Functional traits vary with life stage not community context of the tropical secondary foundation macroalga <i>Turbinaria ornata</i>

The global decline of coral reefs has led to the emergence of novel communities, including macroalgal-dominated states, that can be both prevalent and persistent, making understanding the dynamics of these emergent communities vital. In the South Pacific, emergent stands of Turbinaria ornata, a secondary foundation species, create an associational refuge that protects understory algae from herbivory. Our objective was to utilize a trait-based framework to examine intraspecific trait variation of T. ornata individuals and to explore if this variation differs across life stage and with position within a canopy-forming stand. We compared four functional traits related to the ecological strategies of resistance to herbivory and physical disturbance of large and recruit T. ornata thalli. We collected individuals in two community contexts-both within and at the edge of stands (n = 22 per treatment, N = 88). Trait distributions varied significantly with life stage but not with community context. Small recruits were less tough, less strong, and less compact than larger canopy-forming thalli, indicating higher vulnerability to herbivory and physical disturbance. Our findings demonstrate that the associational refuge provided by large, canopy-forming individuals is likely crucial for the protection of recruits and, therefore, the persistence of the stand. This refuge may ultimately contribute to the expansion and stability of this emerging secondary foundation species.