PANGAEA_990505 Laboratory experiments with simulated marine heatwaves to the giant kelp (Macrocystis pyrifera) Bunting, Imogen C; D'Archino, Roberta; Barr, Neill G; Bury, Sarah J; Desmond, Matthew J; Hepburn, Christopher D; Kok, Yun Yi; Krieger, Erik C; Le, Duong Minh; Cornwall, Christopher Edward Laboratory experiments with simulated marine heatwaves to the giant kelp (Macrocystis pyrifera) 2026-02-16 PANGAEA Dataset https://doi.pangaea.de/10.1594/PANGAEA.990505 Investigator Imogen C Bunting imogenbunting@gmail.com Earth Science Event label Type of study Date/time start, experiment Date/time end, experiment Sampling date/time, experiment Species, unique identification Species, unique identification (Semantic URI) Species, unique identification (URI) Treatment: temperature description Tank number Tank block number Header number Specimen identification Survived heatwave Survived recovery Macrocystis pyrifera, blade length Macrocystis pyrifera, growth rate, blade length Macrocystis pyrifera, biomass, wet mass Macrocystis pyrifera, growth rate, biomass, wet mass Maximum quantum yield of photosystem II Macrocystis pyrifera, biomass as carbon Macrocystis pyrifera, biomass as nitrogen Macrocystis pyrifera, carbon/nitrogen ratio Macrocystis pyrifera, δ13C Macrocystis pyrifera, δ15N geoscientificInformation Break_Sea_Sound D'Urville_Island giant kelp Kelp Laboratory experiment Macroalgae marine heatwaves (MHWs) New Zealand Otago_Karitane Port_Pegasus Sampling by hand Scorching_Bay_Red Scorching_Bay_White thermal tolerance Reference in WoRMS Visual description Ruler tape Fine balance, OHAUS Corporation, Scout SPX2202 Pulse-Amplitude-Modulated (PAM) fluorometer, WALZ GmbH, DIVING-PAM-II/B for blue light Isotope ratio mass spectrometer, Thermo Fisher Scientific, Delta V Advantage with ConFlo IV interface; coupled to elemental analyzer, Thermo Fisher Scientific, Flash 2000 2020-05-03 2023-04-01 Complete -47.3045 -40.71819 166.78183 174.83595 CoRE Coastal People : Southern Skies unrestricted CC-BY-4.0: Creative Commons Attribution 4.0 International English PANGAEA Data Publisher for Earth & Environmental Science https://www.pangaea.de/ Data Center Contact Michael Diepenbroek info@pangaea.de

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Bremen Bremen 28359 Germany online 7819 data points text/tab-separated-values Bunting, Imogen C; D'Archino, Roberta; Barr, Neill G; Bury, Sarah J; Desmond, Matthew J; Hepburn, Christopher D; Kok, Yun Yi; Krieger, Erik C; Le, Duong Minh; Cornwall, Christopher Edward (2026): Similar sensitivity and resilience to marine heatwaves of giant kelp (Macrocystis pyrifera) sporophytes from the northern and southern edges of their distribution in Aotearoa New Zealand. Ocean Ecosystems, 2(1), 1, https://doi.org/10.1186/s44419-025-00002-z Enríquez, Susana; Borowitzka, Michael A (2011): The use of the fluorescence signal in studies of seagrasses and macroalgae. In Suggett, D.J., Prášil, O. and Borowitzka, M.A. (Eds) Chlorophyll a fluorescence in aquatic sciences: Methods and applications. Springer. Accessed 1 May 2024., https://download.pangaea.de/reference/137740/attachments/Enr%C3%ADquez_Borowitzka_2011.pdf Kain, Joanna M; Jones, N S (1976): The Biology of Laminaria Hyperborea . VIII. Growth on Cleared Areas. Journal of the Marine Biological Association of the United Kingdom, 56(2), 267-290, https://doi.org/10.1017/S0025315400018907 Mabin, Christopher J T; Johnson, Craig R; Wright, Jeffrey T (2019): Physiological response to temperature, light, and nitrates in the giant kelp Macrocystis pyrifera, from Tasmania, Australia. Marine Ecology Progress Series, 614, 1-19, https://doi.org/10.3354/meps12900 Paul, Debajyoti; Skrzypek, Grzegorz; Fórizs, István (2007): Normalization of measured stable isotopic compositions to isotope reference scales – a review. Rapid Communications in Mass Spectrometry, 21(18), 3006-3014, https://doi.org/10.1002/rcm.3185

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. Survival was assessed visually at the end of the heatwave and recovery phases. Length was measured with a ruler, and wet weight was measured with a balance, before and after the heatwave and after the recovery phase, and relative growth rates were calculated based on both metrics. Maximum quantum yield was measured using a Walz Diving-PAM blue light fluorometer before and after the heatwave and after the recovery phase. Blade tissue samples were taken at the end of the heatwave and recovery phases; these were oven dried, ground, and analysed using a mass spectrometer to determine total carbon and nitrogen content and δ13C and δ15N stable isotope ratios. It was found that the 22°C heatwave treatment caused 64% mortality and a significant reduction in linear growth rates across all kelp cultures, as well as a non-significant but noticeable reduction in maximum quantum yield. However, all cultures were comparatively resistant to the 18°C treatment, with just 23% mortality during the heatwave. Chemical composition of sporophytes was altered in both heatwave treatments, with total carbon content, carbon:nitrogen ratio, and δ15N values increasing significantly. There was little evidence that long-term storage of kelp gametophytes under red light impacts sporophyte survival or growth. Although survival rates and chemical composition differed between some populations, there was no consistent evidence overall for significant differences in thermal tolerance between northern and southern M. pyrifera cultures. ** For all details see the full metadata description at "https://doi.pangaea.de/10.1594/PANGAEA.990505"!

https://cpss.org.nz/ CoRE https://doi.org/10.1002/rcm.3185 Normalization of measured stable isotopic compositions to isotope reference scales – a review https://doi.org/10.1017/S0025315400018907 The Biology of Laminaria Hyperborea . VIII. Growth on Cleared Areas https://doi.org/10.1186/s44419-025-00002-z Similar sensitivity and resilience to marine heatwaves of giant kelp (Macrocystis pyrifera) sporophytes from the northern and southern edges of their distribution in Aotearoa New Zealand https://doi.org/10.3354/meps12900 Physiological response to temperature, light, and nitrates in the giant kelp Macrocystis pyrifera, from Tasmania, Australia https://www.marinespecies.org Reference in WoRMS DIF 9.4 2026-02-16 2026-04-30