Consumptive and non-consumptive effects of turbellarian (Mesostomasp.) predation on anostracans.

We assessed the predatory impact ofMesostomasp. (Rhabditophora) on hatching and survival ofBranchipodopsis wolfi(Anostraca) under laboratory conditions. The hatching percentages of resting eggs ofB. wolfiwere negatively influenced to a significant degree by the presence ofMesostomasp. or the medium in which the worms were kept before, but only when prey and predator originated from the same pool. This relationship was also not observed when eggs of the American anostracanThamnocephalus platyuruswere exposed to the Turbellaria from Botswana. There was, however, no indication of predation ofB. wolfieggs byMesostomasp., either by eating them totally or by sucking them out. When the same number of anostracans of different ages was offered simultaneously toMesostomasp., the 1- and 3-day-old specimens were eaten significantly faster than the 5-day-old juveniles and the adultB. wolfi. We conclude thatMesostomasp. has a potentially strong influence on the population dynamics and life history characteristics ofB. wolfiin temporary aquatic systems. Additionally, the feeding behaviour ofMesostomasp. was described and the ultra structure of its rostral area was investigated. [ABSTRACT FROM AUTHOR]