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Growth and biochemistry of Saccharina latissima sporophytes in response to gametophyte priming

We examined the effect of gametophyte priming on early life stages of Saccharina latissima (gametophyte growth, sporophyte recruitment, juvenile sporophyte growth) and adult sporophytes harvested after growing for six months in mariculture (size and biomass, biochemical composition) in two experiments. Experiment 1: we primed S. latissima gametophytes (Lofoten 2023; 15°C clonal culture; n = 7) for 3 weeks at 0°C, 10°C, and 20°C and induced gametogenesis at 10°C for 2 weeks, during which we assessed relative gametophyte growth rates (from day 0 – 5), progression of gametogenesis, and sporophyte recruitment. Resulting sporophytes reared at 10°C were subjected to a 14-day temperature gradient treatment spanning 7 temperatures (0, 5, 10, 15, 20, 21.5, 23°C). We measured sporophyte growth (length and relative growth rates) after 7 and 14 days. Experiment 2: primed (0°C, 10°C, 20°C; 3 weeks) gametophytes (Lofoten 2023; 10°C mixed culture; n = 5) were sown on ropes and reared in a mariculture experiment (2 months hatchery, 4 months mariculture). Adult sporophytes were sampled and we measured growth (sporophyte length and width), total biomass (in fresh weight per m rope) and biochemical composition (C, N, mannitol, laminarin, and mineral composition). During the mariculture experiment, seawater temperature and nutrient composition was recorded at different time points. The mariculture field experiment took place at the hatchery of Polaralge AS (Sandhornøy, Norway; December - February 2024) and the deployment site of Lofoten Blue Harvest (Lilje Engla, Lofoten, Norway; 68°16'02.8N 15°06'14.8E; February – June 2024). The laboratory experiments of experiment 1 and the CN-analysis were carried out at the Alfred Wegener Institute in Bremerhaven, Germany; the mannitol analysis at the University of Rostock, Germany; the laminarin analysis at the MPI Bremen, Germany; and the mineral analysis at NIBIO Bodø, Norway.

GTS Bulletin: ISAH02 HKLP - Observational data (Binary coded) - BUFR (details are described in the abstract)

The ISAH02 TTAAii Data Designators decode as: T1 (I): Observational data (Binary coded) - BUFR T1T2 (IS): Surface/sea level T1T2A1 (ISA): Routinely scheduled observations for distribution from automatic (fixed or mobile) land stations (e.g. 0000, 0100, … or 0220, 0240, 0300, …, or 0715, 0745, ... UTC) A2 (H): 90°E - 0° tropical belt(The bulletin collects reports from stations: HKLP;) (Remarks from Volume-C: XXX)

Growth of juvenile Saccharina latissima sporophytes in response to gametophyte priming

We examined the effect of gametophyte priming on early life stages of Saccharina latissima (juvenile sporophyte growth) in a laboratory experiment: we primed S. latissima gametophytes (Lofoten 2023; 15°C clonal culture; n = 7) for 3 weeks at 0°C, 10°C, and 20°C and induced gametogenesis at 10°C for 2 weeks. Resulting sporophytes reared at 10°C were subjected to a 14-day temperature gradient treatment spanning 7 temperatures (0, 5, 10, 15, 20, 21.5, 23°C). We measured sporophyte growth (length and relative growth rates) after 7 and 14 days. The laboratory Experiment was carried out at the Alfred Wegener Institute in Bremerhaven, Germany.

Gametogenesis and gametophyte growth of Saccharina latissima in response to gametophyte priming

We examined the effect of gametophyte priming on early life stages of Saccharina latissima (gametophyte growth and sporophyte recruitment) in a laboratory experiment: We primed S. latissima gametophytes (Lofoten 2023; 15°C clonal culture; n = 7) for 3 weeks at 0°C, 10°C, and 20°C and induced gametogenesis at 10°C for 2 weeks, during which we assessed relative gametophyte growth rates (from day 0 – 5), progression of gametogenesis, and sporophyte recruitment. The laboratory experimentwas carried out at the Alfred Wegener Institute in Bremerhaven, Germany.

Heat stress response of Saccharina latissima sporophytes of different age classes to gametophyte and sporophyte priming - 4

We assessed the heat tolerance of microscopic, juvenile and adult sporophytes under heat stress and in response to gametophyte or sporophyte priming in five experiments. Experiment 1: we primed Saccharina latissima gametophytes (Lofoten 2023; 15°C clonal culture; n = 7) for 3 weeks at 0°C, 10°C, and 20°C and induced gametogenesis at 10°C for 2 weeks. Resulting microscopic sporophytes were subjected to a 14-day heat stress treatment at 20°C, 21.5°C, and 23°C, where we counted the number of alive and dead sporophytes and calculated the survival rates. Experiment 2: sporophytes were cultivated after gametogenesis for an additional 4 weeks before we subjected them to a 14-day simulated heat wave (13°C for 3 days, 16°C for 2 days, 18°C for 2 days, 20°C, 21°C and 22°C for 1 day each, 23°C and 24°C for 4 days each, and recovery at 20°C for 7 days), during which we assessed the photosynthetic performance by measuring quantum yield (Fv/Fm). Sporophytes that survived the heat wave were cultivated at 15°C for 64 days to recover, after which we measured their size (length and blade area). Experiment 3: primed (0°C, 10°C, 20°C; 3 weeks) gametophytes (Lofoten 2023; 10°C mixed culture; n = 5) were sown on ropes and reared in a mariculture experiment (2 months hatchery, 4 months mariculture). Adult sporophytes were sampled and exposed to the same 14-day heat stress treatment at 20°C, 21.5°C, 23°C with a 10°C control group. We measured growth (length and blade area), Fv/Fm, and the percentage of healthy area (as % blade area with Fv/Fm > 0.6). Experiment 4: sporophytes from the 0°C gametophyte priming treatment of the same mariculture experiment recovered at 10°C for 24 days. Meristematic discs were exposed to a 1-day sporophyte priming trigger (T). A control group (C) remained at 10°C. After 3 days recovery at 10°C both groups were subjected to a 7-day heat stress treatment at 20°C, 21.5°C, 23°C, and 25°C, where we measured growth (disc area) and Fv/Fm. Experiment 5: gametogenesis of gametophytes (Spitsbergen 2011, 2015; 5°C clonal culture, n = 5) was induced at 5°C and sporophytes reared for 6 months. Sporophytes were distributed to three treatment groups. A 17-day heat wave (from 5°C to 20°C and back) followed by a 1-day priming trigger at 21.5°C (HWT); 17 days at 10°C and a 1-day priming trigger (T); a control remaining at 10°C throughout (C). All groups were subjected to a 7-day heat stress treatment at 20°C, 21.5°C, 23°C, and 25°C, where we measured Fv/Fm, percentage of healthy area and survival. All laboratory experiments were carried out at the Alfred Wegener Institute in Bremerhaven, from January to July 2024. The mariculture experiment took place at the hatchery of Polaralge AS (Sandhornøy, Norway; December - February 2024) and the deployment site of Lofoten Blue Harvest (Lilje Engla, Lofoten, Norway; 68°16'02.8N 15°06'14.8E; February – June 2024).

Heat stress response of Saccharina latissima sporophytes of different age classes to gametophyte and sporophyte priming - 2

We assessed the heat tolerance of microscopic, juvenile and adult sporophytes under heat stress and in response to gametophyte or sporophyte priming in five experiments. Experiment 1: we primed Saccharina latissima gametophytes (Lofoten 2023; 15°C clonal culture; n = 7) for 3 weeks at 0°C, 10°C, and 20°C and induced gametogenesis at 10°C for 2 weeks. Resulting microscopic sporophytes were subjected to a 14-day heat stress treatment at 20°C, 21.5°C, and 23°C, where we counted the number of alive and dead sporophytes and calculated the survival rates. Experiment 2: sporophytes were cultivated after gametogenesis for an additional 4 weeks before we subjected them to a 14-day simulated heat wave (13°C for 3 days, 16°C for 2 days, 18°C for 2 days, 20°C, 21°C and 22°C for 1 day each, 23°C and 24°C for 4 days each, and recovery at 20°C for 7 days), during which we assessed the photosynthetic performance by measuring quantum yield (Fv/Fm). Sporophytes that survived the heat wave were cultivated at 15°C for 64 days to recover, after which we measured their size (length and blade area). Experiment 3: primed (0°C, 10°C, 20°C; 3 weeks) gametophytes (Lofoten 2023; 10°C mixed culture; n = 5) were sown on ropes and reared in a mariculture experiment (2 months hatchery, 4 months mariculture). Adult sporophytes were sampled and exposed to the same 14-day heat stress treatment at 20°C, 21.5°C, 23°C with a 10°C control group. We measured growth (length and blade area), Fv/Fm, and the percentage of healthy area (as % blade area with Fv/Fm > 0.6). Experiment 4: sporophytes from the 0°C gametophyte priming treatment of the same mariculture experiment recovered at 10°C for 24 days. Meristematic discs were exposed to a 1-day sporophyte priming trigger (T). A control group (C) remained at 10°C. After 3 days recovery at 10°C both groups were subjected to a 7-day heat stress treatment at 20°C, 21.5°C, 23°C, and 25°C, where we measured growth (disc area) and Fv/Fm. Experiment 5: gametogenesis of gametophytes (Spitsbergen 2011, 2015; 5°C clonal culture, n = 5) was induced at 5°C and sporophytes reared for 6 months. Sporophytes were distributed to three treatment groups. A 17-day heat wave (from 5°C to 20°C and back) followed by a 1-day priming trigger at 21.5°C (HWT); 17 days at 10°C and a 1-day priming trigger (T); a control remaining at 10°C throughout (C). All groups were subjected to a 7-day heat stress treatment at 20°C, 21.5°C, 23°C, and 25°C, where we measured Fv/Fm, percentage of healthy area and survival. All laboratory experiments were carried out at the Alfred Wegener Institute in Bremerhaven, from January to July 2024. The mariculture experiment took place at the hatchery of Polaralge AS (Sandhornøy, Norway; December - February 2024) and the deployment site of Lofoten Blue Harvest (Lilje Engla, Lofoten, Norway; 68°16'02.8N 15°06'14.8E; February – June 2024).

Heat stress response of Saccharina latissima sporophytes of different age classes to gametophyte and sporophyte priming - 3

We assessed the heat tolerance of microscopic, juvenile and adult sporophytes under heat stress and in response to gametophyte or sporophyte priming in five experiments. Experiment 1: we primed Saccharina latissima gametophytes (Lofoten 2023; 15°C clonal culture; n = 7) for 3 weeks at 0°C, 10°C, and 20°C and induced gametogenesis at 10°C for 2 weeks. Resulting microscopic sporophytes were subjected to a 14-day heat stress treatment at 20°C, 21.5°C, and 23°C, where we counted the number of alive and dead sporophytes and calculated the survival rates. Experiment 2: sporophytes were cultivated after gametogenesis for an additional 4 weeks before we subjected them to a 14-day simulated heat wave (13°C for 3 days, 16°C for 2 days, 18°C for 2 days, 20°C, 21°C and 22°C for 1 day each, 23°C and 24°C for 4 days each, and recovery at 20°C for 7 days), during which we assessed the photosynthetic performance by measuring quantum yield (Fv/Fm). Sporophytes that survived the heat wave were cultivated at 15°C for 64 days to recover, after which we measured their size (length and blade area). Experiment 3: primed (0°C, 10°C, 20°C; 3 weeks) gametophytes (Lofoten 2023; 10°C mixed culture; n = 5) were sown on ropes and reared in a mariculture experiment (2 months hatchery, 4 months mariculture). Adult sporophytes were sampled and exposed to the same 14-day heat stress treatment at 20°C, 21.5°C, 23°C with a 10°C control group. We measured growth (length and blade area), Fv/Fm, and the percentage of healthy area (as % blade area with Fv/Fm > 0.6). Experiment 4: sporophytes from the 0°C gametophyte priming treatment of the same mariculture experiment recovered at 10°C for 24 days. Meristematic discs were exposed to a 1-day sporophyte priming trigger (T). A control group (C) remained at 10°C. After 3 days recovery at 10°C both groups were subjected to a 7-day heat stress treatment at 20°C, 21.5°C, 23°C, and 25°C, where we measured growth (disc area) and Fv/Fm. Experiment 5: gametogenesis of gametophytes (Spitsbergen 2011, 2015; 5°C clonal culture, n = 5) was induced at 5°C and sporophytes reared for 6 months. Sporophytes were distributed to three treatment groups. A 17-day heat wave (from 5°C to 20°C and back) followed by a 1-day priming trigger at 21.5°C (HWT); 17 days at 10°C and a 1-day priming trigger (T); a control remaining at 10°C throughout (C). All groups were subjected to a 7-day heat stress treatment at 20°C, 21.5°C, 23°C, and 25°C, where we measured Fv/Fm, percentage of healthy area and survival. All laboratory experiments were carried out at the Alfred Wegener Institute in Bremerhaven, from January to July 2024. The mariculture experiment took place at the hatchery of Polaralge AS (Sandhornøy, Norway; December - February 2024) and the deployment site of Lofoten Blue Harvest (Lilje Engla, Lofoten, Norway; 68°16'02.8N 15°06'14.8E; February – June 2024).

Model Output Statistics for HEL (12135)

DWD’s fully automatic MOSMIX product optimizes and interprets the forecast calculations of the NWP models ICON (DWD) and IFS (ECMWF), combines these and calculates statistically optimized weather forecasts in terms of point forecasts (PFCs). Thus, statistically corrected, updated forecasts for the next ten days are calculated for about 5400 locations around the world. Most forecasting locations are spread over Germany and Europe. MOSMIX forecasts (PFCs) include nearly all common meteorological parameters measured by weather stations. For further information please refer to: [in German: https://www.dwd.de/DE/leistungen/met_verfahren_mosmix/met_verfahren_mosmix.html ] [in English: https://www.dwd.de/EN/ourservices/met_application_mosmix/met_application_mosmix.html ]

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.

Algal information along a transect at the island of Helgoland in 2005

A sublittoral transect (P3) in the North of Helgoland that had been investigated ~40 years earlier by Lüning (1970) was traversed again. Scuba dives were carried out between 13.07.2005 and 25.08.2005. For each sampling point, time, date and coordinates were given as well as the depth in m mean low water spring tide. 0.25 m² frames were used to obtain the species composition, total fresh mass and total dry mass. In addition, 1 m² frames were used to record the kelp community by counting the individuals and measuring kelp stipe length, kelp blade area, kelp blade fresh mass, kelp age and fresh mass of epiphytes on the kelp stipes. Equal Location IDs represent the same frame.

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