Such estimations can be derived due to the fact that the predominance of either algal group varies depending on the nutrient conditions of their limnic environment. Diatoms show a high degree of success in water with a high nutrient content as opposed to chyrsophytes, which are better in water with a lower nutrient content.
The relative dominance of diatoms and chrysophytes is influenced by the nutrient content of their aquatic habitat.  Diatoms are more successful in nutrient-rich water, whereas chrysophytes perform better in nutrient-poor conditions.