Donaghay Percy L.

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Percy L.

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  • Article
    Noise level correlates with manatee use of foraging habitats
    (Acoustical Society of America, 2007-05) Miksis-Olds, Jennifer L. ; Donaghay, Percy L. ; Miller, James H. ; Tyack, Peter L. ; Nystuen, Jeffrey A.
    The introduction of anthropogenic sound to coastal waters is a negative side effect of population growth. As noise from boats, marine construction, and coastal dredging increases, environmental and behavioral monitoring is needed to directly assess the effect these phenomena have on marine animals. Acoustic recordings, providing information on ambient noise levels and transient noise sources, were made in two manatee habitats: grassbeds and dredged habitats. Recordings were made over two 6-month periods from April to September in 2003 and 2004. Noise levels were calculated in one-third octave bands at nine center frequencies ranging from 250 Hz to 64 kHz. Manatee habitat usage, as a function of noise level, was examined during four time periods: morning, noon, afternoon, and night. Analysis of sightings data in a variety of grassbeds of equal species composition and density indicate that manatees select grassbeds with lower ambient noise for frequencies below 1 kHz. Additionally, grassbed usage was negatively correlated with concentrated boat presence in the morning hours; no correlation was observed during noon and afternoon hours. This suggests that morning boat presence and its associated noise may affect the use of foraging habitat on a daily time scale.
  • Article
    New approaches and technologies for observing harmful algal blooms
    (Oceanography Society, 2005-06) Babin, Marcel ; Cullen, John C. ; Roesler, Collin S. ; Donaghay, Percy L. ; Doucette, Gregory J. ; Kahru, Mati ; Lewis, Marlon R. ; Scholin, Christopher A. ; Sieracki, Michael E. ; Sosik, Heidi M.
    Harmful algal blooms (HABs) represent a diverse range of phenomena that universally share only two characteristics: they produce effects on ecosystems or food resources that humans perceive as harmful, and their progression is fundamentally a process of population dynamics under oceanographic control. Because of the complexity, scales, and transient nature of HABs, their monitoring and prediction requires rapid, intensive, extensive, and sustained observations at sea. These requirements cannot be met with traditional approaches that depend on ships for sampling and laboratories for chemical or biological analyses. Fortunately, new sensing technologies that operate autonomously in situ will allow, in the near future, the development of comprehensive observation strategies for timely detection of HABs. In turn, developments in modeling will support prediction of these phenomena, based directly on real-time measurements.