Vasconcelos Raquel O, Amorim M Clara P, Ladich Friedrich
Departamento de Biologia Animal e Centro de Biologia Ambiental, Faculdade de Ciências da Universidade de Lisboa. Bloco C2 Campo Grande, 1749-0161 Lisboa, Portugal.
J Exp Biol. 2007 Jun;210(Pt 12):2104-12. doi: 10.1242/jeb.004317.
Underwater noise pollution is an increasing environmental problem which might affect communication, behaviour, fitness and consequently species' survival. The most common anthropogenic noises in aquatic habitats derive from shipping. In the present study we investigated the implications of noise pollution from a ship on the sound detectability, namely of conspecific vocalizations in the Lusitanian toadfish, Halobatrachus didactylus. Ambient and ferry-boat noises were recorded in the Tagus River estuary (Portugal), as well as toadfish sounds, and their sound pressure levels determined. Hearing sensitivities were measured under quiet lab conditions and in the presence of these masking noises at levels encountered in the field, using the auditory evoked potentials (AEP) recording technique. The Lusitanian toadfish is a hearing generalist, with best hearing sensitivity at low frequencies between 50 and 200 Hz (below 100 dB re. 1 microPa). Under ambient noise conditions, hearing was only slightly masked at lower frequencies. In the presence of ship noise, auditory thresholds increased considerably, by up to 36 dB, at most frequencies tested. This is mainly because the main energies of ferry-boat noise were within the most sensitive hearing range of this species. Comparisons between masked audiograms and sound spectra of the toadfish's mating and agonistic vocalizations revealed that ship noise decreased the ability to detect conspecific acoustic signals. This study provides the first evidence that fishes' auditory sensitivity can be impaired by ship noise and that acoustic communication, which is essential during agonistic encounters and mate attraction, might be restricted in coastal environments altered by human activity.
水下噪声污染是一个日益严重的环境问题，可能会影响生物的交流、行为、健康状况，进而影响物种的生存。水生栖息地中最常见的人为噪声来自航运。在本研究中，我们调查了船舶噪声污染对葡萄牙海蟾蜍（Halobatrachus didactylus）声音可探测性的影响，即对同种发声的影响。在塔霍河河口（葡萄牙）记录了环境噪声和渡轮噪声，以及海蟾蜍的声音，并测定了它们的声压级。利用听觉诱发电位（AEP）记录技术，在安静的实验室条件下以及在现场遇到的这些掩蔽噪声存在的情况下测量听觉敏感度。葡萄牙海蟾蜍是一种听觉能力广泛的生物，在50至200赫兹的低频（相对于1微帕为100分贝以下）具有最佳听觉敏感度。在环境噪声条件下，低频时听觉仅被轻微掩蔽。在船舶噪声存在的情况下，在大多数测试频率下，听觉阈值大幅增加，最多可达36分贝。这主要是因为渡轮噪声的主要能量在该物种最敏感的听觉范围内。对海蟾蜍求偶和争斗发声的掩蔽听力图与声谱的比较表明，船舶噪声降低了探测同种声学信号的能力。这项研究首次证明，船舶噪声会损害鱼类的听觉敏感度，并且在争斗相遇和吸引配偶过程中至关重要的声学交流，在受人类活动改变的沿海环境中可能会受到限制。
