Growth and feeding rates of the newly hatched larval ctenophore Mnemiopsis leidyi A. Agassiz (Ctenophora, Lobata)

Abstract

Mnemiopsis leidyi. larvae depend on microplankton ( 0.5 mm in length and can successfully capture and consume mesozooplankton prey. Feeding and growth rates of newly hatched M. leidyi larvae were measured in controlled laboratory experiments. When fed natural microplankton assemblages, newly hatched larvae consumed significant quantities of both autotrophic and heterotrophic prey, including diatoms, phototrophic, heterotrophic and mixotrophic dinoflagellates, euglenoid flagellates, aloricate and tintinnid ciliates, and rotifers. Average per capita clearance rates were 1.99-7.59 mL individual -1 h -1 (X = 4.01 mL individual -1 h -1 ; SD = 1.95) and total per capita ingestion was 0.01-4.70 μg C individual -1 day -1 x 10 2 (X = 0.83 μg C individual -1 day -1 × 10 2 ; SD = 1.89). Larval growth rates were -0.13 to 0.56 mm individual -1 day -1 (equivalent to -1.72 to 4.33 μgC individual -1 day -1 ) over a range of larval sizes from 0.5 ( 2 weeks, and growth rate decreased when larvae reached 4-5 mm in length, corresponding to the beginning of their morphological transition from tentaculate to lobate feeding mode. The gross growth efficiency of larvae fed natural microplankton assemblages was ∼3%.