Epischura lacustris

Forbes, 1882

Epischura lacustris is a predatory calanoid copepod in the Temoridae. It inhabits freshwater lakes across northeastern North America, including all five Great Lakes. The exhibits size-selective on small zooplankton, particularly Bosmina longirostris, and has been observed to consume both phytoplankton and animal prey. It can be distinguished from other Great Lakes calanoids by three stout caudal setae on each caudal ramus and a noticeably bent urosome in mature specimens.

Pronunciation

How to pronounce Epischura lacustris: /ˌɛpɪˈskjʊrə ləˈkʌstrɪs/

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Identification

Distinguished from other Great Lakes calanoids by three stout, well-developed setae on each caudal ramus (other calanoids have four or more thin setae). Mature specimens display a noticeably bent and crooked urosome.

Habitat

Freshwater lakes and waterbodies. Found in lacustrine environments including the Great Lakes and smaller waterbodies throughout its range.

Distribution

North America: northeastern coastal United States west to Minnesota, south to central Illinois. Present in all five Great Lakes and numerous smaller waterbodies within this range.

Diet

with predatory feeding . Consumes phytoplankton (including Cryptomonas erosa) and animal prey including rotifers (Euchlanis dilatata, Polyarthra remata), cladocerans (Bosmina longirostris, Ceriodaphnia reticulata, Holopedium gibberum), and likely other small zooplankton. Exhibits size-selective , preferentially consuming smaller Bosmina (0.2–0.25 mm).

Behavior

Exhibits size-selective on zooplankton prey. Predation rates depend on encounter rate and ingestion probability rather than true behavioral preference or switching. Swimming has been documented among freshwater calanoid copepods. No evidence of prey switching based on previous diet.

Ecological Role

in freshwater planktonic . Functions as an consumer linking and higher . May influence zooplankton structure through size-selective pressure.

Similar Taxa

Other Great Lakes calanoid copepodsE. lacustris differs in having three stout caudal setae versus four or more thin setae, and mature specimens have bent urosomes not seen in other .

More Details

Food resource fluctuations

Survival and vary temporally even when phytoplankton resource availability is held constant, with extended survival and high production in spring declining later in the year. Animal prey may provide more consistent nutritional support across seasons.

Prey vulnerability

Prey vulnerability to depends on encounter rate with the and probability of ingestion. Smaller prey sizes are more vulnerable due to higher ingestion probability rather than encounter rate alone.