Phytoplankton and Zooplankton Identification and Enumeration

Plankton represent the beginning of the lake food chain and are key indicators of the overall water quality of a waterbody. We recommend monthly phytoplankton and zooplankton identification and enumeration.

The phytoplankton (algae) in a lake are a vast community of microscopic single celled photosynthetic plants and quasi-plants that form the base of the food chain.  They are adapted to be in constant suspension in lake water and are dependent on water currents for movement.  The typical groups of phytoplankton observed in lakes are Cyanobacteria, Diatoms, Greens, Chrysophytes, Cryptophytes, Dinoflagellates, and Euglenoids. Phytoplankton are an indicator of the nutrient concentrations in a lake because increased phytoplankton populations increase with higher nutrient concentrations and cause  a decline in water clarity.

Zooplankton are microscopic crustaceans that either feed on phytoplankton or are predatory on other zooplankton. Zooplankton are influenced by predators such as small fish,  and some taxa can regulate phytoplankton populations through their water column filtration capabilities. An understanding of lake plankton allows for a better interpretation of water quality data.

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