Hearing in cetaceans : from natural history to experimental biology

Author Posting. © The Author(s), 2012. This is the author's version of the work. It is posted here by permission of Elsevier for personal use, not for redistribution. The definitive version was published in Advances in Marine Biology 63, edited by Michael Lesser, :197-246. Academic Press (Elsevier), 2013. ISBN: 9780123942821. doi:10.1016/B978-0-12-394282-1.00004-1Sound is the primary sensory cue for most marine mammals, and this is especially true for cetaceans. To passively and actively acquire information about their environment, cetaceans have perhaps the most derived ears of all mammals, capable of sophisticated, sensitive hearing and auditory processing. These capabilities have developed for survival in an underwater world where sound travels five times faster than in air, and where light is quickly attenuated and often limited at depth, at night, and in murky waters. Cetacean auditory evolution has capitalized on the ubiquity of sound cues and the efficiency of underwater acoustic communication. The sense of hearing is central to cetacean sensory ecology, enabling vital behaviors such as locating prey, detecting predators, identifying conspecifics, and navigating. Increasing levels of anthropogenic ocean noise appears to influence many of these activities. Here we describe the historical progress of investigations on cetacean hearing, with a particular focus on odontocetes and recent advancements. While this broad topic has been studied for several centuries, new technologies in the last two decades have been leveraged to improve our understanding of a wide range of taxa, including some of the most elusive species. This paper addresses topics including how sounds are received, what sounds are detected, hearing mechanisms for complex acoustic scenes, recent anatomy and physiology studies, the potential impacts of noise, and mysticete hearing. We conclude by identifying emerging research topics and areas which require greater focus.In compiling this review, TAM was supported by the John E. and Anne W. Sawyer Endowed Fund and the Penzance Endowed Fund

Distribution and Source Apportionment ofPolycyclic Aromatic Hydrocarbons in Bank Soilsand River Sediments From the Middle Reaches ofthe Huaihe River, China

Bank surface soil and river sediment samplesfrom the middle reaches of the Huaihe River were analyzed by GC-MS for polycyclic aromatic hydrocarbons (PAHs). The total PAHs concentrations ranged from104 to 947 ng/g in bank soils and from 83 to 2599 ng/g in river sediments. The PAHs levels of the studied samples are relatively higher as compared to those from other world regions, which suggest an enhanced deposition of atmospheric PAHs derived from the emissions of fossil fuel combustion in this area. Possible sources from soil and sediments were diagnosed by the paired PAHs isomer ratios and principal components analysis, and the resultsindicate that the PAHs in the soilsmainly camefrom coal combustion (74%) followed by combustion of refined petroleum products (26%), and in the sediments mainly from pyrogenic sources (89%) followed by petroleum sources of oil spill emissions (11%). The PAHs exposure risk assessments show that PAHs in majority of the sediments did not pose threats to the ambient ecosystem. However, the calculated total toxic benzo[a]pyrene (BaP) equivalent of PAHs in soil and sediment indicate that BaP is the most potentially carcinogenic individual PAH.</p