Coral reef soundscapes may not be detectable far from the reef

© The Author(s), 2016. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Scientific Reports 6 (2016): 31862, doi:10.1038/srep31862.Biological sounds produced on coral reefs may provide settlement cues to marine larvae. Sound fields are composed of pressure and particle motion, which is the back and forth movement of acoustic particles. Particle motion (i.e., not pressure) is the relevant acoustic stimulus for many, if not most, marine animals. However, there have been no field measurements of reef particle motion. To address this deficiency, both pressure and particle motion were recorded at a range of distances from one Hawaiian coral reef at dawn and mid-morning on three separate days. Sound pressure attenuated with distance from the reef at dawn. Similar trends were apparent for particle velocity but with considerable variability. In general, average sound levels were low and perhaps too faint to be used as an orientation cue except very close to the reef. However, individual transient sounds that exceeded the mean values, sometimes by up to an order of magnitude, might be detectable far from the reef, depending on the hearing abilities of the larva. If sound is not being used as a long-range cue, it might still be useful for habitat selection or other biological activities within a reef.This work was funded by the Woods Hole Oceanographic Institution Ocean Ventures Fund, the PADI Foundation, the Woods Hole Oceanographic Institution Access To The Sea program, and the National Science Foundation grant OCE-1536782

Ambient noise and temporal patterns of boat activity in the US Virgin Islands National Park

Author Posting. © The Author(s), 2015. 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 Marine Pollution Bulletin 98 (2015): 221-228, doi:10.1016/j.marpolbul.2015.06.047.Human activity is contributing increasing noise to marine ecosystems. Recent studies have examined the effects of boat noise on marine fishes, but there is limited understanding of the prevalence of this sound source. This investigation tracks vessel noise on three reefs in the US Virgin Islands National Park over four months in 2013. Ambient noise levels ranged from 106-129 dBrms re 1 μPa (100 Hz – 20 kHz). Boat noise occurred in 6-12% of samples. In the presence of boat noise, ambient noise in a low-frequency band (100-1000 Hz) increased by >7 dB above baseline levels and sound levels were significantly higher. The frequency with the most acoustic energy shifted to a significantly lower frequency when boat noise was present during the day. These results indicate the prevalence of boat noise and its overlap with reef organism sound production, raising concern for the communication abilities of these animals.This research was funded by the Mitsubishi Corporation Foundation for the Americas and WHOI’s Access to the Sea program and was carried out under permit number VHS-2013-SCI-0005 to Mooney and Kaplan

Coral reef soundscapes : spatiotemporal variability and links to species assemblages

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 February 2017Coral reefs are biodiverse ecosystems that are at risk of degradation as a result of environmental changes. Reefs are constantly in a state of flux: the resident species assemblages vary considerably in space and time. However, the drivers of this variability are poorly understood. Tracking these changes and studying how coral reefs respond to natural and anthropogenic disturbance can be challenging and costly, particularly for reefs that are located in remote areas. Because many reef animals produce and use sound, recording the ambient soundscape of a reef might be one way to efficiently study these habitats from afar. In this thesis, I develop and apply a suite of acoustics-based tools to characterize the biological and anthropogenic acoustic activity that largely comprises marine soundscapes. First, I investigate links between reef fauna and reef-specific acoustic signatures on coral reefs located in the U.S. Virgin Islands. Second, I compare those findings to a more expansive study that I conducted in Maui, Hawaii, in which the drivers of bioacoustic differences among reefs are explored. Third, I investigate the distances over which sounds of biological origin may travel away from the reef and consider the range within which these acoustic cues might be usable by pelagic larvae in search of a suitable adult habitat. Fourth, I assess the extent to which the presence of vessel noise in shallow-water habitats changes the ambient soundscape. Finally, I present the results of a modeling exercise that questions how ocean noise levels might change over the next two decades as a result of major projected increases in the number and size of and distance traveled by commercial ships. The acoustics-based tools presented here help provide insight into ecosystem function and the extent of human activity in a given habitat. Additionally, these tools can be used to inform an effective regulatory regime to improve coral reef ecosystem management.Supported by the BP-MIT Energy Fellowship, the MIT Martin Family Fellowship, NSF grant OCE-1536728, NSF Ocean Acidification grant 1220034, Office of Naval Research award number N000141110612 and the WHOI Academic Programs Office. My research was funded by the Mitsubishi Corporation Foundation for the Americas, the PADI Foundation, the WHOI Access To The Sea Fund, the WHOI Coastal Ocean Institute, the WHOI Independent Study awards, the WHOI Ocean Life Institute, and the WHOI Ocean Ventures Fund

Singing whales generate high levels of particle motion : implications for acoustic communication and hearing?

Author Posting. © The Author(s), 2016. This is the author's version of the work. It is posted here by permission of The Royal Society for personal use, not for redistribution. The definitive version was published in Biology Letters 12 (2016): 20160381, doi:10.1098/rsbl.2016.0381.Acoustic signals are fundamental to animal communication and cetaceans are often considered bioacoustic specialists. Nearly all studies of their acoustic communication focus on sound pressure measurements, overlooking the particle motion components of their communication signals. Here we characterize the levels of acoustic particle velocity (and pressure) of song produced by humpback whales. We demonstrate that whales generate acoustic fields that include significant particle velocity components that are detectable over relatively long distances sufficient to play a role in acoustic communication. We show that these signals attenuate predictably in a manner similar to pressure and that direct particle velocity measurements can provide bearings to singing whales. Whales could potentially use such information to determine the distance of signaling animals. Additionally, the vibratory nature of particle velocity may stimulate bone conduction, a hearing modality similar to other low-frequency specialized mammals, offering a parsimonious mechanism of acoustic energy transduction into the massive ossicles of whale ears. With substantial concerns regarding the effects of increasing anthropogenic ocean noise and major uncertainties surrounding mysticete hearing, these results highlight both an unexplored avenue that may be available for whale acoustic communication and the need to better understand the biological role of acoustic particle motion.WHOI’s Independent Study Award to T.A.M

Acoustic and biological trends on coral reefs off Maui, Hawaii

Author Posting. © The Author(s), 2017. This is the author's version of the work. It is posted here under a nonexclusive, irrevocable, paid-up, worldwide license granted to WHOI. It is made available for personal use, not for redistribution. The definitive version was published in Coral Reefs 37 (2018): 121-133, doi:10.1007/s00338-017-1638-x.Coral reefs are characterized by high biodiversity and evidence suggests that reef soundscapes reflect local species assemblages. To investigate how sounds produced on a given reef relate to abiotic and biotic parameters and how that relationship may change over time, an observational study was conducted between September 2014 and January 2016 at seven Hawaiian reefs that varied in coral cover, rugosity, and fish assemblages. The reefs were equipped with temperature loggers and acoustic recording devices that recorded on a 10% duty cycle. Benthic and fish visual survey data were collected four times over the course of the study. On average, reefs ranged from 0 to 80% live coral cover, although changes between surveys were noted, in particular during the major El Niño-related bleaching event of October 2015. Acoustic analyses focused on two frequency bands (50–1200 Hz and 1.8–20.5 kHz) that corresponded to the dominant spectral features of the major sound-producing taxa on these reefs, fish and snapping shrimp, respectively. In the low-frequency band, the presence of humpback whales (December– May) was a major contributor to sound level, whereas in the high-frequency band sound level closely tracked water temperature. On shorter timescales, the magnitude of the diel trend in sound production was greater than that of the lunar trend, but both varied in strength among reefs, which may reflect differences in the species assemblages present. Results indicated that the magnitude of the diel trend was related to fish densities at low frequencies and coral cover at high frequencies; however, the strength of these relationships varied by season. Thus, long-term acoustic recordings capture the substantial acoustic variability present in coral-reef ecosystems and provide insight into the presence and relative abundance of sound-producing organisms.Funding for this research was provided by the PADI Foundation, the WHOI Access To The Sea initiative and Ocean Life Institute, and the National Science Foundation grant OCE-1536782

Repeated call types in Hawaiian melon-headed whales (Peponocephala electra)

Author Posting. © Acoustical Society of America, 2014. This article is posted here by permission of Acoustical Society of America for personal use, not for redistribution. The definitive version was published in Journal of the Acoustical Society of America 136 (2014): 1394, doi:10.1121/1.4892759.Melon-headed whales are pantropical odontocetes that are often found near oceanic islands. While considered sound-sensitive, their bioacoustic characteristics are relatively poorly studied. The goal of this study was to characterize the vocal repertoire of melon-headed whales to determine whether they produce repeated calls that could assist in recognition of conspecifics. The first tag-based acoustic recordings of three melon-headed whales were analyzed. Tag records were visually and aurally inspected and all calls were individually extracted. Non-overlapping calls with sufficient signal-to-noise were then parameterized and visually grouped into categories of repeated call types. Thirty-six call categories emerged. Categories differed significantly in duration, peak and centroid frequency, and −3 dB bandwidth. Calls of a given type were more likely to follow each other than expected. These data suggest that repeated calls may function in individual, subgroup, or group recognition. Repeated call production could also serve to enhance signal detection in large groups with many individuals producing simultaneous calls. Results suggest that caution should be used in developing automatic classification algorithms for this species based on small sample sizes, as they may be dominated by repeated calls from a few individuals, and thus not representative of species- or population-specific acoustic parameters.This project was funded by the Office of Naval Research (award number: N000141110612; Program Manager Michael J. Weise), WHOI Marine Mammal Center, and the Sawyer and Penzance Endowed Funds, with additional field time funded by grants through Cascadia Research Collective by the National Oceanographic Partnership Program (through the Alaska SeaLife Center) and the Pacific Islands Fisheries Science Center

Coral reef species assemblages are associated with ambient soundscapes

Author Posting. © The Author(s), 2015. This is the author's version of the work. It is posted here by permission of Inter-Research for personal use, not for redistribution. The definitive version was published in Marine Ecology Progress Series 533 (2015): 93-107, doi:10.3354/meps11382.Coral reefs provide a wide array of ecosystem services and harbor some of the highest levels of biodiversity on the planet, but many reefs are in decline worldwide. Tracking changes is necessary for effective resource management. Biological sounds have been suggested as a means to quantify ecosystem health and biodiversity, but this requires an understanding of natural bioacoustic variability and relationships to the taxa present. This investigation sought to characterize spatial and temporal variation in biological sound production within and among reefs that varied in their benthic and fish diversity. Multiple acoustic recorders were deployed for intensive 24-hour periods and longer term (~4-month) duty-cycled deployments on three reefs that varied in coral cover and fish density. Short-term results suggest that while there were statistically significant acoustic differences among recorders on a given reef, these differences were relatively small, indicating that a single sensor may be suitable for acoustic characterization of reefs. Analyses of sounds recorded over ~4 months indicated that the strength of diel trends in a low frequency fish band (100-1000 Hz) was correlated with coral cover and fish density but the strength of high-frequency snapping-shrimp (2-20 kHz) trends was not, suggesting that low-frequency recordings may be better indicators of the species assemblages present. Power spectra varied within reefs over the deployment periods, underscoring the need for long-duration recordings to characterize these trends. These findings suggest that, in spite of considerable spatial and temporal variability within reef soundscapes, diel trends in low-frequency sound production correlate with reef species assemblages.This research was funded by the Mitsubishi Corporation Foundation for the Americas and WHOI’s Access to the Sea program

Fluctuations in Hawaii's humpback whale Megaptera novaeangliae population inferred from male song chorusing off Maui

© The Author(s), 2020. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Kugler, A., Lammers, M. O., Zang, E. J., Kaplan, M. B., & Mooney, T. A. Fluctuations in Hawaii's humpback whale Megaptera novaeangliae population inferred from male song chorusing off Maui. Endangered Species Research, 43, (2020): 421-434, https://doi.org/10.3354/esr01080.Approximately half of the North Pacific humpback whale Megaptera novaeangliae stock visits the shallow waters of the main Hawaiian Islands seasonally. Within this breeding area, mature males produce an elaborate acoustic display known as song, which becomes the dominant source of ambient underwater sound between December and April. Following reports of unusually low whale numbers that began in 2015/16, we examined song chorusing recorded through long-term passive acoustic monitoring at 6 sites off Maui as a proxy for relative whale abundance between 2014 and 2019. Daily root-mean-square sound pressure levels (RMS SPLs) were calculated to compare variations in low-frequency acoustic energy (0-1.5 kHz). After 2014/15, the overall RMS SPLs decreased between 5.6 and 9.7 dB re 1 µPa2 during the peak of whale season (February and March), reducing ambient acoustic energy from chorusing by over 50%. This change in song levels co-occurred with a broad-scale oceanic heat wave in the northeast Pacific termed the ‘Blob,’ a major El Niño event in the North Pacific, and a warming period in the Pacific Decadal Oscillation cycle. Although it remains unclear whether our observations reflect a decrease in population size, a change in migration patterns, a shift in distribution to other areas, a change in the behavior of males, or some combination of these, our results indicate that continued monitoring and further studies of humpback whales throughout the North Pacific are warranted to better understand the fluctuations occurring in this recently recovered population and other populations that continue to be endangered or threatened.Funding was provided by The WHOI Access To The Sea initiative and Ocean Life Institute,National Science Foundation grant OCE-1536782, Department of Land and Natural Resources of the State of Hawai’i, Whale Tales Maui, Pride of Maui, the PADI Foundation, and the National Marine Sanctuary Foundation

On Neutrino Emission From Dense Matter Containing Meson Condensates

We consider the rate at which energy is emitted by neutrinos from the dense interior of neutron stars containing a Bose condensate of pions or kaons. The rates obtained are larger, by a factor of 2, than those found earlier, and are consistent with those found for the direct Urca processes.Comment: RevTeX, 10 page

Nonequilibrium Weak Processes in Kaon Condensation II - Kinetics of condensation ---

The kinetics of negatively charged kaon condensation in the early stages of a newly born neutron star is considered. The thermal kaon process, in which kaons are thermally produced by nucleon-nucleon collisions, is found to be dominant throughout the equilibration process. Temporal changes of the order parameter of the condensate and the number densities of the chemical species are obtained from the rate equations, which include the thermal kaon reactions as well as the kaon-induced Urca and the modified Urca reactions. It is shown that the dynamical evolution of the condensate is characterized by three stages: the first, prior to establishment of a condensate, the second, during the growth and subsequent saturation of the condensate, and the third, near chemical equilibrium. The connection between the existence of a soft kaon mode and the instability of the noncondensed state is discussed. Implications of the nonequilibrium process on the possible delayed collapse of a protoneutron star are also mentioned.Comment: 27 pages, incl. 8 eps figures, RevTe