Publication Date

2019-12-10

Availability

Embargoed

Embargo Period

2021-12-09

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PHD)

Department

Marine Biology and Ecology (Marine)

Date of Defense

2019-11-22

First Committee Member

Martin Grosell

Second Committee Member

Lynne A. Fieber

Third Committee Member

Elizabeth A. Babcock

Fourth Committee Member

Joseph E. Serafy

Fifth Committee Member

Chi Hin Lam

Abstract

In the face of rapidly changing environmental conditions due to human mediated climate change and large-scale pollution events such as the Deepwater Horizon oil spill, it is critical to understand the relationship between environmental stimuli and the behavior of marine fishes. Sustainable management of commercially important and highly migratory fish species, such as mahi-mahi (Coryphaena hippurus), as well as unfished reef species, like the bicolor damselfish (Stegastes partitus), depend upon our understanding of their physiology and behavior in response to changing habitat conditions. Olfaction is critical for fish to detect environmental cues and triggers behaviors that maximize individual fitness. This dissertation addresses the role of olfaction in laboratory experiments with control and oil-exposed bicolor damselfish and mahi-mahi in, respectively, avoiding an alarm cue associated with the predation of conspecifics and avoiding oiled seawater. Oil exposure consistently altered behavior for both species, however differential responses in olfactory physiology suggests that the effect of oil exposure on the detection and processing of olfactory cues is a complex process that may be specific to species and cue type. This dissertation additionally addresses knowledge gaps in the understanding of the distribution and activity levels of wild mahi-mahi. Temperature is known to dictate the distribution of pelagic species and rising ocean temperatures are already shifting the distribution of many marine fishes. The present work examined the role of sea surface temperature, diel period, and lunar phase on the vertical and horizontal distribution and activity index of mahi-mahi. Migratory patterns appeared to be seasonally influenced and vertical distributions were highly influenced by sea surface temperature, with warmer temperatures driving fish deeper and into cooler waters while cooler temperatures brought fish closer to the surface and the sub-tropics. Light levels from both the sun and the moon brought mahi-mahi closer to the surface and increased activity in warmer waters at night and in cooler waters at daytime. These results suggest that migratory patterns, vertical habitat use, and activity patterns are affected by temperature and light levels and may be affected by warming ocean waters. As a whole, this dissertation addresses gaps in our understanding of the effects of oil-exposure on olfaction and behavior of two marine fishes with very different life history traits and the role of environmental drivers in the behavior of wild mahi-mahi.

Keywords

Deepwater Horizon; mahi-mahi; bicolor damselfish; physiology; pop-up satellite archival tag; behavior

Available for download on Thursday, December 09, 2021

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