THE ROLE OF HETEROTROPHY IN OCULINA ARBUSCULA’S RESPONSE TO OCEAN ACIDIFICATION

Anthropogenic carbon dioxide emissions have been increasing since the Industrial Revolution. Once CO₂ enters the ocean, chemical reactions occur that result in increased hydrogen ion concentration (and therefore decreased seawater pH) and decreased carbonate ion concentration; this process is known as ocean acidification (OA). Ocean acidification has been well documented to cause dissolution of calcium carbonate, reduced calcification rates, and coral bleaching. In healthy corals, symbiotic algae autotrophically fix carbon in excess, transferring most of it to the coral host which supplies it with up to 100% of its daily needs. Corals also obtain carbon heterotrophically, which contributes up to 60% of fixed carbon. Exposure to OA conditions may induce stress, causing symbiotic algae to be expelled from the coral host and resulting in a loss of autotrophically acquired carbon. Carbon acquisition patterns may change, and heterotrophically acquired carbon can become a more significant source of energy. Oculina arbuscula is a facultatively symbiotic coral that has shown similar resistance to OA in both symbiotic and aposymbiotic corals. To determine the role heterotrophy has in allowing O. arbuscula to ameliorate the effects of OA, a 90-day lab experiment will be conducted exposing O. arbuscula to low pH conditions and varying levels of feeding. Results of this study will contribute to knowledge of what mechanisms aid in coral resistance to OA, and how ocean acidification will affect to calcium carbonate-based organisms.

Presentation Preference: Poster

Primary Presenter: Alejandra Daniel, Department of Biology (ad07436@georgiasouthern.edu)

Authors:

Daniel Gleason, Georgia Southern University  (dgleason@georgiasouthern.edu)

Tyler Cyronak, Georgia Southern University  (tcyronak@georgiasouthern.edu)