Indexed on: 28 Mar '12Published on: 28 Mar '12Published in: Marine Biology
Phenotypic plasticity could be a key mechanism of successful species invasion. Few studies, however, have evaluated whether a non-indigenous species induces anti-herbivore defenses after its introduction to new habitats. We tested how a non-indigenous (Mastocarpus stellatus) and a native red seaweed (Chondrus crispus) responded to grazing by a periwinkle (Littorina littorea) and an isopod (Idotea granulosa) in Helgoland, Germany. In the donor region of the Mastocarpus population, that is Iceland, the periwinkle is missing, whereas the isopod is present. Our results indicate that Mastocarpus experienced less consumption by Littorina (but not by Idotea) than Chondrus. Moreover, Mastocarpus induced defenses in response to Idotea (but not to Littorina) grazing, whereas Chondrus induced anti-herbivory responses to both species of herbivores. Grazed Mastocarpus grew equally to non-grazed conspecifics, while growth of grazed Chondrus was lower than of ungrazed conspecifics. Hence, the non-indigenous Mastocarpus responded differently to grazing stress than the native Chondrus with respect to anti-herbivory and compensatory responses, which perhaps supported the successful Mastocarpus establishment in a new range.