I will examine the response of giant red sea urchin, Mesocentrotus franciscanus, to marine heatwave (MHW) stress and contribute to management goals for this marine invertebrate species. For objective 1, adult red urchins will be collected from sites near Santa Barbara and held in a dynamic marine heatwave simulator for four months during the period of gametogenesis. Urchins will then be spawned and physiological, biochemical, and morphometric analyses will be conducted to assess progeny thermal performance and phenotype. For objective 2, urchins will be held in marine heatwave simulator tanks in four week long feeding trials with Macrocystis pyrifera or Sargassum horneri. Gonad quality and gonadal indices will be assessed. For Objective 3, I will conduct data analyses on existing SBC-LTER datasets to determine if kelp canopy correlates with urchin biomass.