Brown seaweeds as a feed additive for Litopenaeus vannamei reared in a biofloc system improved resistance to thermal stress and white spot disease

Journal of Applied Phycology - This study evaluated the combined use of the brown seaweeds Sargassum filipendula (S) and Undaria pinnatifida (U) dry biomass as feed additive for Pacific white...     

The introduced alga Undaria pinnatifida (Laminariales,Alariaceae) in the lagoon of Venice

Since its appearance in 1992 in the lagoon of Venice, the brown algae Undaria pinnatifida (kelp) has gradually expanded along the banks of canals both at Chioggia and Venice, becoming the dominant species in the local algal community chiefly from February to July. In Chioggia Island, where another brown seaweed (Sargassum muticum) is present since 1992, the spreading of Undaria reaches a plateau. In Venice Island, instead, the colonisation process is still in progress. During 1999, the kelp has colonised the main canals (e.g. The Grand Canal) and, subsequently, the small inner ones. In order to evaluate the dynamics of substrate re-colonisation by Undaria, two mechanical eradications were carried out during (March) and after the fertile period (July) of the algae. Such experimental manipulations provided evidence of the fast re-colonisation potential of the algae mainly attributable to its efficient reproductive system. Eradication made during the fertile period, in fact, permitted the kelp development during the following year, while re-colonisation has started 2 years later where eradication was performed after the reproductive period. A significant decrease in the surface covered by other species has been observed both in shallow (Ulva rigida, Enteromorpha spp., Antithamnion pectinatum, Chondracanthus acicularis) and deeper areas (Rhodymenia ardissonei) during the period of maximum development of U. pinnatifida. On the basis of the results of this study, the following conclusions can be drawn: (1) the alga U. pinnatifida is continuously expanding in lagoon environments of Venice; (2) in order to limit its spreading, mechanical eradications would be done on a large spatial scale and before the zoospores release; (3) there is suggestive evidence of competition between Undaria and the remaining indigenous algae.     

Fucoxanthin as the major antioxidant in Hijikia fusiformis, a common edible seaweed

The radical scavenging activity of Japanese edible seaweeds was screened by the DPPH (1-diphenyl-2-picrylhydrazyl) assay to evaluate the DPPH radical scavenging activity in organic extracts. The fresh brown alga Hijikia fusiformis showed the strongest DPPH radical scavenging activity, followed by Undaria pinnatifida and Sargassum fulvellum. The major active compound from Hijikia fusiformis in its acetone extract was identified as fucoxanthin by 13C-NMR spectroscopy.     

CONTRASTING LIFE HISTORIES AND DEMOGRAPHIES OF LAMINARIAN AND FUCOID ALGAE

Introductions of non-native macroalgae and the subsequent displacement of native species are globally becoming more frequent. The algal genera Undaria, Sargassum , Caulerpa and Codium have been identified as being particularly invasive. An overview on the present knowledge on macroalgal introductions in the Australian region is presented and options for management are discussed, mostly using examples from studies on the introduced Japanese kelp, Undaria pinnatifida. Undaria pinnatifida was first detected in Tasmania, Australia in the early 1980's. Since then, its range has expanded despite eradication efforts. Long distance jumps appear to be the major mode of spread of U. pinnatifida in Tasmania. Studies are underway to distinguish the relative importance of spore dispersal, drift of adult plants and anthropogenic factors in spreading this invasive kelp. Although information on the real impacts of U. pinnatifida and other introduced macroalgae is sparse, the development of management and control strategies is of vital importance to prevent further spread and translocation of these "pest" species.     

褐藻77 K荧光特异性研究

测定了裙带菜、叉开网地藻、海带、囊藻、海蒿子、鼠尾藻、萱藻和水云等8种褐藻的77K荧光光谱并同菠菜和红藻条斑紫菜作了比较。结果表明与红藻和高等植物明显不同,褐藻没有作为PSⅠ特征的730 nm荧光峰。按荧光主峰的波长,可以分为二种类型：裙带菜、叉开网地藻、海带和囊藻的荧光主峰位于690 nm,海蒿子、萱藻、水云和鼠尾藻的荧光主峰在705-720 nm。这种77K荧光特异性预示褐藻同高等植物之间在PSⅠ结构上的差异。     

Water-borne cues of a non-indigenous seaweed mediate grazer-deterrent responses in native seaweeds, but not vice versa

Plants optimise their resistance to herbivores by regulating deterrent responses on demand. Induction of anti-herbivory defences can occur directly in grazed plants or from emission of risk cues to the environment, which modifies interactions of adjacent plants with, for instance, their consumers. This study confirmed the induction of anti-herbivory responses by water-borne risk cues between adjoining con-specific seaweeds and firstly examined whether plant-plant signalling also exists among adjacent hetero-specific seaweeds. Furthermore, differential abilities and geographic variation in plant-plant signalling by a non-indigenous seaweed as well as native seaweeds were assessed. Twelve-day induction experiments using the non-indigenous seaweed Sargassum muticum were conducted in the laboratory in Portugal and Germany with one local con-familiar (Portugal: Cystoseira humilis, Germany: Halidrys siliquosa) and hetero-familiar native species (Portugal: Fucus spiralis, Germany: F. vesiculosus). All seaweeds were grazed by a local isopod species (Portugal: Stenosoma nadejda, Germany: Idotea baltica) and were positioned upstream of con- and hetero-specific seaweeds. Grazing-induced modification in seaweed traits were tested in three-day feeding assays between cue-exposed and cue-free (?=?control) pieces of both fresh and reconstituted seaweeds. Both Fucus species reduced their palatability when positioned downstream of isopod-grazed con-specifics. Yet, the palatability of non-indigenous S. muticum remained constant in the presence of upstream grazed con-specifics and native hetero-specifics. In contrast, both con-familiar (but neither hetero-familiar) native species reduced palatability when located downstream of grazed S. muticum. Similar patterns of grazer-deterrent responses to water-borne cues were observed on both European shores, and were almost identical between assays using fresh and reconstituted seaweeds. Hence, seaweeds may use plant-plant signalling to optimise chemical resistance to consumers, though this ability appeared to be species-specific. Furthermore, this study suggests that native species may benefit more than a non-indigenous species from water-borne cue mediated reduction in consumption as only natives responded to signals emitted by hetero-specifics.     

Antiviral compounds in extracts of Korean seaweeds: Evidence for multiple activities

Extracts of 13 Korean seaweeds, previously shown to contain antiviral activity, were investigated in more detail in order to learn the nature of the antiviral compounds and their mechanisms of action. One extract, from Codium fragile, was active against all three test viruses (herpes simplex, HSV; Sindbis, SINV; polio), whereas the others were more selective. Thus four species, Enteromorpha linza, Colpomenia bullosa, Scytosiphon lomentaria, and Undaria pinnatifida, were active against HSV and SINV, but not poliovirus. The other eight were active against either HSV or SINV. In all cases there was evidence for photosensitizers, since the antiviral activities required or were enhanced substantially by light. In general UVA (long wave ultraviolet) was much more effective than visible light in promoting activity, although the extract of Sargassum sagamianum could be activated equally by either. In experiments to determine the site of action of these antiviral extracts, the predominant activity was virucidal (i.e. direct inactivation of virus particles), rather than inhibition of virus replication, although Sargassum sagamianum also could protect cells against subsequent virus infection. These results imply that different antiviral compounds are present among the extracts, and furthermore the activities cannot be explained in terms of common ingredients such as polysaccharides or tannins. We suggest that seaweeds may be a source of potentially useful and interesting antiviral compounds. This revised version was published online in June 2006 with corrections to the Cover Date.     

Potential Economic seaweeds of Hengchun peninsula,Taiwan

There are 25 genera and 76 species of economically important marine algae found in the Hengchun Peninsula. The greatest number of useful species is found in the Rhodophyta. Sargassum is the most common genus of the Phaeophyta and has the largest biomass and the widest distribution, but fewer useful species. The local people harvest seaweeds from natural beds for food, fodder, fish bait, fertilizer and medical purposes. However, only a few of the available seaweeds are used and in small quantities. Most of the species are seasonal and more abundant in spring and winter than in the summer. Four genera,Sargassum,Enteromorpha,Ulva andCodium have large standing crops and are widely distributed in the coastal water. Production of the other genera is lower. There are many other useful seaweeds present in this area, some of which are also used as landscape plants in aquaria and as fertilizer in horticulture. The potential commercial uses forHalymenia microcarpa are also briefly discussed.     

SIZE STRUCTURE AND DYNAMICS IN A POPULATION OF SARGASSUM MUTICUM (PHAEOPHYCEAE)

Sargassum muticum (Yendo) Fensholt is an introduced brown seaweed with a very distinctive seasonal growth cycle on European shores. The present study links the dynamics of a population of S. muticum with the seasonal growth cycle of the species and the density-dependent processes operating throughout this cycle. Results indicate that both growth cycle and intraspecific competition influenced the structure and population dynamics. Size inequality increased during the slow growth phase (autumn–winter) of the 2-year study. Mechanisms generating inequality of size could be the existence of asymmetric competition and the inherent differences in growth rates between old (regenerated) and new thalli (recruits). Inequality of size distributions decreased progressively during the last months of the growth phase (spring–summer) and could be related to a process of self-thinning. There was a negative biomass–density relationship (as a measure of biomass accumulation-driven mortality) that confirms the importance of self-thinning as a major demographic factor in the S. muticum population.     

Assessment of the seaweed-seagrass resource of Mararison Island,Culasi, Antique,Philippines*

A bimonthly sampling of the seaweed-seagrass resource of Mararison Island, Culasi Antique, was undertaken over 1 year to assess the species composition, similarity of taxa, and biomass (dry weight [d.w.] g m^?2) at seven localities. A total of 45 species was identified: 17 Chlorophyta, seven Phaeophyta, 15 Rhodophyta, one Cyanophyta and five seagrasses. Except for some Rhodophyta and Syringodium isoetifolium (Ascherson) Dandy, the occurrence of species between stations was not significantly different; however, differences in biomass between sampling time (month) were significant. Identical taxa between stations were determined. The highest (40) and lowest (22) number of species collected were in May and July, respectively. The species were most abundant from March to May (dry months) and sparse from July to September (wet months). The most abundant species were: Sargassum polycystum C. Agardh (399 g m^?2) (Phaeophyta), Dictyosphaeria cav-ernosa (Forsskat) Borgesen (43.1 g m^?2) (Chlorophyta), Acanthopeitis japonica Okamura (97.2 gm^?2) (Rhodophyta) and Thalassia hemprichii (Ehrenberg) Ascherson (1370 g m^?2; seagrass). The Phaeophyta were abundant in March, and the Chlorophyta and Rhodophyta in May, while the seagrasses were abundant in September. Some species occurred only during the dry months: two Phaeophyta, nine Chlorophyta and five Rhodophyta. All the seagrasses were found year-round. Almost all of the seaweeds (39/45) were found associated with seagrass. The number of seaweeds in Mararison Island was higher than for seagrasses but the total biomass of the latter was much higher than the combined biomass of the seaweeds.     

Laboratory experiment to determine the potential of two macroalgae from the Russian Far-East as biofilters for integrated multi-trophic aquaculture (IMTA)

Two local macroalgal species (Undaria pinnatifida and Gracilaria vermiculophylla) were tested in laboratory experiments to determine their nutrient uptake potential and their physiological response to waste water effluents from a mariculture project on bivalve mollusks (mussels). No negative effects on the growth and photosynthesis rates of the algae were detected. High nutrient uptake rates and high nutrient removal efficiency were measured in both tested species. We propose that U. pinnatifida be introduced into IMTA systems during the cold-water season to remove nutrients from cultured animals. The culture of this species can be alternated with that of G. vermiculophylla during warm-water season in order to provide a longer biofiltration period.     

Distribution of Diacylglycerylhydroxymethyltrimethyl-{beta}-alanine (DGTA) and Phosphatidylcholine in Brown Algae

Lipids were analyzed in thirteen species of brown algae collectedat the seashore near Tokyo, Japan. Diacylglycerylhydroxymethyltrimethyl-ß-alanine(DGTA), a recently identified betaine lipid, was found as amajor lipid component in eight species of brown algae examined,namely, Ishige okamurai, Dictyota dichotoma, Pachydictyon coriaceum,Padina arborescens, Hizikia fusiformis, Sargassum horneri, S.ringgoldianum and S. thunbergii. However, phosphatidylcholine(PC) was not detected in any of these algae except I. okamurai.By contrast, PC was found as a major lipid component in fiveother species, namely, Colpomenia sinuosa, Endarachne binghamiae,Scytosiphon lomentarius, Eisenia bicyclis, Undaria pinnatifida.These algae in turn did not contain detectable amounts of DGTA.The fatty acid composition of four selected species, S. lomentarius,U. pinnatifida, D. dichotoma and H. fusiformis, was also studied.The fatty acid components of DGTA in D. dichotoma and H. fusiformiswere similar to those of PC in U. pinnatifida, the major componentsbeing 16:0, 18:2 and 20:46 (also 16:1 in D. dichotoma). (Received December 14, 1990; Accepted April 10, 1991)     

Intraspecific variation in palatability and defensive chemistry of brown seaweeds: effects on herbivore fitness

When offered a choice between brown seaweeds (Phaeophyta) from shallow inshore populations versus deeper offshore populations along the mid-Atlantic coast of the United States of America, the herbivorous amphipod Ampithoe longimana consistently preferred plants from the inshore populations. This was the case for three species (Dictyota menstrualis, Spatoglossum schroederi, and Sargassum filipendula) collected from each of a single inshore and offshore site, and for one species (D. menstrualis) collected from each of three inshore and three offshore sites. Bioassay-guided fractionation of chemical crude extracts from D. menstrualis suggested that the relative unpalatability of the offshore plants was due to the lipid-soluble secondary metabolites 4beta-hydroxydictyodial A and 18, O-dihydro-4beta-hydroxydictyodial A 18-acetate, along with minor compounds that were not fully identified. The inshore-offshore pattern did not appear to result from induction of defenses due to herbivory by mesograzers, as mesograzer densities were higher on the more palatable inshore plants. Herbivore feeding preferences for inshore versus offshore seaweeds matched the effects of those seaweeds on their fitness. When juvenile amphipods were raised on inshore versus offshore tissues of D. menstrualis, amphipod survivorship, growth, and ovulation were significantly suppressed on the offshore compared to the inshore tissues. Few previous investigations have studied intraspecific variance in seaweed palatability. We extend these by showing that between-population differences in palatability can persist for several years and by demonstrating that this variance is chemically based and has dramatic effects on herbivore fitness.     

Antibacterial activities of marine epibiotic bacteria isolated from brown algae of Japan

One hundred and sixteen epibiotic bacteria were isolated from the surface of nine species of brown algaeSargassum serratifolium, Sargassum fusiforme, Sargassum filicinum, Padina arborescens, Undaria pinnatifida, Petalonia fascia, Colpomenia sinuosa, Scytosiphon lomentaria andEcklonia cava which were collected at Awaji Island, Japan. Primary screening results using disc-diffusion assay revealed that, among the bacteria isolated 20% of epibiotic bacteria exhibited antibacterial activity. Among them, 10 bacteria which showed high antibacterial activity were further studied for their ability against (i) a set of fouling bacteria isolated from marine natural biofilm, (ii) some luminescentVibrio andPhotobacterium species and (iii) a panel of pathogenic bacteria. In general, inhibitory activities were high or moderate against fouling bacteria,Vibrio andPhotobacterium species, while they were found to be low against pathogenic bacteria tested. The phylogenetic analysis using 16S rRNA sequencing revealed that all of the bacteria with high antibacterial activity showed a close affiliation with genusBacillus. This result suggested that the genusBacillus is efficient producers of of antibacterial compounds and these epibiotic bacteria isolated are highly successful colonizers on macroalgal surfaces.     

海藻多糖的单糖组成对体外抗氧化活性的影响

比较广西北部湾石莼(Ulva lactuca L.)、海带(Laminaria japonica)、裙带菜(Undaria pinnatifida Surin-gar)、紫菜(Porphyra)的单糖组成及抗氧化活性的差异,揭示多糖结构与其体外抗氧化活性的关系。利用PMP柱前衍生化HPLC分析海藻多糖的单糖组成,采用羟自由基清除试验、超氧阴离子自由基清除试验及DPPH自由基清除试验指征其体外抗氧化活性,结果表明,4种海藻多糖的单糖组成在主成分空间分布离散,石莼及紫菜主要由葡萄糖组成,海带主要由甘露糖组成,裙带菜则主要由半乳糖组成;其体外抗氧化活性存在显著差异,裙带菜多糖对DPPH的清除能力(半抑制浓度IC₅₀值为0. 56±0. 02 mg/mL)显著高于其他3种海藻多糖;石莼、裙带菜与海带对羟自由基均有较强的清除活性,而紫菜多糖对羟自由基的清除能力较差(IC₅₀值为26. 59±0. 98mg/mL);石莼与裙带菜对超氧阴离子的清除活性较强,显著高于海带与紫菜,其中石莼显著高于裙带菜,IC₅₀值分别为1. 61±0. 17、2. 73±0. 06 mg/mL。相关性分析及冗余分析结果表明,对抗氧化活性影响较为显著的因子为葡萄糖(Glc)、核糖(Rib)、木糖(Xyl)(P <0. 01)。     

Predictable spatial escapes from herbivory: how do these affect the evolution of herbivore resistance in tropical marine communities?

Summary Between-habitat differences in macrophyte consumption by herbivorous fishes were examined on three Caribbean and two Indian Ocean coral reefs. Transplanted sections of seagrasses were used as a bioassay to compare removal rates in reef-slope, reef-flat, sand-plain, and lagoon habitats. Herbivore susceptibility of fifty-two species of seaweeds from these habitats was also measured in the field. Seagrass consumption on shallow reef slopes was always significantly greater than on shallow reef flats, deep sand plains, or sandy lagoons. Reef-slope seaweeds were consistently resistant to herbivory while reef-flat seaweeds were consistently very susceptible to herbivory. This pattern supports the hypothesis that defenses against herbivores are costly in terms of fitness and are selected against in habitats with predictably low rates of herbivory.Sand-plain and lagoon seaweeds showed a mixed response when placed in habitats with high herbivore pressure; most fleshy red seaweeds were eaten rapidly, most fleshy green seaweeds were eaten at intermediate rates, and most calcified green seaweeds were avoided or eaten at very low rates. Differences in susceptibility between red and green seaweeds from sand-plain or lagoon habitats may result from differential competitive pressures experienced by these seaweed groups or from the differential probability of being encountered by herbivores. The susceptibility of a species to removal by herbivorous fishes was relatively consistent between reefs. Preferences of the sea urchin Diadema antillarum were also similar to those of the fish guilds.Unique secondary metabolites were characteristic of almost all of the most herbivore resistant seaweeds. However, some of the herbivore susceptible species also contain chemicals that have been proposed as defensive compounds. Genera such as Sargassum, Turbinaria, Thalassia, Halodule, and Thalassodendron, which produce polyphenolics or phenolic acids, were consumed at high to intermediate rates, suggesting that these compounds are not effective deterrents for some herbivorous fishes. Additionally, potential for the production of the compounds caulerpin, caulerpicin and caulerpenyne in various species of Caulerpa did not assure low susceptibility to herbivory.Heavily calcified seaweeds were very resistant to herbivory, but all of these species also produce toxic secondary metabolites which makes it difficult to distinguish between the effects of morphological and chemical defenses. Predictions of susceptibility to herbivory based on algal toughness and external morphology were of limited value in explaining differing resistances to herbivory.     

Inhibition of Taq DNA polymerase by seaweed extracts from British Columbia, Canada and Korea

Fifty-nine species of marine macrophytes from the coasts of British Columbia, Canada and Korea have been screened for the presence of PCR inhibitors, namely inhibitors of Taq DNA polymerase. Eleven of the species displayed some inhibitor activity. At the concentration of 5 μg of methanol extract in 25μL reaction mixture of PCR containing 1.5 unit of Taq DNA polymerase, one (Ulva sp.) of 8 Chlorophyta, eight (Colpomenia bullosa, Ecklonia cava, Endarachne binghamiae, Fucus distichus, Hizikia fusiformis, Sargassum confusum, Sargassum sagamianum, and Sargassum thunbergii) of 28 Phaeophyta, and one (Symphyocladia latiuscula) of 34 Rhodophyta showed inhibition in PCR amplification. In the case of the water extract, two (Cladophora columbiana, Ulva sp.) Chlorophyta, seven (Endarachne binghamiae, Fucus distichus, Hizikia fusiformis, Sargassum confusum, Sargassum sagamianum, Sargassum horneri, Scytosiphon dotyi) Phaeophyta, no Rhodophyta and one (Phyllospadix scouleri) seagrass showed inhibition in PCR amplification. the methanol fraction of Sargassum confusum and the water fraction of Fucus gardneri (mid–intertidal) have been found to inhibit PCR at level as low as 0.5 μg in 25μL of PCR reaction mixture. This revised version was published online in August 2006 with corrections to the Cover Date.     

Diurnal, horizontal and vertical dispersal of kelp-associated fauna

The kelp Laminaria hyperborea is host for a rich fauna of mobile invertebrates. Dispersal patterns of these animals may be crucial for their availability to visual predators like fish, which are known to search for food in these productive habitats. Diurnal, horizontal and vertical dispersal within and out of the kelp forest were studied by analysing colonization of artificial substrata placed among kelps. The species composition of the fauna was different on three parts of the kelp: lamina, stipes (with epiphytes) and holdfast. The artificial substrata were colonized mainly by species associated with kelp. More species and individuals colonized the artificial substrata at night than during the day. The most abundant faunal groups on the kelps and the artificial substrata were amphipods and gastropods. Both groups dispersed at a significantly higher rate at night than during the day. Rapid horizontal dispersal out of the kelp forest was found. The artificial substrata were also colonized quickly by kelp fauna at all vertical levels inside and above the kelp forest. However, species associated with the kelp holdfast tended to disperse close to the bottom, while stipe-associated fauna moved through all parts of the kelp forest and even above the canopy layer. A high dispersal rate appears common amongst the mobile species living on kelp and seems to be advantageous, despite the risks involved in emigrating from the habitat and being exposed to predators. Higher activity at night may reduce availability to predators.     

Mass culture of Undaria gametophyte clones and their use in sporeling culture

Hydrobiologia - Undaria pinnatifida (Harv.) Sur. is one of the three main seaweed species under commercial cultivation in China. In the mid-1990s the annual production was about 20 000 tons...     

基于生境适宜性指数模型的俚岛海黍子生境层级分布

为了深入了解海黍子生境,利用模型对山东俚岛海黍子生境进行适宜性分析,分别选取温度、盐度、水深、浊度、底质、无机氮浓度、磷酸盐浓度和距海藻床距离8种环境因子,通过层次分析法赋值因子权重,结合空间分析方法建立了海黍子HSI模型。利用该模型对山东俚岛近岸海域2018年春、秋两季的环境因子调查结果进行了海黍子生境分析。结果表明: 研究区域内的海黍子海藻床区域主要由极佳生境和适宜生境组成,春季和秋季的分布面积分别占14.2%和18.6%。海黍子生境层级分布随季节而变化,且不同季节的生境层级具有一定的空间重合性。温度和磷酸盐浓度的适宜性变化具有明显的季节性差异,是导致俚岛海黍子HSI季节变化的主要原因。海黍子HSI模型不仅可用于检测海黍子海藻床区域的生境层级分布,还能发现海黍子潜在的适宜生境区域。这为今后开展海黍子资源保护和人工增殖工作提供了科学参考。