounds were played. In addition, dolphins significantly increased their rate of echolocation immediately following playbacks of fish sounds. The sounds of snapping shrimp elicited neither directional nor echolocation responses. The occurrence of echolocation sounds was low, except following playback of fish sounds. We conclude that bottlenose dolphins use passive listening extensively during the search phase of the foraging process. By listening passively, dolphins may obtain useful information on the identity, number, size and location of soniferous prey. Once dolphins discover prey by passive means, they then appear to use echolocation to track the prey during the pursuit and capture phases. Such judicious use of echolocation suggests that this sensory modality incurs significant energetic or ecological costs. These findings have implications for coevolution of dolphins and their prey with regard to sound production and detection. Author Affiliation: (*) Duke University Marine Laboratory, Beaufort, North Carolina, U.S.A. (a ) Mote Marine LaboratoryU.S.A. (a ) Chicago Zoological Society, Chicago, Illinois, U.S.A. Article History: Received 23 October 2003; Revised 26 February 2004; Accepted 2 June 2004 Article Note: (miscellaneous) MS. number: A9736

Plasticity in the cardiac function of a marine mammal facilitates rapid adjustments to the contrasting metabolic demands of breathing at the surface and diving during an extended apnea. By matching their heart rate (fH) to their immediate physiological needs, a marine mammal can improve its metabolic efficiency and maximize the proportion of time spent underwater. Respiratory sinus arrhythmia (RSA) is a known modulation of fH that is driven by respiration and has been suggested to increase cardiorespiratory efficiency. To investigate the presence of RSA in cetaceans and the relationship between fH, breathing rate (fR) and body mass (Mb), we measured simultaneous fH and fR in five cetacean species in human care. We found that a higher fR was associated with a higher mean instantaneous fH (ifH) and minimum ifH of the RSA. By contrast, fH scaled inversely with Mb such that larger animals had lower mean and minimum ifHs of the RSA. There was a significant allometric relationship between maximum ifH of the RSA and Mb, but not fR, whichmay indicate that this parameter is set by physical laws and not adjusted dynamically with physiological needs. RSA was significantly affected by fR and was greatly reduced with small increases in fR. Ultimately, these data showthat surface fHs of cetaceans are complex and the fH patternswe observed are controlled by several factors. We suggest the importance of considering RSA when interpreting fH measurements and particularly how fR may drive fH changes that are important for efficient gas exchange. [ABSTRACT FROM AUTHOR]

Six baleen whale species are found in the temperate western North Atlantic Ocean, with limited information existing on the distribution and movement patterns for most. There is mounting evidence of distributional shifts in many species, including marine mammals, likely because of climate‐driven changes in ocean temperature and circulation. Previous acoustic studies examined the occurrence of minke (Balaenoptera acutorostrata) and North Atlantic right whales (NARW; Eubalaena glacialis). This study assesses the acoustic presence of humpback (Megaptera novaeangliae), sei (B. borealis), fin (B. physalus), and blue whales (B. musculus) over a decade, based on daily detections of their vocalizations. Data collected from 2004 to 2014 on 281 bottom‐mounted recorders, totaling 35,033 days, were processed using automated detection software and screened for each species' presence. A published study on NARW acoustics revealed significant changes in occurrence patterns between the periods of 2004–2010 and 2011–2014; therefore, these same time periods were examined here. All four species were present from the Southeast United States to Greenland; humpback whales were also present in the Caribbean. All species occurred throughout all regions in the winter, suggesting that baleen whales are widely distributed during these months. Each of the species showed significant changes in acoustic occurrence after 2010. Similar to NARWs, sei whales had higher acoustic occurrence in mid‐Atlantic regions after 2010. Fin, blue, and sei whales were more frequently detected in the northern latitudes of the study area after 2010. Despite this general northward shift, all four species were detected less on the Scotian Shelf area after 2010, matching documented shifts in prey availability in this region. A decade of acoustic observations have shown important distributional changes over the range of baleen whales, mirroring known climatic shifts and identifying new habitats that will require further protection from anthropogenic threats like fixed fishing gear, shipping, and noise pollution. [ABSTRACT FROM AUTHOR]

Many baleen whales undertake annual fasting and feeding cycles, resulting in substantial changes in their body condition, an important factor affecting fitness. As a measure of lipid-store body condition, tissue density of a few deep diving marine mammals has been estimated using a hydrodynamic glide model of drag and buoyancy forces. Here, we applied the method to shallow-diving humpback whales (Megaptera novaeangliae) in North Atlantic and Antarctic feeding aggregations. High-resolution 3-axis acceleration, depth and speed data were collected from 24 whales. Measured values of acceleration during 5 s glides were fitted to a hydrodynamic glide model to estimate unknown parameters (tissue density, drag term and diving gas volume) in a Bayesian framework. Estimated species-average tissue density (1031.6 ± 2.1 kg m-3, ±95% credible interval) indicates that humpback whale tissue is typically negatively buoyant although there was a large inter-individual variation ranging from 1025.2 to 1043.1 kg m-3. The precision of the individual estimates was substantially finer than the variation across different individual whales, demonstrating a progressive decrease in tissue density throughout the feeding season and comparably high lipid-store in pregnant females. The drag term (CDAm-1) was estimated to be relatively high, indicating a large effect of lift-related induced drag for humpback whales. Our results show that tissue density of shallow diving baleen whales can be estimated using the hydrodynamic gliding model, although cross-validation with other techniques is an essential next step. This method for estimating body condition is likely to be broadly applicable across a range of aquatic animals and environments. [ABSTRACT FROM AUTHOR]

Marine mammals consume large quantities of microplastic particles, likely via trophic transfer (i.e., through prey who have consumed plastic) and direct consumption from seawater or sediment. Microplastics have been found in the stomachs, gastro-intestinal tracts, and feces of cetaceans and pinnipeds. Translocation of ingested microplastics has been documented in other organs of several aquatic species, but has not been examined in marine mammals. Marine mammals have highly specialized lipid-rich tissues which may increase susceptibility to lipophilic microplastics. Here we demonstrate the occurrence of microplastics, ranging in size, mass concentration, and particle count concentration from 24.4 μm – 1387 μm, 0.59 μg/g – 25.20 μg/g, and 0.04 – 0.39 particles/g, respectively, in four tissues (acoustic fat pad, blubber, lung, & melon) from twelve marine mammal species inclusive of mysticetes, odontocetes, and phocids. Twenty-two individuals were examined for microplastics using a combination of Raman spectroscopy and pyrolysis gas chromatography with mass spectrometry. Overall, 68% of individuals had at least one microplastic particle in at least one of the four tissue types, with the most common polymer and shape observed being polyethylene and fibers, respectively. These findings suggest some proportion of ingested microplastics translocate throughout marine mammal bodies posing an exposure risk to both marine mammals and people. For people, exposure could be directly through consumption for those who rely on marine mammals as food and indirectly to peoples globally who consume the same prey resources as marine mammals. Some individuals examined represent samples obtained over two decades ago, suggesting that this process, and thus exposure risk, has occurred for some time. [Display omitted] • Internalized microplastics translocate to marine mammal organs, notably blubber. • Samples containing microplastics spanned over two decades. • 68% of samples contained at least one microplastic particle. • The most common polymer & shape observed were polyethylene & fibers, respectively. • Use of complimentary methods allowed for both mass and count concentrations. [ABSTRACT FROM AUTHOR]

The article offers information on a collection of accounts of Arnoux's beaked whales sighted in the southern-central region of the Gerlache Strait near entrance of the Schollaert Channel between Brabant and Cuverville Islands in Antarctica. According to study, Arnoux's beaked whales are usually found in cold water south of 34°S, and usually in groups of less than 15 individuals. Moreover, it mentions that the large group ever report as of 2009 was 47 individuals.

1. Since the last thorough review of the effects of anthropogenic noise on cetaceans in 1995, a substantial number of research reports has been published and our ability to document response(s), or the lack thereof, has improved. While rigorous measurement of responses remains important, there is an increased need to interpret observed actions in the context of population-level consequences and acceptable exposure levels. There has been little change in the sources of noise, with the notable addition of noise from wind farms and novel acoustic deterrent and harassment devices (ADDs/AHDs). Overall, the noise sources of primary concern are ships, seismic exploration, sonars of all types and some AHDs. 2. Responses to noise fall into three main categories: behavioural, acoustic and physiological. We reviewed reports of the first two exhaustively, reviewing all peer-reviewed literature since 1995 with exceptions only for emerging subjects. Furthermore, we fully review only those studies for which received sound characteristics (amplitude and frequency) are reported, because interpreting what elicits responses or lack of responses is impossible without this exposure information. Behavioural responses include changes in surfacing, diving and heading patterns. Acoustic responses include changes in type or timing of vocalizations relative to the noise source. For physiological responses we address the issues of auditory threshold shifts and ‘stress’, albeit in a more limited capacity; a thorough review of physiological consequences is beyond the scope of this paper. 3. Overall, we found significant progress in the documentation of responses of cetaceans to various noise sources. However, we are concerned about the lack of investigation into the potential effects of prevalent noise sources such as commercial sonars, depth finders and fisheries acoustics gear. Furthermore, we were surprised at the number of experiments that failed to report any information about the sound exposure experienced by their experimental subjects. Conducting experiments with cetaceans is challenging and opportunities are limited, so use of the latter should be maximized and include rigorous measurements and or modelling of exposure. [ABSTRACT FROM AUTHOR]

Large predators should have difficulty catching small prey because small animals demonstrate greater maneuverability and agility compared to large animals. The ability of a predator to capture small prey indicates locomotor strategies to compensate for inequities in maneuverability. Bottlenose dolphins (Tursiops truncatus) in Sarasota Bay, Florida feed on fish at least one order of magnitude smaller than themselves. To examine the locomotor strategies involved in prey capture, the foraging movements of these dolphins were videotaped from overhead using a remotely-controlled camera suspended from a helium-filled aerostar, which was tethered to an observation vessel. Dolphins were observed to rapidly maneuver during chases of fish in open water or around patches of rooted vegetation. Video analysis of the chase sequences indicated that the dolphins could move the rostrum through small radius turns with a mean value of 0.20 body lengths and with a minimum value of 0.08 body lengths. Mean rate of turn was 561.6°/sec with a maximum rate measured at 1,372.0°/sec. High turning rates with small turning radii were primarily the result of maneuvers in which the dolphin rolled 90° and rapidly flexed its body ventrally. The ability of dolphins to change body orientation in multiple rotational axes provides a mechanism to reduce turning radius and increase turning rate to catch small, elusive prey. [ABSTRACT FROM AUTHOR]

The article describe one of the most dramatic behavioral responses individuals have witnessed in several playback trials with natural and anthropogenic sounds to dozens of marine mammal species. Topics include examines three stimuli were presented several min apart and observers on the RHIB were blind to the playback sequence and identity of the calls used in each trial.

Exposure to anthropogenic sound can have a range of negative behavioral and physical effects on marine species and is of increasing ecological and regulatory concern. In particular, the response of marine mammals, and notably the family of cryptic deep-diving beaked whales, to military sonar is a timely and complex issue. To make inference on aspects of response by individual whales to noise of any type, it is critical to either measure or systematically estimate what received levels (RLs) the animal actually experienced. Various tools and techniques exist to monitor RLs and associated responses, each with advantages and disadvantages. Most behavioral response studies to date have used relatively short-term (hours to a few days), high-resolution acoustic tags that provide direct RL measurements. Because of their short duration, these tags do not allow for assessments of longer-duration baseline behavior before and following a disturbance that may tell us more about the nature of response within a broader context for tagged individuals. In contrast, longer-duration (weeks to months), satellite-transmitting tags lack high-resolution kinematic data and the ability to directly measure RL. Herein, we address these issues and efforts to derive robust statistical RL characterizations using animal movement and fine-scale, site-specific sound propagation modeling for longer-duration tags in the context of a behavioral response study off Cape Hatteras, North Carolina. In the autumn of 2017, we tagged nine Cuvier's beaked whales and three short-finned pilot whales and conducted controlled exposure experiments using simulated and operational military mid-frequency active sonar. We used sound propagation modeling methods and modeled positions of individual animals to estimate RLs in four dimensions and to statistically describe uncertainty within volumes of water space where animals were predicted to occur during exposure periods. By properly accounting for positional error in this study, it is clear that previous studies using single median RL estimates drastically underestimate the full range of plausible values; ranges in estimated RLs here often exceeded 40 dB. We also demonstrate how ancillary data from visual focal follows of tagged individuals can significantly narrow estimated RL ranges. Further, we compared measured RLs on a calibrated acoustic tag to modeled RLs at the same position to evaluate our volumetric modeling results. While satellite tags record data over longer time frames, their substantial geospatial error coupled with the unique deep-diving behavior of beaked whales means that estimates of RL can vary broadly and, consequently, that single point estimates from less robust approaches may be substantially in error. Accounting for this uncertainty using robust statistical modeling is critical to fairly characterize variance and effectively assess exposure-response relationships. [ABSTRACT FROM AUTHOR]

This article evaluates Southall et al. (2007) in light of subsequent scientific findings and proposes revised noise exposure criteria to predict the onset of auditory effects in marine mammals. Estimated audiograms, weighting functions, and underwater noise exposure criteria for temporary and permanent auditory effects of noise are presented for six species groupings, including all marine mammal species. In-air criteria are also provided for amphibious species. Earlier marine mammal hearing groupings were reviewed and modified based on phylogenetic relationships and a comprehensive review of studies on hearing, auditory anatomy, and sound production. Auditory weighting functions are derived for each group; those proposed here are less flattened and closer to audiograms than the Southall et al. M-weightings. As in Southall et al., noise sources are categorized as either impulsive or non-impulsive, and criteria use multiple exposure metrics to account for different aspects of exposure. For continuous (non-impulsive) noise sources, exposure criteria are given in frequency-weighted sound exposure level (SEL, given in units relative to 1 µPa2-s or (20 μPa2)-s for water and air, respectively). Dual exposure metrics are provided for impulsive noise criteria, including frequency-weighted SEL and unweighted peak sound pressure level (SPL, given in units relative to 1 μPa or 20 μPa for water and air, respectively). Exposures exceeding the specified respective criteria level for any exposure metric are interpreted as resulting in predicted temporary threshold shift (TTS) or permanent threshold shift (PTS) onset. Scientific findings in the last decade provide substantial new insight but also underscore remaining challenges in deriving simple, broadly applicable quantitative exposure criteria for such diverse taxa. These criteria should be considered with regard to relevant caveats, recommended research, and with the expectation of subsequent revision. [ABSTRACT FROM AUTHOR]