Curriculum Vita Arthur N. Popper
Emeritus Professor and Research Professor, Department of Biology
Emeritus Co-Director, Center for Comparative and Evolutionary Biology of Hearing
Department of Biology, The University of Maryland, College Park, MD 20742
E-mail: apopper@umd.edu
Education
Ph.D. 1969 Biology, City University of New York
B.A. 1964 Biology, New York University, Bronx, NY
Research Interests
The work in my laboratory was, for many years, directed towards understanding basic structure and function of the auditory system in vertebrates, with particular interest in the ear of fishes and its sensory hair cells. These investigations frequently involved a wide number of teleost species (e.g., goldfish, zebrafish, cichlids, American shad, sleeper gobies) and the use of the comparative approach in order to understand the function of the ear as well as its evolution. More recently, the focus of our work has become redirected to apply our expertise on fish bioacoustics to more applied questions that examine the effects of human-generated (anthropogenic) sound on fish.
Past work
Using a variety of different behavioral paradigms, we have determined the range of sounds fish can hear, as well as their ability to discriminate signals. Most recently, we have discovered that the American shad is able to detect ultrasound (up to 180 kHz), in contrast with most other species of fish that can detect sounds to only 1 - 3 kHz. The implications of this finding are considerable, and there are interesting parallels in this system to the system that has evolved in moths to detect ultrasound produced by bats. Indeed, we have evidence that American shad have evolved ultrasound detection to avoid a major predator of theirs, echolocating dolphins!
Other investigations, using neuroanatomical methods, asked questions regarding the central projections of the eighth nerve from individual end organs of the ear to the brain and the organization of the eighth nerve at the level of the various end organs.
Questions of sensory hair cell structure and evolution have been a focal point of much current research. A significant finding, based upon work using electron microscopy, immunocytochemistry and other techniques, has been the discovery of multiple types of sensory hair cells in the ears of fishes. This finding refutes earlier work that suggested that hair cell heterogeneity only occurs in amniotes. Importantly, the discovery of multiple types of hair cells in fishes helps in our understanding of the way that the fish ear functions and also has implications for our understanding of when multiple hair cell types evolved in vertebrates.
Considerable work has also been directed at questions of hair cell addition, development, and regeneration. Unlike most other vertebrates, fishes add very substantial numbers of sensory hair cells to the ear for many years after hatching. We have also demonstrated that fish regenerate hair cells. Current investigations are directed at determining the patterns of hair cell development in fishes, with particular emphasis on questions relating to the similarities and differences between embryonic and post-embryonic hair cell development and between normal development and regeneration. Related studies are asking questions about developmental similarities and differences between different types of sensory hair cells.
More recent work focused on the applied use of sound to control movement of fish and on the effects of anthropogenic (human-generated) sounds on fishes and other aquatic animals.. There is a significant problem in areas of hydropower dams, intakes to power plants, irrigation ditches, and similar places, where fish can move or be carried into areas of danger. A variety of different mechanical and behavioral methods have been tried to protect fish from these dangers, with varying levels of success. One of the most successful techniques has been the use of ultrasound to prevent clupeid fishes (herrings and relatives) from entering power plant intakes.
A bigger issue concerns the effects of human-generated (anthropogenic) sound on aquatic life (e.g., Popper and Hawkins, 2019). Over the past decades there has been a substantial increase in the human-generated sounds in the marine environment. While there has been great concern about the effects of such sounds on marine mammals, far less consideration has been given to the effects of the same sounds on fishes and invertebrates. Since the ear of fishes is based upon the same basic principles and same hair cell system as that of mammals, there is good reason to suspect that anthropogenic sounds, and particularly loud sounds such as those produced by large ships, air-guns, and other sources might impact fish. Impact could include death, damage to sensory cells, or stress-related changes. Less overt, but equally significant, impact could result from long-term changes in behavior that could alter reproductive potential. These impacts are of great potential importance not only since fish make up the major component of the vertebrate marine ecosystem, but also because they are major components in the food chain of many marine mammals, and humans.
Over the past several years, we have also investigated the effects of a wide range of sound sources on fish including seismic air-guns (e.g., McCauley et al. 2003; Popper et al. 2005; Song et al. 2008), sonar (Popper et al. 2007; Kane et al. 2010), increased background levels (Smith et al. 2004a, b, 2006; Wysocki et al. 2007; Davidson et al. 2007), and sounds associated with barging of fish (Halvorsen et al. 2009) (see Publications link to the left to find specific references),
My lab has also investigated the effects of pile driving on fish (see Hastings and Popper 2005 for background). This work, which was overviewed by Halvorsen et al. (2008) is continuing and includes examination of the effects of actual pile driving sounds on fish in the laboratory. More recently, we conducted a series of studies using simulated pile driving sounds to examine the potential trauma from such exposure. This work is discussed here.
Final Projects
Over the past few years I have been collaborating with a group that involved the U.S. Navy and Univeristy of Washington to examine the potential impacts of exposure to explosive sounds on fish physiology. We exposure several fish species to explosions of C-4. Fish were placed at different distances from the source, and after exposure we investigated the impact on external and internal tissues. This work has been published as Dahl et al. (2020), Jenkins et al. (2022), and a paper soon to come out in ICES Marine Science by Bowman et al. (2024). A brief review is provided by Jenkins et al. (2023).
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Click to see recent publications
Click here to see all of the volumes in the Springer Handbook of Auditory Research (SHAR)