Plankton Of the Potomac

Some of the most important studies PEREC has done involve looking closely at populations of microscopic organisms called plankton. Impossible to see with the human eye, plankton are essential to aquatic ecosystems, because they form the foundation the food chain. They also act as a reliable measure of the health of the stream, because plankton are very sensitive to water quality and environmental changes.

What Plankton Do We Study?


Cladocera: Also called water fleas, these small crustaceans only grow to 6 millimeters in length. Cladocera usually reproduce asexually, though they will occasionally partake in sexual reproduction. Out of over 600 species, most are freshwater, though there are a few marine cladocera.

Copepods: Copepods are a diverse group of tiny crustaceans, found in fresh and saltwater habitats throughout the world. They are some of the must numerous organisms on the planet. Copepods have two long antennae, and feed on phytoplankton. They are able to swim using small appendages, and are a food source for many aquatic organisms.

Protozoa: These microscopic organisms are found in aquatic and land ecosystems. People have generally heard of protozoans in regards to human infections however they can also provide food for other microscopic organisms.

Rotifer: These zooplankton are very common in freshwater ecosystems. Rotifers are very diverse in shape and behavior, though all rotifers have bilateral symmetry (they are identical on either side). They eat protozoans, algae, and detritus, and reproduce through various means of sexual reproduction.

Images of zooplankton: