Extended probit mortality model for zooplankton against transient change of PCO2

The direct injection of CO2 in the deep ocean is a promising way to mitigate global warming. One of the uncertainties in this method, however, is its impact on marine organisms in the near field. Since the concentration of CO2, which organisms experience in the ocean, changes with time, it is required to develop a biological impact model for the organisms against the unsteady change of CO2 concentration. In general, the LC50 concept is widely applied for testing a toxic agent for the acute mortality. Here, we regard the probit-transformed mortality as a linear function not only of the concentration of CO2 but also of exposure time. A simple mathematical transform of the function gives a damage-accumulation mortality model for zooplankton. In this article, this model was validated by the mortality test of Metamphiascopsis hirsutus against the transient change of CO2 concentration.