INCREASED EMIGRATION OF THE AMPHIPOD RHEPOXYNIUS-ABRONIUS (BARNARD) AND THE POLYCHAETE NEPHTYS-CAECA (FABRICIUS) IN THE PRESENCE OF INVERTEBRATE PREDATORS

Laboratory experiments tested whether the emigration of 2 infaunal organisms, the amphipod R. abronius (Barnard) and the polychaete N. caeca (Fabricius) increased in the presence of potential predators. Significantly more R. abronius migrated into the water column in the presence of an epibenthic predator, the dungeness crab Cancer magister Dana, and 2 infaunal predatory polychaetes Glycera convoluta Keferstein and N. caeca, than in their absence. Emigration of small N. caeca was greater in the presence of G. convoluta than in the presence of large N. caeca or in the control. Avoidance of predators may sometimes explain the occurrence of benthic organisms in the water column and reductions of infauna by predators in predator inclusion experiments may be due to prey emigration as well as direct predation.