Publication Date



Open access

Embargo Period


Degree Type


Degree Name

Doctor of Philosophy (PHD)


Marine Biology and Fisheries (Marine)

Date of Defense


First Committee Member

Nelson Ehrhardt

Second Committee Member

Daniel Benetti

Third Committee Member

Chris Langdon

Fourth Committee Member

Athula Wikramanayake

Fifth Committee Member

Margaret Miller


Projected increases in atmospheric CO2 and the resulting decrease in oceanic pH over the course of the 21st century warrant studies on the effects of these changes on marine teleosts. The goal of this dissertation was to assess the impact of projected changes in CO2 on the early physiological dynamics and development of cobia, Rachycentron canadum. Spermatozoa respiration rates displayed a non significant decrease from 1.0 + 0.2 nmol O2/mL semen•sec + S.E. at 380 ppm CO2 to 0.7 + 0.1 nmol O2/mL semen•sec + S.E. at 800 ppm CO2. Spermatozoa velocity decreased from 22.1 + 0.5 to 14.9 + 0.4 µm/sec + S.E. for one male and from 16.9 + 0.4 to 15.5 + 0.5 µm/sec + S.E. for the second male. Both decreases in velocity were statistically significant. Regression analysis of embryo respiration did not show a statistically significant difference across the CO2 levels examined (400, 480, 500, 580, 1020, 2920 ppm). Embryonic development after 9 and 19 hrs exposure to elevated levels of CO2 (876, 949, 957 ppm) were not significantly different. Yolk-sac larvae respiration decreased from 10.7 + 3.4 nmol O2/larvae/hr + S.E. at 380 ppm to 6.6 + 2.3 nmol O2/larvae/hr + S.E. at 800 ppm. Yolk-sac larvae total length decreased from 2.59 + 0.34 to 2.29 + 0.28 mm + S.D. at 560 ppm but increased to 2.89 + 0.28 mm + S.D. at 800 ppm CO2. These results suggest early life history stages of cobia may be resistant to near future CO2 levels.


hypercapnia; carbon dioxide; ocean acidification; cobia; yolk-sac larvae