The epifaunal communities of Pelvetia canaliculata and Fucus spiralis

The distribution, size and abundance of Pelvetia canaliculata (L.) and Fucus spiralis L. and the epifaunal communities associated with these two high shore fucoid algae have been studied at several contrasting sites in North Wales. Several environmental parameters were measured at each site and correlated with the distribution of the algae and their associated fauna. These weeds, which occur in perhaps the harshest zone of the shore, support exceedingly impoverished epifaunal communities in which the amphipod Hyale nilssoni (Rathke), small littorinids and acarines predominate. This contrasts markedly with the extremely diverse epifaunal communities associated with algae situated lower in the intertidal zone.     

Influence of light and nitrogen on the phlorotannin content of the brown seaweeds Ascophyllum nodosum and Fucus vesiculosus

Phlorotannins, C-based defence compounds in brown seaweeds, show a high degree of spatial and temporal variation within seaweed species. One important model explaining this variation is the Carbon Nutrient Balance Model (CNBM), which states that the relative supply of carbon and limiting nutrients will determine the level of defence compounds in plants. Nitrogen is often considered to be the limiting nutrient for marine macroalgal growth and the CNBM thus predicts that when the carbon:nitrogen ratio is high, photosynthetically fixed carbon will be allocated to production of phlorotannins. In the present study, we evaluated the effects of light (i.e. carbon) and nitrogen on the phlorotannin content of two intertidal brown seaweeds, Ascophyllum nodosum and Fucus vesiculosus. This was done in an observational field study, as well as in a manipulative experiment where plants from habitats with different light regimes were subjected to different nitrogen and light treatments, and their phlorotannin content was measured after 14 days. The results showed that there was a negative relationship between tissue nitrogen and phlorotannin content in natural populations of F. vesiculosus, but not in A. nodosum. In the short term, the phlorotannin content in both algal species was not affected by changes in nitrogen availability. Exposure to sunlight had a positive effect on the phlorotannin content in natural populations of both algal species but, in the manipulative experiment, only F. vesiculosus showed a rapid response to changes in light intensities. Plants subjected to sunlight contained higher phlorotannin content than shaded plants. In conclusion, the results imply that nitrogen availability explains some of the natural variation in the phlorotannin content of F. vesiculosus, but the light environment has greater importance than nitrogen availability in predicting the phlorotannin content of each species.     

Lipid Metabolism in the Brown Marine Algae Fucus vesiculosus and Ascophyllum nodosum

Lipid metabolism and environmental effects on this process havebeen studied in the marine brown algae Fucus vesiculosus andAscophyllum nodosum. These algae showed very similar patternsof lipid metabolism during 24 h incubations. Labelling from[1-¹⁴C]acetate showed the major labelled lipids to be the ß-alanineether lipid and the neutral lipid fraction in both algae. Ofthe glycolipids, only sulphoquinovosyldiacylglycerol was welllabelled and the phosphoglycerides were all poorly labelled.The major labelled fatty acids were palmitate and oleate, againin both algae, although Fucus vesiculosus also showed significantlabelling of stearate and behenate. Although the amount of fattyacid labelling increased with time, the proportion of labelin palmitate and oleate remained approximately constant. Verylong chain fatty acids (arachidic, behenic) were increasinglylabelled with time. Lowered incubation temperatures decreased labelling of the saturatedfatty acids. Cu²⁺ increased the proportion of oleate labelledin both algae, and of linoleate in Fucus vesiculosus. This cationdecreased the percentage labelling of stearate and myristatein Ascophyllum nodosum. Lipid metabolism in Ascophyllum nodosumwas more sensitive to raised Cu²⁺ levels than in Fucus vesiculosus Key words: Acyl lipid metabolism, Fucus vesiculosus, temperature effects, Ascophyllum nodosum, copper pollution     

Antioxidant and pro-oxidant activities of the brown algae, Laminaria digitata, Himanthalia elongata, Fucus vesiculosus, Fucus serratus and Ascophyllum nodosum

The ability of Laminaria digitata, Himanthalia elongata, Fucus vesiculosus, Fucus serratus and Ascophyllum nodosum to scavenge peroxyl radicals was investigated by kinetic studies in a model system. The thermal initiated oxidation of methyl linoleate was performed at 60°C in heptanol, with or without antioxidants. When they reached 1% of the substrate, seaweed extracts exhibited antioxidant activities by extending the induction period, but they did not suppress the rate of oxygen uptake as did vitamin E. A synergistic effect occurred when both algal extracts (1.5 g L^-1) and vitamin E (0.4 mmol L^-1) were present, and the effectiveness of the combined antioxidants during the whole induction period was vitamin E effectiveness. The synergistic effect of L. digitata, however, was subject to seasonal variations: samples collected in summer were effective synergists, whereas samples collected in winter displayed a marked negative synergism. The phospholipid fractions of F. vesiculosus, F. serratus and A. nodosum, including pigments, accounted for only 6% of the total lipid fraction, and did not exhibit a large synergistic effect. The main phospholipid was not phosphatidyl ethanolamine as usually related, but phosphatidyl inositol. Fucoxanthin had some antioxidant activity per se under our experimental conditions, but did not act as a synergist of vitamin E. The most potent synergists were recognized as chlorophyll a and related compounds by the application of liquid-liquid partition and chromatography for the identification of active components. This revised version was published online in June 2006 with corrections to the Cover Date.     

Spatial distribution and quantification of Fucus species and Ascophyllum nodosum beds in intertidal zones using spot imagery

Low tide SPOT images were selected from two French coast areas characterized by important Fucaceae populations (Pleubian-Bréhat site in Northern Brittany and Ré Island on the Atlantic coast).A specific data transformation yielding the theoretical algal cover was used. This index takes the radiometric properties of the intertidal zone and of the Fucaceae into account. Satellite data cover was validated by comparing it with selected field samples.Other field data indicate that a linear relation exists between cover and biomass. This relationship is quite independent of cover patchiness. However, it can vary according to species, season and location. Hence it was possible to estimate Fucus sp and Ascophyllum nodosum harvestable biomass using appropriate segments of the intertidal zone.     

Isolation and cross‐species amplification of microsatellite loci from the fucoid seaweeds Fucus vesiculosus,F. serratus and Ascophyllum nodosum (Heterokontophyta,Fucaceae)

The Fucaceae is a family of brown seaweeds that dominate and frequently co‐occur on North Atlantic rocky shores. We developed nine polymorphic microsatellite markers for the fucoid seaweeds Fucus vesiculosus, F. serratus and Ascophyllum nodosum using a combined, enriched library. Six of these loci were polymorphic in at least two species, showing from two to eight alleles with heterozygosities ranging from 0.41 to 0.85. Loci were also tested on F. spiralis, revealing five polymorphic microsatellite loci in this species.     

Spatial variation in polyphenolic content of Ascophyllum nodosum (Fucales,Phaeophyta)

Spatial variation in polyphenolic content in annual shoots of the brown alga Ascophyllum nodosum was quantified using a hierarchical sampling design. Three sampling levels, covering distances of 10⁰–10⁶ m, were used. Comparisons were made between two areas, Tjärnö on the Swedish west-coast and the Isle of Man in the Irish Sea, with very different types of environmental conditions. No significant differences in mean polyphenolic levels were found between the two study areas (6.6% of dry mass at Tjärnö and 9.2% at the Isle of Man), whereas significant and substantial differences were found among sites within areas (range 5.7%–11.4%) and among quadrats within sites (range 3.7%–13.1 %). The extensive variation at the smaller spatial scales points out the importance of using thorough sampling procedures at all levels in large-scale studies on algal polyphenolics, e.g. biogeographical comparisons, which have been neglected in several previous studies. Moreover, the results imply that experiments on causal factors of polyphenolic variation should be designed to explain the spatial scales on which the factors are impportant. This study also investigated the relationship between polyphenolic concentration and both plant size and mean area of annual shoots. The mean area was used as an estimate of the mean growth rate of the annual shoots within an individual. No significant relationships were found between shoot growth rate, or plant size, and polyphenolic levels in annual shoots at any of the three spatial scales that were investigated.     

Molecular cloning,structure, and reactivity of the second bromoperoxidase from Ascophyllum nodosum

The sequence of bromoperoxidase II from the brown alga Ascophyllum nodosum was determined from a full length cloned cDNA, obtained from a tandem mass spectrometry RT-PCR-approach. The clone encodes a protein composed of 641 amino-acids, which provides a mature 67.4 kDa-bromoperoxidase II-protein (620 amino-acids). Based on 43% sequence homology with the previously characterized bromoperoxidase I from A. nodosum, a tertiary structure was modeled for the bromoperoxidase II. The structural model was refined on the basis of results from gel filtration and vanadate-binding studies, showing that the bromoperoxidase II is a hexameric metalloprotein, which binds 0.5 equivalents of vanadate as cofactor per 67.4 kDa-subunit, for catalyzing oxidation of bromide by hydrogen peroxide in a bi-bi-ping-pong mechanism (k_cat = 153 s⁻¹, 22 °C, pH 5.9). Bromide thereby is converted into a bromoelectrophile of reactivity similar to molecular bromine, based on competition kinetic data on phenol bromination and correlation analysis. Reactivity provided by the bromoperoxidase II mimics biosynthesis of methyl 4-bromopyrrole-2-carboxylate, a natural product isolated from the marine sponge Axinella tenuidigitata.     

Adaptations by macroalgae to low carbon availability. I. A buffer system in Ascophyllum nodosum, associated with photosynthesis

Abstract The exchange of CO₂, H⁺ and O₂ between seawater and the intertidal brown macroalga Ascophyllum nodosum (L.) Le Jolis were measured in a flowthrough system. While the algae were kept in darkness, seawater with artificially increased alkalinity and pH at 9.85, was alternated with ‘normal’ seawater at pH 8.0. A proton buffering system, with capacity to release and reabsorb about 20 μmol protons per gram alga (fresh weight) was revealed. As the algae were returned to the ‘normal’ seawater, the kinetics of proton reabsorbtion indicated that a proton uptake was gradually induced. This proton uptake, which was not connected to ion exchange in the cell wall, reached its maximum after 12 h. If subjected to high alkalinity seawater in the light, A. Nodosum for a certain period of time was capable of carrying out O, evolution in excess of the import of inorganic carbon. This ‘photosynthetic buffering capacity’ amounted to about 17 μmol O; per gram alga. Besides depending on a buffer of photorcducible substances, this ‘photosynthetic buffering capacity’ appeared to be functionally connected with the proton buffer. The time course for the discharge of the ‘photosynthetic buffer system’ and for the reabsorbtion of protons into the proton buffer (about 6h for 90× of the capacity at a temperature of 6°C) suggests that the ‘photosynthetic buffer system’ has a functional importance in the adaptation of A. nodosum to intertidal regions. The function of the buffer system is discussed in relation to the crassulacean acid metabolism (CAM)-like characteristics recently shown for the intertidal brown algal family Fucaceae.     

First year demography of the foundation species, Ascophyllum nodosum, and its community implications

Long-lived species of large size can play critical roles as ecosystem engineers but the demography of early life stages is poorly known for many such species. For example, the fucoid alga, Ascophyllum nodosum , serves as the foundation species for many sheltered rocky shore communities of the North Atlantic Ocean, yet its early demography is incompletely characterized. Here we provide data on age-specific survivorship throughout the first year. We outplanted zygotes generated from artificial fertilizations and followed their survivorship under different conditions that tested the following hypotheses: (1) survivorship is inversely related to clearing size, (2) germlings survive better in clearings in conspecific stands than in clearings in mussel beds, (3) survivorship in microhabitat refugia (grooves of artificial surfaces) is greater than that on flat surfaces, and (4) protection from grazing and physical factors, like canopy sweeping and desiccation, enhances germling survival. Germlings were censused on days 2, 9, 13, 17, 64, 102, 127 and 399 following outplanting. Germling mortality was consistently higher on flats than in grooves of artificial surfaces, and was greatest within the first two days of life. Germlings protected by cages survived better during the day 0–2 interval, but after 2 days caging did not matter. Interval-specific mortalities after day 2 showed that survivorship was inversely related to clearing size. The type of clearing, in conspecific stands or mussel beds, did not affect survivorship. Ascophyllum nodosum shows a strong type III survivorship curve with mortality during year 1 exceeding 99.9%. The poor survivorship of first year germlings accounts for the paucity of newly recruited juveniles often observed in mature stands of A. nodosum . The lack of juveniles and the scale dependent survivorship of germlings renders populations of A. nodosum , and the associated community that depends on it, vulnerable to large scale perturbations.     

EXTRACELLULAR MICROTUBULES : The Origin, Structure, and Attachment of Flagellar Hairs in Fucus and Ascophyllum Antherozoids

Mastigonemes (Flimmer) from the sperm of Ascophyllum and Fucus were found to consist of a tripartite structure—a ca. 2000-A tapered basal region, a closed microtubular shaft, and a group of terminal filaments. Each of these regions appears to be constructed of globular subunits with a center-to-center distance of about 45 A. The mastigoneme microtubule is of smaller diameter (170–190 A) than cytoplasmic microtubules in these or other plant cells. During the initial stages of flagellar ontogeny, structures similar to mastigonemes (presumptive mastigonemes) are found within membrane-limited sacs in the cytoplasm or within the perinuclear space. Mastigonemes at this time are generally not found on the flagellar surface. Later, when the anterior flagellum acquires mastigonemes, the presumptive mastigonemes are absent from the cytoplasm. The regularity of attachment of mastigonemes to the flagellar surface suggests that specific attachment sites are constructed on the plasma membrane during flagellar ontogeny. No evidence for penetration of the mastigoneme through the plasma membrane was obtained. The origin and structure of mastigonemes are discussed in relation to reports of the origin and structure of other microtubular systems.     

Management and production of the brown algae Ascophyllum nodosum in the Canadian maritimes

Commercial exploitation of Ascophyllum nodosum (rockweed) along the coast of Nova Scotia began in the late 1950s when it was used as a raw material for manufacturing alginate and “kelp” meal. Today, this resource is used as a biostimulant extract for crops and animal feed supplements and is the main economic resource of the seaweed industry in the Maritime Provinces and Canada. The management of rockweed, by dividing the resource into many sectors, permitted the assessment of yield per unit area of bed. In Nova Scotia, mechanical harvesting of A. nodosum operated on a pulse of 2- to 3-year schedule providing yields of 21.9 to 47.7?wet?t ha^?1 averaging 35.3?±?7.6?wet?t ha^?1. Acadian Seaplants Limited (ASL) has become the dominant player in the region since 1995 with more than 75% of the total biomass under its leases and more than 90% of the total landing of rockweed in the last 13?years. Sustained harvests at ASL leases and under an annual harvest schedule using hand cutting methods have averaged 17.4?±?2.6?t ha^?1. Exploitation rates above 35% of the harvestable crop lead to a pulse harvest strategy and the need to move infrastructure year after year. In New Brunswick, a new approach to management began in 1995 with a regulated 17% exploitation rate. Thus, the yield in that province is 14.3?wet?t ha^?1. The current summer standing crop for this region has been calculated at 352,723?wet?t, covering an area of 4,960?ha, with an average biomass of 71.3?t ha^?1. The harvest in the region reached peak landings in 2010 with just over 40,100?t. The consistent yield per hectare of A. nodosum beds is proof of good management practices and an ecologically sustainable harvest in the Canadian Maritimes.     

"Starburst" conjugates of proteins with carbocene polymers,carrying low molecular weight biologically-active compounds,and their immunogenicity

The synthesis of starburst polymer-protein conjugates on the basis of bovine serum albumin and horseradish peroxidase was performed with the aim to study the possibilities of regulation of the immune response against the components of the conjugates. These polymers had one-point binding between the protein and the modifying carbon-chain polymer that contained 1-vinyl-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline (a salsolinol analogue) or bradykinin (peptide hormone) residues in its carbon chain. Changes in the chemical nature of the carbon-chain part of the polymer-protein conjugate were shown to increase or decrease the level of antibody production both against the low-molecular compounds attached to the polymeric fragments and against the protein carrier.     

Long-term changes in heavy metal loadings of Ascophyllum nodosum from the Firth of Clyde,UK

The aim of this work is to describe changes in heavy metal concentrations in Ascophyllum nodosum from 1964 to 1994. Samples were collected from three sites in the Firth of Clyde and analysed for zinc, manganese, iron, copper, lead and nickel. The results were analysed using the multivariate technique Principal Components Analysis (PCA). At the Wemyss Bay site there was a trend towards increasing lead and nickel over the study period, which could not be accounted for by local industrial activity. At the Hunterston site, two groups were well separated by the PCA ordination, based on manganese and zinc concentrations, which corresponded to land reclamation activities in the area. The separation of samples at the Ardneil Bay site correlated well with copper concentration and this corresponded to the termination of industrial effluent with heavy copper loadings. Other changes in industrial effluent were also reflected in the Hunterston and Ardneil Bay site ordinations. The PCA technique highlighted the interplay between metals. The work demonstrated the potential for using multivariate analysis of seaweed metal concentrations in monitoring a posteriori the environmental impact of industrial change.     

Comprehensive profiling of the low molecular weight proteins and peptides in weak cation exchange beads human serum retentate

Mass spectrometric profiling using ProteinChip and magnetic beads has rapidly grown over the past years, particularly to generate serum profiles for cancer diagnosis. The molecular weights of these distinguishing peaks are usually under 30 kDa. To identify those low molecular weight proteins and peptides is important for specific assays to be developed and increases biological insight. In this study, low molecular weight proteins and peptides from serum were purified by a combination of weak cation exchange magnetic beads and high performance liquid chromatography. The purified proteins and peptides were analyzed by 1D SDS PAGE, SELDI and LC-MS/MS. 246 proteins were identified from the HPLC fractions by LC-MS/MS. 95(38.62%) proteins were first identified in serum compare with Sys-BodyFluid database. 11(11/96) proteins were documented cancer associated proteins. We also observed about 109 proteins/peptides in SELDI mass spectrum, and 13 of the SELDI features were identified.     

Biomass and height of Ascophyllum nodosum after two decades of continuous commercial harvesting in eastern Canada

With the increasing demand for seaweed resources worldwide, management must ensure that the harvest of wild seaweed stocks is sustainable. We evaluate the impact of over 25 years of commercial harvesting of Ascophyllum nodosum in eastern Canada by comparing the biomass and height of the seaweed in the late 1990s to the late 2010s over a broad spatial scale spanning the provinces of Nova Scotia and New Brunswick. There has been no significant decrease in the biomass of A. nodosum in either province, and biomass has increased in some regions of New Brunswick during that period. The average height of A. nodosum has decreased by 7.8 cm in Nova Scotia while it increased by 13.8 cm in New Brunswick. Biomass of A. nodosum in unharvested sectors was 7% higher than that in harvested sectors while height of A. nodosum in unharvested sectors in New Brunswick is similar to the values observed in harvested sectors. Over the same period, water temperature has increased in both provinces and, in recent years, has at times exceeded the optimal growing temperature for A. nodosum within bays in Nova Scotia. We conclude that the current management and harvest of A. nodosum in eastern Canada are sustainable and maintain the biomass and height of A. nodosum beds but that control sites are necessary to offer adequate comparisons as environmental conditions are changing.