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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

The behavioral effect of laboratory turbulence on copepods

Rasberry, Katherine Denise 13 July 2005 (has links)
Copepod species are distributed throughout the ocean by many factors, including chemical, biological, and physical effects. Turbulence in the ocean has been suggested as a factor that vertically partitions some species of copepod. Copepods may seek calmer waters by sinking to deeper levels as the surface waters become more turbulent, or may maintain their position in turbulent waters. The goal of this study is to determine the behavioral effects of turbulence on three species of copepod, Calanus finmarchicus, Acartia tonsa, and Temora longicornis. Experiments consisted of exposing each of the species to stagnant water plus four levels of turbulence intensity. The experiments were conducted in a laboratory apparatus that mimics oceanic turbulence. The turbulence characteristics have been previously characterized by particle image velocimetry (PIV), that show the turbulence to be nearly isotropic and homogeneous in the observation region. Behavior responses were quantified via several measures, including the number of animals phototactically aggregating per minute, the number of escape events, the swimming speed, and the net-to-gross-displacement ratio. There are important conclusions about the effect of laboratory turbulence on copepods. The size of the copepod has a significant effect on its aggregation and swimming capability with increasing turbulence. The smaller copepods had less ability to overcome a strong flow field, and they were more likely to be advected by the stronger flow fields. Swim style also can influence how a copepod reacts to increased turbulence. If the copepod is a hop and sink traveler, then the copepod continues to hop and sink more than its cruising counterparts as turbulence increases. The cruise and sink travelers did not alter the number of escapes in response to turbulence.
2

Movements, fishery interactions, and unusual mortalities of bottlenose dolphins

Shippee, Steven 01 January 2014 (has links)
Bottlenose dolphins inhabiting coastlines and estuaries in Florida have been impacted in the past decade by development, algal blooms, catastrophic pollution, and fishery interactions (FI). Dolphins react to disturbance and environmental stressors by modifying their movements and habitat use, which may put them in jeopardy of conflict with humans. FI plays an increasing role in contributing to dolphin mortalities. I investigated dolphin movements, habitat use, residency patterns, and frequency of FI with sport fishing. Tagging studies with short-term data tags and bolt on radio-transmitters were done in several locations in Florida and the east coast providing fine-scale measurements of swimming, daily travels, and foraging activity. Transit speeds agreed with the predicted mean cost of transport as dolphins spent much of their day and night travelling and resting while swimming. Increased foraging was detected by stomach temperature changes revealing dolphins fed at night with a peak starting just after sunset. Dolphin abundance, site fidelity, ranging, stranding mortality, and community structure was characterized at Choctawhatchee and Pensacola Bays in the Florida Panhandle via surveying and photo-identification. Results showed they made frequent inshore movements, maintained site fidelity to specific areas, and comprised several distinct communities. FI was assessed at offshore reefs and coastal fishing piers near Destin, FL and Orange Beach, AL, showing that some dolphins demonstrate affinity to this activity. Harmful interactions with dolphins on reefs and at fishing piers negatively affect their resident communities. Mitigation of FI is suggested by use of avoidance strategies, gear modifications, and improved fish release practices.

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