ALBERT

Description: This Letter proposes a frequency scaling for processing, storing, and sharing high-bandwidth, passive acoustic spectral data that optimizes data volume while maintaining reasonable data resolution. The format is a hybrid that uses 1 Hz resolution up to 455 Hz and millidecade frequency bands above 455 Hz. This hybrid is appropriate for many types of soundscape analysis, including detecting different types of soundscapes and regulatory applications like computing weighted sound exposure levels. Hybrid millidecade files are compressed compared to the 1 Hz equivalent such that one research center could feasibly store data from hundreds of projects for sharing among researchers globally.

Description: © The Author(s), 2017. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Scientific Reports 7 (2017): 8350, doi:10.1038/s41598-017-07676-w.

Description: Although it is known that seals can use their whiskers (vibrissae) to extract relevant information from complex underwater flow fields, the underlying functioning of the system and the signals received by the sensors are poorly understood. Here we show that the vibrations of seal whiskers may provide information about hydrodynamic events and enable the sophisticated wake-tracking abilities of these animals. We developed a miniature accelerometer tag to study seal whisker movement in situ. We tested the ability of the tag to measure vibration in excised whiskers in a flume in response to laminar flow and disturbed flow. We then trained a seal to wear the tag and follow an underwater hydrodynamic trail to measure the whisker signals available to the seal. The results showed that whiskers vibrated at frequencies of 100–300 Hz, with a dynamic response. These measurements are the first to capture the incoming signals received by the vibrissae of a live seal and show that there are prominent signals at frequencies where the seal tactogram shows good sensitivity. Tapping into the mechanoreceptive interface between the animal and the environment may help to decipher the functional basis of this extraordinary hydrodynamic detection ability.

Description: Funding was provided by the NSF GRFP and NISE section 219 to C. Murphy and by the Office of Naval Research (N000141910468) to B. Calhoun.

Description: Acoustic recorders were used to document black drum (Pogonias cromis) sound production during their spawning season in southwest Florida. Diel patterns of sound production were similar to those of other sciaenid fishes and demonstrated increased sound levels from the late afternoon to early evening—a period that lasted up to 12 hours during peak season. Peak sound production occurred from January through March when water temperatures were between 18° and 22°C. Seasonal trends in sound productionmatched patterns of black drum reproductive readiness and spawning reported previously for populations in the Gulf of Mexico. Total acoustic energy of nightly chorus events wasestimated by integration of the sound pressure amplitude with duration above a threshold based on daytime background levels. Maximum chorus sound level was highly correlated with total acoustic energy and was used to quantitatively represent nightly black drum sound production. This studygives evidence that long-term passive acoustic recordings can provide information on the timing and location of black drum reproductive behavior that is similar to that provided by traditional, more costly methods. The methods and results have broad application for the study of many otherfish species, including commercially and recreationally valuable reef fishes that produce sound in association withreproductive behav

Description: Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution September 1995

Description: While many fishes are known to produce sounds during courtship and aggression, the information contained in the sounds and their role in reproduction is not well understood. This thesis is an intensive investigation of the sounds produced by the damselfish Dascyllus albisella, the effect of the environment on their acoustic signals, and how the sounds relate to reproduction. D. albisella males produce pulsed sounds during the signal jump, visiting by females, mating, aggression to heterospecifics and conspecifics, and nest preparation. Females make only aggressive sounds. The pulse period of aggressive sounds was shorter than courtship sounds. There was no difference between visiting and mating sounds, except in pulse duration. Two types of aggressive sounds were produced, pops and chirps. Pops were more commonly made towards heterospecifics than conspecifics. There were no differences in courtship sounds made by males from Johnston Atoll and Hawaii, except in pulse duration, which are likely due to differences in the recording environment. The pulsed sounds produced during the signal jump of D. albisella were analyzed to determine what information they contain about the signal jump and how they change with propagation. There was no relationship between signal jump speed or distance with the number of pulses or pulse period of the sound. There was no consistent change in the peak frequency of pulses in a call. If echoes were present in the sound, the change in echo delay would likely have been too small for damselfish to detect. Sounds attenuated with distance such that the signal to noise ratio decreased from 17-25 dB at 1-2m to 5-10 dB at 11-12 m. It is unlikely that D. albisella can detect sounds at or beyond 11-12m from the sound source, based on noise masking data from other fishes. Pulse period is least affected by propagation when compared to peak frequency, pulse duration, inter-pulse interval, and coefficient of variation of pulse amplitudes within a call. These results suggest that the sound produced during the signal jump acts over short distances and that the pulse period provides the most reliable basis for signal detection. A passive acoustic detection system was developed to continuously record sound production activity of individual males in the field. The rate of sound production could be used to determine the timing of spawning. The daily rate of sound production increased until the day of spawning, after which it decreased by over half. Additionally, the amount of sound production at night was highest just before spawning. The passive acoustic detector also revealed that D. albisella had regular peaks of calling at dawn, similar to the dawn chorus in birds. Patterns of male reproductive success varied for individual males over successive reproductive cycles and was not correlated to male size. The variation in reproductive success suggests that females choose males based on characters that vary from cycle to cycle. Data from the passive acoustic detector showed rates of courtship were positively correlated with reproductive success for three males. The continuous time-series of sound production were analyzed to determine appropriate sampling strategies to measure male sound production over shorter time periods using SCUBA. However, short samples of sound production (10 minutes or 60 minutes per male per day) were poor estimators of peak calling rates and daily calling rates. The rich variation in male courtship rates may contain information about male condition that has been previously ignored. Two reproductive synchrony measures were developed and used in randomization tests to test for synchronization of reproduction within five sites in the Johnston Atoll lagoon. Groups of isolated fish spawned in synchrony, but not in synchrony with other groups, even as close as 20-30 m. There was no apparent selective pressure for synchronous spawning when brood size, brood loss, and brood failure were considered. It is possible, though currently untestable, that there is a benefit of synchronous spawning for larval survival. It is unlikely that reproduction is synchronized in response to an environmental cue, because the scale of synchronization is small. Synchronization might develop through the courtship sound, because it regularly increases and decreases with spawning and the range of detectability is on the order of the range of synchronization. But, it is also possible that males are responding to chemical cues released by females. Spawning synchrony was also analyzed for 10 damsel fish species. D. albisella was among the most synchronized species, along with Abudefduf troschelii. Using a phylogenetic analysis of Chrornis, Amphiprion, and Dascyllus there are three viable hypotheses concerning the evolution of reproductive synchrony in D. albisella 1) it is an evolutionary relict that is no longer selected for and possibly maladaptive, 2) it evolved as part of the harernic lifestyle of the common ancestor of the Dascyllus genus, or 3) it evolved as the result of selection pressure for synchronization during the larval stage.

Description: I was supported by the following grants to Phil Lobel: NOAA National Undersea Research Program (NOAA/NURC-FDU 89-09-NA88A-HURD 20), the Sea Grant program at WHOI (NA86-AA-D-SG090 project R/B-97-PD), the U.S. Army Chemical Materiel Destruction Agency (via NOAA Sea Grant NA90-AA-DSG535 and the Office of Naval Research N00014-91-J1591 and N00014-92-J-1969), the U.S. Army Legacy Resource Management Program (DAMD 17-93-J-3052), the Island Foundation and the Kelley Foundation. The Education office provided funds for travel to scientific meetings and the Copeland Family Foundation supported my connection to the internet.