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  • 1
    Online Resource
    Online Resource
    Table_1.docx
    Frontiers Media SA ; 2022
    In:  Frontiers in Marine Science Vol. 9 ( 2022-7-25)
    Details
    In: Frontiers in Marine Science, Frontiers Media SA, Vol. 9 ( 2022-7-25)
    Abstract: Sea lettuce ( Ulva ) aquaculture has increased the last decade due to high productivity, wide environmental tolerance, and interesting functional and nutritional properties of the crop. Research focus has mainly been on adult biomass production, but knowledge of performance and biochemical content of early developmental stages – which are the basis to any large-scale production - is still limited. The life-history of Ulva alternates between a diploid sporophytic life-stage and a haplontic gametophytic life-stage. Whereas the sporophyte give raise to recombinant gametophytes through zoids, gametophytes can give raise to parthenogenetically developing, clonal gametes in absence of a mating partner. This study shows that recombinant gametophytes have a faster ontogenetic development, higher growth rate, as well as higher protein, fatty acid, and pigment contents compared to clonal gametophytes of the crop Ulva fenestrata . Nutrient addition is required for a normal development, but temperature and swarmer density have relatively small effects on the hatchery success, relative growth rate and biochemical profile of the juvenile biomass. Our study reveals that the selection of the life-history-phase in novel sea lettuce crop strains could largely contribute to the emerging seaweed aquaculture sector.
    Type of Medium: Online Resource
    ISSN: 2296-7745
    URL: Article
    URL: Article
    URL: Article
    URL: Article
    DOI: 10.3389/fmars.2022.942679
    DOI: 10.3389/fmars.2022.942679.s001
    DOI: 10.3389/fmars.2022.942679.s002
    DOI: 10.3389/fmars.2022.942679.s003
    Language: Unknown
    Publisher: Frontiers Media SA
    Publication Date: 2022
    detail.hit.zdb_id: 2757748-X
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  • 2
    Online Resource
    Online Resource
    A tufA metabarcoding approach for Ulva and related seaweeds
    Pensoft Publishers ; 2021
    In:  ARPHA Conference Abstracts Vol. 4 ( 2021-03-04)
    Details
    In: ARPHA Conference Abstracts, Pensoft Publishers, Vol. 4 ( 2021-03-04)
    Abstract: Ulva -like green algae are notoriously difficult to distinguish due to their morphological variability and/or similarity. DNA barcoding approaches are therefore currently essential for their reliable identification. However, such approaches often fail when rare or inconspicuous species are to be detected in large mixed populations of Ulva species, for example, at early stages following the introduction of species into new habitats. We therefore developed a detection method based on next-generation DNA sequencing. The approach is suitable for the analysis of DNA traces in preserved water samples or in particles enriched by filtration from such samples. A new pair of primers was designed to amplify a 475 bp segment within the tufA marker gene. The primers were relatively group specific. 68.5% of all reads obtained after quality filtering represented the genus Ulva, 11.1% other Ulvophyceae, and only 20% other Chlorophyta, despite their relatively higher abundance in phytoplankton. The relatively short target amplicon still allows good differentiation of Ulvales and Ulothrichales at the species level. Using a database containing tufA sequences of 879 species - 281 of which were Ulvophyceae and 35 Ulva - we were able to detect mostly Ulvophyceae that had been previously detected in our study area in northern Germany using Sanger sequencing. However, the number of species detected at individual sites was generally higher than in previous studies, which could be due to drifting DNA: Analysis of samples collected at different distances from shore suggests that a sample collected at a given site may be influenced by Ulvophyceae within a radius of up to about 1 km in winter. In summer, this radius is reduced to less than 100 m, possibly due to the less frequent occurrence of strong wind events. Nonetheless, rare species may be detected with this new approach: At one site, an undescribed Blidingia species that was not previously known from our study area was repeatedly detected. Based on these findings, the species was searched for and found, and its identity confirmed by traditional tufA barcoding.
    Type of Medium: Online Resource
    ISSN: 2603-3925
    URL: Article
    DOI: 10.3897/aca.4.e65495
    Language: Unknown
    Publisher: Pensoft Publishers
    Publication Date: 2021
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  • 3
    Online Resource
    Online Resource
    Post-harvest cultivation with seafood process waters improves protein levels of Ulva fenestrata while retaining important food sensory attributes
    Frontiers Media SA ; 2022
    In:  Frontiers in Marine Science Vol. 9 ( 2022-9-26)
    Details
    In: Frontiers in Marine Science, Frontiers Media SA, Vol. 9 ( 2022-9-26)
    Abstract: Seaweed aquaculture can provide the growing human population with a sustainable source of proteins. Sea-based cultivation is an effective method for farming seaweeds on a large scale and can yield high biomass output. However, the quality and biochemical composition of the biomass is seasonally dependent, which limits the harvests to certain periods of the year. Here we show the possibility to extend the sea-based cultivation season of Ulva fenestrata when aiming for high protein levels, by post-harvest treatment in herring production process waters. We harvested U. fenestrata at an optimal period in terms of yield, but suboptimal in terms of protein content. We then cultivated the seaweed in onshore tank systems with the nutrient-rich process waters for 14 days. We monitored biomass yield, crude protein content, amino acid composition, and content of the health concerning metals arsenic, mercury, lead, and cadmium, as well as the sensory properties of the dried biomass. After cultivation in the process waters, biomass yields were 30 - 40% higher (210 – 230 g fresh weight) compared to in seawater (160 g fresh weight). Also, the crude protein and amino acid content increased three to five times in the process waters, reaching 12 - 17 and 15 – 21% dry weight, respectively. The protein enriched biomass followed food graded standards for heavy metal content, and consumption of the biomass does not exceed health based reference points. Additionally, no sensory attributes regarded as negative were found. This rapid, post-harvest treatment can help extend the cultivation season of sea-based seaweed farms, maximizing their output of sustainable proteins.
    Type of Medium: Online Resource
    ISSN: 2296-7745
    URL: Article
    DOI: 10.3389/fmars.2022.991359
    Language: Unknown
    Publisher: Frontiers Media SA
    Publication Date: 2022
    detail.hit.zdb_id: 2757748-X
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  • 4
    Online Resource
    Online Resource
    Harvest Time Can Affect the Optimal Yield and Quality of Sea Lettuce (Ulva fenestrata) in a Sustainable Sea-Based Cultivation
    Frontiers Media SA ; 2022
    In:  Frontiers in Marine Science Vol. 9 ( 2022-2-25)
    Details
    In: Frontiers in Marine Science, Frontiers Media SA, Vol. 9 ( 2022-2-25)
    Abstract: Seaweed biomass is a renewable resource with multiple applications. Sea-based cultivation of seaweeds can provide high biomass yields, low construction, operation, and maintenance costs and could offer an environmentally and economically sustainable alternative to land-based cultivations. The biochemical profile of sea-grown biomass depends on seasonal variation in environmental factors, and the optimization of harvest time is important for the quality of the produced biomass. To identify optimal harvest times of Swedish sea-based cultivated sea lettuce ( Ulva fenestrata ), this study monitored biomass yield, morphology, chemical composition, fertility, and biofouling at five different harvesting times in April – June 2020. The highest biomass yields (approximately 1.2 kg fw [m rope] –1 ) were observed in late spring (May). The number and size of holes in the thalli and the amount of fertile and fouled tissue increased with prolonged growth season, which together led to a significant decline in both biomass yield and quality during summer (June). Early spring (April) conditions were optimal for obtaining high fatty acid, protein, biochar, phenolic, and pigment contents in the biomass, whereas carbohydrate and ash content, as well as essential and non-essential elements, increased later in the growth season. Our study results show that the optimal harvest time of sea-based cultivated U. fenestrata depends on the downstream application of the biomass and must be carefully selected to balance yield, quality, and desired biochemical contents to maximize the output of future sea-based algal cultivations in the European Northern Hemisphere.
    Type of Medium: Online Resource
    ISSN: 2296-7745
    URL: Article
    DOI: 10.3389/fmars.2022.816890
    Language: Unknown
    Publisher: Frontiers Media SA
    Publication Date: 2022
    detail.hit.zdb_id: 2757748-X
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  • 5
    Online Resource
    Online Resource
    Presentation_1.pdf
    Frontiers Media SA ; 2022
    In:  Frontiers in Marine Science Vol. 9 ( 2022-12-2)
    Details
    In: Frontiers in Marine Science, Frontiers Media SA, Vol. 9 ( 2022-12-2)
    Abstract: There is an increasing interest in the cultivation of seaweeds for food and feed, and the seaweed aquaculture industry is rapidly developing. The nutritional status of the seaweeds is important to ensure a good quality crop. Cost-efficient and straightforward methods for farmers to analyze their crop are essential for the successful development of the industry. In this study, we developed non-destructive, labor- and cost-efficient models to estimate the nitrogen content in the crop seaweed Ulva fenestrata by color image analysis. We quantified tissue nitrogen content and thallus color in sea-farmed seaweed every week throughout a whole cultivation season (15 consecutive weeks) and analyzed data with linear regression models. We showed that color image analysis accurately estimated the nitrogen content in the seaweed (R 2 = 0.944 and 0.827 for fresh tissue and dried powder, respectively), and through tenfold cross validation we showed that the developed models were robust and precise. Based on these models, we developed a web-based application that automatically analyzes the nitrogen content of U. fenestrata . Furthermore, we produced a color guide that can easily be brought to the farm for onsite crude estimation of the nitrogen content of U. fenestrata . Our results demonstrate that color can be a powerful tool for seaweed farmers (and researchers) to estimate seaweeds’ nutritional status. We anticipate that similar models can be developed for other commercially interesting seaweed species.
    Type of Medium: Online Resource
    ISSN: 2296-7745
    URL: Article
    URL: Article
    URL: Article
    DOI: 10.3389/fmars.2022.1081870
    DOI: 10.3389/fmars.2022.1081870.s001
    DOI: 10.3389/fmars.2022.1081870.s002
    Language: Unknown
    Publisher: Frontiers Media SA
    Publication Date: 2022
    detail.hit.zdb_id: 2757748-X
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