Copepods are small aquatic crustaceans that are one of the most abundant multicellular animals on Earth. Copepods may even outnumber insects, although insects are more diverse. The word “copepod” originates from the Greek words “kope”, an oar, and “podos”, a foot. The etymology of its name refers to the flat swimming legs of the copepod (Mauchline 1998).
Copepods have long been recognized as a suitable food for marine fishes, especially for those in first-feeding larval stages. A number of copepod species also have short generation times and the ability to withstand variable conditions (Fleeger 2007). Consequently, copepods have become a favorable source of feed in aquaculture (Marcus 2007). Copepods are cultured for at-home use, as well as mass-cultured for various kinds of fish hatcheries.
Acartia californiensis from Mission Bay, San Diego, CA.
Courtesy of David Elliott.
Copepods occur in both marine and freshwater environments. They can be found across the globe in a variety of ecosystems, such as temperate estuaries, the Great Lakes, and the Southern Ocean. Copepods, like other plankton, are not randomly distributed in the water. Instead, they occur in patches, vertically and horizontally (Mauchline 1998). Due to the patchy distribution of copepods, samples taken by plankton net tows may not accurately represent the entire population (Omori and Hamner 1982).
Past studies have provided ample evidence that copepods often have broad or diverse diets. Copepods may be herbivorous, carnivorous, or omnivorous. The diversity in the diets of copepods provides alternative pathways for acquiring nutrients and thus, increases the chances of copepods obtaining a nutritionally complete diet (Kleppel 1993).
Copepods play a prominent role in the productivity and health of marine and freshwater ecosystems. Like other zooplankton, they serve as an important component of the food web, linking primary producers and other low trophic levels with higher-level consumers, including invertebrates and fish. Studies on copepods shed light on the carbon cycle and energy transfer within a system (Bǎnaru et al. 2014).
Bǎnaru, D., Carlotti, F., Barani, A., Grégori, G., Neffati, N., and Harmelin-Vivien, M. 2014. Seasonal variation of stable isotope ratios of size-fractionated zooplankton in the Bay of Marseille (NW Mediterranean Sea). Journal of Plankton Research 36: 145–156.
Fleeger, J.W. 2007. The potential to mass-culture Harpacticoid copepods for use as food for larval fish. (pp. 11-24).
Kleppel, G. 1993. On the diets of calanoid copepods. Marine Ecology Progress Series 99: 183-195.
Mauchline, J. 1998. The Biology of Calanoid Copepods. Advances in Marine Biology 33: 1-710.
Marcus, N.H. 2007. Calanoid Copepods, Resting Eggs, and Aquaculture. Copepods in Aquaculture. (pp. 3-7).
Omori M. and W.H. Hamner. 1982. Patchy distribution of zooplankton: Behavior, population assessment and sampling problems. Marine Biology 72: 193-200.