Browsing by Subject "bioacoustics"

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    Behavior and Bioacoustics of Invasive Silver and Bighead Carp
    (2016-05) Vetter, Brooke
    Invasive silver (Hypophthalmichthys molitrix) and bighead (H. nobilis) carp (collectively bigheaded carp) dominate the Mississippi River Drainage, outcompete native species, and continue to expand northward. Silver carp demonstrate an unusual jumping behavior to boat traffic. Understanding this response is important from a behavioral standpoint and critical to developing effective control methods. Experiments in outdoor concrete ponds (10 x 5 x 2 m), investigated the impact of pure tones (500 – 2000 Hz) and a recording from an outboard motor (0.06 – 10 kHz) on bigheaded carp swimming. Speakers broadcasting the sound stimuli were placed at either end of the concrete pond and bigheaded carp behavior was assessed using overhead cameras. Silver carp were consistently directed away (mean: 11.8 ± 1.3 consecutive responses) from the broadband sound (outboard motor recording) and the bighead carp were more responsive, exhibiting a median of 20.0 consecutive responses (1st Q: 12.0, 3rd Q: 23.0). However, both species were less reactive and habituated quickly to pure tones (after 1-2 trials). Field observations of silver carp jumping frequency, orientation, and direction in response to fast moving (16 – 40 km/hr) boats suggest that jumping is non-random, as the fish primarily move away from (79.8%) and behind the boat (> 90%), avoiding the area directly astern (< 4 m) in the most turbulent part of the wake. Finally, broadband sound (> 150 dB) stimulated wild silver carp to jump in a small tributary of the Illinois River. The fish demonstrated a different pattern than those reacting to the fast moving boats, with carp jumping all around the slow moving boat. This research suggests that sound can be used to alter the behavior of bigheaded carp with implications for deterrent barriers or other uses (e.g., herding fish to increase harvest).
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    Behavioral differences in sound detection in recently diverged cave and surface forms of Astyanax mexicanus
    (2021) Kistner, Amanda R; Enriquez, Maya S; Michels, Noland O; Mensinger, Allen F
    Astyanax mexicanus, or the Mexican tetra, inhabits both surface streams and cave systems, and has subsequently developed two unique morphologies: a cave morph and a surface morph. Cave morphs of the species have evolved several troglomorphic phenotypes, including vestigial eyes, reduced pigmentation, and increased olfactory and lateral line sensitivity. Interestingly, several satellite populations of surface fish were introduced to a Texas aquifer approximately 100 years ago and, following cave colonization, rapid evolution of various sensory adaptations between the cave and surface populations have been observed. Auditory evoked potential (AEP) data was collected to compare hearing sensitivities between cave and surface satellite populations, and both populations responded to sound presentation up to 4 kHz. However, because AEPs measure action potential summation to screen for frequency sensitivities, behavioral data is needed to determine absolute hearing sensitivity. The current study examines behavioral differences in sound detection between these two populations using reflexive startle behaviors to sound, namely the “C-start” escape response, which has been shown to be a reliable means of determining neurological responses to acoustic stimuli. Based on behavioral audiograms collected on satellite three populations, San Pedro Springs (cave) and Honey Creek (surface) appear to respond more readily to acoustic stimuli and habituate at a similar rate when compared to San Antonio Zoo (surface), which appear to respond less readily and habituate faster. Differences in sound pressure thresholds, as well as stimulus-response latencies between these populations, will be determined through finer volume control and modeling sub-thresholds.
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    Seasonal Changes in Male Oyster Toadfish’s Response to Boatwhistle Playbacks
    (2020-01) Curtis, Nora J; Mackiewicz, Alayna G; Putland, Rosalyn L; Mensinger, Allen F
    Opasanus tau, the Oyster Toadfish inhabits estuaries along the Atlantic coast. Males produce a short, harmonic mating call titled a 'boatwhistle' to attract females from late May to early August. A hydrophone was deployed under the dock at the Marine Biological Laboratory in Woods Hole Massachusetts to passively monitor their mating behavior. An underwater speaker played boatwhistles at the toadfish at varied times throughout the day and season to determine the male response to hearing extraneous noise.