Laboratory experiments with simulated marine heatwaves to the giant kelp (Macrocystis pyrifera)

In this study, juvenile sporophytes were cultured using parental material from five geographically and genetically distinct populations of the giant kelp Macrocystis pyrifera from the northern and southern edges of the species' range in Aotearoa New Zealand. These sporophytes were exposed to simulated 22-day marine heatwaves at either 18°C or 22°C, or a 14°C control. The sporophytes were then kept at 14°C for a further 21 days to observe whether they showed signs of recovery. The experiment also assessed whether the long-term storage of gametophytes under red light could affect sporophyte performance; this was achieved by comparing two cultures from the same population (Wellington) that were cultured either with or without long-term storage under red light. The experiment was carried out in Wellington, New Zealand between June and July 2024.