The Design and Operation of An Ocean Acidification System to Measure Larval Fish Otolith Growth

By the year 2100, it is projected that atmospheric CO₂ concentrations will rise to approximately 1000 matm. As a result, oceanic pH levels are expected to drop 0.5 units, increasing ocean acidification (OA).  Studies have shown that ocean acidification has negatively affected marine calcifying organisms due to changes in the calcium carbonate (CaCO₃) system.  Designing and building systems to test the effects of OA on marine organisms is an important step in OA research.  Controlling temperature in OA systems is integral in maintaining the desired pH level.  We have developed a small, cost effective OA system that consists of (6) 19L aquariums housed in a thermostated water bath capable of maintaining the temperature to within 0.1°C. This system is designed to bubble premixed air of known CO₂ concentrations into the aquariums to adjust pH.  We have employed this system to test the effects of OA on otolith growth in the mummichog (Fundulus heteroclitus), and current research is examining red porgy (Pagrus pagrus) otolith growth.  Details of the design of this system and preliminary research utilizing this system will be discussed.