PREDICTING THE IMPACT OF INTRODUCED MARINE SPECIES - LESSONS FROM THEMULTIPLE INVASIONS OF THE EUROPEAN GREEN CRAB CARCINUS-MAENAS

We compared ecological characteristics of three spatially independent invasions of the European green crab Carcinus maenas to determine whic h characteristics were most consistent across invasions, and hence wou ld be most predictable in future invasions. For invasions in western N orth America (WNA), eastern North America (ENA), and South Africa (SAF ), we compared five characteristics: (1) habitat usage, (2) diet prefe rences, (3) size of individuals, (4) rate of range expansion, and (5) demonstrated and potential impacts. We found that two characteristics, diet preference and ecological impact were relatively similar across the three invasions. Diet preference was particularly consistent with the rank order of taxa being virtually identical at the three sites. I n contrast, habitat usage, individual size, and rate of range expansio n were more variable. Differences in habitat usage and size were parti cularly evident in the WNA invasion, where C. maenas have failed to co lonize protected and exposed rocky shores used elsewhere and have grow n much larger than at other sites. We suggest that the degree of simil arity of these characteristics across invasions provides a valuable me asure of how predictable they will be in future invasions. Copyright ( C) 1996 Elsevier Science Limited