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Sea lettuce, or Ulva spp., dominates global algal biomass and significantly contributes to “green tides.”, representing a sustainable source for biomaterials. This study explores an innovative ultrasound-enzyme assisted extraction method with the novel Cellic® CTEC3 enzyme cocktail, applied for the first time in Ulva spp. succesfully enhancing ulvan release and extraction efficiency. Various processing methods, including ultrafiltration and dialysis, were employed to achieve higher ulvan purity. Dialyzation of ulvan resulted in a more purified product with a carbohydrate content up to 55.34 %, a sulfate content up to 21 %, and no glucose contamination. Liquid extracts were fractionated through ultrafiltration, with a 3 kDa MWCO yielding 93.51 % ulvan precipitate, representing 50.28 % of the total extractable ulvan. Sequential ultrafiltration concentrated ulvans but only partially modified their molecular weight distribution. Depolymerization using microwave and H2O2 shifted ulvans towards lower molecular weights, reducing high molecular weight residue. HPSEC confirmed pH-dependent aggregation behavior, with all isolated ulvans having molecular weights above 786 kDa. Hydrolysis methods were compared, with 2-hour 1 M TFA hydrolysis at 121 °C providing the best monosaccharide profile of ulvan. FTIR and NMR analyses showed preservation of sulfation. Rheology indicated biopolymeric behavior and stable gel formation. Ulvans demonstrated nutraceutical potential, being suitable for a low Na+ and high K+ diet, with a Na+:K+ ratio as low as 0.14, and were rich in Mg2+.

Growing environmental concerns and a desire for health-conscious food choices are driving consumer demand for sustainable and ethical food sources. Ulva seaweed (genus Ulva, Phylum Chlorophyta) emerges as a promising candidate due to its rich nutritional profile, which includes proteins, carbohydrates, lipids, and antioxidants. This review explores the immense potential of Ulva seaweed as an eco-friendly and nutritious food source with promising applications in the food industry. Focusing on its viability as a sustainable solution, we explore Ulva's biochemical composition, potential health benefits beyond established nutrition, and its role in food product development. While challenges remain, including variability in nutrient content, efficient harvesting and processing methods, and ensuring food safety, Ulva's minimal environmental impact and high nutritional value make it a compelling alternative. Furthermore, recent studies reveal Ulva's unique compounds possess impressive health benefits, including antioxidant, antimicrobial, and antiviral properties, which offer exciting possibilities for human health. Furthermore, the integration of Ulva cultivation in Integrated Multitrophic Aquaculture (IMTA) systems demonstrates its feasibility for large-scale production while enhancing environmental sustainability. Additionally, recent studies reveal the impressive health benefits of seaweed's unique compounds, with properties like antioxidant, antimicrobial, and antiviral effects, offering exciting possibilities for human health. This review provides valuable insights for researchers exploring Ulva seaweed, a readily available natural resource that holds the potential to address global malnutrition without compromising the food ecosystem's health.

This study exploits the potential of satellite remote sensing reflectance spectra (Rrs(λ)) for detecting ocean surface algal blooms. Three types of floating surface algae are examined: Sargassum, Ulva, and Trichodesmium. The satellite images are processed with a shortwave infrared (SWIR)-based atmospheric correction processor from the Visible Infrared Imaging Radiometer Suite (VIIRS). We calculate the red-edge reflectance anomaly from the Rrs(λ) data to delineate the notable spectral difference at 671 and 862 nm. The new data have generated floating algal maps comparable with historical methods relying on Rayleigh-corrected reflectance data. The Rrs(λ) spectra are found to have high quality scores over Sargassum and Trichodesmium waters, suggesting less uncertainty from atmospheric correction. With problems to be addressed, this preliminary study finds it promising to use the VIIRS reflectance products for floating algae detection and mapping. Continuous efforts are highly recommended as the new data and approach can not only facilitate a retrospective analysis over global oceans but also benefit a greater application to next-generation hyperspectral satellites.

Green macroalgae (Ulva sp.) and red macroalgae (Solieria sp.) were processed to produce eight different crude extracts enriched for marine sulphated polysaccharides (MSP). While all extracts showed direct anti-bacterial effects to some degree, two red algal extracts, in particular, showed high activity against several pathogenic fish bacteria in vitro. Stimulation of head kidney leukocytes (HKLs) in vitro with MSP-rich extracts showed fish species specific differences. In Nile tilapia, HKLs showed a dose dependent production of reactive oxygen species (ROS) following stimulation with Ulva-derived extracts, while stimulation with Solieria-derived extracts did not induce ROS production. In rainbow trout, HKLs showed relatively high reactive ROS potential and Solieria-derived extracts could induce significant ROS production, albeit without a clear dose dependent response. Gene expression of in vitro stimulated HKLs showed a clear induction of most cytokines measured (il1b, il10, tnfa, ifny, il12p40), with differences between species. Although cytokine gene expressions were more prominently induced in HKLs of Nile tilapia than in HKLs of rainbow trout, immunomodulatory effects of both, Ulva- and Solieria-derived extracts, always appeared evident. It is likely that HKLs have the ability to sense presence of MSP, via so far uncharacterized pattern recognition receptors which have known downstream signalling pathways. Expression of some genes associated with Toll-like Receptor (TLR) signalling, such as irak1 and especially the expression of genes associated with C-type Lectin Receptor (CLR) signalling, such as card9 and bcl10 were evident following stimulation with MSP-rich extracts. Possibly, immunomodulatory effects of MSP could be regulated by at least a CLR-mediated signalling, at least in Nile tilapia, for which most if not all red algae and green algae extracts induced changes in gene expression of card9 and bcl10. Overall, induction of ROS production and gene expression read-outs suggest immunomodulatory effects of MSP-rich extracts derived from green algae (Ulva sp.) and red algae (Solieria sp.), at least in vitro. The observed effects suggest clear fish species specific differences between the effects of MSP-rich extracts.

ABSTRACTMacroalgal biomass production models that capture nutrient dynamics, temperature, light and salinity are important for the design and operation of large-scale farms. The goal of this study is to understand how the nitrogen fertilizing regime, relating to dose (µM N week−1), amplitude (µM N) and duration (hours) of fertilization, affects the dynamics of nitrogen content and biomass production of Ulva sp. We hypothesize that the nitrogen fertilizing regime controls the Ulva Nitrogen Use Efficiency (NUE), defined here as the fraction of fertilizer nitrogen that is utilized and allocated to yield N, and, accordingly, also nitrogen assimilation in the biomass and the growth rate. We test this hypothesis by measuring internal nitrogen and biomass weight and by calculating NUE under various fertilization regimes in controlled photobioreactors. Based on these experimental data, we developed a biomass productivity model that predicts nitrogen and biomass dynamics temporally over three weeks of cultivation. This study highlights efficient fertilizing regimes and enables the development of a comprehensive understanding of the dynamic relationship between external N, internal N and biomass production of Ulva sp. under varying external N levels, which is important for real-world agricultural applications. This study provides a better understanding of the external N-internal N-biomass triangle leading to an improved dynamic cultivation model, enabling better control of nutrient application and biomass production in macroalgal farming for a sustainable marine bioeconomy.

Green tides macroalga, Ultra, has negative effects on the ecology, tourism, seawater intake, etc. No green tides were reported in Qinzhou Bay, a nuclear power plant taking seawater for cooling. In this paper, spatial and temporal characteristics of biomass of green tides macroalga in Qinzhou Bay were assessed during December 2020 to February 2022. The results showed the green tides occured from December to February next year, were similar to Xiamen in low latitudes, and different from the sea in middle latitudes. The maximum of the wet weight of green tides macroalgal occured in January. Green tides disappeared in March, with the rising of the sea surface temperature. The key factor of green tides was temperature. Green tides macroalgal was native species, including Ulva clathrate, Ulva intestinalis, and Ulva linza according to growth sequence. No drifting macroalgal from outside was found. For green tides macroalgal, nutrients were positive, human activities were negative. Green tides macroalgal were not found in beach culture area. Green tides posed risk to the water-cooling system of nuclear power plant which took water from Qinzhou Bay.

In this study, headspace solid phase microextraction (HS-SPME) coupled with gas chromatography-mass spectrometry (GC-MS) was used to determine the volatile flavor compounds of sundried Ulva spp., including U. prolifera collected from Xiamen (sample X), U. linza collected from Yantai (sample Y) and U. clathrata collected from Ningbo (sample N). A total of 61 volatile compounds including 19 aldehydes, 9 ketones, 6 alcohols, 8 acids, 3 esters, 2 sulfur compounds, and 14 other compounds were detected. The content of sulfur compounds was reaching 40.39%~58.09%. Meanwhile, relative odor activity value (ROAV) and sensory evaluation were employed to identify the aroma active components of Ulva spp.. The results revealed that dimethyl sulfide (onion, garlic, sulfur) and β-ionone (violet, floral) were the key aroma active components of dried Ulva spp.. Besides, dimethyl sulfoxide, 4-methyl-3-penten-2-one, benzaldehyde and 5,6,7,7a-tetrahydro-4,4,7a-trimethyl-2(4H)-benzofuranone were the important aroma active components of three Ulva spp.. Among three tested Ulva spp., sample N contained the most abundant volatile compounds especially in aldehydes and ketones, and (E)-2-butenal, (E)-2-octenal, (E)-2,6-nondialdehyde and 1-octene-3-ol were considered as the key volatile substances. Aroma active compounds including 4-ethylbenzaldehyde, (5Z)-1,5-octadiene-3-ol, and 5-methyl furfural were only detected in sample Y, which might correlate to its unique green and fruity flavor. For sample X, the sensory analysis reulst revealed significant fishy smell (P

In this study, we investigated the physiological and biochemical responses of Ulva species to variation in nutrient availability. Sampling was conducted at two sites on Jeju Island, Korea, namely, Handong, which is close to seven intensive land-based fish farms, and Hado, which has no apparent nearby nutrient sources. We examined the water column nutrient concentrations, nitrate reductase (NR) activity, nitrate uptake efficiency, tissue C, N, and P content, and stable isotope ratios of Ulva species. Water column NH4+, NO3− + NO2−, and PO43− concentrations were significantly higher at Handong than at Hado. NR activity and tissue N content of Ulva species were significantly higher at Handong than at Hado. Notably, nitrate uptake efficiency was inversely proportional to NR activity and tissue N content. The physiological and biochemical responses of Ulva species were closely related to dissolved inorganic nitrogen, which stimulates Ulva species to regulate growth. Additionally, the δ15N values of Ulva tissues at both sites were within the previously reported range for fresh groundwater. Therefore, the main nitrogen source for Ulva growth may be submerged groundwater with high nutrient concentrations. Our results provide invaluable information for estimating dissolved inorganic nitrogen levels in water, which may facilitate development of management policies.

Ulva rigida green macroalgae contain a variety of polysaccharides. A recent study investigated the optimum concentration and yield of polysaccharide extraction from oven-dried U. rigida biomass using a water-soluble polysaccharide extraction method that adhered to safety standards. This study utilised complete factorial experiments to examine the effects of varying factors on polysaccharide extraction. Results showed a positive correlation between increased levels of all factors and higher polysaccharide extraction yield. This study also found that the main factors and their interaction had a significant impact on the extracted polysaccharides from U. rigida. The highest polysaccharide content and yield were 9.5 mg/mL and 189 mg/g, respectively. Water-soluble polysaccharides demonstrated the presence of reducing sugar (8 mg/g), phenolics (0.69 mg/g) and flavonoids (1.42 mg/g) and exhibited antioxidant properties. Results revealed that freeze-dried polysaccharide powders were primarily composed of the monosaccharide rhamnose. Preliminary results on the effect of these powders on probiotics demonstrated that supplementation of polysaccharides from U. rigida promoted viable Lactobacillus rhamnosus ATCC 53103 growth during cultivation. This discovery has the potential to revolutionise the human food industry and promote the development of functional ingredients for novel and future food products, with numerous applications in the nutraceutical and pharmaceutical industries.

The medicinal benefits of green seaweed Ulva have been documented in traditional Chinese medicine literatures. Sulfated polysaccharides found in Ulva are recognized as the primary bioactive compounds, known for their immunomodulatory and anti-inflammatory properties. Despite this knowledge, the available information regarding anti-allergic activities of Ulva remains limited. The objective of this study was to prepare and characterize Ulva-derived polysaccharides (UP), oligosaccharides (UO), and residues (UR), followed by assessing their potential in improving allergic enteritis and gut microbiota in a murine model of ovalbumin (OVA)-induced food allergy. The immunomodulatory activities of UP, UO, and UR were evaluated by measuring the expression of serum antibodies, splenic cytokines and duodenal transcript factors of T cell subsets. The impact of UP, UO, and UR on enteric microbiota was explored by 16S rRNA gene sequencing analysis of fresh fecal samples from treated mice. Oral treatment of UP, UO, and UR noticeably attenuated allergic diarrhea and enteritis. Additionally, Ulva samples treatment decreased serum levels of IgG1 and OVA-specific IgE while increased the level of OVA-specific IgG. Enhanced production of IFN-γ and reduced production of IL-4 and IL-10 by splenocytes were observed in the treated mice. In parallel, Ulva samples treatment led to a decreased number of GATA3+ cells and an increased number of T-bet+ cells in the duodenum. However, the population of Foxp3+ cells was not significantly altered. Moreover, treatment of Ulva samples improved enteric dysbiosis evidenced by an increased abundance of Lactobacillus murinus, L. johnsonii, and L. reuteri, and a decreased abundance of Kineothrix alysoides, Lacrimispora saccharolytica, L. aerotolerans, and Erysipelotrichaceae in feces. In conclusion, UP, UO, and UR, which could modulate the Th1/Th2 immune balance, alleviate allergic enteritis and improve enteric dysbiosis in varying degrees, are potential to be developed into therapeutic agents for food allergy.

ABSTRACT Marine macroalgae (seaweeds) are important primary producers and foundation species in coastal ecosystems around the world. Seaweeds currently contribute to an estimated 51% of the global mariculture production, with a long-term growth rate of 6% per year, and an estimated market value of more than US$11.3 billion. Viral infections could have a substantial impact on the ecology and aquaculture of seaweeds, but surprisingly little is known about virus diversity in macroalgal hosts. Using metagenomic sequencing, we characterized viral communities associated with healthy and bleached specimens of the commercially important green seaweed Ulva. We identified 20 putative new and divergent viruses, of which the majority belonged to the Circular Rep-Encoding Single-Stranded (CRESS) DNA viruses [single-stranded (ss)DNA genomes], Durnavirales [double-stranded (ds)RNA], and Picornavirales (ssRNA). Other newly identified RNA viruses were related to the Ghabrivirales, the Mitoviridae, and the Tombusviridae. Bleached Ulva samples contained particularly high viral read numbers. While reads matching assembled CRESS DNA viruses and picorna-like viruses were nearly absent from the healthy Ulva samples (confirmed by qPCR), they were very abundant in the bleached specimens. Therefore, bleaching in Ulva could be caused by one or a combination of the identified viruses but may also be the result of another causative agent or abiotic stress, with the viruses simply proliferating in already unhealthy seaweed tissue. This study highlights how little we know about the diversity and ecology of seaweed viruses, especially in relation to the health and diseases of the algal host, and emphasizes the need to better characterize the algal virosphere. IMPORTANCE Green seaweeds of the genus Ulva are considered a model system to study microbial interactions with the algal host. Remarkably little is known, however, about viral communities associated with green seaweeds, especially in relation to the health of the host. In this study, we characterized the viral communities associated with healthy and bleached Ulva. Our findings revealed the presence of 20 putative novel viruses associated with Ulva, encompassing both DNA and RNA viruses. The majority of these viruses were found to be especially abundant in bleached Ulva specimens. This is the first step toward understanding the role of viruses in the ecology and aquaculture of this green seaweed.

The genus Ulva L. (Sea lettuce), one of the most valuable marine macroalgae, is found in shallow coastal areas and in brackish and fresh water around the world. Ulva species have nutritional and medicinal values in addition to other applications, and contain various compounds such as lipids, proteins and carotenoids. These species have high phenotypic plasticity and varied in response to different environmental conditions. In this study, 38 populations of 10 species of Ulva from the coastal areas of the Persian Gulf and Oman Sea, from different areas of Bushehr, Hormozgan and Sistan and Baluchestan provinces, were studied and identified on the basis of morphological and anatomical traits. Different populations showed variations in characteristics such as height, shape and color of thallus, number of pyrenoids and cell dimensions. Metabolites such as total protein, total oil, chlorophyll a, b and carotenoids contents were measured and compared among the different populations. The results should that the percentage of protein was highest in U. prolifera of Shif Island from Bushehr province as compared with the Ulva species studied, with about 26.5% of dry weight, and the percentage of total oil was lowest in U. flexuosa of Hakhamanesh region from Hormozgan province as compared with the species studied, with about 4.8% of dry weight. These results show that different environmental conditions affect the morphological and anatomical structure of species and the content of their metabolites. Due to the high-protein and low-calorie content of the Ulva genus and the importance of finding new and sustainable resources for food and pharmaceutical industries, the species of this genus have valuable potentials.

Crude and α- and β-cellulose yields were estimated in six macroalgal species belonging to various groups growing in the Mediterranean coast, Egypt. The extracted cellulose yield varied between 11.70% dry weight (DW) for Colpomenia sinuosa and 1.38% DW for Jania rubens. The results revealed that α-cellulose represented the major proportion “43%” to “74%” of cellulose, while β–cellulose represented the minor proportion “2.3%” to “12%”. Cellulose nanofibers (CNFs) were prepared from crude cellulose via acid hydrolysis, and the yield was calculated as “47.74%” to “9.13%”. The seaweed cellulose and CNFs of the maximum-producing species were morphologically characterized via scanning electron microscopy (SEM). The shapes of the extracted cellulose ranged from filaments and plates to web-like structures according to the seaweed species and cellulose fractions. The CNFs exhibited nanosphere shapes, with the average size ranging from 14.94 to 30.82 nm. Chemical analysis of the prepared cellulose performed via Fourier-transform infrared spectrometry (FTIR) demonstrated the similarity between crude and α- and β-cellulose. The CNFs were investigated via Ultraviolet–visible spectroscopy and surface plasmon resonance (SPR) bands, which confirmed the spherical shape of the prepared CNFs. In conclusion, the selected seaweeds can be used as a renewable source of dietary fibers and CNFs with economic applications. Further studies are required to screen numerous species of seaweeds for large-scale production of cellulose.

Ulva is a commercially important marine macroalga. It hosts both epiphytes and endophytes. The latter are assumed to protect Ulva through secondary metabolites. Previously, we demonstrated bioactive endophytes from macroalgae with great potential to control diseases of aquaculture. In this study, we introduced a bioactive bacterial endophyte back into its original host (Ulva sp.) and demonstrated its survival over time in fresh and freeze-dried Ulva sp. We visualized the endophyte’s location and survival in the seaweed using a Green Fluorescent Protein (GFP) reporter gene. The isolate colonized the intercellular space and survived for at least 5 months in fresh, and 12 months in freeze-dried algae, while maintaining its bioactivity against the aquaculture pathogen Streptococcus iniae. We studied the influence of the endophyte on the bacterial community in the Ulva sp. We found that once introduced, the endophyte significantly changed algal microbiota diversity and abundance. Two of Ulva’s associated bacterial species were quantified over time, suggesting different trends in absolute abundance of these bacteria between treatments. To the best of our knowledge, this is the first report of the successful introduction of an endophytic microorganism into macroalgal tissue. These findings may be useful in applied research for the potential management of aquaculture diseases.

Marine macroalgae (seaweeds) are important primary global producers, with a wide distribution in oceans around the world from polar to tropical regions. Most of these species are exposed to variable environmental conditions, such as abiotic (e.g., light irradiance, temperature variations, nutrient availability, salinity levels) and biotic factors (e.g., grazing and pathogen exposure). As a result, macroalgae developed numerous important strategies to increase their adaptability, including synthesizing secondary metabolites, which have promising biotechnological applications, such as UV-absorbing Mycosporine-Like Amino Acid (MAAs). MAAs are small, water-soluble, UV-absorbing compounds that are commonly found in many marine organisms and are characterized by promising antioxidative, anti-inflammatory and photoprotective properties. However, the widespread use of MAAs by humans is often restricted by their limited bioavailability, limited success in heterologous expression systems, and low quantities recovered from the natural environment. In contrast, bloom-forming macroalgal species from all three major macroalgal clades (Chlorophyta, Phaeophyceae, and Rhodophyta) occasionally form algal blooms, resulting in a rapid increase in algal abundance and high biomass production. This review focuses on the bloom-forming species capable of producing pharmacologically important compounds, including MAAs, and the application of proteomics in facilitating macroalgal use in overcoming current environmental and biotechnological challenges.

Abstract Background The molecular mechanism underlying sexual reproduction in land plants is well understood in model plants and is a target for crop improvement. However, unlike land plants, the genetic basis involved in triggering reproduction and gamete formation remains elusive in most seaweeds, which are increasingly viewed as an alternative source of functional food and feedstock for energy applications. Results Gametogenesis of Ulva mutabilis, a model organism for green seaweeds, was studied. We analyzed transcriptome dynamics at different time points during gametogenesis following induction of reproduction by fragmentation and removal of sporulation inhibitors. Analyses demonstrated that 45% of the genes in the genome were differentially expressed during gametogenesis. We identified several transcription factors that potentially play a key role in the early gametogenesis of Ulva given the function of their homologs in higher plants and microalgae. In particular, the detailed expression pattern of an evolutionarily conserved transcription factor containing an RWP-RK domain suggested a key role during Ulva gametogenesis. Conclusions Transcriptomic analyses of gametogenesis in the green seaweed Ulva highlight the importance of a conserved RWP-RK transcription factor in the induction of sexual reproduction. The identification of putative master regulators of gametogenesis provides a starting point for further functional characterization.

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.

Symbiosis is a dominant form of life that has been observed numerous times in marine ecosystems. For example, macroalgae coexist with bacteria that produce factors that promote algal growth and morphogenesis. The green macroalga Ulva mutabilis (Chlorophyta) develops into a callus-like phenotype in the absence of its essential bacterial symbionts Roseovarius sp. MS2 and Maribacter sp. MS6. Spatially resolved studies are required to understand symbiont interactions at the microscale level. Therefore, we used mass spectrometry profiling and imaging techniques with high spatial resolution and sensitivity to gain a new perspective on the mutualistic interactions between bacteria and macroalgae. Using atmospheric pressure scanning microprobe matrix-assisted laser desorption/ionisation high-resolution mass spectrometry (AP-SMALDI-HRMS), low-molecular-weight polar compounds were identified by comparative metabolomics in the chemosphere of Ulva. Choline (2-hydroxy-N,N,N-trimethylethan-1-aminium) was only determined in the alga grown under axenic conditions, whereas ectoine (1,4,5,6-tetrahydro-2-methyl-4-pyrimidinecarboxylic acid) was found in bacterial presence. Ectoine was used as a metabolic marker for localisation studies of Roseovarius sp. within the tripartite community because it was produced exclusively by these bacteria. By combining confocal laser scanning microscopy (cLSM) and AP-SMALDI-HRMS, we proved that Roseovarius sp. MS2 settled mainly in the rhizoidal zone (holdfast) of U. mutabilis. Our findings provide the fundament to decipher bacterial symbioses with multicellular hosts in aquatic ecosystems in an ecologically relevant context. As a versatile tool for microbiome research, the combined AP-SMALDI and cLSM imaging analysis with a resolution to level of a single bacterial cell can be easily applied to other microbial consortia and their hosts. The novelty of this contribution is the use of an in situ setup designed to avoid all types of external contamination and interferences while resolving spatial distributions of metabolites and identifying specific symbiotic bacteria.

The inclusion of macroalgae in the diets of farmed fish offers the opportunity for an added-value dietary ingredient to the nutraceutical feed. The composition of algae varies greatly among species. Several Ulva species have been considered in aquafeed formulations for different farmed fish, and Ulva ohnoi is being applied recently. However, the effects of seaweed dietary inclusion on the host must be evaluated. Considering the important role of the host intestinal microbiota, the potential effects of U. ohnoi dietary inclusion need to be studied. In this study, the characterization of the intestinal microbiome of Solea senegalensis, a flatfish with high potential for aquaculture in South Europe, receiving U. ohnoi (5%)-supplemented diet for 90 days has been carried out. In addition, the functional profiles of bacterial communities have been determined by using PICRUSt, a computational approach to predict the functional composition of a metagenome by using marker gene data and a database of reference genomes. The results show that long-term dietary administration of U. ohnoi (5%)-supplemented feed modulates S. senegalensis intestinal microbiota, especially in the posterior intestinal section. Increased relative abundance of Vibrio jointly with decreased Stenotrophomonas genus has been detected in fish receiving Ulva diet compared to control-fed fish. The influence of the diet on the intestinal functionality of S. senegalensis has been studied for the first time. Changes in bacterial composition were accompanied by differences in predicted microbiota functionality. Increased abundance of predicted genes involved in xenobiotic biodegradation and metabolism were observed in the microbiota when U. ohnoi diet was used. On the contrary, predicted percentages of genes associated to penicillin and cephalosporin biosynthesis as well as beta-lactam resistance were reduced after feeding with Ulva diet.

Ulva green macroalgae or sea lettuce are rich sources of protein with nutritional benefits that promote health as a future plant-based functional ingredient in the food industry. Alkaline pretreatment improved ultrasonic-assisted protein extraction from Ulva rigida biomass. Parameters affecting ultrasonic-assisted extraction of protein were type of solvent, biomass-solvent ratio, biomass preparation and extraction cycle. In vitro digestibility was evaluated from oven- and freeze-dried biomass. Results showed highest concentration and extraction yield of protein from U. rigida using alkaline rather than acid and distilled water. A high biomass–solvent ratio at 1:10 or 0.1 g mL−1 increased protein extraction. Higher alkaline concentration increased protein extraction. Highest protein extractability was 8.5% dry matter from freeze-dried U. rigida biomass, with highest protein extraction and antioxidant activity from extraction of U. rigida macroalgae at high alkaline concentrations. U. rigida macroalgae oven-dried biomass presented suitable human digestibility. Efficient pretreatment of U. rigida maximized protein hydrolysate and bioactive peptide production for wide-ranging applications.

Sea lettuce (Ulva spp.), with its worldwide distribution and remarkable ability to grow rapidly under various conditions, represents an important natural resource that is still under-exploited. Its biomass can be used for a wide range of applications in the food/feed, pharmaceutical, nutraceutical, biofuel, and bioremediation industries. However, knowledge of the factors affecting Ulva biomass yield and composition is far from complete. Indeed, the respective contributions of the microbiome, natural genetic variation in Ulva species, environmental conditions and importantly, the interactions between these three factors on the Ulva biomass, have been only partially elucidated. Further investigation is important for the implementation of large-scale Ulva aquaculture, which requires stable and controlled biomass composition and yields. In this review, we document Ulva biomass composition, describe the uses of Ulva biomass and we propose different strategies for developing a sustainable and profitable Ulva aquaculture industry.

Ulva meridionalis is one of the causal green macroalgae for green tides in Japan and exists in coastal areas of China. In the present study, complete chloroplast (cp) genome sequence of Ulva meridionalis was reported, and the total length of this species was 88,653 bp (GenBank accession number MN889540). The overall base composition of cp genome was A (37.1%), T (39.0%), C (11.4%) and G (12.5%), similar to other Ulva macroalgae within cp genome, and the percentage of A + T (76.1%) was higher than C + G (23.9%). U. meridionalis cp genome encoded 113 genes, including 80 protein-coding genes, 27 transfer RNAs genes and 6 ribosomal RNAs genes. The maximum likelihood phylogenetic analysis shows that Ulva linza is the closest sister species of U. meridionalis.

Opportunistic macroalgal blooms have been used for the assessment of the ecological status of coastal and estuarine areas in Europe. The use of earth observation (EO) data sets to map green algal cover based on a Normalized Difference Vegetation Index (NDVI) was explored. Scenes from Sentinel-2A/B, Landsat-5, and Landsat-8 missions were processed for eight different Irish estuaries of moderate, poor, and bad ecological status using European Union Water Framework Directive (WFD) classification for transitional water bodies. Images acquired during low-tide conditions from 2010 to 2018 within 18 days of field surveys were considered. The estimates of percentage coverage obtained from different EO data sources and field surveys were significantly correlated (R2 = 0.94) with Cohen’s kappa coefficient of 0.69 ± 0.13. The results showed that the NDVI technique could be successfully applied to map the coverage of the blooms and to monitor estuarine areas in conjunction with other monitoring activities that involve field sampling and surveys. The combination of wide-spread cloud-coverage and high-tide conditions provided additional constraints during the image selection. The findings showed that both Sentinel-2 and Landsat scenes could be utilized to estimate bloom coverage. Moreover, Landsat, because of its legacy program, can be utilized to reconstruct the blooms using historical archival data. Considering the importance of biomass for understanding the severity of algal accumulations, an artificial neural networks (ANN) model was trained using the in situ historical biomass samples and the combination of radar backscatter (Sentinel-1) and optical reflectance in the visible and near-infrared (NIR) regions (Sentinel-2) to predict the biomass quantity. The ANN model based on multispectral imagery was suitable to estimate biomass quantity (R2 = 0.74). The model performance could be improved with the addition of more training samples. The developed methodology can be applied in other areas experiencing macroalgal blooms in a simple, cost-effective, and efficient way. The study has demonstrated that both the NDVI-based technique to map spatial coverage of macroalgal blooms and the ANN-based model to compute biomass have the potential to become an effective complementary tool for monitoring macroalgal blooms where the existing monitoring efforts can leverage the benefits of EO data sets.

The green algae, Ulva spp., have been causing environmental problems worldwide, e.g., green tides and biofoulings. Green tides resulted from bloom floating Ulva have caused substantial economic losses. Ulva foulings increase the maintenance cost of marine facilities and contribute to the biomass of floating algae. Chemical methods are generally very inexpensive and convenient for suppression of Ulva spp. during their early life stages, thus solving the green tide and fouling problem at the source. In this paper, classical chemical methods that have been or are in use and emerging chemical methods under research are systematically reviewed. The advantages, disadvantages, mechanisms, and applications of these methods are also summarized. Highly toxic reagents are used in classical chemical methods, including oxidants, acids, heavy metal compounds, and synthetic biocides directly used or applied in antifouling coatings to kill or inhibit Ulva effectively. However, these toxic reagents have a high risk of resulting in secondary environmental problems. In order to minimize other environmental impacts while solving the current problem, emerging, and environmentally friendly chemical methods have been developed, such as the utilization of degradable natural products (mainly allelochemicals) and semi-natural products for Ulva inhibition and fouling control, and the use of flocculating agents to prevent microscopic propagules from germinating. All these chemical methods provide a promising direction for the prevention and control of Ulva.

Nowadays, algae are becoming more and more popular as a food group rich in nutrients, cosmetic raw materials full of antioxidants or valuable dietary supplements. They are of interest for the industry because they are found almost all over the world, in all climatic zones, both in fresh and salt waters. The aim of this study was to take a broad look at green algae (Chlorophyta) and to show how large the variability of the content of active compounds may depend on the species and the place and time of sample collection. Particular attention was paid to compounds with antioxidant activity, whose simplified profiles were created on the basis of complementary, semi-quantitative methods. Additionally, time-yield extraction optimizations were performed. Three different specimens of Ulva lactuca were compared: from the coastal zone of the Baltic Sea, from the open Baltic Sea area around Bornholm and Ulva spiralis (Ulva lactuca polymorph) from the Atlantic Ocean. The studied algae of the Cladophora genera were three different species of freshwater algae from various habitats: a lake (Cladophora glomerata), a river (Cladophora rivularis) and aquarium farming (Cladophora aegagropila, syn. Aegagropila linnaei). The content of antioxidants and the extraction efficiency varied significantly depending on the species.

In this study, we aimed to isolate bacteria capable of degrading the polysaccharide ulvan from the green algae Ulva sp. (Chlorophyta, Ulvales, Ulvaceae) in marine environments. We isolated 13 ulvan-degrading bacteria and observed high diversity at the genus level. Further, the genera Paraglaciecola, Vibrio, Echinicola, and Algibacter, which can degrade ulvan, were successfully isolated for the first time from marine environments. Among the 13 isolates, only one isolate (Echinicola sp.) showed the ability not only to produce externally expressed ulvan lyase, but also to be periplasmic or on the cell surface. From the results of the full-genome analysis, lyase was presumed to be a member of the PL25 (BNR4) family of ulvan lyases, and the bacterium also contained the sequence for glycoside hydrolase (GH43, GH78 and GH88), which is characteristic of other ulvan-degrading bacteria. Notably, this bacterium has a unique ulvan lyase gene not previously reported.

The high-valued utilization of Ulva (previously known as Enteromorpha) bioresources has drawn increasing attention due to the periodic blooms of world-wide green tide. The polysaccharide is the main functional component of Ulva and exhibits various physiological activities. The Ulva oligosaccharide as the degradation product of polysaccharide not only possesses some obvious activities, but also possesses excellent solubility and bioavailability. Both Ulva polysaccharides and oligosaccharides hold promising potential in the food industry as new functional foods or food additives. Studies on Ulva polysaccharides and oligosaccharides are increasing and have been the focus of the marine bioresources field. However, the comprehensive review of this topic is still rare and do not cover the recent advances of the structure, isolation, preparation, activity and applications of Ulva polysaccharides and oligosaccharides. This review systematically summarizes and discusses the recent advances of chemical composition, extraction, purification, structure, and activity of Ulva polysaccharides as well as oligosaccharides. In addition, the potential applications as new functional food and food additives have also been considered, and these will definitely expand the applications of Ulva oligosaccharides in the food and medical fields.

Macroalgae-associated bacteria play an important role in their algal hosts’ biological processes. They are localized on surfaces of the host thalli, as well as between and even within algal cells. To examine the differences in community structures and functions between epi- and endo- bacteria, an effective approach for maximizing epiphyte removal from delicate seaweeds while retaining endophyte fidelity must be developed. In this study, a variety of surface sterilization methods for Ulva prolifera were compared, including mechanical, chemical, and enzymatical treatments. According to the results of scanning electron microscope (SEM) and denaturing gradient gel electrophoresis (DGGE) analysis, almost complete removal of epiphytic bacteria on Ulva was obtained simply by co-vortex of seaweeds with silica sands, causing minimal disturbance to endosymbionts when compared to previous published methods. In addition, the adaptability was also confirmed in additional U. prolifera strains and Ulva species with blade-like or narrow tubular thallus shapes. This easy mechanical method would enable the analysis of community composition and host specificity for Ulva-associated epi- and endo-bacteria separately.

Invasive alien species, on successful establishment, can displace native species. The threat of invasive species arises in view of their ability to outcompete and destabilize native biodiversity. Invasive species are found across all taxonomic groups of plants, animals and microorganisms. The green macroalga Ulva flexuosa has a potential to become invasive and this species was investigated for its hitchhiking potential under laboratory conditions. Zoospores of U. flexuosa were maintained at 4°C for nearly 10 months in the dark. Recruitment potential of zoospores after dark stress was tested in a modified Provasoli medium under optimal laboratory conditions. The success rate of zoospore recruitment was 61%. The paper describes the transfer potential through shipping activities by correlating the Ulva zoospores recruitment potential and survivability.

Gastrointestinal (GI) microbiota has a relevant role in animal nutrition, modulation of the immune system and protection against pathogen invasion. Interest in algae as source of nutrients and functional ingredients for aquafeeds is increasing in order to substitute conventional feedstuffs by more sustainable resources. The diet is an important factor in the modulation of the microbiota composition, and functional ingredients have been proposed to shape the microbiota and contribute benefits to the host. However, fish microbiome research is still limited compared to other hosts. Solea senegalensis is a flat fish with high potential for aquaculture in South Europe. In this study, a characterization of the microbiome of S. senegalensis (GI) tract and the effects of feeding Ulva ohnoi supplemented diet has been carried out. Differences in the composition of the microbiota of anterior and posterior sections of S. senegalensis GI tract have been observed, Pseudomonas being more abundant in the anterior sections and Mycoplasmataceae the dominant taxa in the posterior GI tract sections. In addition, modulation of the GI microbiota of juvenile Senegalese sole fed for 45 days a diet containing low percentage of U. ohnoi has been observed in the present study. Microbiota of the anterior regions of the intestinal tract was mainly modulated, with higher abundance of Vibrio spp. in the GI tract of fish fed dietary U. ohnoi.

Despite the necessary trade-offs between spatial and temporal resolution, remote sensing is an effective approach to monitor macroalgae blooms, understand their origins and anticipate their developments. Monitoring of small tropical lagoons is challenging because they require high resolutions. Since 2017, the Sentinel-2 satellites has provided new perspectives, and the feasibility of monitoring green algae blooms was investigated in this study. In the Poé-Gouaro-Déva lagoon, New Caledonia, recent Ulva blooms are the cause of significant nuisances when beaching. Spectral indices using the blue and green spectral bands were confronted with field observations of algal abundances using images concurrent with fieldwork. Depending on seabed compositions and types of correction applied to reflectance data, the spectral indices explained between 1 and 64.9% of variance. The models providing the best statistical fit were used to revisit the algal dynamics using Sentinel-2 data from January 2017 to December 2019, through two image segmentation approaches: unsupervised and supervised. The latter accurately reproduced the two algal blooms that occurred in the area in 2018. This paper demonstrates that Sentinel-2 data can be an effective source to hindcast and monitor the dynamics of green algae in shallow lagoons.

ABSTRAKKertas seni merupakan kerajinan tangan dengan bahan dasar berbagai macam tanaman berserat. Serat pisang abaka, serat jerami dan serat padi telah mampu diolah menjadi kertas seni secara mandiri tanpa bahan perekat tambahan. Selama ini industri kertas seni yang ada sebagian besar menggunakan bahan baku pelepah pisang raja, pisang abaka, jerami, serat padi dan sebagainya. Oleh karena itu, perlu adanya peningkatan keanekaragaman bahan baku, di antaranya dengan memanfaatkan material dari rumput laut maupun limbah rumput laut limbah pewarna alam tekstil. Tujuan dari penelitian ini adalah untuk mengetahui karakter kertas seni yang terbuat dari limbah pewarna alam dari rumput laut Sargassum sp. dan Ulva serta kombinasinya dengan material serat pisang abaka. Bahan baku pelepah pisang abaka dan limbah rumput laut diolah dengan cara pencacahan dengan ukuran 2-3 cm, direbus dengan soda api selama 2 jam, kemudian disaring dan didinginkan. Bahan kemudian saling dikombinasi dan dijadikan pulp menggunakan mesin blender. Pulp kemudian dicetak dan dianalisis secara fisik. Limbah rumput laut jenis Sargassum sp. dan Ulva dalam keadaan murni (100%) tidak dapat digunakan sebagai bahan pembuatan produk kertas seni, dikarenakan kandungan selulosa yang masih di bawah 40% sehingga kertas yang dihasilkan dari proses pencetakan bersifat rapuh, mudah sobek dan tidak rekat antara satu dengan yang lain. Sedangkan kertas dengan campuran serat pisang abaka, menghasilkan kualitas kertas seni dengan kekuatan fisik yang lebih baik daripada kertas seni murni dari rumput laut Sargassum sp. dan Ulva. Kata Kunci: kertas seni, rumput laut, Sargassum sp., Ulva, pisang abaka ABSTRACTPaper art is a craft that uses a wide variety of fibrous plants. Abaca, straw and rice fibers can be processed into paper art independently without additional adhesive material. During this time, the existing art paper industries use many raw materials such as banana, abaca, etc., Therefore, it is necessary to conduct research and development in exploring new raw materials such as seaweed and waste of natural dyes from seaweed. The purpose of this study is to determine the character of art paper made from waste of natural dyes from Sargassum sp. and Ulva and its combination with abaca fiber. Abacá and waste materials from the seaweed are processed by being cut into 2-3 cm of length, boiled with caustic soda for 2 hours, then filtered and cooled. The materials are combined with each other and converted into pulp using a blender. The pulp is then printed and analyzed physically. Waste of seaweed Sargassum sp. and Ulva in a pure state (100%) cannot be used as materials for art paper products because the content of cellulose is still below 40% so that the paper produced from the printing process are fragile, easily brittle and no adhesion between one another. Meanwhile, the paper art that uses abaca fibers produces paper art with better physical quality than paper art with 100% seaweed Sargassum sp. and Ulva. Keywords: Paper art, seaweed, Sargassum sp., Ulva

European sea bass and Ulva sp. were co-cultured in different tanks of an indoor Recirculating Aquaculture System (Ulva-RAS) with bacterial biofilter, in an effort to optimize the efficiency of the system and to further decrease the waste effluent. A system with similar culture conditions, without Ulva, was used as a control-RAS to elucidate integration effects on growth performance and chemical composition of sea bass. The role of Ulva on N and P concentrations, gas (O2, CO2) and pH in water was also investigated. Fish were fed a diet of fish oil replacement (55%) with a mixture of rapeseed oil and palm oil (1:1). Our data showed that Ulva could uptake N and P nutrients, but could also enrich sea water with phosphates. Sea bass reared in Ulva-RAS exhibited isometric growth, while fish in control-RAS showed a positive allometric growth and an increased variance of body weight and length. In addition, sea bass in Ulva-RAS demonstrated significantly higher levels of condition factor (K), feed intake, protein, lipid, P, EPA and DHA content (% wet weight of total body) and lipid productive value, compared to fish in control-RAS. Ulva, after bi-weekly culture, showed increased protein content (60%) compared to wild seaweed collected nearshore. Cultivated Ulva obtained dark green color, doubled chlorophyll concentrations, and exhibited lower levels of saturated and higher levels of certain monounsaturated and n-3 polyunsaturated fatty acids, indicating increased photosynthetic activity. Present results revealed the beneficial effects of Ulva on sea bass growth and quality, which led to an improved response to the nutritional stress imposed by the fish oil replacement with vegetable oils, thus contributing to a sustainable aquaculture. Moreover, it was concluded that Ulva could improve water quality by increasing pH and O2, reducing CO2 and contribute to bioremediation of ammonia and nitrates from water in integrated aquaculture.

Eutrophic aquatic habitats are characterized by the proliferation of vegetation leading to a large standing biomass that upon decomposition may create hypoxic (low-oxygen) conditions. This is indeed the case in nutrient impacted estuaries of Prince Edward Island, Canada, where macroalgae, from the genus Ulva, form submerged ephemeral mats. Hydrological forces and gases released from photosynthesis and decomposition lead to these mats occasionally floating to the water’s surface, henceforth termed floating mats. Here, we explore the hypothesis that floating mats are refugia during periods of sustained hypoxia/anoxia and examine how the invertebrate community responds to it. Floating mats were not always present, so in the first year (2013) sampling was attempted monthly and limited to when both floating and submerged mats occurred. In the subsequent year sampling was weekly, but at only one estuary due to logistical constraints from increased sampling frequency, and was not limited to when both mat types occurred. Water temperature, salinity, and pH were monitored bi-weekly with dissolved oxygen concentration measured hourly. The floating and submerged assemblages shared many of the same taxa but were statistically distinct communities; submerged mats tended to have a greater proportion of benthic animals and floating mats had more mobile invertebrates and insects. In 2014, sampling happened to occur in the weeks before the onset of anoxia, during 113 consecutive hours of sustained anoxia, and for four weeks after normoxic conditions returned. The invertebrate community on floating mats appeared to be unaffected by anoxia, indicating that these mats may be refugia during times of oxygen stress. Conversely, there was a dramatic decrease in animal abundances that remained depressed on submerged mats for two weeks. Cluster analysis revealed that the submerged mat communities from before the onset of anoxia and four weeks after anoxia were highly similar to each other, indicating recovery. When mobile animals were considered alone, there was an exponential relationship between the percentage of animals on floating mats, relative to the total number on both mat types, and hypoxia. The occupation of floating mats by invertebrates at all times, and their dominance there during hypoxia/anoxia, provides support for the hypothesis that floating mats are refugia.

The current study examined the nutrient uptake efficiency of Ulva lactuca and Gracilaria chilensis cultivated in tanks associated with the wastewater of a land-based abalone culture. The experiments evaluated different seaweed stocking densities (1200, 1900, 2600, and 3200 g m-2) and water exchange rates (60, 80, 125, and 250 L h-1). The results show that both U. lactuca and G. chilensis were efficient in capturing and removing all of the inorganic nutrients originating from the abalone cultivation for all of the tested conditions. Furthermore, an annual experiment was performed with U. lactuca, cultivated at a stocking density of 1900 g m-2 and at a water exchanged rate of 125 L h-1, in order to evaluate seasonal changes in the nutrient uptake efficiency, productivity, and growth rate associated with the wastewater of a land-based abalone culture. The results confirmed high uptake efficiency during the entire year, equivalent to a 100% removal of the NH4, NO3, and PO4 produced by the land-based abalone culture. The growth rate and productivity of U. lactuca presented a marked seasonality, increasing from fall until summer and varying from 0.5 ± 0.2% to 2.6 ± 0.2% d-1 and 10 ± 6.1% to 73.6 ± 8.4% g m-2 d-1 for sustainable growth rate and productivity, respectively. We conclude that there is sufficient evidence that demonstrates the high possibility of changing the traditional monoculture system of abalone in Chile, to a sustainable integrated multi-trophic aquaculture system, generating positive environmental externalities, including the use of U. lactuca as a biofiltration unit.

Ba.ckground: Sunscreen formulations primarily offer protection against UV induced damages however nowadays it also maintains skin natural physiological conditions. Current global market is flooded with numerous sunscreen products which offer protection to skin against several UV induced damages. However most of these sunscreen formulations offers narrow spectrum protection against UV and also suffer from stability as well as toxicity related issues. Methods: Present work aims to isolate mycosporine amino acid (Mgy) from green alga namely Ulva fasciata (U. fasciata) and study its sunscreen potential against widely used domestic marketed formulation. Stability evaluations were also performed for almost 90 days. Results: Results demonstrated that the isolated compound, mycosporine glycine (Mgy) preserved physicochemical properties of the product and offered good stability for all formulations throughout the experimental period. Furthermore, Mgy loaded carbopol gel showed better sunscreen protection against marketed formulation in a concentration dependent manner. (7.709). Conclusion: (6.806) Novel Myg loaded gel was proved to demonstrate several quality characteristics that may unlock new prospects for the production of more efficient, safe, and economic skin-care products.

The roles of organic matter in seawater have often been discussed from the aspect of metal toxicity and bioavailability in seawater. In fact, organic ligands, as part of the organic matter, can work as a trace metal ion buffer system. At the same time, however, the release of well-defined metal chelators as exudates by, for example, marine bacteria is necessary to compete with natural metal complexes and sustain the metal acquisition required for several processes including nitrogen fixation. The identification, isolation and structure elucidation of chelators is, thus, essential to our understanding of metal stress management in the natural habitat and role of these chelators on cellular process. The isolation of an organic ligand from its chemosphere is a challenging task. The purpose of this paper is, therefore, to give an additional perspective on how the effective application of stable isotope pairs of a metal of interest (both cations and oxoanions) combined with mass spectrometric analyses can pave the way to discovering new organic ligands (i.e. metallophores) and the chelating characteristics of dissolved organic matter (DOM): Pairs of isotopes, such as 54Fe and 58Fe (or any other pair of available isotopes of a given metal), can be used to create easily detectable unique isotopic signatures in mass spectra when they are bound by chelators. The identification of organic ligands is outlined for a proposed model system of mutualistic interactions between the green macroalga Ulva (Chlorophyta) and associated bacteria, as well as discussed briefly for DOM along land-sea gradients.

Ulvophycean species with diverse trait characteristics provide an opportunity to create novel allelic recombinant variants. The present study reports the development of seaweed variants with improved agronomic traits through protoplast fusion between Monostroma oxyspermum (Kutz.) Doty and Ulva reticulata Forsskål. A total of 12 putative hybrids were screened based on the variations in morphology and total DNA content over the fusion partners. DNA-fingerprinting by inter simple sequence repeat (ISSR) and amplified fragment length polymorphism (AFLP) analysis confirmed genomic introgression in the hybrids. The DNA fingerprint revealed sharing of parental alleles in regenerated hybrids and a few alleles that were unique to hybrids. The epigenetic variations in hybrids estimated in terms of DNA methylation polymorphism also revealed sharing of methylation loci with both the fusion partners. The functional trait analysis for growth showed a hybrid with heterotic trait (DGR%= 36.7±1.55%) over the fusion partners U. reticulata (33.2±2.6%) and M. oxyspermum (17.8±1.77%), while others were superior to the mid-parental value (25.2±2.2%) (p

Marine eutrophication caused by an excess supply of nutrients is a serious problem in many coastal areas throughout the world. In the present study we used the capacity of macroalgae (Ulva and Enteromorpha) to integrate the nutrient regime of a water body in order to examine the trophic categorization in the embayments studied. We found that the trophic categorization established based on nutrient levels in macroalgae differed from that established based on concentrations in the water. The waters of the innermost areas of the inlets were the most nutrient enriched; the algae appeared to be more affected by specific local conditions and did not display the gradient of decreasing nutrient concentrations from inner to outer areas that was observed in the water samples. The lack of correspondence between nutrients in the water and in the algae in the present study may have been due to the heterogeneous nutrient conditions found in coastal areas, so that the intertidal algae did not adequately reflect the nutrient levels of the inner zones of the embayments under study.

Over the past hundred years, the composition of the submerged aquatic vegetation of the Lagoon of Venice has changed considerably, due to increased anthropic activities and large-scale industrialisation. Seagrasses have gradually been reduced, whereas macroalgae (Ulva rigida, Enteromorpha spp., Cladophora spp., Chaetomorpha spp.) have increased. Macroalgal overgrowths peaked between 1970 and 1990 to the extent that, in order to estimate macroalgal biomass and coverage, the Venice Magistrato alle Acque (the Lagoon water management authority) started a series of investigations including monthly in situ measurements and aerial photo surveys. In the present paper these data are compared with available information on the Lagoon of Venice, and the widespread phenomenon of macroalgal proliferation is described. At the end of the 1980s, in our study area (78 km2 in the central part of the Lagoon) biomass values ranged from 10 to 25 kg wet weight (w.w.) m-2 (sub-areas of Lido and Sacca Sessola), with a total mean biomass of 392,000 t w.w. A slight reduction took place in 1992 and at the end of the 1990s the highest biomass values were relatively low, 5 kg w.w. m-2, with a total mean biomass of 1,600 t w.w. Our qualitative research carried out in 1991 on 130 sampling stations in the study area showed that soft substrates had a greatly reduced floristic composition in the five sub-areas in comparison with the control area (from 18 to 6 taxa), with Chlorophyta (50-80%) prevailing over both Rhodophyta (14-38%) and Phaeophyta (0-14%), and a slight or reduced distribution of seagrasses. The trend in macroalgal reduction during the 1990s corresponded to seagrass recolonisation, mainly of Zostera marina, taking advantage of new, compacted, oxidised and stabilised sediments that were no longer covered by extensive Ulva beds.

Chemical composition of three species of Chlorophyta, Ulva lactuca, Ulva fasciata and Ulvaria oxysperma, was determined. Ulvaria oxysperma showed humidity (16-20%), ash (17-31% dry-base), proteins (6-10%db), lipids (0.5-3.2%db), fibers (3-12%db) and carbohydrates (46-72%db) which corresponded to 192-270 kcal.100g-1 (wet-base). U lactuca (15-18%db) and U fasciata (13-16%db) revealed grades slightly higher for proteins, but with similar energetic contents (250-272 and 225-239 kcal.100g-1), respectively. Natural blades of U lactuca and of U fasciata were more rigid than blades of U oxysperma. Other native algae showed higher protein levels. Ulvaria sp could be cultivated on the cotton-nylon net without having significance competition from other algae or predators degradation. On the other hand, it was essential choose a place without destructive tide action. Cultivated Ulvaria sp showed similar chemical composition as that grown on natural substrates.A composição química de três espécies de Chlorophyta foi determinada. Ulva lactuca se desenvolve em Guaraqueçaba e Ulva fasciata na Ilha do Mel, enquanto que Ulvaria oxysperma se desenvolve nos dois ecossistemas. Umidade (16-20%), cinzas (17-31%, base seca), proteínas (6-10%bs), lipídeos (0,5-3.2%bs), fibras (3-12%bs) e carboidratos (46-72%bs) para U.oxysperma correspondeu a 192-270 kcal.100g-1 (base úmida). U.lactuca (15-18%bs) e U.fasciata (13-16%bs) mostraram teores levemente maiores para a proteína, mas com conteúdos energéticos similares (250-272 e 225-239 kcal.100g-1), respectivamente. As folhas in natura de U.lactuca e de U.fasciata eram mais rígidas do que as de U.oxysperma. Outras algas nativas apresentaram teores de proteínas maiores. Ulvaria sp pode ser cultivada sobre redes, sem apresentar competição com outras algas ou ação significativa de predadores. Ulvaria sp cultivada apresentou composição química similar ao da Ulvaria sp crescida sobre substratos naturais. É essencial escolher um local protegido da ação destrutiva da maré.

The generation of reactive oxygen species (ROS) and scavenging of the superoxide radical by superoxide dismutase (SOD) was studied in mat-like canopies of the green macroalga Ulva rotundata Bliding in a tidal brine pond system in southern Spain. Artificial canopies were covered with different cut-off filters, generating different radiation conditions. ROS and SOD were assessed after three days of exposure. ROS induced lipid peroxidation depended on the position of individual thalli within the canopy and on radiation conditions. Samples exposed to the full solar spectrum were most affected, whereas samples either exposed to photosynthetically active radiation (PAR) alone or UV radiation without PAR exhibited fewer peroxidation products. The activity of SOD appeared to be controlled by the impinging UV-A and UV-B radiation and also increased in response to oxidative stress. The results provide evidence for additive effects of high PAR and UV-B under field conditions and support the previously proposed hypothesis that UV-B effects are mediated by an inhibition of the xanthophyll cycle, which increases ROS production and, consequently, causes oxidative damage to components of the photosynthetic machinery, such as proteins and pigments.

The marine green macroalga Ulva (Chlorophyta) lives in a mutualistic symbiosis with bacteria that influence growth, development, and morphogenesis. We surveyed changes in Ulva’s chemosphere, which was defined as a space where organisms interact with each other via compounds, such as infochemicals, nutrients, morphogens, and defense compounds. Thereby, Ulva mutabilis cooperates with bacteria, in particular, Roseovarius sp. strain MS2 and Maribacter sp. strain MS6 (formerly identified as Roseobacter sp. strain MS2 and Cytophaga sp. strain MS6). Without this accompanying microbial flora, U. mutabilis forms only callus-like colonies. However, upon addition of the two bacteria species, in effect forming a tripartite community, morphogenesis can be completely restored. Under this strictly standardized condition, bioactive and eco-physiologically-relevant marine natural products can be discovered. Solid phase extracted waterborne metabolites were analyzed using a metabolomics platform, facilitating gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-mass spectrometry (LC-MS) analysis, combined with the necessary acquisition of biological metadata. Multivariate statistics of the GC-MS and LC-MS data revealed strong differences between Ulva’s growth phases, as well as between the axenic Ulva cultures and the tripartite community. Waterborne biomarkers, including glycerol, were identified as potential indicators for algal carbon source and bacterial-algal interactions. Furthermore, it was demonstrated that U. mutabilis releases glycerol that can be utilized for growth by Roseovarius sp. MS2.

The bacterium P. tunicata is a common surface colonizer of marine eukaryotes, including the macroalga Ulva australis. Genomic analysis of P. tunicata identified genes potentially involved in surface colonization, including genes with homology to bacterial virulence factors that mediate attachment. Of particular interest is the presence of a gene, designated ptlL32, encoding an ortholog to the Leptospira lipoprotein LipL32, which has been shown to facilitate the interaction of Leptospira sp. with host extracellular matrix (ECM) structures and is thought to be an important virulence trait for pathogenic Leptospira. To investigate the role of PtlL32 in the colonization by P. tunicata we constructed and characterized a ΔptlL32 mutant strain. Whilst P. tunicata ΔptlL32 bound to an abiotic surface with the same capacity as the wild type strain, it had a marked effect on the ability of P. tunicata to bind to ECM, suggesting a specific role in attachment to biological surfaces. Loss of PtlL32 also significantly reduced the capacity for P. tunciata to colonize the host algal surface demonstrating a clear role for this protein as a host-colonization factor. PtlL32 appears to have a patchy distribution across specific groups of environmental bacteria and phylogenetic analysis of PtlL32 orthologous proteins from non-Leptospira species suggests it may have been acquired via horizontal gene transfer between distantly related lineages. This study provides the first evidence for an attachment function for a LipL32- like protein outside the Leptospira and thereby contributes to the understanding of host colonization in ecologically distinct bacterial species.

Ecological theory and experiments indicate that warming can increase the relative strength of top-down effects via alterations to metabolic rates in several different systems, thereby resulting in decreased plant biomass at higher temperatures. However, the general influence of increased environmental temperature on top-down effects is not well understood in systems where organisms experience relatively large variation in temperature. Rapid ocean temperature changes are pervasive throughout the Galápagos Islands due to upwelling and downwelling of internal waves, ENSO events and seasonality. We measured the effect of large, but not uncommon, water temperature variation on the metabolism and grazing rate of a common subtidal herbivore and on photosynthesis of their algal prey in the Galápagos Islands in July 2012. We found that green urchin consumption and metabolism were greater at the higher temperature treatment (28°C), resulting in significantly less algal biomass. Our result that warming increased green urchin metabolic rates, even in a highly dynamic system, provides further support for a mechanistic link between environmental temperature and feeding rates. And further, our findings suggest individual response to temperature results in changes in top-down effects. And if this response is maintained over longer-time scales of days to weeks, this could translate to alterations of larger-scale ecological patterns, such as primary producer community composition and structure.

En el presente trabajo se muestra la concepción de un sistema experimental de laboratorio para el cultivo de macroalgas de la especie Ulva lactuca Linnaeus. El estudio experimental constituye la etapa inicial de un proyecto para la reducción de las emisiones industriales de Dióxido de Carbono mediante su captura en sistemas de cultivo intensivo de macroalgas marinas. El sistema de biorreación consiste en un recipiente de cultivo de algas con alimentación continua de agua de mar y nutrientes. Se realiza la evaluación del sistema a través de la determinación del rendimiento de biomasa algal y el comportamiento del sistema de biorreacción, basado en los consumos de nutrientes. Se determinan las principales variables de diseño del biorreactor, tales como la constante de reacción y el tiempo espacial. A partir de los resultados obtenidos se realiza el escalado para un sistema piloto de cultivo de macroalgas.

Temporal and spatial changes in the coverage of five Ulva L. species (U. prolifera O.F. Müller, U. intestinalis L., U. hookeriana (Kützing) Hayden et al., U. compressa L. and U. linza L.) were analyzed on rocky substrata experimentally immersed in Comodoro Rivadavia Harbor (Argentina). Colonization was studied during an annual period at three levels: upper intertidal, middle intertidal and subtidal. Coverage was significantly higher in the middle intertidal and subtidal levels than in the upper intertidal level, where all species of Ulva were absent. Seasonal changes were also significant: coverage in summer and spring was significantly higher than in autumn and winter. Most species showed high spatial variability among replicates from the same level and season. Zonation patterns within the harbor differed from those observed in natural areas, probably due to low wave exposure and its interaction with herbivory and desiccation stress. Colonization patterns observed in this study indicate nichesegregation in closely related species of the genus Ulva.

Objetivos: Investigar especies de Ulva del Golfo San Jorge, Patagonia Argentina, integrando aspectos bioquímicos, actividad biológica y variaciones estacionales/habitacionales que permitan determinar su potencial aplicación en Salud. Métodos: Las algas se colectaron estacionalmente en playas con y sin contaminación antrópica; se secaron, molieron y extrajeron con etanol. Los extractos se fraccionaron mediante solventes de distinta polaridad. Cada fracción fue caracterizada mediante reacciones químicas cualitativas y cromatografía. Las fracciones ricas en flavonoides se analizaron por HPLC-DAD y los lípidos, por TLC. La actividad biológica se ensayó mediante el test de citotoxicidad de Artemia salina, inhibición de la elongación radicular, inhibición de la xantino oxidasa, actividad antioxidante y antibacteriana. Resultados: Se identificaron Ulva rigida y Ulva lactuca. Ambas evidenciaron flavonoides, taninos, quinonas, lípidos, carbohidratos, esteroides. Los flavonoides resultaron mayoritarios en U. rigida (otoño e invierno) y en U. lactuca (primavera e invierno), destacándose kayaflavona. Se detectaron alcaloides en Ulva rigida (verano). Los lípidos fueron mayoritarios en verano; U. lactuca en invierno mostró monogalactosildiacilglicérido y en otoño, digalactosilacilglicérido y fosfatidilcolina. La actividad inhibitoria de la elongación radicular, que presume actividad antitumoral, fue importante y dosis dependiente, destacándose U. rigida de otoño y primavera (DE50= 480 y 520 µg/ml, respectivamente). Las demás bioactividades resultaron escasas o negativas. Conclusiones: Las variaciones metabólicas observadas muestran la importancia de considerar las condiciones espacio - temporales al planificar una colecta de ejemplares para su estudio y/o aplicación. Este primer análisis integral de especies de Ulva de la Patagonia Argentina, evidencia su potencialidad como antitumoral.