Influences of Spatial and Temporal Variability of Sound Scattering Layers on Deep Diving Odontocete Behavior

dc.contributor.author Copeland, Adrienne
dc.date.accessioned 2017-12-18T22:09:04Z
dc.date.available 2017-12-18T22:09:04Z
dc.date.issued 2016-08
dc.description Ph.D. University of Hawaii at Manoa 2016.
dc.description Includes bibliographical references.
dc.description.abstract Patchiness of prey can influence the behavior of a predator, as predicted by the optimal foraging theory which states that an animal will maximize the energy gain while minimizing energy loss. While this relationship has been studied and is relatively well understood in some terrestrial systems, the same is far from true in marine systems. It is as important to investigate this in the marine realm in order to better understand predator distribution and behavior. Micronekton, organisms from 2 – 20 cm, might be a key component in understanding this as it is potentially an essential link in the food web between primary producers and higher trophic levels, including cephalopods which are primary prey items of deep diving odontocetes (toothed whales). My dissertation assesses the spatial and temporal variability of micronekton in the Northwestern Hawaiian Islands (NWHI), the Main Hawaiian Islands’ (MHI) Island of Hawaii, and the Gulf of Mexico (GOM). Additionally it focuses on understanding the relationship between the spatial distribution of micronekton and environmental and geographic factors, and how the spatial and temporal variability of this micronekton relates to deep diving odontocete foraging. I used both an active Simrad EK60 echosounder system to collect water column micronekton backscatter and a passive acoustic system to detect the presence of echolocation clicks from deep diving beaked, sperm, and short-finned pilot whales. My results provide insight into what might be contributing to hotspots of micronekton which formed discrete layers in all locations, a shallow scattering layer (SSL) from the surface to about 200 m and a deep scattering layer (DSL) starting at about 350 m. In both the GOM and the NWHI, the bathymetry and proximity to shore influenced the amount of micronekton backscatter with locations closer to shore and at shallower depths having higher backscatter. We found in all three locations that some species of deep diving odontocetes were searching for prey in these areas with higher micronekton backscatter. Beaked whales in the NWHI, short-finned pilot whales in the NWHI and MHI, and sperm whales in the GOM where present in areas of higher micronekton backscatter. These hotspots of backscatter may be good predictors of the distribution of some deep-diving toothed whale foragers since the hotspots potentially indicate a food web supporting the prey of the cetaceans.
dc.identifier.uri http://hdl.handle.net/10125/51482
dc.language.iso eng
dc.publisher [Honolulu] : [University of Hawaii at Manoa], [August 2016]
dc.relation Theses for the degree of Doctor of Philosophy (University of Hawaii at Manoa). Zoology
dc.title Influences of Spatial and Temporal Variability of Sound Scattering Layers on Deep Diving Odontocete Behavior
dc.type Thesis
dc.type.dcmi Text
Files
Original bundle
Now showing 1 - 2 of 2
No Thumbnail Available
Name:
2016-08-phd-copeland_r.pdf
Size:
3.69 MB
Format:
Adobe Portable Document Format
Description:
Version for non-UH users. Copying/Printing is not permitted
No Thumbnail Available
Name:
2016-08-phd-copeland_uh.pdf
Size:
3.77 MB
Format:
Adobe Portable Document Format
Description:
For UH users only