Influence of spatial heterogeneity on predation by the flatworm Mesostoma ehrenbergii

TROCHINE, C.; MODENUTTI, BE; BALSEIRO, E.G

JOURNAL OF PLANKTON RESEARCH

Oxford University Press

Lugar: Oxford; Año: 2006 vol. 28 p. 267 - 274

0142-7873

Through laboratory experiments, we analysed the influence of spatial heterogeneity on predation byMesostoma ehrenbergii on the calanoid Boeckella gracilis and the cyclopoid Acanthocyclopsrobustus in four horizontal and two vertical spatial arrangements. This spatial heterogeneitysimulated that of Juncaceae stems, a major macrophyte in the natural environment of thesezooplankton. Our results indicated that M. ehrenbergii preyed differently on these copepod species.The rate of predation of M. ehrenbergii on A. robustus females reached saturation in all thetreatments with and without horizontal spatial heterogeneity but lower predation rates wereobserved in the medium heterogeneity treatment. Predation rates of Mesostoma on B. gracilisincreased with the increase in prey abundance in the treatment without heterogeneity, whilepredation rates reached saturation in the treatments with horizontal spatial heterogeneity. M.ehrenbergii consumed males and females of B. gracilis in each of the arrangements tested. Innatural habitats interaction between extent of macrophyte development and intensity of predation byM. ehrenbergii on copepods species may be expected. We suggest that the structural complexitygiven by macrophytes in Patagonian fishless habitats provide a bottleneck for M. ehrenbergiipredation.