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1.
To prevent grounding of ships and collisions between ships in shallow coastal waters, an underwater data collection and communication network (ACME) using underwater sounds to encode and transmit data is currently under development. Marine mammals might be affected by ACME sounds since they may use sound of a similar frequency (around 12 kHz) for communication, orientation, and prey location. If marine mammals tend to avoid the vicinity of the acoustic transmitters, they may be kept away from ecologically important areas by ACME sounds. One marine mammal species that may be affected in the North Sea is the harbour seal (Phoca vitulina). No information is available on the effects of ACME-like sounds on harbour seals, so this study was carried out as part of an environmental impact assessment program. Nine captive harbour seals were subjected to four sound types, three of which may be used in the underwater acoustic data communication network. The effect of each sound was judged by comparing the animals' location in a pool during test periods to that during baseline periods, during which no sound was produced. Each of the four sounds could be made into a deterrent by increasing its amplitude. The seals reacted by swimming away from the sound source. The sound pressure level (SPL) at the acoustic discomfort threshold was established for each of the four sounds. The acoustic discomfort threshold is defined as the boundary between the areas that the animals generally occupied during the transmission of the sounds and the areas that they generally did not enter during transmission. The SPLs at the acoustic discomfort thresholds were similar for each of the sounds (107 dB re 1 microPa). Based on this discomfort threshold SPL, discomfort zones at sea for several source levels (130-180 dB re 1 microPa) of the sounds were calculated, using a guideline sound propagation model for shallow water. The discomfort zone is defined as the area around a sound source that harbour seals are expected to avoid. The definition of the discomfort zone is based on behavioural discomfort, and does not necessarily coincide with the physical discomfort zone. Based on these results, source levels can be selected that have an acceptable effect on harbour seals in particular areas. The discomfort zone of a communication sound depends on the sound, the source level, and the propagation characteristics of the area in which the sound system is operational. The source level of the communication system should be adapted to each area (taking into account the width of a sea arm, the local sound propagation, and the importance of an area to the affected species). The discomfort zone should not coincide with ecologically important areas (for instance resting, breeding, suckling, and feeding areas), or routes between these areas.  相似文献   

2.
Two harbor porpoises in a floating pen were subjected to five pure tone underwater signals of 70 or 120kHz with different signal durations, amplitudes and duty cycles (% of time sound is produced). Some signals were continuous, others were intermittent (duty cycles varied between 8% and 100%). The effect of each signal was judged by comparing the animals' surfacing locations and number of surfacings (i.e. number of respirations) during test periods with those during baseline periods. In all cases, both porpoises moved away from the sound source, but the effect of the signals on respiration rates was negligible. Pulsed 70kHz signals with a source level (SL) of 137dB had a similar effect as a continuous 70kHz signal with an SL of 148dB (re 1muPa, rms). Also, a pulsed 70kHz signal with an SL of 147dB had a much stronger deterring effect than a continuous 70kHz signal with a similar SL. For pulsed 70kHz signals (2s pulse duration, 4s pulse interval, SL 147dB re 1muPa, rms), the avoidance threshold sound pressure level (SPL), in the context of the present study, was estimated to be around 130dB (re 1muPa, rms) for porpoise 064 and around 124dB (re 1muPa, rms) for porpoise 047. This study shows that ultrasonic pingers (70kHz) can deter harbor porpoises. Such ultrasonic pingers have the advantage that they do not have a "dinner bell" effect on pinnipeds, and probably have no, or less, effect on other marine fauna, which are often sensitive to low frequency sounds.  相似文献   

3.
To prevent grounding of ships and collisions between ships in shallow coastal waters, an underwater data collection and communication network is currently under development: Acoustic Communication network for Monitoring of underwater Environment in coastal areas (ACME). Marine mammals might be affected by ACME sounds since they use sounds of similar frequencies (around 12 kHz) for communication, orientation, and prey location. If marine mammals tend to avoid the vicinity of the transmitters, they may be kept away from ecologically important areas by ACME sounds. One marine mammal species that may be affected in the North Sea is the harbour porpoise. Therefore, as part of an environmental impact assessment program, two captive harbour porpoises were subjected to four sounds, three of which may be used in the underwater acoustic data communication network. The effect of each sound was judged by comparing the animals' positions and respiration rates during a test period with those during a baseline period. Each of the four sounds could be made a deterrent by increasing the amplitude of the sound. The porpoises reacted by swimming away from the sounds and by slightly, but significantly, increasing their respiration rate. From the sound pressure level distribution in the pen, and the distribution of the animals during test sessions, discomfort sound level thresholds were determined for each sound. In combination with information on sound propagation in the areas where the communication system may be deployed, the extent of the 'discomfort zone' can be estimated for several source levels (SLs). The discomfort zone is defined as the area around a sound source that harbour porpoises are expected to avoid. Based on these results, SLs can be selected that have an acceptable effect on harbour porpoises in particular areas. The discomfort zone of a communication sound depends on the selected sound, the selected SL, and the propagation characteristics of the area in which the sound system is operational. In shallow, winding coastal water courses, with sandbanks, etc., the type of habitat in which the ACME sounds will be produced, propagation loss cannot be accurately estimated by using a simple propagation model, but should be measured on site. The SL of the communication system should be adapted to each area (taking into account bounding conditions created by narrow channels, sound propagation variability due to environmental factors, and the importance of an area to the affected species). The discomfort zone should not prevent harbour porpoises from spending sufficient time in ecologically important areas (for instance feeding areas), or routes towards these areas.  相似文献   

4.
The high under-water sound pressure levels (SPLs) produced during pile driving to build offshore wind turbines may affect harbor porpoises. To estimate the discomfort threshold of pile driving sounds, a porpoise in a quiet pool was exposed to playbacks (46 strikes/min) at five SPLs (6 dB steps: 130–154 dB re 1 μPa). The spectrum of the impulsive sound resembled the spectrum of pile driving sound at tens of kilometers from the pile driving location in shallow water such as that found in the North Sea. The animal's behavior during test and baseline periods was compared. At and above a received broadband SPL of 136 dB re 1 μPa [zero-peak sound pressure level: 151 dB re 1 μPa; t90: 126 ms; sound exposure level of a single strike (SELss): 127 dB re 1 μPa2 s] the porpoise's respiration rate increased in response to the pile driving sounds. At higher levels, he also jumped out of the water more often. Wild porpoises are expected to move tens of kilometers away from offshore pile driving locations; response distances will vary with context, the sounds' source level, parameters influencing sound propagation, and background noise levels.  相似文献   

5.
江豚(Neophocaena phocaenoides G. Cuvier)俗称江猪,属鲸目(Cetacea),齿鯨亚目(Odontoceti),鼠海豚科,是海豚类中最小型的一种,也是我国沿海最常见的一种近岸小型无鰭鼠海豚。一般体长不超过2米,体重约30-80公斤,如图1照片所示。 江豚与其他海洋哺乳动物一祥,能发出多变的声信号,而且每一种声信号都受其生态行为的支配。发声系统是它们赖以生存的重要官能。海豚用其发射的声信号测定水下目标的距离、方位和大小,以至判断其形状,因而能有效的绕过障碍,避开或驱逐来犯之敌。依靠其声信号能更有效的捕获足够的食物,营养自身,抚育后代。声信号是海洋哺乳类动物在自然界进行生存斗争的有利武器。声信号又是海洋哺乳动物的语言,借以进行“社会”联络和通讯,甚至教育它们的后代。为此。人们把它们的这种功能称作“第六官能”(sixth sense)。 观察海兽类的声学行为,测试分析其声信号的结构和物理特性,是揭示它们的回声定位系统的机制,破译其“语言”奥密所必不可少的一步。从而将为驯养它们成为人类的水下得力“助手”提供可靠的实验方案,也将为仿生学等新的学科研究提供有效的理论依据。 本实验是为了把江豚驯养成“水下警犬”使其在海湾、河口进行人工放养鱼群的放牧,以及协助人类进行水下作业等目的而进行的基础工作,也是研究海洋哺乳动物回声定位的发射与接收机制的探索。实验工作是在一定的半自然条件下,对江豚某些生态行为下的声信号作了较详细的记录与分析。  相似文献   

6.
World-wide, underwater background noise levels are increasing due to anthropogenic activities. Little is known about the effects of anthropogenic noise on marine fish, and information is needed to predict any negative effects. Behavioural startle response thresholds were determined for eight marine fish species, held in a large tank, to tones of 0.1-64 kHz. Response threshold levels varied per frequency within and between species. For sea bass, the 50% reaction threshold occurred for signals of 0.1-0.7 kHz, for thicklip mullet 0.4-0.7 kHz, for pout 0.1-0.25 kHz, for horse mackerel 0.1-2 kHz and for Atlantic herring 4 kHz. For cod, pollack and eel, no 50% reaction thresholds were reached. Reaction threshold levels increased from approximately 100 dB (re 1 microPa, rms) at 0.1 kHz to approximately 160 dB at 0.7 kHz. The 50% reaction thresholds did not run parallel to the hearing curves. This shows that fish species react very differently to sound, and that generalisations about the effects of sound on fish should be made with care. As well as on the spectrum and level of anthropogenic sounds, the reactions of fish probably depend on the context (e.g. location, temperature, physiological state, age, body size, and school size).  相似文献   

7.
为了解水下强噪声对大黄鱼的影响,结合行为学方法开展了3个年龄的大黄鱼声刺激实验.结果发现:3个年龄的大黄鱼在水中声压约10Pa时均能对声波发生条件反应,但是,它们的声波敏感频率和直接致死的声压阈值差异较大;1个月幼苗和8个月小鱼的声波敏感频率分别为800Hz和600Hz,直接致死的声压阈值约为40Pa和4kPa.13个月大鱼的声波敏感频率也在600Hz,但当声压达到4kPa时,鱼群受惊吓明显,且未能直接致死.另外,这些曾经暴露在强声波中的各年龄段的大黄鱼在随后48h里较多出现相继死亡的现象.表明这些长时间暴露在水下噪声中的大黄鱼可能会因累积效应引起行为模式改变和间接致死等慢性危害.  相似文献   

8.
Hydrophone recordings, made in the presence of North Atlantic right whales (Eubalaena glacialis) in the Bay of Fundy during the daytime in July 1999, are used to determine the characteristics of the recorded sounds. A spectrogram-based method was implemented to discriminate whale sounds from background noise and the time-frequency envelope of the primary harmonic in the spectrogram was used as the basis for sound characterization. Sounds were typically (82%, n=45) in the 300- to 600-Hz range with up- and downsweeping modulations. Lower (<200 Hz) and higher (>900 Hz) frequency sounds were relatively rare. Most sounds were frequency modulated, with 95% of the observed instantaneous relative frequency variation being within /spl plusmn/4.5% of the mean peak frequency. Harmonics were observed in 18% of the sounds. The average sound duration was 0.42 s/spl plusmn/0.26 SD. The sounds occurred at a rate of between 0.3 and 0.7 min/sup -1/. The time intervals between adjacent sounds (2-700 s) were not randomly distributed. The number of sounds occurring among different waiting times did not reflect a Poisson distribution and a clustering of sounds (2 to 5 cluster/sup -1/) was observed. The sound characteristics are compared to those documented elsewhere and as reported for the southern right whale.  相似文献   

9.
Harbour porpoise bycatch may be reduced by deterring porpoises from nets acoustically. In this study, two harbour porpoises were subjected to three acoustic alarms. The effect of each alarm was judged by comparing the animals' position and respiration rate during a test period with that during a baseline period. The XP-10 alarm produced 0.3 s tonal signals randomly selected from a set of 16 with fundamental frequencies between 9 and 15 kHz, with a constant pulse interval of 4.8 s (duty cycle 6%). The 2MP alarm produced 0.3 s tonal signals randomly selected from a set of 16 with similar fundamental frequencies but with random pulse intervals of between 2 and 5 s (duty cycle 8%). The frequency spectra and source levels of the 2MP and XP-10 alarms varied depending on the signal selected. The HS20-80 alarm produced a constant, but asymmetrical frequency modulated sinewave between 20 and 80 kHz with total pulse duration of 0.3 s. with random pulse intervals of between 2 and 5 s (duty cycle 4.6%). The porpoises reacted to all three alarms by swimming away from them and by increasing their respiration rate. The XP-10, which on average had the highest source level, had the strongest effect.  相似文献   

10.
多频海底声学原位测试系统研制和试用   总被引:11,自引:2,他引:9  
海底沉积物的声学特性(最重要的是声速和声衰减)以及它们与物理(包括土力学)特性之间的关系是沉积物声学中两个重要的研究项目.介绍了新研制的实时监控多频海底声学原位测试系统.该系统可测量浅表层沉积物的声速.探测频率为8,10,12,15 kHz,可根据实际情况选择发射波形、接收增益和采样长度,采样率为0.5~2.0 MHz,工作水深为300 m.系统具有倾斜传感器、8通道扩充等功能.用该系统在杭州湾测得了四种频率的沉积物原位声速.  相似文献   

11.
The Ieodo Ocean Research Station(IORS) is an integrated meteorological and oceanographic observation base which was constructed on the Ieodo underwater rock located at a distance of about 150 km to the south-west of the Mara-do, the southernmost island in Korea. The underwater ambient noise level observed at the IORS was similar to the results of the shallow water surrounding the Korean Peninsula (Choi et al. 2003) and was higher than that of deep ocean (Wenz 1962). The wind dependence of ambient noise was dominant at frequencies of a few kHz. The surface current dependence of ambient noise showed good correlation with the ambient noise in the frequency of 10 kHz. Especially, the shrimp sound was estimated through investigations of waveform and spectrum and its main acoustic energy was about 40 dB larger than ambient noise level at 5 kHz.  相似文献   

12.
国外对加州海狮(Zalophus californianus)的回声定位进行了一些研究,但其它种类海狮未见报导.我们在对加州海狮进行了一些实验后,对南海狮(Ostoriabyronia)进行了研究,以对其回声定位能力进行判断和评价,并与加州海狮进行对照比较.  相似文献   

13.
During the recent 2004 Sediment Acoustics Experiment (SAX04), a buried hydrophone array was deployed in a sandy sediment near Fort Walton Beach, FL. The array was used to measure both the acoustic penetration into the sediment and sound speed and attenuation within the sediment while a smaller, diver-deployed array was also used to measure sound speed and attenuation. Both of these systems had been deployed previously during the 1999 Sediment Acoustics Experiment (SAX99). In that experiment, the buried array was used to make measurements in the 11–50-kHz range while the diver-deployed array made measurements in the 80–260-kHz range. For the SAX04 deployment, the frequency range for the measurements using the buried array was lowered to 2 kHz. The diver-deployed array was also modified to cover the 40–260-kHz range. Unlike the SAX99 deployment, there were no obvious sand ripples at the SAX04 buried array site at the time of the measurements. To examine the role of sand ripples in acoustic penetration over this new frequency range, artificial ripple fields were created. For the high frequencies, the penetration was consistent with the model predictions using small-roughness perturbation theory as in SAX99. As the frequency of the incident acoustic field decreased, the evanescent field became the dominant penetration mechanism. The sound speed measured using the buried array exhibits dispersion consistent with the Biot theory while the measured attenuation exceeds the theory predictions at frequencies above 200 kHz.   相似文献   

14.
中国黄渤海沉积物声速与物理性质研究   总被引:1,自引:0,他引:1  
In order to investigate the correlation between a sound velocity and sediment bulk properties and explore the influence of frequency dependence of the sound velocity on the prediction of the sediment properties by the sound velocity,a compressional wave velocity is measured at frequencies of 25–250 k Hz on marine sediment samples collected from the Bohai Sea and the Yellow Sea in laboratory,together with the geotechnical parameters of sediments.The results indicate that the sound velocity ranges from 1.232 to 1.721 km/s for the collected sediment samples with a significant dispersion within the series measuring frequency.Poorly sorted sediments are highly dispersive nearly with a positive linear relationship.The porosity shows a better negative logarithmic correlation with the sound velocity compared with other geotechnical parameters.Generally,the sound velocity increases with the increasing of the average particle size,sand content,wet and dry bulk densities,and decreasing of the clay content,and water content.An important point should be demonstrated that the higher correlation can be obtained when the measuring frequency is low within the frequency ranges from 25 to 250 k Hz since the inhomogeneity of sediment properties has a more remarkably influence on the laboratory sound velocity measurement at the high frequency.  相似文献   

15.
海上风电场建设期风机打桩会产生高强度的水下噪声,研究水下冲击打桩噪声的监测方法、特性分析及对海洋生物的影响是非常重要的。采用自容式水下声音记录仪,多点同步测量了福建省兴化湾海上风电场二期工程建设期单次完整的水下冲击打桩噪声,从时频域特性进行了分析,并利用最小二乘法拟合得到了打桩声源级和声暴露级。结果表明:水下冲击打桩噪声是典型的低频、高强度的脉冲信号,单个脉冲持续时间约90~100 ms,峰值声源级约209.4±2 dB,声暴露级约197.7±2 dB;主要能量分布在50 Hz~1 kHz频段,750 m测量点的该频段声压级相比海洋环境背景噪声,提高了约40~50 dB。水下冲击打桩噪声频域能量分布与大黄鱼的听觉敏感频段相重叠,对大黄鱼影响程度和范围较大,实际工程应用中宜采用声暴露级作为评价指标。  相似文献   

16.
Small cetacean bycatch in gillnet fisheries may be reduced by deterring odontocetes from nets acoustically. However, different odontocete species may respond differently to acoustic signals from alarms. Therefore, in this study a striped dolphin and a harbour porpoise were subjected simultaneously to sounds produced by the XP-10 experimental acoustic alarm. The alarm produced 0.3s tonal signals randomly selected from a set of 16 with fundamental frequencies between 9 and 15kHz, with a constant pulse interval of 4.0s (duty cycle 8%) and a Source Level range of 133-163dB re 1muPa (rms). The effect of the alarm was judged by comparing the animals' respiration rate and position relative to the alarm during test periods with those during baseline periods. As in a previous study on two porpoises with the same alarm, the porpoise in the present study reacted strongly to the alarm by swimming away from it and increasing his respiration rate. The striped dolphin, however, showed no reaction to the active alarm. Based on harbour porpoise audiograms and the specific audiogram of the striped dolphin in the present study, and the low background noise levels during the experiment, both animals must have heard the alarm signals clearly. This study indicates that cetacean species are not equally sensitive to human-made noise disturbance. Therefore, source levels of acoustic alarms should be adapted to the species they are supposed to deter. In addition, alarms should be tested on each odontocete species for which they are intended to reduce bycatch.  相似文献   

17.
The approach to determine working frequencies of acoustic in-situ detector for seafloor hydrothermal fluid is presented. Based on the research of deep-sea noise and the sound generated by mid-ocean ridge black smoker hydrothermal vents, and on the hydrothermal-vent animal hearing ranges, coupled with influences of suspended particles of hydrothermal on acoustic attenuation under different frequencies, the optimal frequency range for detection of acoustical signal near black smokers is determined. The optimal frequencies providing the maximum ratio of receiver signal to background noise are obtained. We have developed a laboratory experimental setup for the optimal frequencies selection. In particular, we evaluated time-of-flight performance with respect to the source signal parameters of center frequency and bandwidth. The experimental results confirm the effectiveness of our approach. Current results indicate that individual transducers operated in the range of 18 ~ 25 kHz are immune to most interfering sounds and suitable for our system.  相似文献   

18.
High-frequency bubble layer scattering investigations require the measurement of the intensity of backscattered sound and the corresponding depth of the scatterers below the moving surface. Especially at high sea state conditions and high acoustic frequencies, bubbles acoustically mask the surface, i.e., the surface return cannot be detected. However, this environmental condition is the most interesting one in bubble scattering investigations and a reliable method is required to determine the range of the scatterers to the surface displacement. A method for the determination of the vertical profiling of acoustic scattering in the presence of bubbles at high sea state conditions is presented. It is based on the transmission of a low-frequency signal alternately to the high-frequency signal at which the scattering investigations are performed. The only information that is extracted from the low-frequency echo is the onset of the surface return. It is used to compute the true depth of scatterers at the high frequency. Experiments were conducted to determine the optimum low frequency at which the detection of the surface onset in the presence of a high bubble concentration is ensured. A screening ratio is defined to give a measure of the acoustic masking of the sea surface. It is depicted for an extreme wind condition (20 m/s) for the frequency range of 5-25 kHz and as a function of wind speed for 50 kHz measurements. Selected results of subsurface bubble scattering at 50 kHz from experiments under open sea conditions are presented for the wind speed regime from 9 to 22 m/s. Additionally, the two-frequency scatterometer is used to measure sea state characteristics simultaneously to the scattering investigations by remote sensing techniques  相似文献   

19.
正弦波交替音对黑鲷音响驯化的实验研究   总被引:1,自引:0,他引:1  
音响驯化作为一种控制鱼群行为的技术,在海洋牧场开发中的应用前景广阔。在室内控温和投饵条件下,用300 Hz和400 Hz正弦波交替音对黑鲷(Sparus macrocephalus)进行音响驯化实验。结果表明,黑鲷对交替音的驯化效果经历了适应期、变化期和维稳期3个阶段;黑鲷的反应时间逐日缩短并逐渐接近对照组,第1~4天黑鲷的反应时间显著高于对照组(P<0.01),第5天开始对刺激产生正反馈,第10天低于对照组并出现实验期最小反应时间;聚集率则逐日增加并从第5天开始显著高于对照组 (P<0.01),第7天后聚集率稳定在100%;驯化后的黑鲷在饥饿状态下对音响刺激的兴奋度比饱食后相对更高。由此可见,300 Hz和400 Hz正弦波交替音对黑鲷的反应和聚集具有明显的效果,交替音可作为黑鲷音响驯化的一种有效手段,结合投饵可以在控制鱼类行为中发挥出更大作用。  相似文献   

20.
海洋生物声学的研究,在第二次世界大战后已取得了很大进展,并已在军事和生产上得到应用,取得了效果。海洋动物发声是海洋环境噪声的一个组成部分,也是声纳系统的水下背景干扰源,尤其是在近岸海区,往往不可忽视。所以,研究海洋动物发声,除了在海洋生物学的研究中有明显的重要性外,对进一步了解海洋环境噪声的产生原因、变化规律及其物理机理,以及在声纳设计等方面也是十分重要的。已有报道,人们曾观測到鼓虾、石首鱼类、海胆、殆贝、藤壶、鲸等海洋动物集群发出的声音,往往造成很强的海洋噪声源。这些生物机体噪声通常还具有季节性或周日性的变化。有关海洋生物机体发声的观测和信号分析研究,国外虽有一些报道,但仅限于某些海区。 据不完全统计,我国近岸海区的发声生物在100种以上,其中不少种类具有集群大、发声强的特点。石首鱼科鱼类是我国近岸海区主要的海洋发声鱼类,约占我国海洋发声鱼类总数的三分之一,在渤海、黄海、东海和南海均有分布。其主要发声器官为鳔和邻近的鼓肌,当鼓肌收縮时压迫内脏,使鳔壁共振发出声音。他们在上述某些海区集群发出的声音,有时在海面也能清晰听到。 本文主要对过去多年来我国渤海、黄海、东海近岸海区,某些集群大、发声强、具有代表性的石首科鱼的现场观测资料作了分析和阐述,其中包括集群发声的声学特征,以及随时间、地点的変化。  相似文献   

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