| Chthamalus proteus is the most recent invasive barnacle in the Hawaiian Islands, arriving some time after 1973. A native of the Gulf of Mexico, Caribbean Sea and southwestern Atlantic Ocean, C. proteus is now found throughout the main Hawaiian Islands. While still mainly restricted to harbors on neighbor islands, C. proteus has spread around the island of Oahu, inhabiting the intertidal zone in open-coast settings and attaining high abundance in wave-protected harbors and bays.; Aspects of the barnacle's life history were investigated at several locations within its home range and in Hawaii. While there were some differences in fecundity and vertical range between locations, there was overall little change in life history characteristics between the native and invaded ranges. We predict that the barnacle will continue to spread throughout the islands and to other areas in the Pacific that receive shipping traffic from Hawaii.; Competitive interactions between C. proteus and two other barnacles, an earlier invader, Balanus reticulatus , and the native Nesochthamalus intertextus were investigated at three locations on Oahu. Competition for space does not appear to be occurring between C. proteus and the native barnacle, but the newer invader is able to outcompete B. reticulatus via substrate pre-emption. Variation in recruitment between sites appears to be more important than competition in determining barnacle abundance and which barnacle will be the numerical dominant.; Interactions between C. proteus and the native limpet Siphonaria normalis were also examined. While the presence of the limpet enhances settlement of the barnacle, limpets prefer barnacle-free areas and move into patches cleared of barnacles. Whether interactions between the barnacle and limpet will be positive or negative may vary with densities of the two organisms.; A "field microcosm" experiment, in which tiles were assembled with one or three species of native bivalves and then placed into the intertidal zone, was used to test the idea that higher diversity leads to invasion resistance. There was no difference due to diversity in the communities of organisms that invaded tiles, but the presence or absence of certain bivalves in the original assembled communities led to differences in invaders. |
