O.1 Mortality

Natural mortality, or the ‘dark-death rate’ \(k_d^{pth}\) is an important process influencing protozoan, bacterial and viral dynamics in surface and coastal waters. Two of the predominant environmental factors known to modify this dark death rate are temperature and salinity, and as such the resultant mortality flux is computed via Equation (O.1). \[\begin{equation} \href{AppDiags.html#WQDiagPathMort}{F_{mor}^{pth}} = \left[k_d^{pth} + C_{SM}^{pth} \times S^{\alpha}\right] \times \left[\theta_{mor}^{pth}\right]^{T-20} \times \left(\left[PTH_a\right] + \left[PTH_t\right]\right) \tag{O.1} \end{equation}\] \(k_d^{pth}\) is the user specified dark death rate in freshwater at 20\(^o\)C, \(C_{SM}^{pth}\) is the salinity effect on mortality, \(S\) is ambient salinity, \(\alpha\) is a parameter controlling salinity dependence, \(\theta_{mor}^{pth}\) is the corresponding temperature coefficient, \(T\) is ambient water temperature, and \(\left[PTH_a\right]\) and \(\left[PTH_t\right]\) are the concentrations of free and attached pathogens, respectively. If attached pathogens are not simulated, then the latter concentration is set to zero for the purposes of the above flux calculation.