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Sustainable development is an integrated approach to tackle ongoing global challenges such as resource depletion, environmental degradation, and climate change. However, a paradigm shift from a fossil-based economy to a bio-based economy must accomplish the circularity principles in order to be sustainable as a solution. The exploration of new feedstock possibilities has potential to unlock the bio-based economy’s true potential, wherein a cascading approach would maximize value creation. Seaweed has distinctive chemical properties, a fast growth rate, and other promising benefits beyond its application as food, making it a suitable candidate to substitute fossil-based products. Economic and environmental aspects can make seaweed a lucrative business; however, seasonal variation, cultivation, harvesting, and product development challenges have yet not been considered. Therefore, a clear forward path is needed to consider all aspects, which would lead to the commercialization of financially viable seaweed-based bioproducts. In this article, seaweed’s capability and probable functionality to aid the bio-based economy are systematically discussed. The possible biorefinery approaches, along with its environmental and economic aspects of sustainability, are also dealt with. Ultimately, the developmental process, by-product promotion, financial assistance, and social acceptance approach are summarized, which is essential when considering seaweed-based products’ feasibility. Besides keeping feedstock and innovative technologies at the center of bio-economy transformation, it is imperative to follow sustainable-led management practices to meet sustainable development goals.

Geographical discontinuities in the composition of species assemblages are often mirrored by genetic clines and local adaptation in species that extend across such biogeographic disjunction. Species distributed across such biogeographic discontinuities are thus more prone to develop genetic clines and adaptations to environmental variation. The northwest coast of France encompasses a biogeographic boundary between cold- and warm-temperate marine ecosystems. Distinct hydrographic features characterize northern and southern shores, promoting physical oceanographic breaks that can affect dispersal and connectivity between populations. Furthermore, mosaics of contrasting conditions may affect local patterns of species assemblages and potential adaptive pressures. Along this stretch of coast, the intertidal habitat is largely dominated by brown algae of the genus Fucus, key structuring species common along North Atlantic shorelines. Fucus spiralis, F. guiryi and F. vesiculosus are sister species with different mating systems. They have extensive sympatric geographical distributions and distinct but overlapping vertical distributions in the intertidal zone. We examined genetic structure and diversity across this major environmental transition zone using neutral microsatellite markers to investigate patterns of differentiation between populations of each species inhabiting the two different biogeographic regions. We found contrasting results between the dioecious species (F. vesiculosus) and the two selfing hermaphroditic lineages (F. spiralis and F. guiryi). Genetic differentiation of northern and southern populations of F. vesiculosus followed the expectation from a hypothetical oceanographic discontinuity across this biogeographical transition zone, but this was not the case for the two hermaphroditic species. The former had higher genetic diversity and structure along the distribution range investigated whereas selfing hermaphrodites had less variability and were not geographically structured. Our results suggest that genetic patterns are correlated with this biogeographical transition zone but this effect is dependent on mating system, a determining factor affecting population structure. Additionally, other factors such as intertidal elevation may also play a role in observed difference in genetic structuring. Fundacao para a Ciencia e a Tecnologia (FCT-MEC, Portugal) [CCMAR - UID/MULTI/04326/2013, EXCL/AAG-GLO/0661/2012, IF/01413/2014/CP1217/CT0004] info:eu-repo/semantics/publishedVersion

Based on the results of a pilot study in 2007, which found high mixing ratios of molecular iodine (I2) above the intertidal macroalgae (seaweed) beds at Mweenish Bay (Ireland), we extended the study to nine different locations in the vicinity of Mace Head Atmospheric Research Station on the west coast of Ireland during a field campaign in 2009. The mean values of I2 mixing ratio found above the macroalgae beds at nine different locations ranged from 104 to 393 ppt, implying a high source strength of I2. Such mixing ratios are sufficient to result in photochemically driven coastal new-particle formation events. Mixing ratios above the Ascophyllum nodosum and Fucus vesiculosus beds increased with exposure time: after 6 h exposure to ambient air the mixing ratios were one order of magnitude higher than those initially present. This contrasts with the emission characteristics of Laminaria digitata, where most I2 was emitted within the first half hour of exposure. Discrete in situ measurements (offline) of I2 emission from ambient air-exposed chamber experiments of L. digitata, A. nodosum and F. vesiculosus substantially supported the field observations. Further online and time-resolved measurements of the I2 emission from O3-exposed macroalgal experiments in a chamber confirmed the distinct I2 emission characteristics of A. nodosum and F. vesiculosus compared to those of L. digitata. The emission rates of A. nodosum and F. vesiculosus were comparable to or even higher than L. digitata after the initial exposure period of ~20–30 min. We suggest that A. nodosum and F. vesiculosus may provide an important source of photolabile iodine in the coastal boundary layer and that their impact on photochemistry and coastal new-particle formation should be reevaluated in light of their longer exposure at low tide and their widespread distribution.

International audience; Colonizations of freshwater by marine species are rare events, and little information is known about the underlying mechanisms. Brown algae are an independent lineage of photosynthetic and multicellular organisms from which few species inhabit freshwater. As a marine alga that is also found in freshwater, Ectocarpus is of particular interest for studying the transition between these habitats. To gain insights into mechanisms of the transition, we examined salinity tolerance and adaptations to low salinities in a freshwater strain of Ectocarpus on physiological and molecular levels. We show that this isolate belongs to a widely distributed and highly stress-resistant clade, and differed from the genome-sequenced marine strain in its tolerance of low salinities. It also exhibited profound, but reversible, morphological, physiological, and transcriptomic changes when transferred to seawater. Although gene expression profiles were similar in both strains under identical conditions, metabolite and ion profiles differed strongly, the freshwater strain exhibiting e.g. higher cellular contents of amino acids and nitrate, higher contents of n-3 fatty acids, and lower intracellular mannitol and sodium concentrations. Moreover, several stress markers were noted in the freshwater isolate in seawater. This finding suggests that, while high stress tolerance and plasticity may be prerequisites for the colonization of freshwater, genomic alterations have occurred that produced permanent changes in the metabolite profiles to stabilize the transition.

Brown algae are important organisms both because of their key ecological roles in coastal ecosystems and because of the remarkable biological features that they have acquired during their unusual evolutionary history. The recent sequencing of the complete genome of the filamentous brown alga Ectocarpus has provided unprecedented access to the molecular processes that underlie brown algal biology. Analysis of the genome sequence, which exhibits several unusual structural features, identified genes that are predicted to play key roles in several aspects of brown algal metabolism, in the construction of the multicellular bodyplan and in resistance to biotic and abiotic stresses. Information from the genome sequence is currently being used in combination with other genomic, genetic and biochemical tools to further investigate these and other aspects of brown algal biology at the molecular level. Here, we review some of the major discoveries that emerged from the analysis of the Ectocarpus genome sequence, with a particular focus on the unusual genome structure, inferences about brown algal evolution and novel aspects of brown algal metabolism.

International audience; Brown algae are important organisms both because of their key ecological roles in coastal ecosystems and because of the remarkable biological features that they have acquired during their unusual evolutionary history. The recent sequencing of the complete genome of the filamentous brown alga Ectocarpus has provided unprecedented access to the molecular processes that underlie brown algal biology. Analysis of the genome sequence, which exhibits several unusual structural features, identified genes that are predicted to play key roles in several aspects of brown algal metabolism, in the construction of the multicellular bodyplan and in resistance to biotic and abiotic stresses. Information from the genome sequence is currently being used in combination with other genomic, genetic and biochemical tools to further investigate these and other aspects of brown algal biology at the molecular level. Here, we review some of the major discoveries that emerged from the analysis of the Ectocarpus genome sequence, with a particular focus on the unusual genome structure, inferences about brown algal evolution and novel aspects of brown algal metabolism.

International audience; The content and chemical composition of soluble and insoluble dietary fibres from the brown marine alga Laminaria digitata (kombu breton) were determined. Two enzymic-gravimetric methods were used to determine (1) the content of soluble and insoluble fibres according to a modification of the AOAC procedure, and (2) the distribution of the soluble fibres in saline buffer at 37-degrees-C and at pH 2.0 and 7.5 used to simulate the gastric and intestinal phases of digestion, respectively. The total dietary fibre contents obtained by the two methods were similar (37.3 and 40.0%) and of these 84.8- 87.4% was soluble. A partitioning of soluble fibres may occur during digestion since 49.3% was recovered in saline buffer at pH 2.0 whereas 50.7% was recovered in saline buffer at pH 7.5. Solubility of dietary fibres was related to the chemistry of brown algal polysaccharides. Fucans and laminarans were essentially soluble at pH 2.0 and alginate at pH 7.5, and insoluble fibres consisted primarily of cellulose. Oil adsorption and hydration properties (uptake, retention and swelling) in water, 154 mM NaCl, and 38 mM CaCl2 at 20 and 37- degrees-C of three particle sizes of L digitata were measured. Oil adsorptiion was low (0.16-0.41 g g-1) and was related to the particle size of the fibres. Hydration properties were more important with small particles except in CaCl2 solution and followed the order water > NaCl > CaCl2. Water uptake and swelling were greater at 37-degrees-C than at 20-degrees-C. The overall decrease in hydration properties observed with solutions of ionic strength approximately 0.15 was interpreted as reflecting the decrease in the electrostatic repulsion between charged polysaccharides. The lowest water uptake, water retention and swelling were obtained with solutions of CaCl2 and were related to the known selective affinity of alginate for calcium. Thus, L digitata is especially rich in soluble dietary fibres, and these have physico-chemical properties characteristic of the polysaccharides present. Water absorption and uptake and welling can be modulated according to various physical and chemical parameters.

We present investigations of the reactive iodine species (RIS) IO, OIO and I2 in a coastal region from a field campaign simultaneously employing active long path differential optical absorption spectroscopy (LP-DOAS) as well as passive multi-axis differential optical absorption spectroscopy (MAX-DOAS). The campaign took place at the Martin Ryan Institute (MRI) in Carna, County Galway at the Irish West Coast about 6 km south-east of the atmospheric research station Mace Head in summer 2007. In order to study the horizontal distribution of the trace gases of interest, we established two almost parallel active LP-DOAS light paths, the shorter of 1034 m length just crossing the intertidal area, whereas the longer one of 3946 m length also crossed open water during periods of low tide. In addition we operated two passive Mini-MAX-DOAS instruments with the same viewing direction. While neither OIO nor I2 could be unambiguously identified with any of the instruments, IO could be detected with active as well as passive DOAS. The IO column densities seen at both active LP-DOAS light paths are almost the same. Thus it can be concluded that coastal IO is almost exclusively located in the intertidal area, where we detected mixing ratios of up to 29±8.8 ppt (equivalent to pmol/mol). Nucleation events with particle concentrations of 106 cm−3 particles were observed each day correlating with high IO mixing ratios. Therefore we feel that our detected IO concentrations confirm the results of model studies, which state that in order to explain such particle bursts, IO mixing ratios of 50 to 100 ppt in so called "hot-spots" are required.