Publication Date

2013-04-22

Availability

Open access

Embargo Period

2013-04-22

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PHD)

Department

Marine Biology and Fisheries (Marine)

Date of Defense

2013-04-05

First Committee Member

Su Sponaugle

Second Committee Member

Robert K. Cowen

Third Committee Member

Martin Grosell

Fourth Committee Member

Chris Langdon

Fifth Committee Member

Julia Dallman

Abstract

Ocean acidification is of particular concern for vulnerable larval stages or marine organisms that are critical to population replenishment and connectivity. In fishes, the existing body of ocean acidification research has focused mostly on small demersal species, which may be more resistant to acidification than less well-studied offshore pelagic species. A better understanding of the effects of ocean acidification on these understudied species requires examination of biological factors that influence larval ability to successfully survive, navigate, and recruit to adult populations. This dissertation reports a series of studies researching the impact of ocean acidification on the larval stages of two widely distributed, pelagic, tropical fish species, cobia (Rachycentron canadum) and mahi-mahi (Coryphaena hippurus). Larvae were raised for up to 21 d under several projected acidification scenarios, including scenarios for year 2100 (800 "mu"atm pCO2), year 2300 (1700-2100 "mu"atm pCO2), comparative worst-case scenarios (up to 5400 "mu"atm pCO2), and multi-stressor experiments crossing acidification with increased temperature and starvation stress. Treatment effects were evaluated throughout ontogeny using selected metrics including larval growth, size, development (flexion), swimming ability (Ucrit), swimming activity, and otolith (ear stone) formation. Additionally, novel in situ analysis of otoliths using three-dimensional micro-computed tomography and subsequent modeling of otolith mechanical function was performed to evaluate potential ocean acidification impacts to the auditory sensitivity and hearing range of larval fish in a high-CO2 ocean. Collectively, this research provides unprecedented perspective on the potential impacts of ocean acidification on two valuable pelagic fish species and identifies promising areas for future research.

Keywords

ocean acidification; larvae; fish; otolith; cobia; mahi

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