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1.
Loss of acoustic habitat due to anthropogenic noise is a key environmental stressor for vocal amphibian species, a taxonomic group that is experiencing global population declines. The Pacific chorus frog (Pseudacris regilla) is the most common vocal species of the Pacific Northwest and can occupy human‐dominated habitat types, including agricultural and urban wetlands. This species is exposed to anthropogenic noise, which can interfere with vocalizations during the breeding season. We hypothesized that Pacific chorus frogs would alter the spatial and temporal structure of their breeding vocalizations in response to road noise, a widespread anthropogenic stressor. We compared Pacific chorus frog call structure and ambient road noise levels along a gradient of road noise exposures in the Willamette Valley, Oregon, USA. We used both passive acoustic monitoring and directional recordings to determine source level (i.e., amplitude or volume), dominant frequency (i.e., pitch), call duration, and call rate of individual frogs and to quantify ambient road noise levels. Pacific chorus frogs were unable to change their vocalizations to compensate for road noise. A model of the active space and time (“spatiotemporal communication”) over which a Pacific chorus frog vocalization could be heard revealed that in high‐noise habitats, spatiotemporal communication was drastically reduced for an individual. This may have implications for the reproductive success of this species, which relies on specific call repertoires to portray relative fitness and attract mates. Using the acoustic call parameters defined by this study (frequency, source level, call rate, and call duration), we developed a simplified model of acoustic communication space–time for this species. This model can be used in combination with models that determine the insertion loss for various acoustic barriers to define the impact of anthropogenic noise on the radius of communication in threatened species. Additionally, this model can be applied to other vocal taxonomic groups provided the necessary acoustic parameters are determined, including the frequency parameters and perception thresholds. Reduction in acoustic habitat by anthropogenic noise may emerge as a compounding environmental stressor for an already sensitive taxonomic group.  相似文献   
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Unmanned aerial vehicles (UAVs) are increasingly used for wildlife research and monitoring, but little information exists on their potential effect on marine mammals. We assessed the effects of a UAV on the behavior of southern right whales (Eubalaena australis) in Australia. Focal follows of ten right whale mother-calf pairs were conducted using a theodolite. Control data were recorded for 30 min, and then a DJI Inspire 1 Pro was flown above the whales for 10 min at 5 m altitude. Potential changes to horizontal behavior (swim speed and turning angle) and surfacing pattern (interbreath intervals) were investigated by comparing mother-calf behavior before and during UAV approaches. Changes in respiration rate were used to quantify energetic effects. We also explored acoustic cue perceptibility of the UAV at 5, 10, and 30 m altitude, by measuring the received UAV underwater noise level on whales equipped with acoustic tags (DTAGs). The received noise levels were 86.0 ± 3.9 dB re 1 μPa, while the measured ambient noise was 80.7 ± 7.3 dB re 1 μPa in the same frequency band (100–1,500 Hz). No behavioral response to the UAV was observed. This provides support for UAVs as a noninvasive tool to study baleen whale behavior and ecophysiology.  相似文献   
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Shifts in habitat use and distribution patterns in dolphins are often concerns that can result from habitat degradation. We investigated how potential changes to a habitat from human activity may alter dolphin distributions within Lingding Bay in the Pearl River Estuary, China, by studying the relationship between fish choruses, vessel presence and Indo‐Pacific humpback dolphin (Sousa chinensis) detection rates. Analyses revealed temporal and spatial variation within fish choruses, vessel presence and dolphin detection rates. After accounting for any temporal autocorrelation, correlations between fish choruses and dolphin detection rates were also found; however, no relationship between fish choruses and vessel presence or dolphin detection rates and vessel presence were observed. Furthermore, fewer dolphins were detected at sites where fish activity was less intense. Thus fish activity, rather than vessels, may be a key factor influencing the distribution of the dolphins within the estuary. These findings emphasize the risk of potential shifts in habitat use for Indo‐Pacific humpback dolphins due to detrimental changes to prey availability and dolphin feeding grounds from human activity, such as overfishing and coastal developments, within the estuary. This is a critical conservation issue for this dolphin population that is facing intense anthropogenic pressure.  相似文献   
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Maritime traffic is an issue of major ecological concern, and vessel noise may be an important source of disturbance for coastal cetaceans. In the Sado estuary, Portugal, core habitat areas of a small resident population of bottlenose dolphins (Tursiops truncatus) overlap with routes of intense maritime traffic, which presents an opportunity to assess vocal responses of these dolphins to specific vessel noise sources. Field recordings of dolphin vocalizations were made from April to November 2011, using a calibrated system. Dolphin behavior and group size were recorded, as well as the operating boat condition (no boats or specific boat type) in a 1,000 m radius. Spectral analyses of vocalizations allowed the categorization and quantitative analysis of echolocation click trains and social calls, including whistles. Mean overall call rates decreased significantly in the presence of operating vessels. Creaks (fast click trains) were significantly reduced in the presence of ferry boats. Significant differences were also observed in the whistles' minimum, maximum, and start frequencies. These changes in call emission rates and temporary shifts in whistles characteristics may be a vocal response to the proximity of operating vessels, facilitating communication in this busy, noisy estuary.  相似文献   
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Comparative analysis was performed of sensitivity of three populations of neurons of the inferior colliculus central nucleus and of neurons of the auditory cortex A1 and AAF fields of the house mouse Mus musculus to series of signals of wideband noise with spectral notch shifting along the frequency axis and to series of the band noise signals with shifting band. Sensitivity to spectral notches in noise was estimated from a change of impulse activity depending on notch location on the frequency axis (modulation coefficients were determined as the normalized difference between the maximal and minimal spike number in neuronal responses to all noises with notch exposed in the series). It was shown that the highest modulation coefficient values and accordingly the highest frequency-dependent sensitivity to spectral notches in the noise were peculiar to inhibition-dependent inferior colliculus neurons. Statistical analysis confirmed that distribution of modulation coefficients for the group of the inhibition-dependent neurons differed statistically significantly from the distribution for groups of primary-like and V-shaped inferior colliculus neurons as well as of cortical neurons (U-test, p < 0.0001). The lowest sensitivity to spectral notches was revealed in the V-shaped inferior colliculus neurons and cortical neurons; in these groups, distribution of modulation coefficients did not differed statistically significantly (p > 0.3). Thus, although a part of cortical neurons does have the frequency-dependent selectivity to spectral localizationally informative changes in sound signals, its formation needs participation of the inferior colliculus and its inhibition-dependent neurons. Selectivity to direction of the shift of spectral changes in noise signals in neurons of the inferior colliculus and auditory cortex was similar and was manifested mainly as shift along the frequency axis of dependences of the spike number in the neuronal responses and latent periods on central frequency of notch in noise (the noise band).  相似文献   
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豚鼠暴露于125dB SPL噪声下1小时后即刻、1天内耳组织中葡萄糖(46.0±18.3μg/mg蛋白,102.2±56.3μg/mg蛋白)及丙酮酸量(30.6±8.4μg/g蛋白,47.1±15.7μg/g蛋白)均显著地高于对照组(葡萄糖26.4±8.9μg/mg蛋白,丙酮酸23.7±8.9μg/g蛋白),p<0.05。与此同时豚鼠听功能耳廓反射阈衰减dB值(30.0±12.2dB,44.8±2.5dB)显著地低于暴露前水平(49.4±2.9dB,46.2±1.9dB),P相似文献   
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