Methodology for Impact Assessment of Ocean CO2 Sequestration on Deep-sea Organisms

In order to assess the biological impact of ocean CO₂ sequestration, we present a methodology to quantify impacts of elevated CO₂ concentration on marine organisms using existing biological data and discuss required research work for the future. For a quantitative assessment of deep-sea CO₂ injection (mid- depth type) impacts on marine organisms, we estimated No Observed Effect Concentration (NOEC) of CO₂ for copepods. Our preliminary analysis indicated that the NOECco₂ for copepods including deep-sea species is ap Delta3,000 ppm. However, further data are needed on acute, chronic and ecosystem impacts for applying reduced Assessment Factor (AF) which is essential for reliable estimation of Predicted No Effect Concentration (PNECco₂). For an acute impact assessment, careful consideration on differences in sensitivities to CO₂ between shallow and deep- sea species is required. For the purpose of accurate chronic impact assessment, long-term experiments on sub-lethal impacts are required. However, ecosystem impacts would be difficult to predict based only on laboratory experiments and field experiments are necessary for confirming expected consequences from laboratory experiments and for lessening the uncertainties of extrapolation.