The term oligotrophic is derived from the Greek term meaning "poorly nourished" and refers to an aquatic system that has low overall levels of primary production, principally because of low concentrations of the nutrients that plants require. The bottom waters of an oligotrophic lake do not become depleted of oxygen in summer, when rates of primary productivity in surface waters of the lake are typically at their highest. Oligotrophic bodies of water tend to have a more diverse community of zooplankton than waters with high levels of primary production. The term can also be used to describe any organism that only needs a limited supply of nutrients, or an insect that only utilizes a few plants as habitat.