Coliform dynamics and the implications for source tracking

Summary In many parts of the world, coliform counts in recreational waters are unacceptably high. In an attempt to rectify this problem, programmes are under way to develop methods that will allow the sources of the faecal contamination thought to be responsible for these elevated counts to be identified. The success of these efforts depends on the validity of several assumptions that underlie many of the proposed methods. One of the critical assumptions is that the clonal composition of the coliform species being monitored in a water body reflects the clonal composition of the species in the host populations responsible for the faecal inputs into that water body. To determine the extent to which among‐strain variation in a coliform species might invalidate this assumption, a series of simple mathematical models was proposed and analysed. The first series of models assumed that all cells of species were identical. The question posed was – is the density of a coliform species in a body of water linearly related to the rate at which cells of the species enter the water body via faecal production? The results of these models suggest that, over a wide range of conditi