CO2 and temperature effects on ear bones

Elevated carbon dioxide (CO2) threatens marine ecosystems and organisms. There are recorded disruptions of calcification processes, internal acid-base balance, behaviour and sensory systems. Our study investigated the effects of predicted CO2 levels, alongside increasing temperatures, on fish ear bone (otoliths) development in a diadromous fish. We examined otolith size, shape and chemistry, with the latter aimed at developing a chemical tracer of environmental pCO2. At elevated pCO2 levels we found significant effects to otolith perimeter and contour, with otolith becoming more irregular and jagged. There was no affect to chemistry, suggesting elements tested are unsuitable tracers of pCO2. Otoliths are an important sensory organ and developmental disruptions may have long-term impacts to fish functionality and survivability. This study highlights the need to investigate species-specific effects of elevated CO2 combined with relevant stressors, such as temperature, to understand full ecological implications.

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Reference information

Martino, Doubleday, Woodcock and Gillanders (2017) Elevated carbon dioxide and temperature affects otolith development, but not chemistry, in a diadromous fish. Journal of Experimental Marine Biology and Ecology 495: 57-64