Lethal Effect of Elevated pCO2 on Planktons Collected from Deep Sea in North Pacific

Abstract

The lethal effects of high partial pressure of CO2 (pCO2) to the pelagic zooplankton have been identified. Ocean sequestration of CO2 has great potential for the mitigation of the increasing levels of atmospheric CO2, but there is little information about the environmental effects, especially to deep-sea organisms. These appear to be more sensitive to the environmental change than surface organisms, as the environmental fluctuation in the deep sea is less than that of the surface layer. If deep-sea organisms have high sensitivity to high CO2, it is necessary to compensate to apply the experimental results for deep-sea organisms. However, there is no information to evaluate the above problem. The experiments were performed from the sub-arctic to the sub-tropical region and compared the sensitivities to the high pCO2 between surface organisms (0–500 m) and deep-sea organisms (500–1,500 m). When organisms were exposed at a pCO2 from 500 to 100,000 μatm, half the organisms died within 1 day to 2 weeks after exposure. From the half lethal time (LT50) calculated from the survival curve, higher pCO2 resulted in earlier death of the zooplankton. However, deep-sea animals in the sub-arctic region were less sensitive to the increasing of pCO2 compared with the others. The apparent LT50 on higher pCO2 showed that deep-sea organisms are more tolerant than surface ones.