Influence of ocean acidification on otolith calcification and behavior in fish larvae

• Main Author: Maneja, Rommel
• Format: Thesis
• Language: English
• Published: 2012
• Subjects: atlantic cod; Gadus morhua; Ocean acidification
• Online Access: https://oceanrep.geomar.de/id/eprint/16585/; https://oceanrep.geomar.de/id/eprint/16585/1/Maneja%20RH%20PhD%20thesis%204.pdf; https://macau.uni-kiel.de/receive/diss_mods_00009784

The shift in the ocean's carbonate system towards a lower pH equilibrium, termed as ocean acidification, due to anthropogenic emissions of CO2 has potential influence on the formation of calcium carbonate structures in marine organisms. This is because the precipitation of the calcified structures is dependent on seawater chemistry, with higher pH and aragonite saturation state favoring calcification. A number of studies reported different patterns of impact on calcification ranging from reduction to hypercalcification with some species showing no effects, which means that compensatory mechanisms are available to counteract the effects of reduced pH and elevated pCO2. In marine fishes, the structures for mechanoreception known as otoliths are composed of aragonitic calcium carbonate and function for detection of motion and acceleration, maintaining balance, and sound localization. The morphology of the otoliths is species-specific and linked to the functional requirements for specific habitats and swimming behavior. In this thesis, the response of the otolith calcification in larval Atlantic cod (Gadus morhua L.) and Atlantic herring (Clupea harengus L.) to elevated pCO2 and the possible consequences to the behavior of the larvae were investigated. The main results of the investigation were derived from an ocean acidification experiment conducted in the landbased mesocosm facility in the University of Bergen's Espegrend Marine Station from March to May 2010. Based on the results, the thesis concluded that otolith calcification in both Atlantic cod and herring larvae was significantly affected by increase in seawater pCO2 concentrations. However, the direction of the effects was different between the two species with increase in otolith growth in cod larvae but a decrease in herring larvae. On the other hand, the changes observed in the otolith growth had no impact on the swimming behavior of both species. The swimming behavior was resilient to elevated pCO2 despite the changes in the growth of the otoliths. ...