The gowth and reproduction of Daphnia lumholei, an an invasive species in the Southern United States, is highly influenced by temperature and abundance of food. In the absence of predators, Daphnia is faced with a trade off. They can either live in the epilimnion where development in the
warm water is fast, but food shortage causes low egg production, or in the hypolimnion, where food availability is high but development is slow because of low temperatures.
In this study, Kessler and Lampert test whether Daphnia is affected by light to choose the best depth of the water for reproductive or growth purposes. They also tested the depth preferences of varying Daphnia size classes and egg-bearing females . However, they found no direct correlation between light and Daphnia’s physical necessities. In fact, large and egg-bearing females, being forced into deeper layers by the residual light response during the day , experienced a lower average temperature during day than juveniles.
Kessler, K., and Lampert, W. 2004. Depth distribution of Daphnia in response to a deep-water algal maximum: The effect of body size and temperature gradient. Freshwater Biology 49(4): 392-401.