Seaweeds from Vietnam used for functional food, medicine and biofertilizer

Several Vietnamese seaweed species have economic importance as food for humans, as industrial materials, as ingredients in traditional medicine, and as biofertilizers. The nutritional values of nine representative Vietnamese seaweed species were analyzed. In this report, all of the species studied are rich in proteins, lipids (especially polyunsaturated fatty acids), vitamins, pigments, and macro- and micro-elements. The effect of the physiological activities of the green alga, Ulva reticulata, on hepatic fatty acid metabolism were examined in mice. The results indicate that Vietnamese seaweeds are abundant and have high quality materials for industrial and agricultural purposes. Presented at the 6th Meeting of the Asian Pacific Society of Applied Phycology, Manila, Philippines.     

Present and future needs for algae and algal products

A review of the present needs, mainly for production of phycocolloids and food condiments, is given. Supply and demand vary from balanced, in some, to disproportionate in other fields. World-wide shortage of agarophytes contrasts with huge, unexploited beds of brown seaweeds.In future, partly conflicting trends will decide the needs for algae and algal products. Growth in the human population, pollution, overexploitation of land and lack of freshwater will encourage use of seaweeds. Modern biotechnology will favour this development, but will also be a serious threat to industrial exploitation of seaweeds. Future uses of marine algae will be decisively influenced by the effort put into and the results coming out of seaweed research.     

Phytogeography of seaweeds of the Azores

189 species of seaweeds have been recorded for the Atlantic archipelago of the Azores (114 Rhodophyceae, 41 Phaeophyceae and 34 Chlorophyceae). Ten of these have been described as endemic algae. The taxonomic status of these “endemics” is far from clear, however. Studies on the relatedness of this seaweed flora to seaweed floras of surrounding areas using clustering methods indicate its intermediary position between the seaweed floras of the subtropical Macaronesian Islands (Canaries Madeira and Salvages) on the one side and those of the warm temperate Eurafrican coasts on the other side. The geographic position of the Azores is NW of the other Macaronesian Archipelagos and thus nearer to the American coast. The Gulf stream may easily transport seaweeds from the Carribean to the Azores. Nevertheless, the number of species of these islands in common with the American Atlantic coast is much lower than with, for example, the W. Mediterranean. Of one group of seaweeds, viz. algae with a strictly warm temperature distribution, not a single species occurs likewise on American coasts. This absence is probably explicable because of the narrow temperature range for survival of these seaweeds. Temperatures of surface waters around the Azores during pleistocene glaciations were not much lower than they are at present. Nevertheless, it can be supposed that a number of seaweeds now occurring in the Azores have become extinct during the last glaciation. Paper presented at the XIV International Botanical Congress (Berlin, 24 July–1 August, 1987), Symposium 6-15, “Biogeography of marine benthic algae”. CANCAP-project. Contributions to the zoology, botany and paleontology of the Canarian-Cape Verdean region of the North Atlantic Ocean. No. 67.     

Climate change and disease: bleaching of a chemically defended seaweed

Disease is emerging as an important impact of global climate change, due to the effects of environmental change on host organisms and their pathogens. Climate‐mediated disease can have severe consequences in natural systems, particularly when ecosystem engineers, such as habitat‐formers or top predators are affected, as any impacts can cascade throughout entire food webs. In temperate marine ecosystems, seaweeds are the dominant habitat‐formers on rocky reefs. We investigated a putative bleaching disease affecting Delisea pulchra, a chemically defended seaweed that occurs within a global warming ‘hot‐spot’ and assessed how patterns of this phenomenon were influenced by ocean temperature, solar radiation, algal chemical defences and microbial pathogens. Warmer waters were consistently and positively correlated with higher frequencies of bleaching in seaweed populations, but patterns of bleaching were not consistently influenced by light levels. Bleached thalli had low levels of antibacterial chemical defences relative to healthy conspecifics and this was observed across entire thalli of partially bleached algae. Microbial communities associated with bleached algae were distinct from those on the surfaces of healthy seaweeds. Direct testing of the importance of algal chemical defences, done here for the first time in the field, demonstrated that they protected the seaweed from bleaching. Treatment of algal thalli with antibiotics reduced the severity of bleaching in experimental algae, especially at high water temperatures. These results indicate that bleaching in D. pulchra is the result of temperature‐mediated bacterial infections and highlight the potential for warming to influence disease dynamics by stressing hosts. Understanding the complex ways in which global change may affect important organisms such as habitat‐forming seaweeds, is essential for the management and conservation of natural resources.     

53 A Seaweed's perspective on marine reserves

In response to major changes in coastal ecosystems in recent decades, a number of governmental agencies around the world are establishing marine reserves – areas where removal of animals or plants is prohibited. Although marine reserves are touted as an ecosystem based approach to management of marine resources, the vast majority of attention on reserve design and impact focuses solely on fish. Although a few species of algae are commercially harvested, most are not. As a result, they will receive little direct benefit from protection by reserves aside from habitat protection. From the perspective of a seaweed, the primary impacts of marine reserves will therefore be indirect through species interactions. We examine the rapidly growing theoretical and empirical literature on marine reserves to anticipate the likely responses of seaweeds to exclusion of fishing. The key issues that emerge are: the trophic level of prior fishing and the dispersal scales of seaweeds relative to their competitors and consumers. The latter issue is poorly understood and poses a key challenge to phycologists if we are to effectively incorporate seaweeds into future marine reserve design.     

Biochemical characteristics of cellulose and a green alga degradation by Gilvimarinus japonicas 12-2T,and its application potential for seaweed saccharification

ABSTRACT

Cellulose is one of the major constituents of seaweeds, but reports of mechanisms in microbial seaweed degradation in marine environment are limited, in contrast to the multitude of reports for lignocellulose degradation in terrestrial environment. We studied the biochemical characteristics for marine cellulolytic bacterium Gilvimarinus japonicas 12-2^T in seaweed degradation. The bacterial strain was found to degrade green and red algae, but not brown algae. It was shown that the bacterial strain employs various polysaccharide hydrolases (endocellulase, agarase, carrageenanase, xylanase, and laminarinase) to degrade seaweed polysaccharides. Electrophoretic analysis and peptide sequencing showed that the major protein bands on the electrophoresis gel were homologous to known glucanases and glycoside hydrolases. A seaweed hydrolysate harvested from the bacterial culture was found useful as a substrate for yeasts to produce ethanol. These findings will provide insights into possible seaweed decomposition mechanisms of Gilvimarinus, and its biotechnological potential for ethanol production from inedible seaweeds.     

The influence of environmental features in the content of mycosporine‐like amino acids in red marine algae along the Brazilian coast

Mycosporine‐like amino acids (MAA) are ultraviolet screen substances synthesized by marine algae. The physiological function of these substances is related to cellular protection against UV radiation and as a protective mechanism against oxidative stress. These substances can be found mainly in the ocean, among red seaweeds. Its concentration in organisms has been related to ultraviolet radiation and availability of inorganic nitrogen in the environment. We start our study of MAA content in different species to understand if environmental conditions influence the concentration of MAAs in red seaweeds. The Brazilian coast presents abiotic factors that interact to create different physical‐chemical features in the environment. We collected 441 samples from 39 species of red seaweed easily found in the intertidal zone, in low tide, during the summer of 2015. The sampling encompassed a latitudinal gradient (3° S to 28°5′ S) at 23 points along the coast. We quantified and identified the content of MAAs in species through the method of high performance liquid chromatography. We detected for the first time the occurrence of MAAs in certain species of red algae that have not been reported to contain MAAs before. We confirmed that some environmental factors influenced the content of MAAs. Enhanced MAA contents, for example, were found in environments with a basic pH, a high ultraviolet index, and high concentrations of phosphate and nitrate. Salinity, dissolved oxygen and variations of sea surface temperature also influenced, in a secondary way, MAA content in algae in their natural environments.     

Bulk hydrogen stable isotope composition of seaweeds: Clear separation between Ulvophyceae and other classes

Little is known about the bulk hydrogen stable isotope composition (δ²H) of seaweeds. This study investigated the bulk δ²H in several different seaweed species collected from three different beaches in Brazil, Australia, and Argentina. Here, we show that Ulvophyceae (a group of green algae) had lower δ²H values (between ?94‰ and ?130‰) than red algae (Florideophyceae), brown algae (Phaeophyceae), and species from the class Bryopsidophyceae (another group of green algae). Overall the latter three groups of seaweeds had δ²H values between ?50‰ and ?90‰. These findings were similar at the three different geographic locations. Observed differences in δ²H values were probably related to differences in hydrogen (H) metabolism among algal groups, also observed in the δ²H values of their lipids. The marked difference between the δ²H values of Ulvophyecae and those of the other groups could be useful to trace the food source of food webs in coastal rocky shores, to assess the impacts of green tides on coastal ecosystems, and to help clarify aspects of their phylogeny. However, reference materials for seaweed δ²H are required before the full potential of using the δ²H of seaweeds for ecological studies can be exploited.     

Occurrence of conjugated polyenoic fatty acids in seaweeds from the Indian Ocean

Three species of red marine macro algae (Rhodophyta) from the Indian Ocean were analysed for the occurrence of conjugated polyenes. The composition of different lipid classes in these seaweeds along with their fatty acid composition has also been reported. Analysis of lipid classes of these seaweeds revealed that both Acanthophora spicifera (Ceramiales, Rhodophyta) and two species of Gracilaria, viz. G. edulis and G. folifera (Gracilariales, Rhodophyta) were rich in glycolipids followed by neutral- and phospholipids. The fatty acid composition of these seaweeds revealed C16:0 as the predominant fatty acid in all three species. However, A. spicifera had significantly higher amounts of eicosapentaenoic acid (EPA) and arachidonic acid (AA) as compared to negligible amount of these fatty acids in both species of Gracilaria. The red seaweed Acanthophora spicifera contained conjugated eicosapentaenoic acid (CEPA) and conjugated arachidonic acid (CAA) in all lipid classes except glycolipids.     

A Multinucleated Marine Amoeba Which Digests Seaweeds1

Marine amoebae were isolated during a search for organisms which degrade cell walls of seaweed. One of the isolates, a multinucleated amoeba (referred to here as Amoeba-I-7 or Am-I-7) was isolated from live tissues of the brown seaweed Sargassum muticum. It digested a variety of brown and red seaweeds including their walls and cuticles. Axenic clone cultures were isolated from cells that migrated on agar. Cultures were grown on agar or in liquid media. Seaweeds, seaweed wall extracts, and unicellular algae were tested as food sources.     

18S rDNA gene metabarcoding of microeukaryotes and epi-endophytes in the holobiome of seven species of large brown algae

Brown algae (Phaeophyceae) are habitat-forming species in coastal ecosystems and include kelp forests and seaweed beds that support a wide diversity of marine life. Host-associated microbial communities are an integral part of phaeophyte biology, and whereas the bacterial microbial partners have received considerable attention, the microbial eukaryotes associated with brown algae have hardly been studied. Here, we used broadly targeted “pan-eukaryotic” primers (metabarcoding) to investigate brown algal-associated eukaryotes (the eukaryome). Using this approach, we aimed to investigate the eukaryome of seven large brown algae that are important and common species in coastal ecosystems. We also aimed to assess whether these macroalgae harbor novel eukaryotic diversity and to ascribe putative functional roles to the host-associated eukaryome based on taxonomic affiliation and phylogenetic placement. We detected a significant diversity of microeukaryotic and algal lineages associated with the brown algal species investigated. The operational taxonomic units (OTUs) were taxonomically assigned to 10 of the eukaryotic major supergroups, including taxonomic groups known to be associated with seaweeds as epibionts, endobionts, parasites, and commensals. Additionally, we revealed previously unrecorded sequence types, including novel phaeophyte OTUs, particularly in the Fucus spp. samples, that may represent fucoid genomic variants, sequencing artifacts, or undescribed epi-/endophytes. Our results provide baseline data and technical insights that will be useful for more comprehensive seaweed eukaryome studies investigating the evidently lineage-rich and functionally diverse symbionts of brown algae.     

Seaweed micropropagation techniques and their potentials: an overview

The seaweed industry worldwide uses 7.5–8.0 million tonnes of wet seaweeds annually with a majority of it derived from cultivated farms, as the demand for seaweed based-products exceeds the supply of seaweed raw material from natural stocks. The main advantage of cultivation is that it not only obviates overexploitation of natural populations but also facilitates the selection of germplasm with desired traits. To enhance the economic prospects of seaweed cultivation, varied practices, such as simple and cost effective cultivation methods, use of select germplasm as seed stock coupled with good farm management practices, etc., are adopted. Nevertheless, in vitro cell culture techniques have also been employed as they facilitate development and propagation of genotypes of commercial importance. There are more than 85 species of seaweeds for which tissue culture aspects have been reported. Although the initial aim of these techniques focuses mostly on genetic improvement and clonal propagation of seaweeds for mariculture, recently the scope of these techniques has been extended for use in bioprocess technology for production of high value chemicals of immense importance in the pharmaceutical and nutraceutical sectors. Recently, there has been a phenomenal interest in intensifying seaweed tissue and cell culture research to maximize the add-on value of seaweed resources. This paper deals with the status of seaweed micropropagation techniques and their applications in the context of the marine biotech industry. Further, it also provides an analysis of the problems to be resolved for removing the barriers that are impeding the true realization of potentials offered by these techniques for sustainable development and utilization of seaweed resources.     

SEASONALITY OF SELECTED NUTRITIONAL CONSTITUENTS OF EDIBLE DELMARVA SEAWEEDS

Edible seaweeds have not been thoroughly explored for food, medicinal, or industrial purposes in the United States. This study compared selected proximate constituents of three edible seaweed species (Ulva lactuca L., Fucus vesiculosus L., and Gracilaria tikvahiae McLachan) at two sites for possible future development as a food crop on the Delmarva Peninsula. Sampling was conducted bimonthly at Chincoteague Memorial Park, Virginia, and Indian River Inlet, Delaware, from 2005 to 2008. Proximate constituents of moisture, ash, dietary fiber, proteins, and fat were measured seasonally and calorific values were calculated. Data were analyzed using correlation, paired samples t‐tests and one‐ and two‐way ANOVA. Significant variations in the proximate constituents were found among seasons, species, and between sites. The brown seaweed (Fucus) at both sites had higher fiber, fat, and ash (mineral) content than the green (Ulva) or the red (Gracilaria). Ulva and Gracilaria had higher protein content than Fucus. Seaweeds from Delaware had more fat, ash, and protein than from Virginia, potentially because of the more polluted, nutrient rich environment at the Delaware site. Positive correlations between seaweed fat and protein content may indicate an increase in the synthesis of both components under optimal growth conditions. Species' physiology differences and the water quality at the two sites likely impacted proximate constituent values. This study contributed new information to the existing body of knowledge in the areas of nutrition and ecology of seaweeds and their potential as a cash crop.     

A risk assessment of aquarium trade introductions of seaweed in European waters

Aquaculture and maritime traffic have been identified as the main vectors for introductions of alien marine species. Except for one notorious case of Caulerpa taxifolia, the role of aquarium trade towards the introduction of alien seaweeds has been largely unassessed. Here, we address the risk of accidental release of seaweed species from the aquarium trade market in European waters. We assessed the importance and diversity of seaweed species in the European online aquarium retail circuit. Our web survey revealed more than 30 genera available for online sale into Europe, including known introduced and invasive species. A second aspect of the study consisted in sampling algal diversity found in aquaria. While allowing direct and accurate identification of the specimens, this approach was targeting not only ornamental species, but also seaweeds that may be accidentally present in the aquarium circuit. By DNA-barcoding we identified no less than 134 taxa, 7 of which are flagged as introduced in Europe and 5 reported as invasive. Climate envelope models show that at least 23 aquarium species have the potential to thrive in European waters. As expected by the tropical conditions in most aquaria, southern Atlantic regions of Europe and the Mediterranean are the most vulnerable towards new introductions. Further predictions show that this risk will increase and shift northwards as global warming proceeds. Overall our data indicate that aquarium trade poses a potential risk of new seaweed introductions, and calls for a cautious approach.     

Distribution of rare earth elements in seaweed: implication of two different sources of rare earth elements and silicon in seaweed

Rare earth elements (REEs) and Si in five species of seaweed, ambient surface seawaters, and suspended solid particles in the seawaters were determined separately. Inductively coupled plasma mass spectrometry (ICP-MS) was used for REEs and inductively coupled plasma emission spectrometry (ICP-ES) was used for Si in order to evaluate REEs as a tracer in seaweeds and to understand the source of inorganic elements, especially Si, in seaweeds. Two different REE patterns, one similar to that of the seawater solution and another resembling that of suspended particles, were observed in seaweeds, and the variation of REE patterns seems to show a clear dependence on the abundance of Si. The REE pattern and Si concentration seem to vary depending on the division: green and red algae showed REE patterns similar to that of suspended particles, but brown algae showed patterns closer to that of seawater solutions and relatively lower Si concentration. The possibility of contamination from silicate particles on the surface of seaweeds was ruled out for several reasons. Silicate particles, not dissolved silicate, have been identified as the direct source of REEs and Si in plants ( Fu et al. 1998 ), and seaweeds are no exception. We have to consider that seaweeds can take up Si from suspended particles through their blade or branches. From the appearance of tetrad-effect-like variation of REEs, Si is assumed to enter a dissolved state just before the particles are taken up. From the results of a sonication experiment, REEs, once taken up as silicate particles, seem to be separated from Si in the thallus.     

Contemporary Gathering Practice and Antioxidant Benefit of Wild Seaweeds in Hawai’i

Contemporary Gathering Practice and Antioxidant Benefit of Wild Seaweeds in Hawai’i. Wild-gathered seaweeds (limu) are a prominent component of Native Hawaiian diet and culture, but are understudied for their nutritional benefits and contemporary cultural use. This study uses a combination of ethnographic, pharmacological, and ecological approaches to document contemporary levels of wild seaweed gathering and consumption, and it explores the impact of cultivation and eutrophication on the disease-preventive benefits wild seaweeds may provide. Levels of gathering and consumption of seaweed were assessed with surveys of high school students and interviews with adult limu gatherers on O’ahu island, Hawai’i. Antioxidant activity was assessed with laboratory-based assays. Almost all students surveyed reported consuming cultivated seaweeds, one-third reported having consumed wild seaweeds, and one-fifth had gathered them, confirming that gathering practice and traditional diet have persisted in Hawai’i despite major social and environmental change. Wild gathering was three times as high and consumption 60% more prevalent among Native Hawaiians compared to non-Hawaiian students. Further, students with a parent who gathered limu were six times more likely to have gathered limu themselves, asserting the importance of within-family transmission to cultural continuity. A larger proportion of male than female Hawaiian students reported gathering wild seaweeds, indicating a cultural shift from pre-Contact Hawai’i, when women were the predominant gatherers and consumers of limu. The wild seaweeds assessed demonstrated higher levels of antioxidant activity than did cultivated seaweeds. Eutrophication was correlated with a decline in antioxidant activity, indicating that changing ocean conditions may alter the nutritional quality of this traditional food. Today, nearly all students are receiving some antioxidant benefits from seaweed, with Native Hawaiian youth from families that gather seaweed most likely to receive this health benefit. Conservation and restoration of near-shore environments to promote native edible seaweeds in pollution-free areas would provide greater opportunities for Native Hawaiian gathering practice and would support Native Hawaiian health.     

Sustainable harvesting of wild seaweed resources

Abstract

Macroalgae have played an important role in coastal communities for centuries. In the past, they have been harvested and gathered from shorelines around the world for traditional uses such as food, animal feed and a crude fertilizer (marine manure). Today, seaweeds are used in a multitude of applications with expanding global industries based on hydrocolloids, cosmetics and food supplements, and also as a potential biofuel source. However, of the approximately 10?000 algal species reported to exist, only a small number are commercially utilized. While representing only a small fraction of total global seaweed production, harvesting and gathering ‘wild’ seaweeds has had, and continues to have, an integral role in many coastal societies, often being intrinsically linked to the cultural identity of those coastal communities. Today, 32 countries actively harvest seaweeds from wild stocks, with over 800?000 t harvested annually from natural beds. It is vitally important that seaweeds are utilized sustainably and that natural resources are effectively managed by coastal communities with vested interests around the world. As the popularity of seaweeds increases and the use of less traditional species with novel applications comes to the fore, it is critically important to make certain that the sustainability of the resource is ensured given the increased pressures of harvesting. Issues exist regarding ownership of the resource and its over-exploitation, and the implementation of environmentally damaging harvesting techniques must be avoided. Resource scientists, managers, conservationists, governments, and other stakeholders need to be proactive in the sustainable management of these vulnerable, yet valuable, resources.     

Heavy metals dynamics in seaweeds and seagrasses in Bahía Magdalena,B.C.S., México

The process of metal bioaccumulation in marine food chains is poorly understood because very little data is available on metal concentration at different trophic levels and their temporal or spatial variation. Because of that, we were interested to (1) determine the concentration range of heavy metals in seaweed and seagrasses species in Magdalena Bay; (2) describe the spatial and temporal variation of heavy metal concentrations in the seaweeds and seagrasses. Seasonal collections were done at Estero Banderitas in November 2004, February, and April 2005 wherein we divided the estuary into three major areas (upper, middle, and lower), and within each area, two sites were selected. Our results showed that iron, copper, and magnesium were the most significant metals found in seagrasses, red, and green algae. We found significant more variation in temporal heavy metal concentrations in relation to the maximum abundance in the samples and spatial variation in relation to the studied taxa suggesting that hervibores have a differential intake of the metals. Also, our results suggest that heavy metals might be incorporated regularly in the diet of many herbivorous animals with severe consequences to their health. Management strategies for these species should consider monitoring the levels of metals.