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排序方式: 共有254条查询结果,搜索用时 15 毫秒
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Binding of inorganic elements to kelp residues 总被引:1,自引:1,他引:0
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Kiara Franke Lisa C. Matthes Angelika Graiff Ulf Karsten Inka Bartsch 《Journal of phycology》2023,59(3):518-537
Coastal kelp forests produce substantial marine carbon due to high annual net primary production (NPP) rates, but upscaling of NPP estimates over time and space remains difficult. We investigated the impact of variable underwater photosynthetically active radiation (PAR) and photosynthetic parameters on photosynthetic oxygen production of Laminaria hyperborea, the dominant NE-Atlantic kelp species, throughout summer 2014. Collection depth of kelp had no effect on chlorophyll a content, pointing to a high photoacclimation potential of L. hyperborea towards incident light. However, chlorophyll a and photosynthesis versus irradiance parameters differed significantly along the blade gradient when normalized to fresh mass, potentially introducing large uncertainties in NPP upscaling to whole thalli. Therefore, we recommend a normalization to kelp tissue area, which is stable over the blade gradient. Continuous PAR measurements revealed a highly variable underwater light climate at our study site (Helgoland, North Sea) in summer 2014, reflected by PAR attenuation coefficients (Kd) between 0.28 and 0.87 m−1. Our data highlight the importance of continuous underwater light measurements or representative average values using a weighted Kd to account for large PAR variability in NPP calculations. Strong winds in August increased turbidity, resulting in a negative carbon balance at depths >3–4 m over several weeks, considerably impacting kelp productivity. Estimated daily summer NPP over all four depths was 1.48 ± 0.97 g C · m−2 seafloor · d−1 for the Helgolandic kelp forest, which is in the range of other kelp forests along European coastlines. 相似文献
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Brooke L. Weigel Sadie L. Small Helen D. Berry Megan N. Dethier 《Journal of phycology》2023,59(5):893-907
Warming ocean temperatures have been linked to kelp forest declines worldwide, and elevated temperatures can act synergistically with other local stressors to exacerbate kelp loss. The bull kelp Nereocystis luetkeana is the primary canopy-forming kelp species in the Salish Sea, where it is declining in areas with elevated summer water temperatures and low nutrient concentrations. To determine the interactive effects of these two stressors on microscopic stages of N. luetkeana, we cultured gametophytes and microscopic sporophytes from seven different Salish Sea populations across seven different temperatures (10–22°C) and two nitrogen concentrations. The thermal tolerance of microscopic gametophytes and sporophytes was similar across populations, and high temperatures were more stressful than low nitrogen levels. Additional nitrogen did not improve gametophyte or sporophyte survival at high temperatures. Gametophyte densities were highest between 10 and 16°C and declined sharply at 18°C, and temperatures of 20 and 22°C were lethal. The window for successful sporophyte production was narrower, peaking at 10–14°C. Across all populations, the warmest temperature at which sporophytes were produced was 16 or 18°C, but sporophyte densities were 78% lower at 16°C and 95% lower at 18°C compared to cooler temperatures. In the field, bottom temperatures revealed that the thermal limits of gametophyte growth (18°C) and sporophyte production (16–18°C) were reached during the summer at multiple sites. Prolonged exposure of bull kelp gametophytes to temperatures of 16°C and above could limit reproduction, and therefore recruitment, of adult kelp sporophytes. 相似文献
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Different from the traditional knowledge about kelp, three sexual phenotypes (female, male, and monoecious) exist in the haploid gametophytes of Undaria pinnatifida. However, the sex-determining mechanisms remain unknown. Genetic linkage mapping is an efficient tool to identify sex-linked regions. In the present study, we resequenced a segregating gametophyte family based on the male genome of U. pinnatifida. A high-density genetic linkage map was constructed using 9887 SNPs, with an average distance of 0.41 cM between adjacent SNPs. On the basis of this genetic map and using the composite interval mapping method, we identified 62 SNPs significantly linked with the sexual phenotype. They were located at a position of 67.67 cM on the linkage group 23, corresponding to a physical range of 14.67 Mbp on the HiC_Scaffold_23 of the genome. Reanalysis of the previous specific length amplified fragment sequencing data according to the reference genome led to the identification of a sex-linked genomic region that encompassed the above-mentioned 14.67 Mbp region. Hence, this overlapped genomic range was likely the sex-determining region. Within this region, 129 genes were retrieved and 39 of them were annotated with explicit function, including the potential male sex-determining gene-encoding high mobility group (HMG) domain protein. Relative expression analysis of the HMG gene showed that its expression was higher in male gametophytes during the vegetative phase and monoecious gametophytes during both the vegetative and gametogenesis phases, but significantly lower in male gametophytes during the gametogenesis phase. These results provide a foundation for deciphering the sex-determining mechanism of U. pinnatifida. 相似文献
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A series of comparative culture experiments were conducted in order to determine responses of Laminaria longicruris male and female gametophytes and juvenile sporophytes to several temperatures (5, 10, 15, 20 °C), light levels (10, 35, 75 µmol m–2 s–1) and media nitrogen concentrations (0, 20, 100 µM ammonium-nitrogen). Responses were measured as numbers of male and female gametophytes producing gametangia and number of sporophytes produced following fertilization. Both male and female gametogenesis was reduced at 5 and 20 °C versus 10 and 15 °C. At 20 °C gametogenesis inhibition was greater with higher levels of ammonium-nitrogen concentration (100 µM). Sporophyte production was more sensitive to light, temperature and nitrogen concentration than gametogenesis. Production of sporophytes was inhibited completely at 20 °C. At lower temperatures, increasingly higher nutrient concentrations produced greater inhibition of production of sporophytes. 相似文献
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The artificial culture of Macrocystis integrifolia in southeastern Alaskan waters has been initiated as a first step in a project to augment the existing herring roe-on-kelp fishery in the state. The growing of Macrocystis in Prince William Sound has the potential of considerably enhancing this fishery by eliminating the costly importation of this kelp from southeast Alaska. In an ongoing feasibility study, Macrocystis has been cultured under laboratory conditions through the embryonic sporophyte stage and outplanted in waters near Sitka, Alaska (57° N). Growth of the outplanted kelps has been monitored as a function of the time and depth of the outplanting. Preliminary results suggest that light is limiting for growth in winter and that the optimal depth for outplanting will vary with the season. 相似文献