High prey capture efficiencies of oceanic epipelagic lobate and cestid ctenophores

Abstract

Ctenophores are numerically dominant members of oceanic epipelagic communities around the world. The ctenophore community is often comprised of several common, co-occurring lobate and cestid genera. Previous quantifications of the amount of fluid that lobate ctenophores entrain in their feeding currents revealed that oceanic lobates have the potential for high feeding rates. In order to more directly examine the trophic role of oceanic lobate ctenophores, we quantified the encounter and retention efficiencies of several co-occurring species (Bolinopsis vitrea, Ocyropsis crystallina, Eurhamphea vexilligera and Cestum veneris) in their natural environments. Encounters and predator–prey interactions were video recorded in the field using specialized cameras and SCUBA techniques. The lobate species encountered, on average, 2.4 prey per minute and ingested 40% of these prey. This translated to an estimated ingestion rate of close to 1 prey per minute. Cestum veneris and most of the lobate species retained prey as efficiently as the voracious coastal lobate predator Mnemiopsis leidyi, suggesting that these oceanic species have a similar predation impact in their environments as M. leidyi does in coastal ecosystems. Hence, quantified in situ predatory-prey interactions indicate that epipelagic ctenophores have a significant impact on oceanic ecosystems worldwide.