Barnacle growth under crowding conditions

Size data of adult Jehlius (j) and Notochthamalus (n) collected from experimental plots where focal individuals were photographed seasonally under under three different “crowding conditions”: 1) ‘isolated individuals’ with less than 25% of their shells in contact with neighboring barnacles of any species; 2) ‘conspecific crowding’ individuals that were in aggregated groups, with a minimum of 50% and up to 100% of their shells in contact with other adult individuals of the same species, and 3) ‘heterospecific crowding’ individuals that were in aggregated groups with 50-100% of their shells in contact with adults of the other species. The maximum opercular carino-rostral length, survival, percent contact with and number of neighboring individuals were recorded roughly every 3 months.