Prey preference and utilization by Mesostoma lingua (Turbellaria, Rhabdocoela) at a low arctic site

Abstract

The rhabdocoel Mesostoma lingua is a common inhabitant of rock bluff ponds in the area

Benthic predators and zooplanktonic prey: predation by Crangonyx shoemakeri (Crustacea; Amphipoda) on Daphnia obtusa (Crustacea; Cladocera)

“…The average number of Daphnia consumed per amphipod during a 24 h period ranged from 1 .9 to 4 .2 . This rate is considerably lower than that found for obligate invertebrate predators such as Chaoborus (Pastorok, 1980), Hydra (Schwartz et al, 1983), and Mesostoma (Schwartz & Hebert, 1982, 1986 . This low rate is probably explained by Daphnia not being the primary food of amphipods .…”

“…There is mounting evidence that invertebrate benthic predators can play important roles in determining the structure of pond zooplankton communities (Schwartz et al, 1983 ;Schwartz & Hebert, 1986 ;Blaustein, 1990 ;Blaustein & Dumont, 1990) . In ponds lacking species traditionally regarded as predatory, other species may act as facultative predators .…”

“…Sedentary littoral zone predators such as Hydra readily capture and consume planktonic cladocerans . Interestingly, Hydra have relative difficulty detecting and capturing co-existing prey species (Schwartz, Hann & Hebert, 1983 ;Schwartz & Hebert, 1986) . Potential prey species in the littoral zone have a suite of adaptations that limit the effectiveness of predators they typically encounter .…”

“…Potential prey species in the littoral zone have a suite of adaptations that limit the effectiveness of predators they typically encounter . Active benthic predators, such as flatworms of the genus Mesostoma, discriminate between a variety of cladoceran prey species and have a distinct preference for planktonic species (Schwartz & Hebert, 1982, 1986Blaustein & Dumont, 1990) . Mesostoma ehrenbergii even enters the pelagic zone in pursuit of planktonic prey (Maly, Schoenholtz & Arts, 1980) .…”

“…Mesostoma ehrenbergii even enters the pelagic zone in pursuit of planktonic prey (Maly, Schoenholtz & Arts, 1980) . Given the ubiquity of benthic invertebrates it is possible they are important regulators of zooplankton community diversity and structure (Schwartz et al, 1983 ;Schwartz & Hebert, 1986 ;Blaustein, 1990 ;Blaustein & Dumont, 1990), particularly in shallow habitats lacking vertebrate predators . A common environment lacking vertebrate predators is the seasonal woodland pool .…”