It is essential to have a good understanding of the environmental factors determining an organisms survival and distribution before meaningful interpretations can be made of palaeoassemblages. Therefore once we understand the situations prevailing in modern lake systems and their cladoceran communities we can infer past conditions from their remains in the sediment.
Algal bloom on an Anglesey Lake
Cladocera can be found in a wide range of lakes with varying chemical conditions. Some generalisations are possible but they should not be considered in isolation from other environmental factors. In brief, an increase in pH, alkalinity and/or conductivity correlates with a decrease in faunal diversity. They also respond to changes in plant or phytoplankton growth induced by changes in water nutrient concentrations.
Under some circumstance Cladocera are a practical alternative to diatom analysis e.g. in alkaline or saline systems where the dissolution of silica is problematic.