Feeding preferences for juvenile and adult algae depend on algal stage andherbivore species

Juvenile marine organisms are;physically and chemically different from adul ts. Consequently, the ecology of juveniles, particularly their interactions with other organisms, may change as they age. Yet, they are often consider ed to function as 'miniature adults'. To explore how ecological interaction s change as juvenile seaweeds mature, we investigated among-species food pr eferences of 4 species of grazers for 8 species of common intertidal and su btidal macroalgae in laboratory multiple-choice feeding-preference experime nts. Grazers were offered either juvenile tissues or adult tissues of 8 spe cies of macroalgae. Food preferences of grazers among both juvenile and adu lt brown algae differed among herbivore species. Within herbivore species, the relative grazing rates on juveniles of a given species were not signifi cantly correlated with grazing rates on adult tissues of that species. Thus , food preferences of herbivores among species of macroalgae are dependent upon the age of the algal tissue and the species of herbivore being conside red. Stage-specific differences in preferences between juveniles and adults are likely a result of chemical and morphological changes occurring during algal development. Further work is needed to characterize these changes an d further determine their impacts on the ecological characteristics of juve nile marine macroalgae.