An assessment of genetic diversity of marine populations is critical not only for the understanding and preserving natural biodiversity but also for its commercial potential. As commercial demand rises for marine resources, it is critical to generate baseline information for monitoring wild populations. Furthermore, anthropogenic stressors on the coastal environment, such as warming sea temperatures and overharvesting of wild populations, are leading to the destruction of keystone marine species such as kelps. In this study, we conducted a fine-scale genetic analysis using genome-wide high-density markers on Northwest Atlantic sugar kelp. The population structure for a total of 149 samples from the Gulf of Maine (GOM) and Southern New England (SNE) was investigated using AMOVA, FST, admixture, and PCoA. Genome-wide association analyses were conducted for six morphological traits, and the extended Lewontin and Krakauer (FLK) test was used to detect selection signatures. Our results indicate that the GOM region is more heterogeneous than SNE. These two regions have large genetic difference (between-location FST ranged from 0.21 to 0.32) and were separated by Cape Cod, which is known to be the biogeographic barrier for other taxa. We detected one significant SNP (P = 2.03 × 10−7 ) associated with stipe length, and 248 SNPs with higher-than-neutral differentiation. The findings of this study provide baseline knowledge on sugar kelp population genetics for future monitoring, managing and potentially restoring wild populations, as well as assisting in selective breeding to improve desirable traits for future commercialization opportunities.
Digital library
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Eight carrageenophytes, representing seven genera and three families of Gigartinales (Florideophyceae), were studied for 15 months. The reproductive status, dry weight, and carrageenan content have been followed by a monthly random sampling. The highest carrageenan yields were found in Chondracanthus acicularis (61.1%), Gigartina pistillata (59.7%), and Chondracanthus teedei var. lusitanicus (58.0%). Species of Cystocloniaceae family produces predominantly iota-carrageenans; Gigartinaceae family produces hybrid kappa-iota carrageenans (gametophytic plants) and lambda-family carrageenans (sporophytic plants); Phyllophoraceae family produces kappa-iota-hybrid carrageenans. Quadrate destructive sampling method was used to determine the biomass and line transect. Quadrate nondestructive sampling method, applied along a perpendicular transect to the shoreline, was used to calculate the carrageenophytes cover in two periods: autumn/winter and spring/summer. The highest cover and biomass were found in Chondrus crispus (3.75%–570 g/m2 ), Chondracanthus acicularis (3.45%–99 g/m2 ), Chondracanthus teedei var. lusitanicus (2.45%–207.5 g/m2 ), and Mastocarpus stellatus (2.02%–520 g/m2 ).
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Recent studies combining biochemical, molecular, and traditional morphological and ecological traits have shown that some currently recognized species of the red algal genus Porphyra are actually form species or complexes comprising several morphologically similar but genetically distinct taxa. Conflicting reports of chromosome numbers and differences in DNA sequences for Porphyra purpurea (Roth) C. Agardh have raised suspicion that more than one taxon has been confused under this name in the Northwest Atlantic. We have identified one of these cryptic taxa and describe it here as a new species, Porphyra birdiae. Like P. purpurea, it has an ovate to broadly elongate, foliose blade with reproductive areas segregated by a distinct line into male and female sectors. While reproductive specimens have historically been confused with P. purpurea, non-reproductive specimens of P. birdiae have been incorrectly identified as P. umbilicalis Kutzing. Although P. birdiae is morphologically similar to both of these species, sequences of SSU (nuclear small subunit rRNA gene) and rbcL (plastid ribulose-1,5-bisphosphate carboxylase/oxygenase large subunit gene) indicate that it is not closely related to either one. Based on rbcL sequences, P. birdiae is closely related to P. aestivalis Lindstrom et Fredericq, a proposed new species from Alaska.
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PDF of picture slides of Porphyra culture in Nantong, Jiangsu Province.
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FAO fisheries fact sheet of Porphyra tenera (Kellman 1897), also known as nori and laver.
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Marine algae, popularly known as sea-weeds, are sources of food, fodder, ferti-lizer, medicine and chemicals1. Worldtrade in seaweed and its products was val-uedat US $50million in 1970, US $250million in 1990 and US $6.2billion in1999 (refs 1 and 2). About 20,000 marinealgae species are distributed throughoutthe world, out of which only 221 speciesare utilized commercially. These include145 species for food and 110 species forphycocolloid production1.Porphyra(Ban-giales,Rhodophyta) popularly known as‘Nori’ in Japan, ‘Kim’ in Korea and ‘Zicai’in China has an annual value of over US$1.8billion3.Porphyrais primarily usedas food, wrapped around the Japanesedelicacy ‘Sushi’ whichconsists of roas-ted blades, raw fish, rice and other ingre-dients. The alga is not only delicious butalso contains high levels of protein (25–50%), vitamins (higher vitamin C than inoranges), trace minerals and dietary fibres4.The plant contains nearly17 types offree amino acids, including taurine whichcontrols blood cholesterol levels5. Thealga is a preferred source of the red pig-mentr-phycoerythrin, which is utilizedas a fluorescent ‘tag’ in the medical diag-nostic industry6.Porphyrahas been cul-tivated for the past hundred years in Japanand today it is one of the largest aquacul-ture industries in Japan, Korea andChina6. Because of its economic impor-tance and other health benefits,Porphyracultivation is now being expanded toother countries7. Recently, it has beenfound that the plant has much more poten-tial and can be used as an experimentalsystem likeArabidopsis thalianain thehigher plants, some aspects of which arediscussed here.
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Porphyra encompasses a large group of multicellular red algae that have a prominent gametophytic phase. The complex, heteromorphic life history of species in this genus, their remarkable resilience to high light and desiccation, ancient fossil records, and value as human food (e.g., laver, nori), make Porphyra a compelling model for genome sequencing. Sequencing of the nuclear genome of Porphyra umbilicalis from the northwestern Atlantic is currently in process. The ~270 Mb genome of this alga is much larger than that of the unicellular acidophilic Cyanidioschyzon merolae (16.5 Mb), the only rhodophyte for which there is a fully sequenced genome, and is approximately twice as large as the Arabidopsis genome. Future analyses of the P. umbilicalis genome should provide opportunities for researchers to (1) develop an increased understanding of the ways in which these algae have adapted to severe physiological stresses, (2) elucidate the molecular features of development through the complex life history, and (3) define key components required for the transition of growth from a single cell to a multicellular organism.
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Eight carrageenophytes from the Centre and North coast of Portugal, representing seven genera and three families of Gigartinales, were studied in 15 different coastal stations in a geographic study, from Baleal (Peniche), in the central zone, to Moledo, in the northern zone. In order to characterize the different carrageenan types, 1H NMR spectroscopy was used to identify and quantify the different carrageenan fractions in the extracted phycocolloids (both water and alkali extractions). Thereby, detailed information concerning the properties and structure of these polysaccharides at molecular level was revealed. Based on the results of the analysis of the carrageenan types, the following conclusions were made: female gametophytes and non-fertile thalli of Chondrus crispus, Mastocarpus stellatus, Chondracanthus teedei var. lusitanicus, Gigartina pistillata, Chondracanthus acicularis and Gymnogongrus crenulatus, presented a varying degrees of kappa–iota hybrid carrageenan (co-polymers of kappa–iota carrageenan). The kappa/iota ratio ranged from 0 to 2.2. The carrageenans extracted from Ahnfeltiopsis devoniensis were mainly iota-carrageenan, but some geographic variations in the composition of carrageenans were found. Calliblepharis jubata contained carrageenans of iota-type in all reproductive stages. Lambda-family carrageenans were found in tetrasporophytes of C. cripus (lambda), M. stellatus (lambda), C. teedei var. lusitanicus (hybrid xi–theta), C. acicularis (hybrid xi–theta) and G. pistillata (hybrid xi–lambda).
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Seaweeds have been incorporated in the daily diet of several human cultures since ancient times, due to their nutritional characteristics and healthy properties. The brown seaweeds Undaria pinnatifida, Saccharina latissima, Sacchoriza polyschides, and Laminaria ochroleuca were collected in the Viana do Castelo (Portugal) bay to assess their proximate composition analysis. As a result, the algal biomass was dried, and its moisture and ash content were determined. The dried biomass was then analyzed for total nitrogen/total protein (using the Kjeldahl method), total fiber content (through fiber analyzer digestion), total lipids (in a Soxhlet apparatus), and fatty acid characterization (by gas chromatography-mass spectrometry). Apart from phosphorus, which was analyzed by spectrophotometry, the ashes were employed for mineral and trace element characterization via dry mineralization and quantified using flame atomic absorption spectrometry. Moreover, the total phenolic content was assessed spectrophotometrically by the Folin-Ciocalteu method in the algal aqueous extracts. Analyses showed that their protein concentrations ranged from 12 to 24% dry weight (DW), while lipid concentrations varied between 0.51% and 1.52% DW. Regarding the carbohydrate concentration in these seaweeds, a concentration between 48% and 60% DW was observed. The S. polyschides had the highest overall total phenolic content (6.19 × 10−3 g GAE/100 g of dried algae), while L. ochroleuca had the lowest amount (3.72 × 10−3 g GAE/100 g of dried algae). U. pinnatifida had the highest total fatty acid content (35.13 mg/g DW), whereas S. latissima presented the lowest value (22.59 mg/g DW). Significant concentrations of highly unsaturated fatty acids (HUFA) were observed in both seaweeds, with U. pinnatifida having the highest value (10.20 mg/g DW) and S. latissima the lowest content (4.81 mg/g DW). It is also highlighted that these seaweeds have a nutritional relevance as a source of essential nutrients, including nitrogen, potassium, sodium, calcium, magnesium, and iron.
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1. Positive interspecific interactions such as mutualism, commensalism, and facilitation are globally ubiquitous. Although research on positive interactions in terrestrial and marine systems has progressed over the past few decades, comparatively little is known about them in freshwater ecosystems. However, recent advances have brought the study of positive interactions in freshwater systems to a point where synthesis is warranted. 2. In this review, we catalogue the variety of direct positive interactions described to date in freshwater ecosystems, discuss factors that could influence prevalence and impact of these interactions, and provide a framework for future research. 3. In positive interactions, organisms exchange key resources such as nutrients, protection, transportation, or habitat to a net benefit for at least one participant. A few mutualistic relationships have received research attention to date, namely seed-dispersing fishes, crayfishes and their ectosymbiotic cleaners, and communal-spawning stream fishes. Similarly, only a handful of commensalisms have been studied, primarily phoretic relationships. Facilitation via ecosystem engineering has received more attention, for example habitat modification by beavers and bioturbation by salmon. 4. It is well known that interaction outcomes vary with abiotic and biotic context. However, only a few of studies have examined context dependency in positive interactions in freshwater systems. Likewise, positive interactions incur costs as well as benefits; conceptualising interactions in terms of net cost/benefit to participants will help to clarify complex interactions. 5. It is likely that there are many positive interactions that have yet to be discovered in freshwater systems. To identify these interactions, we encourage inductive natural history studies combined with hypotheses deduced from general ecological models. Research on positive interactions must move beyond small-scale experiments and observational studies and adopt a cross-scale approach. Likewise, we must progress from reducing systems to oversimplified pairwise interactions, toward studying positive interactions in broader community contexts. Positive interactions have been greatly overlooked in applied freshwater ecology, but have great potential for conservation, restoration, and aquaculture.
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