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Found 7 results.

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Seasonal and inter-annual variability in the heatwave tolerance of the kelp Saccharina latissima

Temperature is a major driver for the geographical distribution of organisms, such as the foundation kelp species Saccharina latissima. Globally rising sea surface temperatures and intensification of marine heatwaves have already led to local loss of kelp populations. We investigated temporal variations in the thermal susceptibility of S. latissima. Therefore, we assessed the stress responses of field sporophytes sampled from Helgoland (German Bight) to an experimental heat wave scenario in June 2018, August 2018, and August 2019. The experiment in June 2018 was conducted by Diehl et al. (2021a) and the respective dataset (Diehl et al. 2021b, https://doi.org/10.1594/PANGAEA.931637) was re-evaluated for this study. Treatment temperatures (18, 20, 22, 24 °C) were based on 18 °C summer mean sea surface temperature on Helgoland as control, and Δ+2, Δ+4, Δ+6 °C as temperature-amplitude treatments, mimicking marine heatwaves. After a three-days wound healing phase, seven days of temperature acclimation (day 0-7) and seven days of temperature treatment (day 8-14) followed. The survival, growth and maximum photosynthetic quantum yield (Fv/Fm; June 2018/August 2018: ImagingPAM, Walz Imaging PAM Maxi Version M-series; August 2019: Portable Chlorophyll Fluorometer PAM-2100, Heinz Walz GmbH, Effeltrich, Germany) were measured on day 0 and day 14. To highlight changes as response to the experimental heat wave, physiological parameters were shown as percentage of the initial values. Absolute concentrations of pigments were analyzed using a HPLC. Afterwards, accessory pigment (Acc) and xanthophyll cycle pigment (VAZ) concentration, as well as the de-epoxidation state of the xanthophyll cycle (DPS) and ratios were calculated.

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.

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.

Heatwave experiment in Kiel Outdoor Benthocosms, 2015: dataset for Fucus vesiculosus and Zostera marina response variables

13 response variable have been measured for Fucus vesiculosus and Zostera marina. Year: 2015 Where: Kiel Outdoor Benthocosm Treatments: - Co (0HW) = ambient treatment with no heatwaves - 1HW = one summer heatwave - 3HWs = three heatwaves, 2 spring/early summer heatwaves After 3HW means end of the experiment.

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