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Found 6 results.

Thermal plasticity of Laminaria digitata - seasonal growth; recruitment; thermal physiology of juvenile sporophytes

We investigated effects of temperature during ontogeny of the kelp Laminaria digitata across haploid gametophyte and diploid sporophyte life cycle stages in 5 distinct genetic lines. We sampled meristematic discs from wild sporophytes on the island of Helgoland (North Sea; 54.1779 N, 7.8926 E) in May 2017, July 2017 and February 2018 and conducted a seasonal growth experiment at 5°C and 15°C over 14 days (experiment 1). Based on meiospores from five individuals (genetic lines) sampled in July 2017, we applied a full-factorial experimental design to generate different temperature histories by applying 5°C and 15°C during meiospore germination, gametogenesis of parental gametophytes and recruitment of offspring sporophytes (19-26 days; recruitment), and juvenile sporophyte rearing (91-122 days). We then tested for thermal plasticity among temperature history treatments at 5°C and 15°C in a final 12-day experiment assessing growth, the storage compound mannitol, carbon and nitrogen contents, and fluorometric responses in 3-4 month old sporophytes (experiment 2).

Laminaria digitata gametophyte survival and microscopic sporophyte formation, abundance and growth during exposure to decreased temperatures

To assess the thermal adaptation of microscopic stages of the kelp Laminaria digitata along latitudes, we conducted laboratory experiments on samples from six locations in the NE Atlantic (Spitsbergen (SPT), Tromsø (TRM), Bodø (BOD; all Norway), Helgoland (HLG; Germany), Roscoff (ROS) and Quiberon (QUI; both France)), spanning the species' entire distribution range. Gametophyte stock cultures from the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research were used. Prior to the experiments, cultures were stored at 15°C in iron-free ½ Provasoli enriched seawater in 3-4 µmol photons/m²/s red light. In experiment 2, samples were subjected to (sub-) optimal low temperatures (0-15°C) for 21 days, to assess gametophyte survival, sporophyte formation and growth. During the experiments, samples were kept in 15 µmol photons/m²/s white light under a 16:8h light:dark cycle. Sporophyte growth rates both in length and in width were determined as follows: GR = (x2-x1)/(t2-t1), where x is the length or width (μm) and t is the time in weeks at time point 1 and 2.

Laminaria digitata gametophyte survival and sporophyte formation during exposure to increased temperatures

To assess the thermal adaptation of microscopic stages of the kelp Laminaria digitata along latitudes, we conducted laboratory experiments on samples from six locations in the NE Atlantic (Spitsbergen (SPT), Tromsø (TRM), Bodø (BOD; all Norway), Helgoland (HLG; Germany), Roscoff (ROS) and Quiberon (QUI; both France)), spanning the species' entire distribution range. Gametophyte stock cultures from the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research were used. Prior to the experiments, cultures were stored at 15°C in iron-free ½ Provasoli enriched seawater in 3-4 µmol photons/m²/s red light. In experiment 1, we exposed gametophytes to (sub-) lethal high priming temperatures (20-25°C) for two weeks, followed by two weeks of recovery at 15°C, to observe gametophyte survival and sporophyte formation. During the experiments, samples were kept in 15 µmol photons/m²/s white light under a 16:8h light:dark cycle.

Integrated survival of Laminaria digitata gametophytes exposed to increased temperatures

To assess the thermal adaptation of microscopic stages of the kelp Laminaria digitata along latitudes, we conducted laboratory experiments on samples from six locations in the NE Atlantic (Spitsbergen (SPT), Tromsø (TRM), Bodø (BOD; all Norway), Helgoland (HLG; Germany), Roscoff (ROS) and Quiberon (QUI; both France)), spanning the species' entire distribution range. Gametophyte stock cultures from the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research were used. Prior to the experiments, cultures were stored at 15°C in iron-free ½ Provasoli enriched seawater in 3-4 µmol photons/m²/s red light. In experiment 1, we exposed gametophytes to (sub-) lethal high priming temperatures (20-25°C) for two weeks, followed by two weeks of recovery at 15°C, to observe gametophyte survival and sporophyte formation. During the experiments, samples were kept in 15 µmol photons/m²/s white light under a 16:8h light:dark cycle.

Local adaptation of microscopic stages of North Atlantic Laminaria digitata to high and low temperatures along latitudes: survival, reproduction and growth

To assess the thermal adaptation of microscopic stages of the kelp Laminaria digitata along latitudes, we conducted laboratory experiments on samples from six locations in the NE Atlantic (Spitsbergen (SPT), Tromsø (TRM), Bodø (BOD; all Norway), Helgoland (HLG; Germany), Roscoff (ROS) and Quiberon (QUI; both France)), spanning the species' entire distribution range. In experiment 1, we exposed gametophytes to (sub-) lethal high priming temperatures (20-25°C) for two weeks, followed by two weeks of recovery at 15°C, to observe gametophyte survival and sporophyte formation. In experiment 2, samples were subjected to (sub-) optimal low temperatures (0-15°C) for 21 days, to assess gametophyte survival, sporophyte formation and growth. During the experiments, samples were kept in 15 µmol photons/m²/s white light under a 16:8h light:dark cycle. Prior to the experiments, cultures were stored at 15°C in iron-free ½ Provasoli enriched seawater in 3-4 µmol photons/m²/s red light.

Heat resilience of intraspecific outbred compared to inbred lineages in the kelp Laminaria digitata: gametogenesis, thermal tolerance and growth

In a mechanistic investigation of heat stress, heterosis (hybrid vigour), and underlying gene expression patterns, we assessed the thermal performance of inbred (selfings) and outbred (reciprocal crosses) sporophytes of the N-Atlantic kelp Laminaria digitata among clonal isolates from two divergent populations; one from the temperate North Sea (Helgoland) and one from the Arctic (Spitsbergen). First, we investigated the upper thermal tolerance of microscopic sporophytes in a 14-day experiment applying sublethal to lethal 20–23°C. We then subjected 4–7 cm long sporophytes to a control temperature (10°C), moderate (19°C) and sublethal to lethal heat stress (20.5°C) for 18 days to assess the physiological parameters growth and optimum quantum yield.

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