Description: Kelp forests are important habitats in the strongly environmentally and seasonally variable Arctic. There is a critical lack of knowledge about how seasonal conditions and climate change scenarios influence survival and reproduction of kelp early life stages. To better understand the regulation of kelp life cycle processes in this harsh environment we focused on the physiological performance and reproductive success of early life stages in Alaria esculenta and Laminaria digitata from Kongsfjorden, Spitsbergen. Gametophyte growth and survival during Arctic winter and subsequent sporophyte recruitment under spring conditions were investigated. Winter conditions (2°C, complete darkness) halted gametophyte growth and prevented the onset of gametogenesis in both species. The gametophytes of L. digitata but not A. esculenta became fertile after returning to spring conditions, suggesting that sporogenesis, sexual reproduction and recruitment in A. esculenta must occur successively during summer/autumn while in L. digitata a new generation of sporophytes could develop from overwintering gametophytes. The effects of simulated canopy shading (offering protection against extreme irradiance stress, particularly as sea ice retreats), present-day and projected Arctic summer seawater temperatures, and nutrient levels on gametophyte survival, fertility and sporophyte recruitment success were also investigated in both species. A. esculenta gametophytes had greater survival and reproductive success than L. digitata, except under very low light (simulating dense canopy). In contrast, shading was required for reproductive success in L. digitata gametophytes. Predicted summer temperatures of 9°C reduced sexual reproduction in both species. Interactions observed between these environmental drivers probably reflect species-specific seasonal patterns of survival and reproduction. These differences between kelp species in response to abiotic factors and light levels (simulated canopy shading) suggest that climate change could alter community structure in the Arctic through effects on sexual reproduction and sporophyte recruitment success.

Description: Macroalgae are major primary producers and ecosystem engineers along rocky shores of the Arctic. With Svalbard being a hotspot of global warming, macroalgal species distribution and biomass is undergoing rapid changes, presumably affecting all associated life forms. The overall retreat of the yearly ice cover is only the centerpiece in a complex interplay of environmental drivers noticeably altering light availability, disturbance regimes and nutrient supply for Arctic seaweeds. Between 1996/1998 and 2012/2013 ecosystem changes were observed at our study site Hansneset in Kongsfjorden, as algal biomass in the littoral zone doubled and the macroalgal biomass peak, as well as the lower distribution limit of most dominating kelp species, shifted upwards by several meters. In summer 2021, we seek to complement these datasets. Our interdisciplinary group will repeat the quantitative monitoring study to examine how the community pattern of seaweeds and their associated fauna has changed since the last expedition. In detail, we will quantify macroalgal biomass and biodiversity, the age structure and fertility of kelp species, and the biomass and biodiversity of associated animals along a depth gradient between 0 and 15 m. Incorporated into the European Horizon 2020 project FACE-IT and two associated Svalbard Science Forum field grants, our superior aim is to analyse the response of benthic macroalgal assemblages to observed cryosphere changes in a broad context. In this poster, we will share the first results from this year’s field samplings and show how abundances, biomass and species diversity of macroalgae have changed over the last decades at our investigation site and what this means in general for the development of macroalgae on Arctic coasts.

Description: Marine forests and kelps as their foundation species are threatened by ocean warming especially at the warm distributional edges. Previously identified genetic divergence and ecotypic differentiation within kelp species may allow to produce more resilient lineages by intraspecific outbreeding among populations. 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. The upper survival temperature of microscopic sporophytes was lower for the inbred Arctic selfing (21°C) than for the temperate selfing and the reciprocal crosses (22°C). Only in the temperate selfing, 4.5% of sporophytes survived 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 gene expression in addition to physiological parameters. Growth and optimum quantum yield decreased similarly in the reciprocal crosses and the temperate selfing at 19 and 20.5°C, while inbred Arctic sporophytes died within seven days at both 19 and 20.5°C. In response to 20.5°C, 252 genes were constitutively regulated across all surviving lineages, which we use to describe metabolic regulation patterns in response to heat stress in kelp. At sublethal 20.5°C, ca. 150 genes were differentially expressed by either crossed lineage in comparison to the temperate selfing, indicating that they maintained a growth response similar to the temperate selfing with differential metabolic regulation during sublethal heat stress. Subtle differences in physiology and the differential expression of nine genes between the reciprocal crosses at 20.5°C indicate that female and male gametophytes may contribute differently to offspring traits. We consider potential inbreeding depression in the Spitsbergen selfing and quantify the better performance of both crosses using heterosis-related parameters. We discuss the potential and risks of outbreeding to produce more resilient crops for mariculture and marine forest restoration.

Description: Many organisms have endogenous clocks that synchronize biological processes with environmental changes, leading to optimized development and reproduction. However, certain environments, like the Arctic, pose a special challenge to circadian clocks, particularly due to extreme seasonal changes in daylength, ranging from permanent sunlight to complete darkness. Kelps seem to be well adapted to the variable environmental conditions characteristic of this region. However, daylength might affect kelp species that use circadian rhythms to control the timing of daily egg release from female gametophytes. We aimed to investigate how daylength and light intensity affect gametogenesis and reproductive success of summer-reproducing kelp species (using Alaria esculenta as a model). As daylength and temperature co-vary most of the year, we also investigated the thermal resilience of the sporophytes developed under different daylengths to understand if there is a cross-tolerance between light doses and temperature tolerance. Although continuous daylight, characteristic of Arctic summers, enhanced gametogenesis and increased gametophyte vegetative growth, and thereby the number of potential reproductive gametophyte cells, sporophyte production was higher under long (16 h light:8 h dark) and intermediate (12:12 h) days. Sporophyte growth was triggered by changing daylength from short to long days, suggesting a synchronization with annual daylength variation. High daily light doses during reproduction and early development improved subsequent sporophyte survival at high (sub)lethal temperatures, indicating cross-tolerance between light and temperature. Reproductive success in Arctic A. esculenta was hampered under continuous light, and we hypothesize that this might result from disturbance of synchronized egg release and subsequent fertilization.

Description: Endemic Antarctic macroalgae are especially adapted to live in extreme Antarctic conditions. Their potential biogeographic distribution niche is primarily controlled by the photoperiodic regime and seawater temperatures, since these parameters regulate growth, reproduction, and survival during the entire life cycle. Here we analyzed the upper survival temperature (UST) of juvenile sporophytes and the temperature range for sporophyte formation from gametophytes of Desmarestia menziesii, one of the dominant endemic Antarctic brown algal species. This process is a missing link to better evaluate the full biogeographical niche of this species. Two laboratory experiments were conducted. First, growth and maximum quantum yield of juvenile sporophytes were analyzed under a temperature gradient (0, 5, 10, 12, 13, 14, 15, and 16 °C) in a 16:8 h light:dark (LD) regime (Antarctic spring condition) for 2 weeks. Second, the formation of sporophytes from gametophytes (as a proxy of gametophyte reproduction) was evaluated during a 7 weeks period under a temperature gradient (0, 4, 8, 12, and 16 °C), and two different photoperiods: 6:18 h LD regime simulating winter conditions and a light regime simulating the Antarctic shift from winter to spring by gradually increasing the light period from 7.5:16.5 h LD (late winter) to 18.5:5.5 h LD (late spring). Sporophytes of D. menziesii were able to grow and survive up to 14 °C for 2 weeks without visible signs of morphological damage. Thus, this species shows the highest UST of all endemic Antarctic Desmarestiales species. In turn, gametophyte reproduction solely took place at 0 °C but not at 4–8 °C. The number of emerging sporophytes was six times higher under the light regime simulating the transition from winter to spring than under constant short day winter conditions. There was a negative relationship between the number of sporophytes formed and the gametophyte density at the beginning of the experiment, which provides evidence that gametophyte density exerts some control upon reproduction in D. menziesii. Results strongly indicate that although sporophytes and gametophytes may survive in warmer temperatures, the northernmost distribution limit of D. menziesii in South Georgia Islands is set by the low temperature requirements for gametophyte reproduction. Hence, global warming could have an impact on the distribution of this and other Antarctic species, by influencing their growth and reproduction.

Description: Kelp forests in the North Atlantic are at risk of decline at their warm temperature distribution margins due to anthropogenic temperature rise and more frequent marine heat waves. To investigate the thermal adaptation of the cold-temperate kelp Laminaria digitata, we sampled six populations, from the Arctic to Brittany (Spitsbergen, Tromsø, Bodø [all Norway], Helgoland [Germany], Roscoff and Quiberon [both France]), across the species’ entire distribution range, spanning 31.5° latitude and 12-13°C difference in mean summer sea surface temperature. We used pooled vegetative gametophytes derived from several sporophytes to approximate the genetic diversity of each location. Gametophytes were exposed to (sub-) lethal high (20-25°C) and (sub-) optimal low (0-15°C) temperature gradients in two full-factorial, common-garden experiments, subjecting subsets of populations from different origins to the same conditions. We assessed survival of gametophytes, their ability to develop microscopic sporophytes, and subsequent growth. We hypothesized that the thermal performance of gametophytes and microscopic sporophytes corresponds to their local long-term thermal history. Integrated gametophyte survival revealed a uniform upper survival temperature (UST) of 24°C among five tested populations (Tromsø to Quiberon). In contrast, following two weeks of thermal priming of gametophytes at 20-22°C, sporophyte formation at 15°C was significantly higher in southern populations (Quiberon and Roscoff) compared to the high-latitude population of Tromsø. Between 0-15°C, survival of the Arctic population (Spitsbergen) was negatively correlated with increasing temperatures, while the southernmost population (Quiberon) showed the opposite. Thus, responses of survival at low, and sporophyte formation at high temperatures, support the concept of local adaption. On the other hand, sporophyte formation between 0-15°C peaked at 6-9°C in the Quiberon and at 9-12°C in the Spitsbergen population. Sporophyte growth rates (GR) both in length and width were similar for Spitsbergen, Tromsø and Quiberon; all had maximum GRs at 12-15°C and low GRs at 0-6°C. Therefore, responses of sporophyte formation and growth at low temperatures do not reflect ecotypic adaptation. We conclude that L. digitata populations display trait-dependent adaptation, partly corresponding to their local temperature histories and partly manifesting uniform or unpredictable responses. This suggests differential selection pressures on the ontogenetic development of kelps such as L. digitata.

Description: 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

Description: 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

Description: 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.

Description: 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.