SUBLETHAL EFFECTS PROVOKED BY THE PRESENCE OF THE PREDATOR NUCELLA CRASSILABRUM (LAMARCK) UPON THE MUSSEL PERUMYTILUS-PURPURATUS (LAMARCK) IN CHILE

Biotic interactions in marine invertebrates were analyzed under labora tory conditions. An oxygen debt was observed for the intertidal mussel Perumytilus purpuratus (Lamarck) in contact with the gastropod predat or Nucella crassilabrum (Lamarck). This response was detected after a short contact with the snail. The oxygen debt was similar to that dete rmined after anoxia (N2 supply). Mussels maintained in the presence of whelks and control animals without predators, were sequentially subje cted to high temperatures during 2 h of air exposure. The mortality ra te was higher in experimental individuals (previously in contact with predators) than in controls. Experimental animals (previously exposed to predators) experienced greater water losses (weight drop) than cont rols, after high emersion temperature treatment. The results suggest t hat predators could be the cause of mortality not only when organisms are directly consumed, but also due to cumulative sublethal effects.