FACTORS INFLUENCING FOOD SELECTION IN THE ABALONE HALIOTIS-RUBRA (MOLLUSCA, GASTROPODA)

The feeding rates of the abalone Haliotis rubra were measured for a ra nge of macroalgal diets. The macroalgae Gigartina radula, Plocamium me rtensii, Ecklonia radiata, Phyllospora comosa, Jenerettia lobata, Ulva lactuca and Macrocystis augustofolia showed interspecific variation i n ash, nitrogen and energy content; toughness (resistance to penetrati on); and rates of assimilation and food conversion efficiency by H. ru bra. Tests with an artificial diet (agar) showed that feeding rates by H. rubra were influenced by toughness. Toughness also accounted for m uch of the variation (60%) in the feeding rate on the macroalgal diets . The results of our study show little evidence for chemical deterrenc e of herbivory for H. rubra, but suggest that food toughness is a prim ary factor in the feeding preferences of abalone.