Castle Lake Limnological Research Station

Food webs are a conceptual organization of different life forms that shows the flow of energy (as food) from one group to another. Food webs describe how each life form is inherently related/connected in a given ecosystem. A simplified food web is described below for Castle Lake.

A food web describes a cycle of energy and material flow so the beginning point is arbitrary. Using sunlight, CO₂ and other available nutrients, algae grows and reproduces their biomass. The amount of algal growth determines the majority of the new biomass production in the food web, thus algae are usually referred to as at the base of the foodweb. Different types of zooplankton eat algae, and grow in number and size. In turn, fish prey on zooplankton and other benthic invertebrates (including insect larve). Ospreys, which eat fish, are the so-called top predators (excluding humans) at Castle Lake. All animals excrete CO₂ and feces, which contain nitrogen (NH₄), phosphorus, and other nutrients that are essential for algal growth. All dead life forms are decomposed by a rich variety of microbes. Decomposition releases a significant amounts of nutrients into the water as well.

Fish were introduced into Castle Lake, as with many surrounding lakes, in the 1930's for recreation fishing. Previously Castle was a fishless lake and the ecosystem consisted of algae, zooplankton, aquatic insects, and probably frogs.

This diagram will be improved in the future.