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The rising global significance of sea lettuce (Ulva spp.) in aquaculture stems from its versatility, rapid growth, and nutritional benefits. Cultivation expansion into lower salinity areas, like the Baltic Sea, is crucial for advancing aquaculture beyond traditional environments. This study investigated the impact of long-term (8 weeks) low salinity treatments on the biochemical content of eight Ulva strains – encompassing some of the most common Ulva crop species (Ulva lacinulata, Ulva linza, Ulva intestinalis, Ulva fenestrata) of the wider Baltic Sea area – from varying source salinities (30, 14, 9, 7). Most strains exhibited significantly higher growth rates and contents of crude protein under low salinity treatments, irrespective of where they came from (i.e. euhaline or mesohaline environments). However, effects on pigments and phenolic contents were strain-specific. Ulva lancinulata showed high resilience to salinity changes. Cultivating Ulva under low salinity conditions enhances its nutritional attributes and identifies the broader Baltic Sea as a viable cultivation environment. Nevertheless, careful selection of strains is crucial due to significant inter- and intraspecific differences. This research underscores the importance of tailored cultivation strategies for optimizing Ulva biomass production, particularly in the context of the expanding Blue Economy industry. [ABSTRACT FROM AUTHOR]

The article "Phylogeny and ecology of the green seaweed Ulva. Part II" explores the genus Ulva, also known as sea lettuce, and its significance in various fields such as aquaculture, biotechnology, and environmental management. Researchers are studying Ulva's potential applications and ecological challenges, including green tides caused by Ulva blooms. The article emphasizes the importance of tailored cultivation strategies, ecological monitoring, and taxonomic frameworks to harness Ulva's potential while addressing environmental risks. The research is part of the European Cooperation in Science and Technology (COST) Action SeaWheat project, focusing on Ulva as a model for innovative mariculture. [Extracted from the article]

The genus Ulva Linnaeus 1753 is well known for its global distribution and containing many taxonomically debated species. Their morphological plasticity and cryptic nature overrepresent and underrepresent, respectively, the biodiversity of these species. The difficulty in morphologically identifying Ulva species has led to the accumulation of many species names that are currently considered synonyms. The correct identification of these species is crucial due to their significant role in marine ecosystems and mariculture. In the last 30 years, several checklists and taxonomic contributions have been made from the Italian coast on Ulva species, almost entirely based on morphological studies and only a few papers with molecular data have been published. In this study, samples deposited at the Institute of Marine Sciences (ISMAR) and Phycological Lab (PHL) herbaria have been reviewed by sequencing the chloroplast-encoded elongation factor Tu (tufA) barcode marker. The results obtained provide an update of the DNA barcode inventory of Ulva species for the Lagoon of Venice and the Strait of Messina, two ecosystems characterized by a high algal biogeographical diversity and continuous introduction due to anthropogenic activities. Here, ten Ulva species were identified based on molecular data. Furthermore, we record the presence of Ulva chaugulei on the coast of Tunisia. [ABSTRACT FROM AUTHOR]

Species classified in the genus Ulva are important foundational marine primary producers distributed worldwide. These species are particularly abundant and diverse through the northwest Pacific (NWP) where they experience marked latitudinal gradients of environmental heterogeneity. It is unclear, however, to what extent such dynamic conditions can modulate phenotypic and genetic patterns in these organisms, potentially reflecting the influence of historical and contemporary biotic and abiotic factors. Here, we assessed inter- and intra-specific genetic patterns of Ulva species through the NWP using plastid rbcL and tufA gene sequences. Although we initially targeted Ulva australis based on morphological identification, we recovered eight Ulva genetic entities masked by morphological similarities. Except for the Ulva linza–procera–prolifera and U. lactuca–reticulata complexes, six of these genetic entities were recovered as individual species (i.e., U. australis, U. ohnoi, U. californica, U. compressa, U. lacinulata, and U. arasakii), and showed biogeographic patterns likely explained by clines in sea surface temperature and ocean current dispersal. At intra-specific level, all the genetic entities showed low genetic variation and divergence based on rbcL (0–0.3 %) and tuf A (0–0.9 %) data. Our results provide insights regarding intra- and inter-specific genetic patterns characterizing morphologically similar Ulva species through the NWP. However, further studies are needed to understand the mechanisms underpinning such patterns and the associated ecological and evolutionary implications. [ABSTRACT FROM AUTHOR]

DNA sequences were obtained from 32 blade-forming Ulva specimens collected in 2018 and 2019 from four islands in the Galápagos Archipelago: Fernandina, Floreana, Isabela and San Cristóbal. The loci sequenced were nuclear encoded ITS and plastid encoded rbcL and tufA, all recognized as barcode markers for green algae. Four species were found, Ulva adhaerens, U. lactuca, U. ohnoi and U. tanneri, all of which have had their type specimens sequenced, ensuring the correct application of these names. Only one of these, U. lactuca, was reported historically from the archipelago. Ulva adhaerens was the species most commonly collected and widely distributed, occurring on all four islands. Previously known only from Japan and Korea, this is the first report of U. adhaerens from the southeast Pacific Ocean. Ulva ohnoi was collected on three islands, Isabela, Floreana, and San Cristóbal, and U. lactuca only on the last two. Ulva tanneri is a diminutive, 1–2 cm tall, high intertidal species that is easily overlooked, but likely far more common than the one specimen that was collected. This study of blade-forming Ulva species confirms that a concerted effort, using DNA sequencing, is needed to document the seaweed flora of the Galápagos Archipelago. [ABSTRACT FROM AUTHOR]

This document is a summary of a special issue of the journal Botanica Marina focused on the green seaweed Ulva. The collection of articles explores various aspects of Ulva, including its ecology, phylogeny, and practical applications in aquaculture. The articles cover topics such as taxonomy, cross-kingdom interactions with bacteria and fungi, and the cultivation of Ulva for sustainable alternatives to essential fatty acids. The special issue aims to advance our understanding of Ulva and its potential in sustainable aquaculture and ecological contexts. The collection is dedicated to the late Prof. Dr. Klaus Lüning, a renowned marine botanist who made significant contributions to the study of Ulva. The special issue is also supported by the EU-funded COST Action SeaWheat, which aims to integrate Ulva into various industries and daily life. [Extracted from the article]

During the cultivation of Ulva fenestrata in a land-based aquaculture system, the colonisation of the water tanks' surfaces and eventually the macroalgal biomass by the biofouling diatom Fragilariopsis oceanica compromises the production process. Since germanium dioxide (GeO2) is an effective growth inhibitor of diatoms, this study aimed to understand how it affects the presence of F. oceanica and the photosynthesis and growth of U. fenestrata as a primary parameter contribution to the biomass production. A toxicological dose-response experiment showed that the diatom's growth was inhibited at the low GeO2 concentration of 0.014 mg l−1. In contrast, the photosynthetic performances and growth rates of U. fenestrata remained unaffected under a wide GeO2 concentration range (0.022–2.235 mg l−1) in small- and large-scale experiments in 1-l glass beakers and 100-l Plexiglass water tanks, respectively. In the latter, the diatom density in the tanks was reduced by 40 %. The costs arising from the use of GeO2 can range between €2.35 and €8.35 kg−1 fresh weight of produced U. fenestrata biomass under growth conditions resulting in growth rates of 20 and 11.5 % d−1, respectively. GeO2 is an effective agent to control biofouling diatoms such as F. oceanica during the land-based biomass production of U. fenestrata. [ABSTRACT FROM AUTHOR]

The 2007 flora "Green Seaweeds of Britain and Ireland" did not present the molecular data underpinning the Ulvaceae treatment, mostly ITS sequences. Subsequently, names have changed as type material of Ulva species is sequenced and intensive sampling with DNA barcoding adds new European species. To update the Ulvaceae, we systematically sampled from 2007 to 2021, identifying specimens using various molecular markers alongside DNA from type material of four species. We show here that Ulva gigantea, based on rbcL, tufA and ITS sequences of its holotype, is assigned to Ulva compressa, as is the lectotype of Ulva curvata. Ulva gigantea sensu GenBank and Ulva pseudocurvata are conspecific. The correct name is U. pseudocurvata based on rbcL sequences of the lectotype. Two species of monostromatic Ulvaceae were included in the 2007 flora, but we show that both of them and all earlier British monostromatic collections represent Ulvaria splendens, a species originally described from Alaska. Analysis of two rbcL amplicons of the Ulva sordida lectotype shows that it is conspecific with Ulvaria splendens. Our first genuine collections of Ulvaria obscura from SW England and SW Wales correspond to topotype material from the Bay of Biscay, recent samples from Galicia and unpublished tufA sequences from Britanny. [ABSTRACT FROM AUTHOR]

Axenic cultures of the green seaweed Ulva mutabilis were inoculated with bacteria providing essential algal growth and morphogenesis-promoting factors (AGMPFs) and were exposed to temperature shifts from 18 °C to 30 °C. The temperature-dependent effect of bacteria on longitudinal algal growth and the molecular composition of the chemosphere in the algal culture medium was explored. The reductionist tripartite model system of U. mutabilis, Roseovarius sp. MS2, and Maribacter sp. MS6 was applied as a reference and has been changed by substituting Roseovarius with isolates that phenocopy this strain. Rathayibacter festucae IH2 and Roseovarius aestuarii G8 boosted growth at 18 °C but slowed it down at 30 °C. Additional inoculation of Roseovarius sp. MS2 mitigated these adverse bacterial effects partially. At 30 °C, the molecular profile of the chemosphere differed dramatically between all tested tripartite communities, indicating different traits of the same bacterium with changing temperatures. Functional examinations should, therefore, accompany microbiome analysis to detect changing traits with the same microbiome composition. [ABSTRACT FROM AUTHOR]

Misapplication of Ulva epithets in GenBank has led to confusion in the scientific literature and community. To solve some of the problems, targeted DNA sequencing of plastid encoded rbcL gene amplicons or high-throughput sequencing was performed on all blade-forming Ulva type specimens from the northeast Pacific. Recently collected specimens from at or near type localities were also analyzed for some taxa. Based on these genetic analyses, we confirmed currently recognized species: U. californica, with U. angusta and U. scagelii as heterotypic synonyms, U. stenophylla, U. taeniata, and U. tanneri. Ulva dactylifera, currently considered a synonym of U. taeniata based on morpho-anatomy, is recognized as a distinct species, as is U. expansa whose type specimen was sequenced in 2018. All but two of the ITS, rbcL and tufA sequences in GenBank that were labeled U. californica were correctly named, in contrast to U. taeniata, for which only one of 14 sequences was correctly labeled. These results show that DNA sequencing of Ulva type specimens is essential for the correct application of names. [ABSTRACT FROM AUTHOR]

The use of high-value fatty acids (FA), omega-3 (n-3), and omega-6 (n-6) from seaweed could relieve the pressure from natural wild fish sources and reduce overfishing worldwide. This research is designed to explore how the harvest season (winter, spring, and summer) and culture period influence the biomass production yield, lipid content, and FA composition in the green seaweed Ulva sp. The studied seaweed was grown in plastic sleeves with flowthrough seawater in Mikhmoret (East Mediterranean, Israel) from July 2019 to December 2020. The Ulva species was identified as Ulva lactuca Linnaeus by DNA barcoding using rbcL, ITS, and tufA markers. No detectable genetic variability in U. lactuca samples was found throughout the research period. A quantitative examination of the lipid and FA content in U. lactuca in different harvest seasons revealed that the maximum content of lipids was in the summer, and that of polyunsaturated fatty acids (PUFAs) was in the winter. The PUFA profile included eicosapentaenoic acid, docosapentaenoic acid, docosahexaenoic acid, n-3, and n-6, where the n-6/n-3 ratio was comparable with the desired range for a balanced nutritional diet. [ABSTRACT FROM AUTHOR]

Several studies have shown that endophytic fungal metabolites possess vital biological activities; nevertheless, there is a lack of knowledge regarding the medicinally important marine endophytic fungi associated with the seaweeds mainly found in the Bay of Bengal, Bangladesh. In this study, six endophytic fungi, belonging to five genera and four classes, were isolated from the well-known chlorophyte, Ulva sp. and were most closely related to Chaetomium globosum, Nigrospora magnoliae, Curvularia sp., Curvularia moringae, Aspergillus terreus and Collariella sp. This is the first report of these fungi as endophytes associated with Ulva sp. from the Bay of Bengal, Bangladesh. A preliminary biological evaluation of the ethyl acetate extract of each endophytic fungal crude extract was the prime objective of this research, e.g., antimicrobial assay, 2,2-diphenyl-1-picrylhydrazyl free radical scavenging activity and brine shrimp lethality bioassay. Evaluation of test results revealed that each fungal crude extract possessed one or more relevant biological activities. Preliminary chemical screening using TLC and NMR spectroscopic analysis revealed the presence of several secondary metabolites in the crude fungal extracts. These findings suggest that the marine endophytic fungus may be a valuable source for investigating potentially bioactive chemicals or leads for novel drug candidates. [ABSTRACT FROM AUTHOR]

Unialgal stock cultures for seeding the tank water can be used for the mass cultivation of seaweeds in artificial seawater, as in microalgal mass cultivation. High costs for artificial sea salt mixtures and distilled water would be required, however, to use artificial seawater in big tanks for commercial purposes, but frequent medium changes may not be required, since the major ions contained in artificial seawater, such as sodium, will barely be utilised by the cultured algae during long periods of time, even over years. Similar growth rates were obtained at the start and end of an experiment conducted with Ulva pseudocurvata cultivated unialgally for two years without water change, at a low algal density and with weekly addition of Provasoli Enrichment. Growth in this experiment was increasingly impeded due to gamete swarming events causing dark greenish water every few weeks. The experimental water had then to be boiled in order to kill the gametes. In a second experiment, this time performed at a high algal density, maximum yield values were 20–30 g fresh weight m−2 d−1, both for 2-year-old and newly prepared artificial seawater. These results verified the hypothesis that long-term Ulva cultivation in artificial seawater is possible without frequent medium changes. [ABSTRACT FROM AUTHOR]

The effects of ocean acidification on macroalgae have been extensively studied. However, most studies focused on the adult stages, while other life cycle stages have been overlooked. To better understand the influence of the marine environment on macroalgae, their whole life cycle should be considered, especially the juvenile stage. In this study, Ulva prolifera was cultured under two CO2 concentrations (400 and 1000 ppmv) and at 10, 18, 30, and 55% of incident sunlight to assess the photosynthetic performance. Our results showed that the acidification treatment had a negative effect on growth at the juvenile stage, but a positive effect at the adult stage. The relative growth rate and effective quantum yield of PSII increased with decreased light levels, irrespective of the CO2 concentration. At the adult stage, the Chlorophyll (Chl) a, Chl b, and carotenoid contents declined under the high CO2 concentration. The protein content significantly increased at 18, 30%, and full sunlight levels under the high CO2 but not under the low CO2 concentration. Our results suggest that juveniles were less tolerant of the acidic stress compared with the adult stage, although the alga was able to increase cellular proteins in response to the acidic stress. [ABSTRACT FROM AUTHOR]

Thraustochytrids are fungoid protists ubiquitous in the marine environment and found to be associated with decaying macroalgae. Not much is known about their association with living macroalgae. Hence in the present study, different macroalgal samples were collected from various beaches of Goa to examine the presence of thraustochytrids during a four-year-long study. Brown, red and green algae were found to be substrata of thraustochytrids. Thraustochytrids were isolated on pine pollen baiting from 17 to 58% of the specimens. Thraustochytrids isolated from various macroalgae belonged to the genera Oblongichytrium, Schizochytrium, Ulkenia, and Thraustochytrium. Labyrinthula sp. was also found once on the green alga Bryopsis hypnoides. These were generally found during dry seasons rather than in monsoons. The seasonal occurrence of thraustochytrids was found to be associated with temporal variation in macroalgal diversity. The statistical analysis supported individual or interactive effects of both factors viz, seasons and macroalgal diversity, on the occurrence of thraustochytrids. Thraustochytrids were also isolated from seawater adjoining macroalgae and from estuarine water at all times of the year. Oblongichytrium sp. was isolated from the green alga Ulva compressa and Anjuna seawater samples at the same time, thus indicating that thraustochytrids from seawater could inhabit the macroalgae. [ABSTRACT FROM AUTHOR]

Since 2011 we have been documenting seaweed diversity and abundance along a poorly studied area of the central coast of British Columbia, Canada. This first installment focuses on the Chlorophyta. To date, 42 species have been recorded, and we have obtained DNA sequences for most. Although most of these species reportedly have wide distributions along the west coast of North America, others appear to represent new northern or southern records or possible introductions, and a number have yet to be described. New southern limits are recorded for Acrosiphonia sonderi, Acrosiphonia sp., Protomonostroma undulatum, and Ulva pouliotii sp. nov., and new northern records are documented for Ulva expansa, U. stenophylla, and another undescribed species of Ulva. Among species of Cladophoraceae, we obtained a sequence only for Cladophora opaca, a Japanese species not previously recorded from North America, and an undetermined species of Rhizoclonium. We sequenced three species of Derbesia, none of which is D. marina, the currently recognized species for this area; all three require taxonomic treatment. A sequence for a shell-boring species, which is tentatively identified as Eugomontia sacculata, was also obtained. These findings extend our understanding of the diversity and biogeography of green macroalgae in the northeast Pacific. [ABSTRACT FROM AUTHOR]

Seaweeds cover a wide range of applications, e.g. as food supplements, in animal feed, as biofuels or as sources of bioactive compounds. The Greek coast in the East Mediterranean is rich in various seaweeds that remain unexploited because their chemical and nutritional content has not yet been characterized. In the present study, eight seaweeds belonging to the Rhodophyta, Ochrophyta (class Phaeophyceae) and Chlorophyta were biochemically characterized and evaluated as potential food sources. Total polyphenol content, antioxidant activity, fatty acids and elemental composition were measured. Acanthophora nayadiformis, Ceramium sp. (Rhodophyta), Codium fragile (Chlorophyta), Cystoseira foeniculacea and Gongolaria barbata (formerly Cystoseira barbata) (Ochrophyta, Phaeophyceae) had the highest phenolic content and strongest antioxidant activity. Both brown and red seaweeds were rich in minerals, with G. barbata, Dictyopteris polypodioides (formerly Dictyopteris membranacea) (Chlorophyta, Phaeophyceae) and A. nayadiformis being the richest in macro- and microelements. The low Na/K ratio in most seaweeds (0.03–3.49) and the high iron content of red and brown algae (1.01–52.40 mg 100 g−1 of wet tissue) make algal consumption an attractive option. Chlorophyta and Phaeophyceae had the lowest n-6/n-3 PUFA ratios, with α-linolenic acid being the most abundant n-3 PUFA. The green algae Codium fragile and Ulva lactuca had the highest oleic and docosahexaenoic acid content, respectively. Finally, Rhodophyta were the highest producers of eicosapentaenoic acid. The findings confirmed the nutritional value of all seaweeds, highlighting brown seaweeds Cystoseira foeniculacea, G. barbata, and D. polypodioides as potential sources for food supplements and candidate species for seaweed cultivation in Mediterranean coastal waters. [ABSTRACT FROM AUTHOR]

Controlling the life cycle of the green macroalga Ulva (Chlorophyta) is essential to maintain its efficient aquaculture. A fundamental shift in cultivation occurs by transforming the thallus cells into gametangia and sporangia (sporulation), with the subsequent release of gametes and zoids. Sporulation occurrence depends on algal age and abiotic stimuli and is controlled by sporulation inhibitors. Thus, quantification of sporulation intensity is critical for identifying the biotic and abiotic factors that influence the transition to reproductive growth. Here, we propose to determine the sporulation index by measuring the number of released gametes using flow cytometry, in proportion to the total number of thallus cells present before the occurrence of the sporulation event. The flow cytometric measurements were validated by manually counting the number of released gametes. We observed a variation in the autofluorescence levels of the gametes which were released from the gametangia. High autofluorescence level correlated to phototactically active behaviour of the gametes. As autofluorescence levels varied between different groups of gametes related to their mobility, flow cytometry can also determine the physiological status of the gametes used as feedstock in seaweed cultivation. [ABSTRACT FROM AUTHOR]

Phosphorus is a key macronutrient in macroalgal physiology, including carbohydrate anabolism. To determine the effects of phosphorus on different physiological parameters, we cultivated Ulva fasciata specimens from distinct localities (upwelling and non-upwelling sites) in the presence of different phosphate concentrations (0, 2, and 4 µM PO 4 3 − ${\text{PO}}_{4}^{3-}$). After 15 days, growth rates were similar (approx. 12% day−1) and carbohydrate contents had increased in individuals from both sites. In individuals from the upwelling site, carbohydrate contents were high in all treatments (71% dry mass), whereas non-upwelling site individuals cultivated under the highest phosphate concentration showed the lowest carbohydrate content (46% DM). Nevertheless, we observed higher rates of phosphorus uptake in individuals from the non-upwelling site cultivated under the highest phosphate concentration, indicating a stress response to elevated nutrient concentrations. Individuals from both sites cultivated with phosphate maintained healthy photosystems over the experimental period (Fv/Fm = 0.788), whereas those cultivated in the absence of phosphate showed evidence of photosystem impairment, as indicated by a progressive decline in maximum quantum yield. Altogether, our results indicate that site origin and phosphate concentration influence the carbohydrate content in U. fasciata and that individuals from sites with broad environmental variation, such as upwelling events, can show higher productivity. [ABSTRACT FROM AUTHOR]

The seaweed industry of temperate Southern Africa was last reviewed in 2003. Since then there have been considerable changes. There are three main uses of kelp (mostly Ecklonia maxima, with some Laminaria pallida) in South Africa. The collection of wash-up for drying and exporting for alginate extraction has drastically reduced to very small amounts in recent years. The boat harvest of fresh kelp for abalone feed in land-based farms has reached a plateau of between 4000 and 5000 t fresh per annum. The diver harvest of E. maxima for agricultural liquid plant growth enhancer shows a constant increase over several years, is still growing, and is currently over 3000 t fresh per annum. The small intertidal collection of Gelidium pristoides as export for agar production has maintained a small, sustainable production of around 100 t dry for many years. Former Gracilaria industries in sheltered bays in both South Africa and Namibia have collapsed, and there is currently no commercial collection. There was commercial raft aquaculture production of Gracilaria in Lüderitz Bay, Namibia for a number of years, but this is no longer practised. Currently, the only commercial seaweed use in Namibia is of L. pallida. Annually, ca. 150 t of fresh wash-up is collected, in Lüderitz, to be used as feed in land-based abalone aquaculture. There are a number of small start-up companies experimenting with seaweed products for cosmetics and nutritional products in both countries, some involving species of Ulva and Porphyra. The former species is a major aquaculture product, with around 2000 t fresh yr–1 being produced in integrated land-based systems with abalone. [ABSTRACT FROM AUTHOR]

In spite of the natural harsh marine environments and continuous global change stressors affecting the Levant basin, the Israeli marine flora in the Eastern Mediterranean Sea is quite diverse, with about 300 recognized species. Such high seaweed biodiversity for a small maritime area is remarkable compared to the ca. 1200 species described for the entire Eastern Mediterranean Sea. Since about the year 1890, the Levant basin has been hosting over 115 seaweeds species that migrated from the Indo-Pacific through the Suez Canal. Indeed, approximately 16% of the marine flora is regarded as invasive or exotic to the Israeli shores, in a process that constantly reshapes seaweed populations and their biodiversity. In spite of significant contributions by Israeli scientists to the general biology and technologies for seaweed cultivation worldwide, Israel has little historical and cultural tradition of commercial seaweed cultivation, or use. At present, only two commercial companies are engaged in land-based seaweed cultivation (Ulva sp. and Gracilaria sp.) with a number of products marketed locally and abroad. Recently, offshore cultivation and biorefinery approaches have been explored, but not yet commercialized. [ABSTRACT FROM AUTHOR]

Green tide algal blooms occur worldwide, especially in China's Yellow Sea, and have caused serious damage to local ecological environments and economies. As a dominant agent of green tides, the green macroalga Ulva has caused widespread concern. In this study, phylogenetic clades were constructed among related Ulva species isolated from Pyropia rafts at six sites over 1.5 years based on internal transcribed spacer (ITS) and tufA sequences. In addition, traditional observation ploidy methods and flow cytometry methods were used to analyse continuous change in the biphase and sex ratios of Ulva species and to assess the changes in phase advantages over time. The results showed that the perennial Ulva populations on rafts mainly consisted of Ulva flexuosa and Ulva prolifera, and the biphasic dominance of the attached Ulva populations changed with the seasons: sporophytes were predominant mainly in winter and spring, and gametophytes were predominant mainly in summer and autumn. At the same time, there were some differences in gametophyte and sporophyte frequencies (mainly sporophyte biased) compared to the null model prediction of a √2:1 ratio, while the sex ratio of male and female gametophytes remained 1:1 throughout the year. Our results indicate the presence of both phases of bloom-forming species of Ulva in green tides year round, and that multiple generations coexist and grow continuously. [ABSTRACT FROM AUTHOR]

Land-based cultivation of marine macroalgae may open up the possibility to produce high quality algal biomass as required in various application areas all year round. In this context, the potential of a recently developed ring-shaped cultivation system with algae moving in a circular way, simulating the movement pattern in a standard tank cultivation vessel was evaluated using the green alga Ulva lactuca. Plants were cultivated under outdoor conditions at ambient (37 μmol CO2 kg−1 seawater) and increased CO2 concentration (152 μmol CO2 kg−1 seawater). Biomass growth and photosynthetic performance of algae were analyzed over a test period of 7 d. Elevated CO2 concentration significantly stimulated algal growth and also helped to compensate the effects of environmental stress conditions. This was indicated by the predominant stability of photosynthetic competence and represented by maximum photosynthetic electron transport rates, efficiency of light-harvesting and photon fluence rates (PFR) saturating photosynthetic electron transport at low PFR. At high PFR, no difference in photosynthetic competence was detected between algae cultivated at the high CO2-concentration and those grown at ambient CO2. Under elevated CO2 concentrations, photochemical energy dissipation decreased more distinctly at low PFR. This may reflect a declining energy demand necessary to maintain photosynthetic capacity. Under elevated CO2, the apparent changes in the quantum yields of regulated and unregulated non-photochemical energy dissipation of PS II at high PFR possibly reflected the enhanced capacity of photoprotection under the prevailing environmental conditions. [ABSTRACT FROM AUTHOR]

Examining morphological and anatomical characters, eight bloom-forming Ulva species were identified from La Paz Bay, Gulf of California, Mexico. However, DNA sequencing, using a multi-gene approach (rbcL, ITS2 and tufA) revealed that, of the eight species, four species were genetically distinct, none of which belonged to the species they would have been ascribed based on morpho-anatomical observations. The Ulva lactuca and Ulva rigida morphotypes (blades two cells thick, unbranched, attached by a small discoid holdfast) corresponded to Ulva ohnoi; the Ulva intestinalis morphotype (tubular and smooth thallus, one cell thick) corresponded to Ulva tepida; the Ulva clathrata and Ulva flexuosa morphotypes (tubular to slightly compressed thallus) corresponded to Ulva torta. The Ulva acanthophora morphotype (more or less tubular, profusely branched) did not correspond molecularly to any currently described species. Attempts to sequence the remaining two species, morpho-anatomically identified as Ulva lobata and Ulva nematoidea, were unsuccessful. This study similarly highlights the high degree of cryptic diversity in the genus Ulva, provides a nomenclature adjustment for several species of the genus Ulva from northwestern Mexico and is the first to report U. ohnoi, U. tepida and U. torta for the region. [ABSTRACT FROM AUTHOR]

Ulva blooms are highly productive ephemeral communities that occur in coastal systems, associated with nutrient enrichment. The objective was to estimate variations in succession, cover, recruitment and length of Ulva species in four blooms and assess their relationship with environmental parameters in Bahía de La Paz, Baja California Sur. At each locality, monthly samplings were performed to register the presence, recruitment, length and cover of species, and temperature, salinity, turbidity and nutrient concentration in surface seawater from February 2013 to October 2015. The species found were Ulva acanthophora, Ulva clathratha, Ulva intestinalis, Ulva flexuosa, Ulva lactuca, Ulva lobata, Ulva nematoidea and Ulva rigida. The Ulva blooms in Casa del Marino, San Juan de la Costa and El Tecolote were multi-species, with U. rigida displaying the highest presence, cover and recruitment, followed by U. acanthophora. Significant differences were found between localities, years and months for biological and environmental factors. A principal component analysis (PCA) revealed significant relationships between higher cover, recruitment and length with higher nutrients concentrations at San Juan de La Costa, Casa del Marino and El Tecolote, indicating favourable conditions that allowed rapid growth. The cover, recruitment and length of U. flexuosa at El Portugués were inversely correlated with temperature. [ABSTRACT FROM AUTHOR]

Growth and morphogenesis of the sea lettuce Ulva (Chlorophyta) depends on the combination of regulative morphogenetic compounds released by specific associated bacteria. Axenic Ulva gametes develop parthenogenetically into callus-like colonies consisting of undifferentiated cells without normal cell walls. In Ulva mutabilis Føyn, two bacterial strains, Maribacter sp. strain MS6 and Roseovarius strain MS2, can restore the complete algal morphogenesis forming a tripartite symbiotic community. Morphogenetic compounds ( = morphogens) released by the MS6-strain induce rhizoid formation and cell wall development in U. mutabilis, while several bacteria of the Roseobacter clade, including the MS2-strain, promote blade cell division and thallus elongation. In this study, 12 type strains of the Flavobacteriaceae family, including six Maribacter strains, were examined for their morphogenetic activity in comparison to the original MS6-strain isolated from U. mutabilis. The bioassay is based on the functional complementation of the tested Flavobacteriaceae strain with the Roseovarius MS2-strain. If the teststrain possesses morphogenetic activity complementary to the factor of the MS2-strain, the complete morphogenesis of U. mutabilis can be restored. This bioassay revealed not only the stand-alone activity of certain bacteria, but also their essential capability to take part in the orchestrated bacteria-induced morphogenesis of U. mutabilis. All Maribacter type strains isolated from Ulva could phenocopy the MS6-strain, whereas some distantly related Flavobacteriaceae and a Maribacter strain isolated from a red alga did not possess any activity. [ABSTRACT FROM AUTHOR]

Cell structure and microtubule organisation during gametogenesis of the green alga Ulva mutabilis was studied using light microscopy, transmission electron microscopy (TEM) and tubulin immunofluorescence. Microtubules in vegetative cells are organised in parallel bundles traversing the cortical cytoplasm. During gametogenesis, induced blade cells are transformed to gametangia, depending on the maturity of the algae and the removal of regulatory sporulation inhibitors. This differentiation is accompanied by formation of a conical cell projection (papilla) towards the exterior of the thallus. Microtubules form a clear, basket-like configuration converging towards the conical tip, but not reaching it. The conical microtubule structure stops below the tip, leaving a circular "opening". Parallel to the above, the cell wall of the tip is differentiated, forming a "cap". Nuclear divisions start at this stage, finally forming the nuclei of future gametes. Cytokinesis takes place by membrane furrowing and vesicle fusion, giving rise to 16 oval-shaped gametes. The conical microtubule organisation is gradually depolymerised, and a cortical, intensely fluorescing microtubule bundle is formed in each gamete. At this stage, the cap at the conical cell wall projection is removed and the exit pore opens. The biflagellate gametes remain initially motionless, connected by thin cytoplasmic bridges. Finally, they are released to the environment upon additional removal of a swarming inhibitor accumulated in the growth medium during gametogenesis. [ABSTRACT FROM AUTHOR]

Marine macroalgal biomass is a promising sustainable feedstock for biorefineries. However, the development of macroalgal biomass for industrial cultivation and processing has been slow. In terrestrial plants, highthroughput phenotyping provides rapid imaging methods to select specimens with required properties, rapidly transforming traditional breeding techniques. To foster the development of macroalgal biomass for biorefinery applications, we developed a near-infrared spectrometrybased method for rapid phenotyping of the macroalga Ulva fasciata based on its glucose, rhamnose, xylose and glucuronic acid contents. Spectral slopes were calculated as indicative of major carbohydrate content change. In addition, different spectral indices were generated to distinguish between low and high contents of glucose, rhamnose, xylose and glucuronic acid in wet and dry biomass. Since glucose is a major monosaccharide in Ulva that is fermentable to bioethanol, as an example of future application, we developed a multivariate data analysis based on partial least squares regression to predict its content in dry and wet biomass samples solely from reflectance data. These methods could provide a useful, high-throughput tool to rapidly select thalli with high carbohydrate content for further propagation and to be used for feedstock development for marine biorefineries. [ABSTRACT FROM AUTHOR]

Species of Ulva are distributed worldwide in various aquatic habitats and their morphological characters change considerably in response to environmental conditions, which makes identification in this genus problematic. All Ulva species so far described from the Persian Gulf, Iran, have been identified by classical taxonomic methods. In this study, Ulva spp. collected from the Persian Gulf were identified by combined morphological and molecular methods. We sequenced the internal transcribed spacer ITS2 and the rbcL gene in 15 specimens, representing typical morphotypes of over 50 samples. Maximum likelihood, maximum parsimony and Bayesian inference (BI) phylogenetic reconstructions using ITS and rbcL revealed clades, which we identified as Ulva chaugulii, U. paschima and U. ohnoi. These three species have not been recorded from the Persian Gulf, Iran before. The morphology of U. chaugulii differed considerably from its species description, showing further evidence for extreme intraspecific variation in morphology in this cosmopolitan genus. [ABSTRACT FROM AUTHOR]

Temperate coastal estuaries worldwide, such as Narragansett Bay, Rhode Island, are influenced by seasonal macroalgal blooms (e.g., Ulva) during warm months, whereas bloom-forming macroalgae are rarely encountered during winter. We assessed the ability of distromatic Ulva to overwinter through fragments, recruits, and/or microscopic propagules. We documented (a) small tissue fragments in sediment cores and the water column, (b) recruits and microscopic propagules on field-based settlement tiles, and (c) production of reproductive propagules, throughout the winter months. Laboratory culturing experiments indicated that both fragments and propagules are viable. Our data indicate that bloom-forming overwintering Ulva simultaneously use multiple reproductive strategies. [ABSTRACT FROM AUTHOR]

Relatively little is known about the causes of species distribution within macroalgal blooms occurring on or over soft substrata. We examine the roles of aerial exposure and desiccation in determining elevational patterns of two dominant bloom-forming ulvoid algae, Ulva lactuca and Ulvaria obscura, on the northeastern Pacific coast. These species were stressed with constant desiccation time, desiccation to a constant water potential, and desiccation to a fixed water loss. As a measure of health, we examined net photosynthesis by oxygen evolution or photosynthetic yield via pulse amplitude modulated fluorometry. By all measures, Ulva was physiologically superior in the intertidal zone. Under constant exposure, it desiccated more slowly than Ulvaria. When desiccated to a constant dryness, Ulva better maintained photosynthetic parameters. These observations are consistent with Ulva's usual dominance over Ulvaria in intertidal macroalgal blooms. Given these and other observed differences between the two species, natural resource managers should not regard the two as ecologically equivalent, even though they have similar functional forms. [ABSTRACT FROM AUTHOR]

There is confusion about the identity of laminar Ulva thalli in Italian and Mediterranean transitional systems and on the open coasts. Although some authors report the presence of both U. rigida and U. laetevirens, systematic revisions for the Adriatic and Mediterranean Seas recognise only the presence of U. laetevirens. This paper uses anatomical and environmental analyses to provide evidence for the presence of both species. The only diagnostic character that distinguishes the two is cell shape in cross section of rhizoidal and basal regions. Therefore, identification of floating thalli in these regions is not possible. The species grow and coexist in the same environments and on the same substrata, but analysis of environmental data suggests that U. rigida occurs preferentially in eutrophic environments, especially lagoon areas rich in phosphate, ammonium and phytoplankton, whereas U. laetevirens is more abundant in areas where nutrient levels are low. [ABSTRACT FROM AUTHOR]

The capacity of Ulva rigida as a bioindicator of Zn, Cu, Pb and Cd contamination in oligohaline coastal waters was investigated. Metal concentrations in U. rigida, water and sediments and several environmental variables were measured seasonally at four stations in the coastal section of the Evros River Delta, Aegean Sea. All four metals in sediments had a significant local variation; in particular, they decreased with increasing distance from the fluvial end-member of Evros River. Mean Zn, Cu, Pb and Cd concentrations in U. rigida were 61.0, 22.4, 6.1 and 1.1 μg g-1 dry weight, respectively. This macroalga, compared to other co-occurring macroalgal species, had a high metal accumulation capacity, mainly of Cu and Cd. Local patterns of Zn, Cu and Pb in U. rigida were similar to those in sediments, while that of Cd was not; moreover, Cu and Pb in U. rigida correlated positively with their sediment contents, suggesting that this seaweed satisfies the basic prerequisite for a bioindicator of these elements in oligohaline environments. No metal in U. rigida displayed a significant seasonal variation, and there was no significant variation in ambient concentrations. A negative correlation between Zn in U. rigida and water salinity was found, probably due to both a higher metal burden in the freshwater flowing in the study area and to a decrease in Zn uptake with increasing salinity; Cd in the macroalga correlated negatively with water column ammonium. [ABSTRACT FROM AUTHOR]

The photosynthetic performance of an estuarine population of Ulva rotundata Bliding was determined under natural radiation during a daily cycle. The primary production was estimated following two methods, oxygen evolution and dissolved inorganic carbon (DIC) uptake calculated from the pH change and alkalinity in the media after incubation in closed bottles. Maximum values of oxygen evolution (261 μmol O2 m­2 min­1) were reached during midday. The daily course of the DIC uptake rates was different since the maximum rate (248±10 μmol C m­2 min­1) was obtained later in the afternoon. In any case, no photoinhibition was detected by either O2 evolution or DIC uptake. Additionally, the parameters of photosynthesis vs. photon fluence density curves were similar in spite of the technique used. During the daily cycle, significant changes in CA activity and percentage of photosynthetic inhibition following the addition of an external CA inhibitor (acetazolamide) were produced. However, these changes appeared to have a limited effect on photosynthesis. On the other hand, chlorophyll a and b contents decreased drastically in the afternoon and there was not a good correlation between pigment content and photosynthesis rates. Taken into account the results obtained, the daily primary production of U. rotundata based on oxygen evolution was 20% higher than that based on DIC up-take (1.8 and 1.5 g C m­2 day­1, respectively). [ABSTRACT FROM AUTHOR]

Examines the long-term effects of full-spectrum solar radiation, solar radiation without ultraviolet light in Ulva rigida C. Agardh. Analysis of the winter levels of UV radiation; Investigation of the changes in relative growth ratem photosynthesis, and pigment content; Enhancement of relative growth rate.

The correct bionote of Estela M. Plastino is as follows: Estela M. Plastino, Marine Algae Laboratory, Institute of Biosciences, University of São Paulo, Rua do Matão 277, São Paulo 05508-090, Brazil Estela M. Plastino, associate professor and researcher at the University of São Paulo, Institute of Biosciences. The effects of phosphate on physiological responses and carbohydrate production in I Ulva fasciata i (Chlorophyta) from upwelling and non-upwelling site. [Extracted from the article]

The new species Ulva ardreana is here proposed to replace Ulva bifrons, an invalid name because no holotype was designated in the protologue. The new species consists of two to three distromatic blades arising from a short stipe, and it is easily distinguished from the other blade-like Ulva species in having a remarkable diversity in both shape and size of cells in the two layers. [ABSTRACT FROM AUTHOR]