Virginia Institute of Marine Science
During May 2015, passive acoustic recorders were deployed at eight subtidal oyster reefs within Harris Creek Oyster Sanctuary in Chesapeake Bay, Maryland USA. These sites were selected to represent both restored and unrestored habitats having a range of oyster densities. Throughout the survey, the soundscape within Harris Creek was dominated by the boatwhistle calls of the oyster toadfish, Opsanus tau. A novel, multi-kernel spectral correlation approach was developed to automatically detect these boatwhistle calls using their two lowest harmonic bands. The results provided quantitative information on how call rate and call frequency varied in space and time. Toadfish boatwhistle fundamental frequency ranged from 140 Hz to 260 Hz and was well correlated (r = 0.94) with changes in water temperature, with the fundamental frequency increasing by similar to 11 Hz for every 1 degrees C increase in temperature. The boatwhistle call rate increased from just a few calls per minute at the start of monitoring on May 7 th to similar to 100 calls/min on May 10 th and remained elevated throughout the survey. As male toadfish are known to generate boatwhistles to attract mates, this rapid increase in call rate was interpreted to mark the onset of spring spawning behavior. Call rate was not modulated by water temperature, but showed a consistent diurnal pattern, with a sharp decrease in rate just before sunrise and a peak just after sunset. There was a significant difference in call rate between restored and unrestored reefs, with restored sites having nearly twice the call rate as unrestored sites. This work highlights the benefits of using automated detection techniques that provide quantitative information on species-specific call characteristics and patterns. This type of non-invasive acoustic monitoring provides longterm, semi-continuous information on animal behavior and abundance, and operates effectively in settings that are otherwise difficult to sample.
SOUND PRODUCTION; MATING CALL; CRABS
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This work is licensed under a Creative Commons Attribution 4.0 License.
This work received support from the National Science Foundation (OCE-1234688) to DBE and DRB https://www.nsf.gov/; North Carolina Sea Grant (RMRD56/12-HCE-2) to DBE https:// ncseagrant.ncsu.edu/; and NC State University, Center for Marine Sciences and Technology https://cmast.ncsu.edu/. Funding for field operations was provided as part of a larger research program supported by the National Oceanic Atmospheric Administration Chesapeake Bay Office (NA13NMF4570209 and NA14NMF4570287) to MLK, https://chesapeakebay.noaa.gov/. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Ricci, Shannon W.; Bohnenstiehl, DelWayne R.; Eggleston, David B.; Kellogg, M. Lisa; and Lyon, R. Patrick, Oyster toadfish (Opsanus tau) boatwhistle call detection and patterns within a large-scale oyster restoration site (2017). PLOS ONE, 12(8).