Ocean acidification and dynamic energy budget models: Parameterisation and simulations for the green-lipped mussel

Ocean acidification (OA), the change in ocean chemistry caused by carbon dioxide emissions, poses a serious imminent threat to marine organisms, especially those with calcium carbonate shells. The green-lipped mussel (Perna canaliculus), endemic to New Zealand, is common in coastal ecosystems and is an economically important aquaculture species. As a step towards supporting aquaculture management in a changing environment, we used a dynamic energy budget (DEB) model to investigate the potential influence of OA on growth and reproduction of the mussel. Zero-variate and growth data from local mussel farms were used to parameterise the model with the AmP method. The parameter estimation showed an acceptable goodness of fit, with a low mean relative error of 0.143 and the symmetric mean squared error of 0.125. The model was subsequently modified to estimate parameter values under OA conditions, based on data obtained from laboratory experiments where mussels were grown at future projected reduced pH (elevated pCO2) levels. The maintenance ([ṗM]) and volume-specific cost for growth ([EG]) were identified as the key parameters in response to OA. The model was then applied to simulate mussel energetics under pCO2 scenarios projected for 2050 and 2100. The model predicts that decreasing pH would cause reductions in shell length growth, flesh weight and reproductive capacity. As well as providing a quantitative tool for understanding the influence of OA on mussel physiology, this DEB model is also an important component of individual-based population and ecosystem models, enabling simulation of complex population and ecosystem level responses to OA.