| Popis: |
Larvae and post-larvae of the lobate ctenophore Mnemiopsis leidyi consumed significant quantities of microphytoplankton and microzooplankton prey in controlled experiments where they were fed in situ assemblages of microplankton prey. Prey taxa ingested included phototrophic and heterotrophic dinoflagellates, choreotrich ciliates, cyclotrich ciliates and euglenoid flagellates. Per capita clearance and ingestion rates varied with consumer size, prey taxon and prey abundance. Average per capita clearance rates for the 11 size classes of larvae and post-larvae examined ranged from 9 to 230 mL individual � 1 h � 1 . Average per capita clearance rates for tentaculate-stage, transition-stage and lobate-stage individuals were 40, 31 and 95 mL individual � 1 h � 1 , respectively. Total ingestion rate varied similarly with consumer size, prey taxon and prey abundance, ranging from 1 to 6259% body carbon day � 1 . All size classes of M. leidyi larvae and post-larvae derived more nutrition from dinoflagellates than from ciliates. Both positive and negative selection of specific prey taxa were observed, and varied with larval size and prey taxonomic composition. The results contradict the prevailing view that all life history stages of M. leidyi are primarily carnivorous. The measured clearance rates are sufficiently high that the larvae, when abundant, have the potential to exert a significant predation impact on their prey populations in the water column. Understanding the processes that influence survival during early developmental stages may provide one key to understanding the initiation and maintenance of the adult M. leidyi blooms that are commonly observed in coastal waters. |
