10.1594/PANGAEA.990505Bunting, Imogen CImogen CBunting0009-0009-5407-0163School of Biological Sciences, Victoria University of Wellington Te Herenga Waka, KelburnD'Archino, RobertaRobertaD'ArchinoEarth Sciences New ZealandBarr, Neill GNeill GBarrEarth Sciences New ZealandBury, Sarah JSarah JBuryEarth Sciences New ZealandDesmond, Matthew JMatthew JDesmondDepartment of Marine Science, Portobello Marine Laboratory, University of OtagoHepburn, Christopher DChristopher DHepburnDepartment of Marine Science, Portobello Marine Laboratory, University of OtagoKok, Yun YiYun YiKokEarth Sciences New ZealandKrieger, Erik CErik CKriegerRed Sea Research Centre, King Abdullah University of Science and TechnologyLe, Duong MinhDuong MinhLeDepartment of Marine Science, Portobello Marine Laboratory, University of OtagoCornwall, Christopher EdwardChristopher EdwardCornwall0000-0002-6154-4082School of Biological Sciences, Victoria University of Wellington Te Herenga Waka, KelburnPANGAEA2026giant kelpKelpLaboratory experimentMacroalgaemarine heatwaves (MHWs)New Zealandthermal toleranceEvent labelType of studyDate/time start, experimentDate/time end, experimentSampling date/time, experimentSpecies, unique identificationSpecies, unique identification (Semantic URI)Species, unique identification (URI)Treatment: temperature descriptionTank numberTank block numberHeader numberSpecimen identificationSurvived heatwaveSurvived recoveryMacrocystis pyrifera, blade lengthMacrocystis pyrifera, growth rate, blade lengthMacrocystis pyrifera, biomass, wet massMacrocystis pyrifera, growth rate, biomass, wet massMaximum quantum yield of photosystem IIMacrocystis pyrifera, biomass as carbonMacrocystis pyrifera, biomass as nitrogenMacrocystis pyrifera, carbon/nitrogen ratioMacrocystis pyrifera, δ13CMacrocystis pyrifera, δ15NSampling by handReference in WoRMSVisual descriptionRuler tapeFine balance, OHAUS Corporation, Scout SPX2202Pulse-Amplitude-Modulated (PAM) fluorometer, WALZ GmbH, DIVING-PAM-II/B for blue lightIsotope ratio mass spectrometer, Thermo Fisher Scientific, Delta V Advantage with ConFlo IV interface; coupled to elemental analyzer, Thermo Fisher Scientific, Flash 2000Coastal People : Southern Skies (CoRE)2020-05-03T00:00:00/2023-04-01T00:00:00Dataset10.1186/s44419-025-00002-z10.1017/S002531540001890710.3354/meps1290010.1002/rcm.31857819 data pointstext/tab-separated-valuesCreative Commons Attribution 4.0 InternationalIn 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.166.78183174.83595-47.3045-40.71819Fiordland, New ZealandMarlborough, New ZealandOtago, New ZealandStewart Island, New ZealandWellington, New Zealand