Search

The suspension-feeding sea cucumber Cucumaria frondosa has become commercially important in recent years. Finding proper diets is the first important step for intensive aquaculture of this sea cucumber. In this study, adult C. frondosa were exposed to one of the following diet treatments: control (no diet provided), two powdered seaweeds (Ascophyllum nodosum and Saccharina latissima), a commercially available microalgal diet (shellfish diet) and natural seston. The effects of diets on the feeding behavior and physiological properties of sea cucumbers were investigated after a 5-week rearing period. Results show that sea cucumbers fed with shellfish diet exhibited a significantly higher tentacle insertion rate (1.80±0.20 insertion/min) than these fed with seaweed powders, and there was no significant different between the two groups fed by seaweed powders. No significant difference was found on the fecal production rate among the feeding groups. The minimum oxygen consumption rate was observed in the control group (5.76±0.99 μg O 2/(g·h)), which is significantly lower than individuals fed with A. nodosum, shellfish diet, and natural seston; however, no significant difference was shown between those of control and S. latissimi groups. The maximum ammonium excretion rate was found in the A. nodosum group (0.03±0.01 μmol/(g·h)), which is significantly higher than other groups. The minimum O/N ratio was observed in the A. nodosum group (14.57±1.04), which is significantly lower than the S. latissima, shellfish diet, and natural seston groups. Individuals fed with seaweed powders had similar physiological properties with these fed with microalgae diet and natural seston, indicating that A. nodosum and S. latissima can be explored as promising diets for intensive aquaculture of C. frondosa. [ABSTRACT FROM AUTHOR]

Gonad size, color, texture and taste of Mesocentrotus nudus sea urchins collected from a barren can be improved by a short-term cage culture while being fed fresh Saccharina japonica kelp during May–July. We investigated the effect of S. japonica feeding during May–July on the improvement of gonad flavor in M. nudus collected from a barren. After feeding, we analyzed the odor-active volatile organic compounds (VOCs) from the gonads using gas chromatography-mass spectrometry and GC-sniffing analyses and compared to those from the gonads of wild sea urchins from an Eisenia kelp bed (fishing ground) and a barren. A total of 48 VOCs were detected from the gonads of cultured and wild sea urchins. Of them, a larger number of odor-active compounds were detected in the gonads of cultured sea urchins (25) than in those from the Eisenia bed (14) and the barren (6). Dimethyl sulfide from the gonads of sea urchins from the barren was described as having a strong, putrid odor. Sea urchin-like aromas were attributed to 2-butanol, 2-ethylhexanol, benzaldehyde and ethylbenzene from the gonads of cultured sea urchin and those of the Eisenia bed. Kelp feeding decreased the putrid odor from dimethyl sulfide, and enhanced pleasant, sweet aromas. [ABSTRACT FROM AUTHOR]

Archaeognatha (Machilida plus †Monura), with ~450 extant species worldwide, represent a key lineage for the understanding of insect evolution. In a recently published phylogenetic analysis on Archaeognatha, based on a total‐evidence approach, a Machilidae key fossil (Gigamachilis triassicus) from the Middle Triassic Lagerstätte of Monte San Giorgio and a representative of †Monura (Dasyleptus triassicus) from the same fossiliferous site, were not considered. In the present study, the phylogenetic analyses performed by Zhang et al. (2018) using maximum parsimony and Bayesian inference were repeated including these two key taxa; in addition, Tricholepidion gertschi and Lepisma saccharina were included as representatives of Zygentoma. In the total‐evidence Bayesian analysis, †Monura was found to be paraphyletic, whereas in the maximum parsimony analysis, performed only on morphological characters, they were monophyletic. Moreover, the attribution of G. triassicus to Machilidae is now confirmed by these analyses, indicating that members of the extant group of Machilidae were already present in the Middle Triassic, at least ~100 Myr before the previous estimate. [ABSTRACT FROM AUTHOR]

The Arctic region is currently facing substantial environmental changes due to global warming. Melting glaciers cause reduced salinity environments in coastal Arctic habitats, which may be stressful for kelp beds. To investigate the responses of the kelp Saccharina latissima to the warming Arctic, we studied the transcriptomic changes of S. latissima from Kongsfjorden (Svalbard, Norway) over a 24‐hour exposure to two salinities (Absolute Salinity [SA] 20 and 30) after a 7‐day pre‐acclimation at three temperatures (0, 8 and 15°C). In addition, corresponding physiological data were assessed during an 11‐days salinity/temperature experiment. Growth and maximal quantum yield for photosystem II fluorescence were positively affected by increased temperature during acclimation, whereas hyposalinity caused negative effects at the last day of treatment. In contrast, hyposalinity induced marked changes on the transcriptomic level. Compared to the control (8°C – SA 30), the 8°C – SA 20 exhibited the highest number of differentially expressed genes (DEGs), followed by the 0°C – SA 20. Comparisons indicate that S. latissima tends to convert its energy from primary metabolism (e.g. photosynthesis) to antioxidant activity under hyposaline stress. The increase in physiological performance at 15°C shows that S. latissima in the Arctic region can adjust and might even benefit from increased temperatures. However, in Arctic fjord environments its performance might become impaired by decreased salinity as a result of ice melting. [ABSTRACT FROM AUTHOR]

The aquaculture of macroalgae for human consumption and other high-end applications is experiencing unprecedented development in European countries, with the brown algae Saccharina latissima being the flag species. However, environmental conditions in open sea culture sites are often unique, which may impact the biochemical composition of cultured macroalgae. The present study compared the elemental compositions (CHNS), fatty acid profiles, and lipidomes of S. latissima originating from three distinct locations (France, Norway, and the United Kingdom). Significant differences were found in the elemental composition, with Norwegian samples displaying twice the lipid content of the others, and significantly less protein (2.6%, while French and UK samples contained 6.3% and 9.1%, respectively). The fatty acid profiles also differed considerably, with UK samples displaying a lower content of n-3 fatty acids (21.6%), resulting in a higher n-6/n-3 ratio. Regarding the lipidomic profile, samples from France were enriched in lyso lipids, while those from Norway displayed a particular signature of phosphatidylglycerol, phosphatidylinositol, and phosphatidylcholine. Samples from the UK featured higher levels of phosphatidylethanolamine and, in general, a lower content of galactolipids. These differences highlight the influence of site-specific environmental conditions in the shaping of macroalgae biochemical phenotypes and nutritional value. It is also important to highlight that differences recorded in the lipidome of S. latissima make it possible to pinpoint specific lipid species that are likely to represent origin biomarkers. This finding is relevant for future applications in the field of geographic origin traceability and food control. [ABSTRACT FROM AUTHOR]

SUMMARY Laminarialean plants undergo heteromorphic alternation of generations between the macroscopic diploid sporophyte and the microscopic haploid gametophyte. The generations change through the formation and release of asexual or sexual reproductive cells. It is difficult to monitor the release and diffusion of zoospores into the environment. Furthermore, even if zoospores can be detected, species identification remains difficult. This study attempted to develop a sensitive and fast identification method for laminarialean zoospores using quantitative PCR. In addition, we aimed to estimate the density of zoospores in natural seawater. Specific primers for Saccharina japonica and Undaria pinnatifida were designed and used to estimate the quantity of zoospores in seawater. DNA samples (environmental DNA) were collected from seawater once or twice each month for 2 years at the same area, and seasonal variations in the release of zoospores was monitored. The estimated maturation period based on the number of released zoospores in this study was comparable with those of the previously reported maturation periods of S. japonica and U. pinnatifida sporophytes. This supports the validity of our method in estimating zoospore release from laminarialean plants. The method will be a useful tool for ecological studies on these commercially relevant species. [ABSTRACT FROM AUTHOR]

Summary: Brown algae have convergently evolved plant‐like body plans and reproductive cycles, which in plants are controlled by differential DNA methylation. This contribution provides the first single‐base methylome profiles of haploid gametophytes and diploid sporophytes of a multicellular alga.Although only c. 1.4% of cytosines in Saccharina japonica were methylated mainly at CHH sites and characterized by 5‐methylcytosine (5mC), there were significant differences between life‐cycle stages. DNA methyltransferase 2 (DNMT2), known to efficiently catalyze tRNA methylation, is assumed to methylate the genome of S. japonica in the structural context of tRNAs as the genome does not encode any other DNA methyltransferases. Circular and long noncoding RNA genes were the most strongly methylated regulatory elements in S. japonica.Differential expression of genes was negatively correlated with DNA methylation with the highest methylation levels measured in both haploid gametophytes. Hypomethylated and highly expressed genes in diploid sporophytes included genes involved in morphogenesis and halogen metabolism.The data herein provide evidence that cytosine methylation, although occurring at a low level, is significantly contributing to the formation of different life‐cycle stages, tissue differentiation and metabolism in brown algae. [ABSTRACT FROM AUTHOR]

This study investigated seasonal variations in the composition of the kelp species Saccharina latissima cultivated on the Swedish west coast and, using an in vitro fermentation system, evaluated the effect of fermented whole S. latissima biomass or biomass components on the gut microbiota of broiler chickens. Caecal contents of six Ross 308 broilers fed a standard wheat and soy-based diet were retrieved on two different occasions, with three birds sampled per occasion. Two in vitro fermentation batches (A, B) were established using caecal contents as inoculum, and whole S. latissima , ethanol-washed S. latissima , laminarin extract or inulin (control) as substrate. Total short-chain fatty acid (SCFA) content, gas production, pH and changes in microbiota composition were studied after 6, 12 and 24 h of fermentation. Analysis of seasonal variations revealed that S. latissima harvested in June had the highest laminarin content and lowest ash and crude protein content. Broiler microbiota, SCFA profile, gas production and pH mainly varied depending on fermentation inoculum, but there were also some variations depending on substrate. For instance, uncultured bacterium from Clostridiales _vadinBB60_group showed higher relative abundance (RA) in batch A, while Faecalibacterium showed higher RA in batch B. Whole and ethanol-washed S. latissima resulted in highest RA of unclassified Ruminococcaceae and Tyzzerella for both batches, while ethanol-washed S. latissima and laminarin gave highest RA of Erysipelatoclostridium. Inulin resulted in highest RA for the genus Subdoligranulum. Acetic, n-butyric and propionic acid were the main fermentation products and total SCFA level was higher in batch B. Within batch B, inulin and laminarin generated higher levels of acetic and butyric acid. When using inulin and laminarin, gas production was lower in batch B compared with batch A. In summary, this study showed that S. latissima is a good source of laminarin, especially when harvested in summer. Within the in vitro system, the microbiota was affected by different substrates, but inoculum source was identified as an important contributor to microbial community development during fermentation. • Saccharina latissima represents a good resource for extraction of laminarin. • S. latissima derived substrates can modulate broiler gut microbiota. • Inoculum composition has an impact on production of short-chain fatty acids. [ABSTRACT FROM AUTHOR]

Alginates are valued in many industries, due to their versatile properties. These polysaccharides originate from brown algae (Phaeophyceae) and some bacteria of the Azotobacter and Pseudomonas genera, consisting of 1 → 4 linked β- d -mannuronic acid (M), and its C5-epimer α- l -guluronic acid (G). Several applications rely on a high G-content, which confers good gelling properties. Because of its high natural G-content (F G = 0.60–0.75), the alginate from Laminaria hyperborea (LH) has sustained a thriving industry in Norway. Alginates from other sources can be upgraded with mannuronan C-5 epimerases that convert M to G, and this has been demonstrated in many studies, but not applied in the seaweed industry. The present study demonstrates epimerisation directly in the process of alginate extraction from cultivated Saccharina latissima (SL) and Alaria esculenta (AE) , and the lamina of LH. Unlike conventional epimerisation, which comprises multiple steps, this in-process protocol can decrease the time and costs necessary for alginate upgrading. In-process epimerisation with AlgE1 enzyme enhanced G-content and hydrogel strength in all examined species, with the greatest effect on SL (F G from 0.44 to 0.76, hydrogel Young's modulus from 22 to 34 kPa). As proof of concept, an upscaled in-process epimerisation of alginate from fresh SL was successfully demonstrated. [Display omitted] [ABSTRACT FROM AUTHOR]

Until recently, Arctic kelp forests were so understudied that they did not even appear in global kelp forest maps. An increasing focus on Arctic coastal ecosystems has documented extended kelp forests along Arctic coastlines but the distribution of the forests is still not well documented and opens up for surprises. Here, we report kelp depth limits deeper than 61 m (median: 38.4 m, 10–90% percentiles: 10.8–54.4 m) in the Disko Bay region, Greenland, at latitudes of 67–70°N. We compiled, for comparison, existing records of kelp depth limits in high latitude (50°N) regions (median: 17.7 m, 10–90% percentiles: 9.0–38.1 m), which underline that the Disko Bay kelps hold a depth-record for this region. The deepest kelps were located at offshore sites beyond the Disko Island and the main coast. The clear waters offshore with euphotic zones (1% of surface irradiance) extending to 67 m depth provide, along with deep rocky seafloors and low density of sea urchins, the basis for these deep kelps. The sites were ice-covered for 77–133 days year-1, which is beyond the length of the polar night (30–60 days year-1) in the region, suggesting a potential for further depth penetration of kelp forests in a future with longer open water periods and more light potentially reaching the seafloor.

Background: Alginate is an important cell wall component and mannitol is a soluble storage carbon substance in the brown seaweed Saccharina japonica. Their contents vary with kelp developmental periods and harvesting time. Alginate and mannitol regulatory networks and molecular mechanisms are largely unknown. Results: With WGCNA and trend analysis of 20,940 known genes and 4264 new genes produced from transcriptome sequencing of 30 kelp samples from different stages and tissues, we deduced that ribosomal proteins, light harvesting complex proteins and "imm upregulated 3" gene family are closely associated with the meristematic growth and kelp maturity. Moreover, 134 and 6 genes directly involved in the alginate and mannitol metabolism were identified, respectively. Mannose-6-phosphate isomerase (MPI2), phosphomannomutase (PMM1), GDP-mannose 6-dehydrogenase (GMD3) and mannuronate C5-epimerase (MC5E70 and MC5E122) are closely related with the high content of alginate in the distal blade. Mannitol accumulation in the basal blade might be ascribed to high expression of mannitol-1-phosphate dehydrogenase (M1PDH1) and mannitol-1-phosphatase (M1Pase) (in biosynthesis direction) and low expression of mannitol-2-dehydrogenase (M2DH) and Fructokinase (FK) (in degradation direction). Oxidative phosphorylation and photosynthesis provide ATP and NADH for mannitol metabolism whereas glycosylated cycle and tricarboxylic acid (TCA) cycle produce GTP for alginate biosynthesis. RNA/protein synthesis and transportation might affect alginate complex polymerization and secretion processes. Cryptochrome (CRY-DASH), xanthophyll cycle, photosynthesis and carbon fixation influence the production of intermediate metabolite of fructose-6-phosphate, contributing to high content of mannitol in the basal blade. Conclusions: The network of co-responsive DNA synthesis, repair and proteolysis are presumed to be involved in alginate polymerization and secretion, while upstream light-responsive reactions are important for mannitol accumulation in meristem of kelp. Our transcriptome analysis provides new insights into the transcriptional regulatory networks underlying the biosynthesis of alginate and mannitol during S. japonica developments. [ABSTRACT FROM AUTHOR]

Acadian Seaplants, Ltd., marine plant extract powder (AMPEP) is a commercially available extract derived from the brown seaweed, Ascophyllum nodosum. This extract is widely applied to increase the performance of land crops and has been reported to enhance growth of some seaweed crops. To assess the effects of AMPEP on the growth and thermal tolerance of Saccharina latissima and S. angustissima cultivars, we performed two experiments. First, juvenile sporophytes were dipped (i.e., 30 or 60 min) in AMPEP solutions of different concentrations (0.001, 0.005, 0.05, 1, and 5 g L−1). Sporophytes were then cultivated in half strength Provasoli's enriched seawater (PES) and allowed to grow at different temperatures (12, 16, 19, 23, and 25 ± 1 °C) for 20 days using a temperature gradient table. Photoperiod was maintained at 12:12 L:D with photosynthetically active radiation (PAR) of 90 ± 10 μmol photons m−2 s−1. Results show a differential response between the two species tested. Sporophytes of both species cultured at 23 and 25 °C died during the first 7 days post dipping in AMPEP. After the 20-day period, the surviving sporophytes were transferred to an incubator set at 18 ± 1 °C (i.e., LT50 after 20 days). These sporophytes remained for 14 additional days to assess for any delayed effect on thermal tolerance, with treated sporophytes showing a higher percentage of survival and growth than control sporophytes never exposed to AMPEP. Furthermore, after the 14-day incubation at 18 °C, treated sporophytes of both species showed blades more than three times thicker than control sporophytes. These preliminary results indicate that AMPEP may enhance the growth capacity of S. latissima and S. angustissima when exposed to suboptimal temperatures, allowing them to overcome heat stress more effectively while maintaining growth. [ABSTRACT FROM AUTHOR]

• Using CO 2 in pyrolysis of brown algae enhanced the production of gaseous products by 610%. • Pyrolysis of brown algae in two-stage pyrolysis setup yielded a negligible amount of pyrolytic oil. • Oyster shell effectively provided CO 2 in in situ pyrolysis of brown algae in N 2 and enhanced CO production by 185%. • Ex situ brown algae pyrolysis in CO 2 with oyster shell at ≥315 °C produced 670% more CO and 3120% more H 2 than in situ pyrolysis. In this work, the pyrolysis of brown algae (Saccharina japonica (S. japonica)) was investigated to recover energy as a form of syngas (H 2 and CO). For this, this work emphasizes the use of CO 2 as a pyrolysis medium and oyster shell as a catalytic material in the pyrolysis of S. japonica. Pyrogenic products generated from the catalytic pyrolysis of S. japonica in N 2 and CO 2 were characterized. In particular, the enhanced generation of CO was substantial at 720 °C. This enhanced generation of CO was most likely because of the enhanced thermal cracking of volatile matter that evolved during the catalytic pyrolysis of S. japonica. The enhanced CO generation was likely catalytically expedited by biogenic salts such as calcite (CaCO 3) in the oyster shell. The introduced approach for exploiting CO 2 in the catalytic pyrolysis could be a more sustainable option to treat algal biomass such as brown algae and develop an effective waste-to-energy strategy. [ABSTRACT FROM AUTHOR]

Fucoidan is a kind of brown algae-derived macromolecule suggested to have hypolipidemic activity. Saccharina sculpera has attracted interest because it is rich in fucoidan. The monosaccharide composition and structural characteristics of isolated fractions (F1, F2 and F3) were determined using high-performance liquid chromatography (HPLC), Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance spectroscopy (NMR). The hypolipidemic effects of fucoidan fractions from Saccharina sculpera cultured in northern China were clarified by measuring cholesterol levels, antioxidative indicators and hepatic gene mRNA expression using an established hyperlipidemic Wistar rat model. The results showed that F1 is an acetylated galactofucan and that F2 consists of fucose, galactose, mannose and glucuronic acid. F3 is an acetylated galactofucan with high fucose. Fucoidan fractions from Saccharina sculpera could effectively reduce the level of lipids in serum by reducing the TG, TC, and LDL-C levels and increasing HDL-C levels and could effectively prevent lipid accumulation in the liver. The findings obtained from hepatic gene expression showed that fucoidan could inhibit cholesterol synthesis via downregulation of HMG-CoA-R and upregulation of LCAT, slow the synthesis of fatty acids via downregulation of SREBP-1c, and promote β-oxidation of fatty acids via upregulation of PPARα, PPARγ and LPL. These results demonstrated that the hypolipidemic activity of fucoidan was related to the inhibition of cholesterol synthesis and reverse transport, the regulation of fatty acid synthesis, and acceleration of mitochondrial β-oxidation. [ABSTRACT FROM AUTHOR]

Structural, functional and nutritional properties of protein recovered from brown seaweed, S. latissima with alkaline solubilization/isoelectric precipitation as a function of different post-harvest stabilization methods were studied. The latter included freezing at −20 °C/-80 °C, oven-drying, sun-drying, freeze-drying and ensilaging. Also, the efficacy of freeze/thaw-aided precipitation (F/T) in improving protein recovery of the process was evaluated. The freeze-dried, oven-dried, and −20 °C frozen seaweeds resulted in significantly higher protein yield than the −80°C-frozen, sun-dried and ensiled biomasses. F/T increased protein precipitation and doubled total protein yield. Sun-drying and −20°C-freezing caused extensive protein degradation as revealed by SDS-PAGE and HP-SEC, while oven-drying altered the seaweed protein structure with less α-helices. Functional properties of the seaweed proteins were remarkably affected by stabilization condition and F/T, but nutritional value of the proteins was only dependent on stabilization method. Thus, to efficiently recover seaweed proteins, its post-harvest stabilization condition must be carefully chosen based on the final application of the proteins. Image 1005 • Protein yield was strongly governed by post-harvest stabilization method. • Freeze/thawing doubled total protein yield of the process. • Functional properties of proteins were remarkably affected by stabilization method. • Structure and molecular weight of proteins were governed by stabilization method. [ABSTRACT FROM AUTHOR]

Ocean acidification and eutrophication are two major environmental issues affecting kelp mariculture. In this study, the growth, photosynthesis, and biochemical compositions of adult sporophytes of Saccharina japonica were evaluated at different levels of pCO2 (400 and 800 µatm) and nutrients (nutrient-enriched and non-enriched seawater). The relative growth rate (RGR), net photosynthetic rate, and all tested biochemical contents (including chlorophyll (Chl) a, Chl c, soluble carbohydrates, and soluble proteins) were significantly lower at 800 µatm than at 400 µatm pCO2. The RGR and the contents of Chl a and soluble proteins were significantly higher under nutrient-enriched conditions than under non-enriched conditions. Moreover, the negative effects of the elevated pCO2 level on the RGR, net photosynthetic rate, Chl c and the soluble carbohydrates and proteins contents were synergized by the elevated nutrient availability. These results implied that increased pCO2 could suppress the growth and biochemical composition of adult sporophytes of S. japonica. The interactive effects of ocean acidification and eutrophication constitute a great threat to the cultivation of S. japonica due to growth inhibition and a reduction in quality. [ABSTRACT FROM AUTHOR]

Algae biomass is considered as a promising energy feedstock, and bioenergy recovery from algae can be significantly enhanced by pretreatment. This study compared the effect of different pretreatment methods, including heat, acid, base, heat-acid and heat-base on macroalgae Saccharina japonica , and dark fermentation was conducted to achieve a couple generation of bioenergy and biomaterials. All the pretreatment could enhance the hydrogen production and energy recovery from macroalgae, and the combined pretreatment showed significant advantage in organics solubilization. Heat-base pretreated macroalgae achieved the highest hydrogen yield (17.5 mL/g TS added), while highest total energy conversion efficiency (35.4%) was obtained from heat-acid pretreated macroalgae, which was 2.1- and 2.9-fold compared to the control test. Hydrogen production can be further enhanced by microbial acclimation to high Na+ concentration to relieve its inhibition. • Treatment by heat, acid, base, heat-acid and heat-base could disrupt macroalgal. • Macroalgal biomass was further hydrolyzed during fermentation process. • Heat-base pretreatment enhanced energy conversion efficiency by 2.9 times. • Soluble metabolites were dominated by acetate and lactate. • Hydrogen production was further enhanced by acclimation to high Na+ concentration. [ABSTRACT FROM AUTHOR]

• Fucoidan LlF from L. longipes was α-L-fucan with unusual structure. • LlF consisted of 1,2-, 1,3- and 1,4-linked α-L-Fuc residues. • Fucans LlF and ScF had anticancer effect on melanoma and colon cancer cells. • Fucans LlF and ScF possessed comparable radiosensitizing activity. The sulfated α- l -fucans ScF and LlF were obtained from brown algae of the Laminariaceae family (Saccharina cichorioides and Laminaria longipes). According to spectroscopy NMR, the LlF fucan predominantly contained the →3)-α- l -Fuc p- (2SO 3 –)-(1→4)-α- l -Fuc p -(1→2)-α- l -Fuc p- (4SO 3 –)-(1→ repeating units, with small amounts of disaccharide 1,4-linked fragments and 3-sulfated fucose residues. Mass spectrometric analysis revealed the presence of the following fragments in the fucan structure: α- l -Fuc p- (2SO 3 –)-(1→4)-α- l -Fuc p -(2SO 3 –)-(1→3)-α- l -Fuc p -(4SO 3 –); α- l -Fuc p- (2,4SO 3 –)-(1→3)-α- l -Fuc p -(1→3)-α- l -Fuc p- (4SO 3 –); α- l -Fuc p- (2SO 3 –)-(1→2)-α- l -Fuc p ; α- l -Fuc p- (2SO 3 –)-(1→2)-α- l -Fuc p- (4SO 3 –); α- l -Fuc p- (2SO 3 –)-(1→3)-α- l -Fuc p ; α- l -Fuc p- (2,4SO 3 –)-(1→3)-α- l -Fuc p ; α- l -Fuc p- (4SO 3 –)-(1→4)-α- l -Fuc p ; and α- l -Fuc p -(4SO 3 –)-(1→4)-α- l -Fuc p -(2SO 3 –). Both ScF and LlF fucoidans inhibited colony formation and growth of melanoma and colon cancer cells and sensitize-tested cancer cells to X-ray radiation to a comparable degree. [ABSTRACT FROM AUTHOR]

• Hydrothermal pretreatment was assessed for H 2 and CH 4 co-production from seaweed. • Increasing hydrothermal temperature resulted in increased seaweed solubilization. • Seaweed pretreated at 140 °C enhanced CH 4 yield by 22.6% compared to raw seaweed. • Theoretical energy conversion efficiency of 72.8% was achieved after co-production. • Process energy efficiency can be optimised to 56.9% by pretreatment heat recovery. Marine macroalgae (seaweed) is a promising feedstock for producing biohydrogen and biomethane via dark fermentation and anaerobic digestion, respectively. However, one of the limiting steps in the biological process is the conversion of polymeric carbohydrates into monomeric sugars. Here hydrothermal pretreatments were assessed for hydrolysis and subsequent production of biohydrogen and biomethane from the brown seaweed Saccharina latissima. The solubilization of S. latissima improved with increasing temperatures from 100 to 180 °C, resulting in a maximum yield of 0.70 g soluble chemical oxygen demand/gram volatile solid (sCOD/g VS); equivalent to an increase of 207.5% compared with untreated seaweed. However, the yield of the derived monomeric sugar mannitol peaked at 140 °C and decreased with increasing temperatures, likely due to production of fermentative inhibitors. Microstructural characterization revealed that the algal structure was significantly damaged, and the major chemical groups of carbohydrates and proteins were weakened after pretreatment. Regardless of hydrothermal temperatures, biohydrogen yield only slightly increased in dark fermentation, while biomethane yield significantly increased from 281.4 (untreated S. latissima) to 345.1 mL/g VS (treated at 140 °C), leading to the sCOD removal efficiency of 86.1%. The maximum energy conversion efficiency of 72.8% was achieved after two-stage biohydrogen and biomethane co-production. In comparison, considering the energy input for pretreatment/fermentation/digestion, the highest process energy efficiency dropped to 37.8%. Further calculations suggest that a significant improvement of efficiency up to 56.9% can be achieved if the heat from pretreatment can be recovered. [ABSTRACT FROM AUTHOR]

In haplodiplontic lineages, sexual reproduction occurs in haploid parents without meiosis. Although widespread in multicellular lineages such as brown algae (Phaeophyceae), haplodiplontic gametogenesis has been little studied at the molecular level. We addressed this by generating an annotated reference transcriptome for the gametophytic phase of the sugar kelp, Saccharina latissima. Transcriptional profiles of microscopic male and female gametophytes were analysed at four time points during the transition from vegetative growth to gametogenesis. Gametogenic signals resulting from a switch in culture irradiance from red to white light activated a core set of genes in a sex-independent manner, involving rapid activation of ribosome biogenesis, transcription and translation related pathways, with several acting at the post-transcriptional or post-translational level. Additional genes regulating nutrient acquisition and key carbohydrate-energy pathways were also identified. Candidate sex-biased genes under gametogenic conditions had potentially key roles in controlling female- and male-specific gametogenesis. Among these were several sex-biased or -specific E3 ubiquitin-protein ligases that may have important regulatory roles. Females specifically expressed several genes that coordinate gene expression and/or protein degradation, and the synthesis of inositol-containing compounds. Other female-biased genes supported parallels with oogenesis in divergent multicellular lineages, in particular reactive oxygen signalling via an NADPH-oxidase. Males specifically expressed the hypothesised brown algal sex-determining factor. Male-biased expression mainly involved upregulation of genes that control mitotic cell proliferation and spermatogenesis in other systems, as well as multiple flagella-related genes. Our data and results enhance genome-level understanding of gametogenesis in this ecologically and economically important multicellular lineage. [ABSTRACT FROM AUTHOR]

Seaweed aquaculture is a relatively young industry in the United States compared to Asian countries. Early attempts at seaweed aquaculture in California, Washington State, New York and the Gulf of Maine in the 1980s and 1990s did not result in commercial production but provided important lessons. Since 2010, commercial cultivation of kelp (Saccharina latissima, Laminaria digitata, and Alaria esculenta) and other seaweeds (Palmaria palmata and Porphyra umbilicalis) began in the Gulf of Maine and Long Island Sound. Seaweed aquaculture is now a fast-growing maritime industry, especially in New England. If seaweed aquaculture is to maintain its momentum, it is important to (1) emphasise the environmental benefits; (2) domesticate a variety of local species; and (3) diversify seaweed products for food, animal feed, phycocolloids, cosmeceuticals, nutraceuticals, and ultimately biofuels if it becomes economically viable due to the cost of production. The exclusive economic zone (EEZ) of the United States offers opportunities for expansion of seaweed aquaculture in an area greater than the entire land mass of the United States and with limited user conflicts. This study reviews the past and current status of seaweed aquaculture in the United States and discusses potential opportunities and challenges of open-water seaweed aquaculture. [ABSTRACT FROM AUTHOR]

Implementation of open sea seaweed aquaculture has been pursued in Europe for high biomass production to be used for different purposes, including the biorefinery pipeline. Offshore cultivation has been proposed to avoid conflict with other uses of coastal areas such as fishing and recreational activities, and preferably associated with other compatible activities such as wind energy production or fish aquaculture to optimise costs and operation. Saccharina latissima is a European kelp species that finds its southern distribution limit in northern Portugal and is considered a good candidate for commercial cultivation. The present work studied growth performance of this species in exposed conditions, at 5, 10 and 15 m depth from February until September. Photosynthetic performance was also assessed at those depths in summer. Saccharina latissima grew in offshore exposed conditions at the southern distribution limit of the species, with growth rates of 3.3%–4.5% day−1 between January and May, while withstanding high wave heights. Results indicate that for food applications the growing season in these conditions may be extended until May. If used for applications with less stringent demands for appearance – for example, feed or biofuels – harvest can be delayed further. Optimisation of technology and understanding the underlying biology of S. latissima is needed for cultivation in these conditions. This will include development of low-maintenance/high-resistance support structures and harvest techniques, in addition to strategies for early deployment to improve cultivation reliability and to extend the growth period. [ABSTRACT FROM AUTHOR]

We hereby report the finding of Ctenolepisma longicaudata (Escherich, 1905) in the Faroe Islands (62°N; 7°W), an isolated group of islands in the Northern Atlantic, approximately midway between Scotland and Iceland and > 300 km from the nearest land mass (Shetland). C. longicaudata is a wingless insect belonging to the order Zygentoma. Other insects in this group include the common silverfish, Lepisma saccharina, which has previously been reported in the Faroe Islands, but it seems less common than C. longicaudata. C. longicaudata and L. saccharina are superficially similar, but there are several features that distinguish the two species, such as the much longer tail filaments in the former. Although previously unregistered in the Faroes, a citizen-science approach using social media showed that C. longicaudata is widespread and common. Both insects often live in households. Although generally harmless, they may cause damage on paper, tapestries, etc. While L. saccharina needs warm and humid conditions, C. longicaudata can stand drier conditions, and thus can be more of a problem in archives, museums and alike. [ABSTRACT FROM AUTHOR]

The stoloniferous hydrozoan Obelia geniculata commonly colonizes macroalgae such as Saccharina japonica. Each Obelia colony consists of thread-like hydrorhizae attached to the seaweed thallus. The early signaling proteins of epiphytic contamination can be identified using proteomics. To isolate these early signals, parts of the thallus proximal to the hydrozoans were separated from beneath the colony front and from healthy tissue. From the proteomic profiles of S. japonica, we detected 110 protein spots from tissue proximal to hydrozoan colonies (56 increased, 53 decreased, and 1 unchanged in expression relative to healthy tissue) and 133 spots from tissue at the colony front (67 increased, 60 decreased, and 6 unchanged in expression). Of the proteins with increased and decreased expression, SIPA1L1 and actin increased strongly only in the proximal tissues, while NEK2 kinase decreased. CIPK20 and SIPA1L2 increased markedly in both the colony-front and proximal tissues, while CaMK2N2 and GK25369 decreased in both tissues. ATPase β, ADA, kinesin, and HECT domain proteins increased only in the colony-front tissues. Among them, SIPA1L2 increased strongly in both the thallus tissues proximal to the hydrozoans and those beneath the colony front, but was not expressed in response to bryozoan infection. [ABSTRACT FROM AUTHOR]

Brown macroalgae Saccharina latissima (30–40 individuals) and Alaria esculenta (15–20 individuals) were collected from natural populations in winter in Iceland. The algal thalli were sectioned into different parts (e.g. holdfast, stipe, old frond, young frond and sori-containing frond sections) that differed in age and biological function. The work elucidated that arsenic (As) was not uniformly distributed within the two brown macroalgal species, with lower levels of total As were found in the stipe/midrib compared to other thallus parts. The arsenosugars mirrored the total arsenic in the seaweed mainly due to AsSugSO3 being the most abundant As species. However, arsenic speciation using parallel HPLC-ICP-MS/ESI-MS elucidated that the arsenic-containing lipids (AsL) had a different distribution where the arsenosugarphospholipids (AsPL) differed by approximately a factor of 4 between the sections containing the lowest and highest concentrations of AsPLs. When placing the sections in order of metabolic activity and an estimate of tissue age, there appeared to be a relationship between the activity and AsPLs, with lower levels of AsPLs in oldest parts. This is the first time such a relationship has been shown for AsLs. Hence, by applying sophisticated analytical techniques, it was possible to gain a deeper understanding of arsenolipids in seaweed. [ABSTRACT FROM AUTHOR]

The aim of this work was to assess the potential use of different dried macroalgae as food in the rearing of Paracentrotus lividus. Growth, consumption and food conversions were compared in adult sea urchins fed with fresh or dried thalli of four macroalgae species. Six experimental diets were tested: (a) fresh Palmaria palmata; (b) fresh Saccharina latissima; (c) dry P. palmata; (d) dry S. latissima; (e) dry Laminaria digitata and (f) dry Grateloupia turuturu. Linear growth rates were similar for all treatments. Specific growth rate was higher in sea urchins fed with fresh P. palmata, but no difference was found between animals fed with fresh S. latissima and those fed with dried diets. Regarding daily food consumption (DFC), sea urchins consumed the same amount of dried macroalgae as fresh but exhibited a higher food conversion efficiency (FCE) when fed with fresh P. palmata. However, this FCE was only significantly higher when compared to sea urchins fed with dry L. digitata. Dried G. turuturu is not a suitable diet due to its rapid degradation after rehydration. The results suggest that P. lividus adults can be reared on dried macroalgae thalli without detriment to their somatic growth, especially over short periods. The low cost of feeding sea urchins with this diet could help small shellfish farmers to diversify their production into echinoculture. [ABSTRACT FROM AUTHOR]

It has been ascertained in our laboratory that fucoidan, a polysaccharide contained in Saccharina japonica, shows anti-allergic activity through galectin 9 secretion in blood. A crude fucoidan fraction was chromatographically fractionated into three fractions using a Toyopearl-DEAE 650 M column in stepwise elusion with 0, 0.5 and 1.0 M NaCl in 0.05 M Tris-HCl buffer (pH 7.4). Each fraction was assessed using the passive cutaneous anaphylaxis (PCA) reaction. The non-absorbed fraction of the three fractions suppressed PCA, whereas the fractions eluted with 0.5 M and 1.0 M NaCl did not. Moreover, it was discovered that heat treatment of fucoidan at 50 °C for 10 min abolished its anti-allergic activity in the PCA reaction. Using DEAE chromatography, it was demonstrated that heat-treatment of the crude fucoidan fraction decreased the nonabsorbed fraction, which possessed the anti-allergic activity, and increased the two fractions eluted with 0.5 M and 1.0 M NaCl. This clearly revealed the importance of temperature in maintaining the anti-allergic activity of fucoidan. [ABSTRACT FROM AUTHOR]

Uptake rates of dissolved inorganic phosphorus and dissolved inorganic nitrogen under unsaturated and saturated conditions were studied in young sporo phytes of the seaweeds Saccharina latissima and Lami naria digitata (Phaeophyceae) using a "pulse-andchase" assay under fully controlled laboratory condi tions. In a subsequent second "pulse-and-chase" assay, internal storage capacity (ISC) was calculated based on VM and the parameter for photosynthetic efficiency Fv/ Fm. Sporophytes of S. latissima showed a VS of 0.80 ± 0.03 lmol • cm-2 • d-1 and a VM of 0.30 ± 0. 09 μmol • cm-2 ± d-1 for dissolved inorganic phos phate (DIP), whereas VS for DIN was 11.26 ± 0.56 μmol • cm-2 ± d-1 and VM was 3.94 ± 0.67 μmol • cm-2 ± d-1. In L. digitata, uptake kinetics for DIP and DIN were substantially lower: VS for DIP did not exceed 0.38 ± 0.03 μmol • cm-2 ± d-1 while VM for DIP was 0.22 ± 0.01 μmol • cm-2 ± d-1. VS for DIN was 3.92 ± 0.08 μmol • cm-2 ± d-1 and the VM for DIN was 1.81 ± 0.38 μmol • cm-2 ± d-1. Accord ingly, S. latissima exhibited a larger ISC for DIP (27 μmol • cm-2) than L. digitata (10 μmol • cm-2), and was able to maintain high growth rates for a longer period under limiting DIP conditions. Our standardized data add to the physiological under standing of S. latissima and L. digitata, thus helping to identify potential locations for their cultivation. This could further contribute to the development and modification of applications in a bio-based economy, for example, in evaluating the potential for bioremediation in integrated multitrophic aquacultures that produce biomass simultaneously for use in the food, feed, and energy industries. [ABSTRACT FROM AUTHOR]

Anthropogenic disturbances, including coastal habitat modification and climate change are threatening the stability of kelp beds, one of the most diverse and productive marine ecosystems. To test the effect of temperature and irradiance on the microscopic gametophyte and juvenile sporophyte stages of the rare kelp, Saccharina angustissima, from Casco Bay, Maine, USA, we carried out two sets of experiments using a temperature gradient table. The first set of experiments combined temperatures between 7-18°C with irradiance at 20, 40, and 80 µmol photons m-2 s-1. The second set combined temperatures of 3-13°C with irradiance of 10, 100, and 200 µmol photons m-2 s-1. Over two separate 4-week trials, in 2014 and again in 2015, we monitored gametogenesis, the early growth stages of the gametophytes, and early sporophyte development of this kelp. Gametophytes grew best at temperatures of 8-13°C at the lowest irradiance of 10-µmol photons m-2 s-1. Light had a significant effect on both male and female gametophyte growth only at the higher temperatures. Temperatures of 8-15°C and irradiance levels of 10-100 µmol photons m-2 s-1 were conditions for the highest sporophyte growth. Sporophyte and male gametophyte growth was reduced at both temperature extremes--the hottest and coldest temperatures tested. S. angustissima is a unique kelp species known only from a very narrow geographic region along the coast of Maine, USA. The coupling of global warming with high light intensity effects might pose stress on the early life-history stages of this kelp, although, as an intertidal species, it could also be better adapted to temperature and light extremes than its subtidal counterpart, Saccharina latissima. [ABSTRACT FROM AUTHOR]

Highlights • Acoustic target strength (TS) of one common kelp species was in a wide range for each specimen suspended under water current in a seawater tank. • Mean TS of the kelp specimens was from −58.2 dB to −41.6 dB, similar with values of fishes without swim bladder. • Positive linear correlation was found between mean TS and common logarithm weight of kelp specimens which were same size shaped and suspended. Abstract Knowledge about kelp forests spatial distribution and biomass is necessary for ecosystem conservation and sustainable use of fishery resources in coastal waters. The acoustic method has been suggested useful for estimating kelp forest thickness and spatial distribution in a large region; and is expected to be useful for biomass estimation; however, echo intensity per unit of kelp [i.e., target strength (TS)], which is a necessary parameter for estimating biomass, has not been revealed. The objective of this study was to obtain TS of the most common and commercially important kelp species, Saccharina japonica. We sampled 12 specimens of various weights in the coastal waters off Hakodate, Hokkaido, Japan, and measured the length, wet and dry weights, target strength of the blade body individually after they were folded and fixed to the same shape (0.3 × 0.3 m) using a quantitative echosounder at 120 kHz frequency in an indoor seawater tank. The TS of each specimen varied when they swayed slightly owing to the derived water currents, and a positive correlation was confirmed between the TS and length, wet weight (p < 0.05). Mean TS (TS mean) of samples were from –58.23 to –41.6 dB re 1 m2. Moreover, a positive linear correlation was found between TS mean and the logarithm weight (TSW mean ＝ 15.3 logW kg − 43.4, r2 = 0.79), which indicates the possibility for estimating biomass of kelp forests using TS mean by acoustic method, and the confirmation and accuracy increasing is expected. [ABSTRACT FROM AUTHOR]

Although mariculture activities play a significant role in coastal carbon cycling, there is a lack of research on sedimentary organic carbon (SOC) in mariculture areas. In this study, remineralization of SOC in Ailian Bay, China, and an adjacent offshore control area was analyzed by combining sediment and pore water analyses, to investigate the effects of mariculture on the preservation of SOC and the related mechanisms. The significant higher total organic carbon (TOC) to sediment surface area in abalone culture area (0.74 ± 0.10 mg·m−2) than those in control area (0.59 ± 0.06 mg·m−2) suggested the maricultural activities may increase the preservation efficiency of SOC. During anaerobic incubations, higher vertical profiles and production rates of ΣCO 2 in pore water of sediments in the abalone culture area than those in the control area indicated that maricultural activities may increase the rate of organic carbon remineralization. Furthermore, similar findings in dissolved organic carbon (DOC) suggested maricultural activities may increase the release of DOC in the sedimentary environment, which is an important supplement to the marine DOC pool. Additionally, the higher vertical concentrations and fluxes of the three major cations (i.e., K+, Ca2+, and Mg2+) coupled with the increased rate of SOC remineralization in the abalone culture area demonstrated that the maricultural activities strongly strengthened the formation of authigenic mineral. In conclusion, these findings suggested that maricultural activities play an important role in the coastal carbon cycle, significantly affecting the remineralization, preservation of SOC and the biogeochemical cycling of other important biogenic elements. • Maricultural activities promoted the preservation efficiency of sedimentary organic carbon (SOC). • Maricultural activities increased the rate of SOC remineralization. • Higher SOC deposition and remineralization rates in the mariculture area enhance the authigenic mineral formation. [ABSTRACT FROM AUTHOR]

In the present study, the kelp Saccharina latissima was cultivated at three sites in Troms, northern Norway (at 69–70oN). These sites, while close to each other geographically, were characterized by differences in exposure to waves and influence from oceanic water, and arranged in a gradient from semi-offshore through intermediate exposure to a more sheltered fjord with a stronger influence from freshwater run-off. The effect on kelp biomass and biofouling was studied from February to August in 2014. Large variation in biofouling cover was observed between sites. The site with highest exposure had the maximum kelp biomass, but also the highest cover of fouling organisms. The frond area covered by epibionts varied by a factor of 8 with lowest cover at the fjord site, intermediate cover at the inshore site and highest cover at the semi-offshore site. Species composition of the biofouling community also varied between sites, with the dominant taxa being hydroids at the most protected, and bryozoans at the most exposed site. The present study shows that both biomass yield and biofouling can vary profoundly within short geographical ranges and it thereby underlines the importance of thorough site selection for kelp cultivation in order to achieve maximum kelp biomass and minimum biofouling. It also reveals promising opportunities for kelp cultivation at higher latitudes. • High variation in biofouling cover and species between kelp cultivation sites within the same region. • The study elucidate favorable sites and areas for kelp cultivation. • High biomass yield at all sites studied indicate that cultivation of S. latissima is promising above the Arctic Circle. [ABSTRACT FROM AUTHOR]

Effects of photosynthetically active radiation (PAR) and temperature on the photosynthesis of a subarctic edible brown alga, Saccharina angustata (Laminariaceae, Laminariales), from Hokkaido, Japan, were determined using a pulse amplitude modulation (PAM)–chlorophyll fluorometer and optical dissolved oxygen sensors. Photosynthesis–PAR experiments at 8, 16, and 20 °C revealed highest net photosynthetic rates at 16 °C; whereas, the temperature effect on maximum quantum yield (Fv/Fm) showed the highest Fv/Fm at 7.0 to 8.4 °C. These temperatures corresponded to the optimum temperatures for growth of Japanese Saccharina species. The maximum gross photosynthetic rate from gross photosynthesis–temperature curve was at 21.2 °C. Though consistent with the highest seawater temperature in the study site, it is close to the limit for thermal inhibition, because Fv/Fm above 20 °C was compromised after 48–72 h of incubation. Continuous 6-h exposures to PAR of 200 µmol (low) and 1000 µmol (high) photons m−2 s−1 at 8, 16, and 20 °C caused chronic photoinhibition in the alga, with greater declines in effective quantum yields of photosystem II (ΦPSII) and failure of recovery in post-dark acclimation Fv/Fm under high PAR. This physiological performance provides a basis for understanding the persistence of S. angustata near its southern boundary in the western Pacific. [ABSTRACT FROM AUTHOR]

Ocean acidification and warming represent major environmental threats to kelp mariculture. In this study, sporophytic photochemical efficiency and gametophytic growth of Saccharina japonica and Undaria pinnatifida were evaluated under different pCO 2 levels (360, 720, and 980 ppmv) and temperatures (5, 10, 15, and 20 °C for sporophytes; 15 and 20 °C for gametophytes). Sporophytic photochemical efficiencies of both kelps were significantly greater at 720 ppmv than at 360 and 980 ppmv. Female gametophytes of both kelps grew significantly better at 360 ppmv than at higher pCO 2 levels. The growth of U. pinnatifida gametophytes was significantly greater at 20 °C than at 15 °C, while no significant difference was observed for the growth of S. japonica. These results indicate that increased pCO 2 stimulated sporophytic photochemical efficiency while inhibited gametophytic growth of these kelps, which might negatively affect their seedling cultivation. U. pinnatifida exhibited higher productivity in warmer ocean than S. japonica. • Increased pCO 2 enhanced sporophytic photosynthesis of S. japonica and U. pinnatifida. • Increased pCO 2 inhibited gametophytic growth of these two kelps. • Ocean acidification and warming represent major threats to kelp mariculture. • U. pinnatifida showed higher productivity in warmer ocean than S. japonica. [ABSTRACT FROM AUTHOR]

Saccharina , as one of the most important brown algae (Phaeophyceae) with multicellular thallus, has a very remarkable evolutionary history, and globally accounts for most of the economic marine aquaculture production worldwide. Here, we present the 580.5 million base pairs of genome sequence of Saccharina japonica , whose current assembly contains 35,725 protein-coding genes. In a comparative analysis with Ectocarpus siliculosus , the integrated virus sequence suggested the genome evolutionary footprints, which derived from their co-ancestry and experienced genomic arrangements. Furthermore, the gene expansion was found to be an important strategy for functional evolution, especially with regard to extracelluar components, stress-related genes, and vanadium-dependent haloperoxidases, and we proposed a hypothesis that gene duplication events were the main driving force for the evolution history from multicellular filamentous algae to thallus algae. The sequenced Saccharina genome paves the way for further molecular studies and is useful for genome-assisted breeding of S. japonica and other related algae species. [ABSTRACT FROM AUTHOR]

Saccharina japonica undergoes an alternating life cycle during which the diploid sporophyte generation alternates with the happloid gametophyte generation. Saccharina japonica uses the UV sex determination system to determine the sex of its haploid gametophytes. However, the sex‐determining genes and the sex‐determining mechanisms of kelp gametophytes have not been thoroughly elucidated to date. In this study, a kelp HMG‐box‐containing gene (SjHMG), which is located within the sex determination region of S. japonica, was isolated and characterized. SjHMG contained an open reading frame of 1,266 bp in length and encoded a deduced protein of 421 amino acid residues with two HMG‐box domains. Phylogenetic analysis showed the strongest relationship between SjHMG and its orthologs in brown algae. An alternatively spliced transcript (SjHMG isoform‐2) encoding a protein of 256 amino acid residues was also identified. The two isoforms were specific for male gametophytes. A real‐time quantitative PCR analysis showed significantly higher abundances of two isoforms in immature male gametophytes than in mature ones. These findings suggested that the SjHMG gene is a candidate male gametophyte determination gene of kelp. In addition, the abundance of SjHMG isoform‐2 transcripts was significantly lower than that of SjHMG isoform‐1 transcripts, and only an HMG‐box domain was conserved among species in the order Laminariales, which indicated that the gene is specifically involved in sex regulation in some species of the order Laminariales by alternative splicing. [ABSTRACT FROM AUTHOR]

Studies of postglacial range shifts could enhance our understanding of seaweed species' responses to climate change and hence facilitate the conservation of natural resources. However, the distribution dynamics and phylogeographic diversification of the commercially and ecologically important kelp Saccharina japonica in the Northwest Pacific (NWP) are still poorly surveyed. In this study, we analyzed the evolutionary history of S. japonica using two mitochondrial markers and 24 nuclear microsatellites. A STRUCTURE analysis revealed two partially isolated lineages: lineage H, which is scattered along the coast of Japan; and lineage P, which occurs along the west coast of the Japan Sea. Ecological niche modeling projections to the Last Glacial Maximum (LGM) revealed that the southern coasts of the Japan Sea and the Pacific side of the Oshima and Honshu Peninsulas provided the most suitable habitats for S. japonica, implying that these regions served as ancient refugia during the LGM. Ancient isolation in different refugia may explain the observed divergence between lineages P and H. An approximate Bayesian computation analysis indicated that the two lineages experienced post‐LGM range expansion and that postglacial secondary contact occurred in Sakhalin. Model projections into the year 2,100 predicted that S. japonica will shift northwards and lose its genetic diversity center on the Oshima Peninsula in Hokkaido and Shimokita Peninsula in Honshu. The range shifts and evolutionary history of S. japonica improve our understanding of how climate change impacted the distribution range and diversity of this species and provide useful information for the conservation of natural resources under ongoing environmental change in the NWP. [ABSTRACT FROM AUTHOR]

Abstract Macroalgae contain significant amounts of inorganic compounds (K, Na, Mg, and Ca) that cause problems during thermal processing (ash fouling or agglomeration of char and bed material). The macroalga Saccharina japonica (S.J) was demineralized with diluted acid solution to remove inorganic species before using this matter for fast pyrolysis in a bubbling fluidized-bed reactor. The effect of acid washing on the product yield and the quality of bio-oil was systematically investigated. When the pyrolysis temperature increased from 400 to 500 °C, the bio-oil yield was 39.70–45.36 wt%. The major compounds in the bio-oil were levoglucosan and di-anhydromannitol. The fractional catalytic pyrolysis of pre-treated S. japonica using HZSM-5 catalyst (calcined at 550 °C) was investigated in fluidized-bed reactor under the same conditions. Pyrolysis of the pretreated sample with catalyst resulted in 35.37–39.05 wt% liquid yield, which was lower than that from using silica sand. Using HZSM-5 catalytic pyrolysis bio-oil showed a decrease in dianhydromannitol and 2-furyl methyl ketone, and an increase in aromatic compounds such as derivatives of phenol, indole, and naphthalene. The effect of pretreatment by acid washing, and the effect of this catalyst on the pyrolysis product distribution and composition were clarified in relation to previous work. Highlights • Catalytic pyrolysis of acid-washed S. japonica was carried out in a bubbling fluidized-bed reactor. • Liquid yield showed an increase in the order raw S. japonica < 1% AW < 5% AW. • Acid-washed sample using HZSM-5 catalyst resulted in 35.37–39.05 wt% liquid yield. • The HHVs of bio-oil from catalytic pyrolysis of S. japonica sample was in the range 24.98–27.19 MJ/kg. [ABSTRACT FROM AUTHOR]

Abstract Brown algae play a dominant role in the primary productivity of coastal ecosystems and may have an efficient carbon fixation. In this work, 56 genes involved in inorganic carbon fixation were identified from the Saccharina japonica genome. Sequence structure analysis of these genes showed the existence of corresponding function domains and active amino acid sites highly conserved with other stramenopile species. The predicted subcellular localizations showed that Calvin cycle-related enzymes predominantly reside in the plastid and that putative C 4 -related enzymes are mainly distributed in the mitochondrion. We determined the transcriptional profiles and enzymatic activities of these C 4 -related enzymes in response to the KHCO 3 concentrations and light intensities. Pyruvate orthophosphate dikinase (PPDK) presented the greatest response to low HCO 3 − concentrations and high light intensity. Phosphoenolpyruvate carboxykinase (PEPCK) was up-regulated at low HCO 3 − concentrations to compensate for ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) and might be the crucial decarboxylase in this kelp. We propose that S. japonica might possess a PPDK- and PEPCK-dependent C 4 -like pathway that enables its rapid growth in natural coastal environments. Highlights • The complete set of genes in Calvin cycle and C 4 /CAM pathway exist in Saccharina japonica. • A C 4 -like pathway might exist in mitochondrion of S. japonica. • A possible PPDK- and PEPCK-dependent C4-like pathway might respond to environments and contribute to rapid growth of kelp. [ABSTRACT FROM AUTHOR]

Abstract To investigate the effects of mariculture on the sources, distribution and preservation of sedimentary organic carbon (SOC), sediments from an mariculture area in Ailian Bay, China, and a control area were analyzed for grain size composition, total organic carbon (TOC), total nitrogen (TN), carbon/nitrogen (C/N) ratio, and stable carbon and nitrogen isotopic composition (δ13C and δ15N). The sedimentary type of sediments in study area was clay silt. TOC, TN, C/N, δ13C, and δ15N ranged from 0.58 to 1.21%, 0.06–0.17%, 6.29–9.82, −23.20 to −18.50‰, and 6.17–7.38‰, respectively, and followed similar spatial patterns. TOC, TN and δ13C were higher in mariculture area than in control area. Biodeposit and kelp OC contributions greater of SOC in mariculture area than the control area (biodeposits: 20.10 ± 4.84 to 6.2 ± 1.3%; kelp: 15.3 ± 6.63 to 5.2 ± 0.84%). Overall, mariculture activities significantly influence the sources, distribution and preservation of SOC. Highlights • We use Monte Carlo simulation to discern sedimentary organic carbon (SOC) sources. • Mariculture OC sources were notably greater in culture area than the control area. • Mariculture activities increased SOC content and decreased sediment grain size. • This study indicated that mariculture activities can promote SOC preservation. [ABSTRACT FROM AUTHOR]

Biodiversity loss is driven by interacting factors operating at different spatial scales. Yet, there remains uncertainty as to how fine-scale environmental conditions mediate biological responses to broad-scale stressors. We surveyed intertidal rocky shore kelp beds situated across a local gradient of wave action and evaluated changes in kelp diversity and abundance after more than two decades of broad scale stressors, most notably the 2013–2016 heat wave. Across all sites, species were less abundant on average in 2017 and 2018 than during 1993–1995 but changes in kelp diversity were dependent on wave exposure, with wave exposed habitats remaining stable and wave sheltered habitats experiencing near complete losses of kelp diversity. In this way, wave exposed sites have acted as refugia, maintaining regional kelp diversity despite widespread local declines. Fucoids, seagrasses and two stress-tolerant kelp species (Saccharina sessilis, Egregia menziesii) did not decline as observed in other kelps, and the invasive species Sargassum muticum increased significantly at wave sheltered sites. Long-term monitoring data from a centrally-located moderate site suggest that kelp communities were negatively impacted by the recent heatwave which may have driven observed losses throughout the region. Wave-sheltered shores, which saw the largest declines, are a very common habitat type in the Northeast Pacific and may be especially sensitive to losses in kelp diversity and abundance, with potential consequences for coastal productivity. Our findings highlight the importance of fine-scale environmental heterogeneity in mediating biological responses and demonstrate how incorporating differences between habitat patches can be essential to capturing scale-dependent biodiversity loss across the landscape. [ABSTRACT FROM AUTHOR]

The processes limiting the population recovery of the kelp Saccharina latissima after recent large‐scale loss from the south coast of Norway are poorly understood. Previous investigations do, however, suggest that the impacts of biotic interactions (epibiosis and competition) and increased water turbidity are important. We investigated the depth‐related patterns of growth, epibiosis, and mortality in two sample populations of kelp, from the south and the southwest coast of Norway. The investigations were performed over a period of seven months, in a crossed translocational study, where kelps were mounted on rigs at six depths (1, 3, 6, 9, 15, and 24 m). In a second experiment, the amounts of light blocked by different epibiont layers growing on the kelp frond were investigated. While growth decreased with depth in spring and summer, the kelp grew faster at 15 m than at shallower depths in fall. Survival was low both in shallow water and below 15 m depth. Epibionts covered the kelp growing at depths from 1 to 9 m, and the laboratory study showed that the coverage may have deprived the individuals of as much as 90% of the available light. Although the depth‐related results we present apply—in the strictest sense—only to kelp translocated on rigs, we argue that the relative patterns are relevant for natural populations. Growth and survival of S. latissima is likely to be reduced by heavy loads of epibionts, while depths where epibionts are sparse may be close to the lower limit of the kelps depth distribution along the south coast of Norway. This suggests that a vertical squeeze, or narrowing of the distribution range of kelp forests may be occurring in Norway. Growth and survival of kelp is likely to be reduced by heavy loads of epibionts, while depths where epibionts are sparse may be close to the lower limit of the kelps depth distribution along the south coast of Norway. This suggests that a vertical squeeze, a narrowing of the distribution range of kelp forests may be happening in this region. These findings are important in a global context because there has been an accelerating worldwide loss of kelp forests over the past decade. [ABSTRACT FROM AUTHOR]

Abstract Pyrolysis characteristics of Saccharina japonica fermentation residue (SJFR) were systematically investigated using a thermogravimetric analyzer and a bubbling fluidized-bed reactor. Thermogravimetric (TG) characteristics of the SJFRs with increasing fermentation time (1–6 day) showed a decrease of second peak related to fermentable carbohydrates (e.g., alginate and fucoidan) and an increase of third peak related to non-fermentable carbon sources. The calculated apparent activation energy of the SJFRs ranged from 20.21 to 295.46 kJ/mol, depending on the conversion rate of 5–80%. Between 10 and 40% conversion at 225–310 °C, the apparent activation energies of the SJFRs on each conversion decreased with increasing the fermentation time (1–6 day). The bubbling fluidized-bed pyrolysis of the SJFR-4D and -6D showed the high bio-oil yield of 39.86 and 40.12 wt%, respectively at 375 °C and 4.0 × U mf , and the HHVs of the organic bio-oils were 28.95–29.34 MJ/kg. The characteristics of the bio-oil derived from SJFRs were analyzed by GC-MS and the TG-based simulated distillation. The fractions of gas oil and heavy gas oil were increased, whereas the one of gasoline decreased with increasing fermentation time. It is attributed to a decrease of the fermented carbohydrates (e.g., alginate and fucoidan) related to the gasoline fraction. Highlights • Pyrolysis behavior of SJFR samples under different anaerobic fermentation time was investigated. • Anaerobic fermentation had discriminative effects on calculated activation energy of SJFRs. • Fast pyrolysis of SJFRs was carried out in a bubbling fluidized-bed reactor. • The highest bio-oil yield of 40 wt% was obtained from SJFR-4D and -6D at 375 °C and 4.0 U mf. • The HHVs of the organic bio-oils derived from SJFR-4D and -6D were 28.95–29.34 MJ/kg. [ABSTRACT FROM AUTHOR]

The settlement of zygotes in the right place is the most critical step for the survival of young kelp sporophytes in the marine environment. The eggs of Saccharina species were connected to oogonia with two flagella projected from its basal part, and this connection lasted even after fertilisation and first cell division of the zygote. Transmission electron microscopy showed that the egg flagella have a unique structure and arrangement of basal bodies different from those of other flagella appearing throughout the life cycle. Fluorescein isothiocyanate (FITC)-lectin labelling showed that a significant modification of carbohydrate composition occurred at the surface of the zygote after fertilisation. When the eggs and zygotes were artificially detached from the oogonia at early developmental stage, most sporophytes failed to attach to a substrate and remained in two- to three-cell stage even in 15 days after fertilisation; whereas, fluorescein diacetate (FDA) staining showed that most zygotes (> 95%) detached from the oogonia were still alive and had intact cell membranes. On the contrary, zygotes connected to the oogonia developed into multicellular blades composed of hundreds of cells 15 days after fertilisation with elongated rhizoids extending from the basal portion of the blade. These results suggest that the egg flagella ensure close contact and orientation of the zygote to the oogonial wall, and later binding between zygote and oogonium occurs by means of glycoconjugates. These consecutive events appear to be essential for the survival and development of young sporophytes in Saccharina species. [ABSTRACT FROM AUTHOR]

Kelp are main iodine accumulators in the ocean, and their growth and photosynthesis are likely to benefit from elevated seawater CO2 levels due to ocean acidification. However, there are currently no data on the effects of ocean acidification on iodine metabolism in kelp. As key primary producers in coastal ecosystems worldwide, any change in their iodine metabolism caused by climate change will potentially have important consequences for global geochemical cycles of iodine, including iodine levels of coastal food webs that underpin the nutrition of billions of humans around the world. Here, we found that elevated pCO2 enhanced growth and increased iodine accumulation not only in the model kelp Saccharina japonica using both short‐term laboratory experiment and long‐term in situ mesocosms, but also in several other edible and ecologically significant seaweeds using long‐term in situ mesocosms. Transcriptomic and proteomic analysis of S. japonica revealed that most vanadium‐dependent haloperoxidase genes involved in iodine efflux during oxidative stress are down‐regulated under increasing pCO2, suggesting that ocean acidification alleviates oxidative stress in kelp, which might contribute to their enhanced growth. When consumed by abalone (Haliotis discus), elevated iodine concentrations in S. japonica caused increased iodine accumulation in abalone, accompanied by reduced synthesis of thyroid hormones. Thus, our results suggest that kelp will benefit from ocean acidification by a reduction in environmental stress however; iodine levels, in kelp‐based coastal food webs will increase, with potential impacts on biogeochemical cycles of iodine in coastal ecosystems. Kelp are main iodine accumulators in the ocean, and their growth and photosynthesis are likely to benefit from elevated seawater CO2 levels due to ocean acidification. However, there are currently no data on the effects of ocean acidification on iodine metabolism in kelp. Here, we found that ocean acidification increases iodine accumulation in kelp‐based coastal food webs. There is a potential risk of iodine overconsumption in consumers of kelps if pCO-2 increases as projected for the coming decades. [ABSTRACT FROM AUTHOR]

Background: There has been a rapid increase in the number of seaweed farms in the Western world, and it is crucial for these companies and their customers to have standardized methods for quality assessment and optimization. The aim of this study was to adapt known methods for food‐quality determination for the analysis of seaweed quality, including color, texture, and microbiology, and to discuss optimal heat treatments for the popular macroalgae Saccharina latissima and Alaria esculenta. Results: The development of an attractive, green color during heating was highly specific to species, freezing history, and part of the thallus. Resilience and thermostability were also species dependent. Low microbial numbers (1–3 log cfu/g) for total aerobic count, psychrotrophic bacteria, and spore‐forming bacteria were found, but Bacillus spp. were isolated. No enterococci, coliforms, pathogenic vibrios, or Listeria monocytogenes were detected. Conclusion: The methods employed were able to describe clearly the physical and microbial qualities of A. esculenta and S. latissima, and quality changes during processing. Based on the results, optimal cooking for a minimum of 15 min at 95 °C was suggested for S. latissima. Fresh and frozen A. esculenta showed the greenest color after heating for 5–9 s at a high temperature (> 85 °C). If a higher heat load is needed to achieve safe and stable food products, using fresh and not frozen A. esculenta is highly recommended, as fresh specimens remain green even after 15 min at 95 °C. © 2018 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

The sugar kelp Saccharina latissima is cultivated in Europe for food, feed and ultimately the production of chemical commodities and bioenergy. Being cultivated in the open sea, S. latissima is exposed to potentially harmful organisms, such as Laminarionema elsbetiae, a filamentous brown algal endophyte with a very high prevalence in wild populations of European S. latissima. As it was shown previously that S. latissima sporophytes get infected by L. elsbetiae very early in their life, seeding the spores on collectors and keeping them under controlled conditions during the critical time of a possible infection with filamentous endophytes could be advantageous over direct seeding techniques, where the ropes are deployed within days after seeding. We used a qPCR-assay to assess the prevalence of the endophyte L. elsbetiae in S. latissima cultivated during winter in Northern Brittany, comparing individuals from direct-seeded ropes and collector-seeded lines that were kept in laboratory conditions for different time spans. No DNA of the endophyte was detected in the samples, suggesting that either the kelps were not infected or the amount of endophytic filaments were below the detection rate of the qPCR assay. Furthermore, L. elsbetiae could not be detected in the seawater surrounding the kelp farm, indicating that L. elsbetiae is not fertile or disperses at a very small scale in Northern Brittany during the deployment time of young kelps. Our results suggest that infections of cultivated S. latissima with the endophyte L. elsbetiae might be a minor problem in kelp farms in Northern Brittany if the seeding production is kept under controlled conditions without external contamination. [ABSTRACT FROM AUTHOR]

Thermophysical properties such as thermal conductivity (k), bulk density (ρ), specific heat (C), and thermal diffusivity (D) are crucial for simulating dynamic thermal processes such as drying and temperature-controlled storage. In this study, the effects of product temperatures (T) and moisture contents (MC) on different thermophysical properties of kelp were studied. The thermal conductivity and thermal diffusivity of the samples were measured using a KD2 Pro dual-needle sensor for a temperature range of 30–70° C and moisture content varying from 6 to 90 g (100 g sample)−1. The particle density and the bulk densities of the samples were estimated using a pycnometer with toluene as a working liquid. The k, C, and D values were fitted with a regression equation considering the individual and interaction factors (MC × T). Moisture content and temperature of the sample have significant effects (p < 0.05) on its thermophysical properties. The thermophysical properties calculated using the Choi and Okos' model based on the mass fraction of individual components present in sugar kelp and temperature were significantly (p < 0.05) different as compared to the experimental values. An artificial neural network (ANN) model evaluated eight different configurations of neurons in a single hidden layer for 180 data. The prediction performances of the ANN were evaluated in terms of mean absolute error (MAE), mean relative error (MRE), standard error (SE) and coefficient of determination in MATLAB. Overall, the ANN model's performance was superior to the Choi and Okos empirical model in predicting the thermophysical properties with a relatively high coefficient of determination and low MAE, MRE, and SE. [ABSTRACT FROM AUTHOR]