Lake Habitats

Littoral region of an Irish lake

Lake habitats for Cladocera can be conveniently divided into two overlapping areas - limnetic (open water) and littoral regions. Distinct cladoceran assemblages have developed in both habitats. Strong swimmers (e.g. Bosmina and Daphnia) are usually found in open water. In contrast the most diverse cladoceran family, the chydorids, are relatively weak swimmers and they occur on vegetation or in association with benthic substrates in the littoral region. Therefore any environmental factors which cause a change in the littoral/open water habitat area should be reflected in a shift between open water and littoral cladoceran species remains in the lake sediments.

The availability of these two habitats is influenced by factors such as water transparency and basin morphology which may alter with time and nutrient status. Turbidity caused by the input of large amounts of organic material causes a reduction in species abundance and diversity. Likewise turbidity caused by planktonic algae results in a reduction in diversity but also a general increase in abundance of limnetic animals.