Thermal tolerance of putative chimeric and non-chimeric Macrocystis pyrifera (Laminariales, Phaeophyceae) juvenile sporophytes from the central coast of Peru

Rising ocean temperatures threaten kelp forests, especially Macrocystis pyrifera, an ecologically dominant species in temperate marine ecosystems. We tested whether chimerism, i.e., the fusion of genetically distinct individuals, improves thermal tolerance in juvenile M. pyrifera from the central coast of Peru. Juveniles were grown at 15, 18, 21, and 24°C for 14days in controlled conditions. As temperatures rose, growth and survival declined, but putative chimeric juveniles persisted and grew at 24°C (39% survival), while non-chimeric juveniles failed above 21°C. Our results indicate that chimerism might enhance thermal tolerance in kelps, suggesting potential relevance for restoration and cultivation under climate change.