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The mission of the Mak Pak Scale Up project 2021 present) is to develop a seaweed based food packaging material and to sustainably scale up the production of seaweed, including Ulva spp in a recirculating land based facility supplemented with artificial seawater that requires a selection and optimization of the seaweed of interest The Ulva genus has previously shown high plasticity and capacity to acclimate and develop under broad ranges of environmental conditions, suggesting this may be a promising candidate for production in a RAS with low salinity artificial seawater Selecting an Ulva strain well adapted to such conditions will help reduce the costs of salt and, therefore, optimize production The aim of this study was to determine how salinity can be used and adapted throughout the entire Ulva production to define several key points 1 strain selection 2 nursery and seeding 3 optimized production in adult Ulva and 4 increasing functionality (e g high antioxidant activity) Based on the results of three different experiments, it was possible to conclude how salinity impacts different strains of Ulva (tubular and blade species) from warm temperate environments, during three key moments of their development and with that, conclude which strains would be more suited to be scaled up within the scope of land based production At the same time, the data presented serve as a baseline for further work with Ulva under different cultivation conditions

Haben Sie schon einmal darüber nachgedacht, dass Meeresalgen eine Lösung für die weltweite Plastikverschmutzungskrise bieten könnten? Die Verwendung von Einweg-Verpackungsmaterialien hat in den letzten Jahrzehnten parallel zu den zunehmenden Trends in Sachen Convenience und Fast-Food dramatisch zugenommen. Die meisten dieser Verpackungsmaterialien bestehen aus biologisch nicht abbaubaren, erdölbasierten Polymeren, die sich negativ auf die Umwelt auswirken und zur globalen Plastikverschmutzungskrise beitragen. Die Plastikverschmutzung in den Ozeanen zerstört die Ökosysteme und bedroht in der Folge unsere eigene Gesundheit, die Lebensmittelsicherheit und den Küstentourismus. Die Suche nach alternativen Verpackungsmaterialien ist ein wichtiger Schritt zum Aufbau einer biobasierten Kreislaufwirtschaft und zum Erreichen unserer Nachhaltigkeitsziele. Unsere Ozeane könnten eine Lösung in Form von Makroalgen bieten. Das Mak-Pak Scale-Up Projekt konzentriert sich auf die Skalierung und Optimierung der Produktion von Meeresalgen, um nachhaltiges, biologisch abbaubares und/oder essbares Verpackungsmaterial auf Makroalgenbasis für die Fast-Food-Industrie zu schaffen, das potenziell Einweg-Plastikverpackungen ersetzen könnte. Dieser Vortrag stellt das Mak-Pak Scale-Up Projekt vor, einschließlich des Hintergrunds, der wichtigsten Errungenschaften, der aktuellen Aktivitäten und der Zukunftspläne im Rahmen der UN-Nachhaltigkeitsziele und der Kreislaufwirtschaft.

Kelps are important foundation species in coastal ecosystems currently experiencing pronounced shifts in their distribution patterns caused by ocean warming. While some populations found at species’ warm distribution edges have been recently observed to decline, expansions of some species have been recorded at their cold distribution edges. Reduced population resilience can contribute to kelp habitat loss, hence, understanding intraspecific variations in physiological responses across a species’ latitudinal distribution is crucial for its conservation. To investigate potential local responses of the broadly distributed kelp Saccharina latissima to marine heatwaves in summer, we collected sporophytes from five locations in Europe (Spitsbergen, Bodø, Bergen, Helgoland, Locmariaquer), including populations exposed to the coldest and warmest local temperature regimes. Meristematic tissue from sporophytes was subjected to increasing temperatures of Δ+2, Δ+4 and Δ+6°C above the respective mean summer temperatures (control, Δ±0°C) characteristic for each site. Survival and corresponding physiological and biochemical traits were analyzed. Vitality (optimum quantum yield, Fv/Fm) and growth were monitored over time and biochemical responses were measured at the end of the experiment. Growth was highest in northern and lowest in southern populations. Overall, northern populations from Spitsbergen, Bodø and Bergen were largely unaffected by increasing summer temperatures up to Δ+6°C. Conversely, sporophytes from Helgoland and Locmariaquer were markedly stressed at Δ+6°C: occurrence of tissue necrosis, reduced Fv/Fm, and a significantly elevated de epoxidation state of the xanthophyll cycle (DPS). The variations in phlorotannins, mannitol and tissue C and N contents were independent of temperature treatments and latitudinal distribution pattern. Pronounced site-specific variability in response to increasing temperatures implies that exceeding a threshold above the mean summer temperature exclusively affect rear-edge (southernmost) populations.

Introduction The use of single-use packaging materials has increased dramatically in recent decades in parallel with increasing trends in convenience and fast-food. Most of these packaging materials are made of non-biodegradable, petroleum-based polymers that have degradative impacts on the environment and contribute to the global plastic pollution crisis. Finding alternative packaging materials is an important step towards building a bio-based circular economy. Sustainable land-based macroalgae cultivation can provide a solution, as it eliminates land-use pressure on coastal areas, doesn’t interfere with recreational activities or agriculture, reduces seasonal limitations, allows for complete control over product quality, and ensures consistent quality and traceability. Here, we present the success story of land-based macroalgae production for sustainable packaging solutions in the food industry via the Mak-Pak and Mak-Pak Scale-Up projects. Materials and Methods An initial screening of local macroalgae species was conducted based on detailed knowledge of growth rates, seasonality, geographic range, edibility, iodine content, biochemical properties, bioactivity, robustness and ease of cultivation. Different combinations of selected macroalgae were tested to develop a biodegradable, edible packaging prototype that was rated by consumer tests. In a follow-up project, we are focusing on eliminating the biggest bottleneck: scaling-up biomass production. We have partnered with a local, innovative farmer to sustainably scale-up and optimize biomass production for our sustainable, biodegradable macroalgae-based packaging material for the food industry. Results Several species of suitable macroalgae were selected based on the screening protocol and a method for using different combinations of selected species is described in a patent application for the packaging prototype. The packaging prototype was positively reviewed in consumer tests, where the consumers were pleasantly surprised by the neutral taste and smell. We could also show that certain components of the macroalgae that are important for packaging functionality (e.g. antioxidant activity) could be optimized during land-based production in artificial seawater. Currently we are in the early stages of scaling-up production and selecting strains to optimize growth rates and robustness, where we can complete the life cycle of one selected species from single cells to mature gametophytes within 6 weeks. With controlled induction of reproduction, we can continually provide material for transplantation to large-scale systems. Discussion The Mak-Pak and Mak-Pak Scale-Up projects have been featured in numerous news articles, exhibitions, and podcasts throughout Germany, Europe and even New Zealand. Our experience has shown that there is a lot of public interest in macroalgae-based packaging solutions. Consumers have become aware of the plastic pollution crisis and are open to alternatives to plastic packaging. Consequently, we have recently seen rapid changes in packaging trends in the cosmetic and food industries. Here we show that it is possible to produce a biodegradable, edible packaging from macroalgae biomass for the food-industry. Not only is this a success story for sustainable aquaculture, but also for macroalgae cultivation in general. This project has increased public awareness of macroalgae and contributed to a dialogue about the diversity of products and services that macroalgae can provide as we strive towards a sustainable, circular economy. However, optimization of the raw material production as well as the packaging itself is still underway. Furthermore, limitations in the food-industry require that our raw material meets high quality standards. In other industries where the quality of the raw material is not a limiting factor, there is enormous potential for macroalgae-based packaging solutions.

In the original article, there were mistakes in Tables 2–4 and associated legends and text as published. The original article contained errors in the reported modeled macroalgal distribution area in the pan-Arctic and its subregions because the polygons used to calculate the areas were not correctly defined.

Kelps, the marine forest foundation species, are threatened by ocean warming at their warm distributional edges. To mechanistically investigate inheritance of thermal traits, we assessed thermal tolerance of inbred (selfings) and outbred (crosses) sporophytes of the N-Atlantic kelp Laminaria digitata among isolates from the genetically distinct populations of Helgoland (North Sea) and Spitsbergen (Arctic). First, we investigated the upper thermal tolerance of microscopic sporophytes in a 14-day experiment applying 20–23°C. The upper survival temperature was lower for the Spitsbergen selfing (21°C) than for the Helgoland selfing and the reciprocal crosses (22°C). We then subjected 4–7 cm long sporophytes to a control temperature (10°C), moderate (19°C) and sub-lethal heat stress (20.5°C) to assess metabolic regulation via whole-transcriptome analysis in addition to physiological parameters. Growth and optimum quantum yield decreased similarly in both crosses and the Helgoland selfing at 19 and 20.5°C, while inbred Spitsbergen sporophytes died within seven days at both 19 and 20.5°C. At 10°C, the Spitsbergen selfing showed the highest differential gene expression. Considering only the three surviving lineages at 20.5°C, differential gene expression was 61–78% lower in the crosses compared to the Helgoland selfing, including reduced expression of transcripts related to cellular stress responses. This implies that both intraspecific crosses maintained a growth response similar to the Helgoland selfing with reduced metabolic regulation during sublethal heat stress, indicating subtle heterosis (hybrid vigour) as a beneficial effect of outbreeding. Results are discussed in the frame of mariculture and marine forest restoration.

In recent years, kelp populations worldwide have faced decline and extirpation at their equatorward limits, while models predict a poleward shift of kelp ecosystems during climate change. To gain an understanding of local thermal adaptation and response plasticity in a forest-forming kelp species, we assessed populations of Laminaria digitata along its entire European distribution range for their capacity to withstand high temperature stress, and analysed population structure and diversity with microsatellite markers (n=12). We sampled wild meristematic L. digitata material (n=30) at six locations ranging from Kongsfjorden, Spitsbergen, to the southernmost distribution limit in Quiberon, France. In a heatwave experiment, we subjected samples from all locations to the same, sublethal temperature treatments (15–23°C for eight days including acclimation) and assessed growth, storage compounds, photosynthetic efficiency and pigment contents as response traits. Recovery was assessed following seven days at 15°C. Microsatellite genotyping revealed all sampled populations to be genetically distinct entities, underlying strong regional structuring between southern and northern clades. Genetic diversity was highest at the southern distribution limit in Quiberon and lowest in the geographically isolated population on the island of Helgoland in the North Sea. The physiological response of L. digitata to temperature was similar over the entire distribution range and did not reflect the mean temperature gradient along the latitudinal gradient. However, material from Spitsbergen and Helgoland presented subtle differentiations in their temperature responses, which reflect long-term local temperature histories at these sites. Finally, a heatwave reaching 23°C for five days led to a cessation of growth, from which none of the sampled populations recovered. Our results suggest that the heat stress response of L. digitata is generally stable across its distribution range, despite strong genetic structuring of the populations. Slight local differentiation occurred in populations from the most distinct thermal environments, but 23°C posed a growth limit for all populations. This implies that local adaptation in trailing edge populations of L. digitata might not alleviate detrimental effects of global warming.

ESKP-Themenspezial: Biodiversität, Für die EU-Wasserrahmenrichtlinie wird an ausgewählten Standorten auch die Biodiversität von marinen Makroalgen erfasst. Dieses Monitoring wird zurzeit nur durch wenige Spezialisten sichergestellt. Der Rote-Liste-Bericht (2012) konstatiert jedoch, dass an Nord- und Ostsee vor allem kleine und unauffällige Makroalgenarten seit Jahrzehnten häufig nicht erfasst wurden. Dies resultiert unter anderem aus einer schwindenden Kompetenz bei der Bestimmung von Makroalgen. Ein besserer Bestimmungsschlüssel für Makroalgen soll nun die wissenschaftliche Praxis unterstützen.

Saccharina latissima is an economically and ecologically relevant kelp species in Europe and North America. In kelps, the sexuality is expressed during the haploid life stage and the microscopic gametophytes exhibit significant sexual dimorphism. To understand the sex-dependent impact of temperature on the gametophyte stage, we analyzed for the first time, gene expression profiles of male and female gametophytes at three different temperatures (4, 12, and 20°C) characteristic for the species distribution range by using RNA-sequencing. We identified several differentially expressed genes (DEGs) between sexes; while female biased genes were enriched in general metabolism and energy production, male biased genes function within cell cycle and signaling. In our study, temperature modulated sex-biased gene expression, with only a small percentage of DEGs consistently male (7%) or female-biased (12%) at the three temperatures. Female gametophytes responded stronger to higher temperatures than males, suggesting that males are more heat tolerant. Differences between S. latissima and other brown algal gender-dependent gene expression might mirror the different evolutionary and ecological contexts. Genomic information on kelp gametophyte is still scarce and thus this study adds to our knowledge on sex differences in abiotic stress responses in macroalgae at the transcriptomic level.