Saccharina Longicruris Research Articles

Macroalgal habitats support a sustained flux of floating biomass but limited carbon export beyond a Greenland fjord

Despite growing attention on the contribution of macroalgae to carbon cycling and sequestration (blue carbon), more observational data is needed to constrain current estimates. In this study, we estimate the floating macroalgal carbon flux within and beyond a large sub-Arctic fjord system, Nuup Kangerlua, Greenland, which could potentially reach carbon sinks. Our study estimates 1) the fjord-scale area with macroalgal coverage and barrens caused by sea urchin grazing, 2) the floating macroalgal biomass in the fjord, and 3) the annual export flux of floating macroalgae out of the fjord system. ROV surveys documented that macroalgal habitats cover 32 % of the seafloor within the photic zone (0-30 m) with an average coverage of 39.6, 22, and 7.2 % in the depth intervals 0–10, 10–20, and 20-30 m, respectively. 15 % of the area suitable for macroalgae was denuded by sea urchin grazing. Floating macroalgae were common with an average biomass of 55 kg wet weight km−2. Densities and species composition varied seasonally with the highest levels after storms. The floating biomass was composed of intertidal macroalgal species (58 %) (Fucus vesiculosus, Fucus distichus, and Ascophyllum nodosum) and kelps (42 %) (Saccharina longicruris, S. latissima, and Alaria esculenta). We deployed surface GPS drifters to simulate floating macroalgal trajectories and velocity. Data indicated that 80 % of the floating biomass is retained in the fjord where its fate in relation to long-term sequestration is unknown. Export beyond the fjord was limited and indicated an annual floating macroalgal export beyond the fjord of only 6.92 t C yr−1, which is equal to ~0.02 % of the annual net primary production. Our findings suggest that floating macroalgae support a limited blue carbon potential beyond this fjord and that future research should focus on the fate of retained floating macroalgae and subsurface export to resolve the connectivity between macroalgal habitats and long-term carbon sinks.

Characterisation and chemometric evaluation of 17 elements in ten seaweed species from Greenland.

Several Greenland seaweed species have potential as foods or food ingredients, both for local consumption and export. However, knowledge regarding their content of beneficial and deleterious elements on a species specific and geographical basis is lacking. This study investigated the content of 17 elements (As, Ca, Cd, Cr, Cu, Fe, Hg, I, K, Mg, Mn, Na, Ni, P, Pb, Se and Zn) in 77 samples of ten species (Agarum clathratum, Alaria esculenta, Ascophyllum nodosum, Fucus distichus, Fucus vesiculosus, Hedophyllum nigripes, Laminaria solidungula, Palmaria palmata, Saccharina latissima and Saccharina longicruris). Element profiles differed between species but showed similar patterns within the same family. For five species, different thallus parts were investigated separately, and showed different element profiles. A geographic origin comparison of Fucus species indicated regional differences. The seaweeds investigated were especially good sources of macrominerals (K > Na > Ca > Mg) and trace minerals, such as Fe. Iodine contents were high, especially in macroalgae of the family Laminariaceae. None of the samples exceeded the EU maximum levels for Cd, Hg or Pb, but some exceeded the stricter French regulations, especially for Cd and I. In conclusion, these ten species are promising food items.

PH gradients in the diffusive boundary layer of subarctic macrophytes

Highly productive macrophytes produce diurnal and seasonal cycles in CO2 concentrations modulated by metabolic activity, which cause discrepancies between pH in the bulk water and near seaweed blades, especially when entering the diffusion boundary layer (DBL). Calcifying epiphytic organisms living in this environment are therefore exposed to a different pH environment than that of the water column. To evaluate the actual pH environment on blade surfaces, we measured the thickness of the DBL and pH gradients within it for six subarctic macrophytes: Fucus vesiculosus, Ascophyllum nodosum, Ulva lactuca, Zostera marina, Saccharina longicruris, and Agarum clathratum. We measured pH under laboratory conditions at ambient temperatures (2–3 °C) and slow, stable flow over the blade surface at five light intensities (dark, 30, 50, 100 and 200 µmol photons m−2 s−1). Boundary layer thickness ranged between 511 and 1632 µm, while the maximum difference in pH (∆pH) between the blade surface and the water column ranged between 0.4 ± 0.14 (average ± SE; Zostera) and 1.2 ± 0.13 (average ± SE; Ulva) pH units. These differences in pH are larger than predictions for pH changes in the bulk water by the end of the century. A simple quadratic model best described the relationship between light intensity and maximum ∆pH, pointing at relatively low optimum PAR of between 28 and 139 µmol photons m−2 s−1 to reach maximum ∆pH. Elevated pH at the blade surface may provide chemical “refugia” for calcifying epiphytic organisms, especially during summer at higher latitudes where photoperiods are long.

Characterization of antibacterial activity from protein hydrolysates of the macroalga Saccharina longicruris and identification of peptides implied in bioactivity

The macroalga Saccharina longicruris proteins were extracted and hydrolysed with the enzyme trypsin in order to recover antibacterial peptides, which could be used in reducing food spoilage. The >10 kDa protein hydrolysate fraction exhibited activity against the bacterium Staphylococcus aureus with a significant decrease of the maximum specific growth rate, µmax, from concentrations of 0.31 mg/mL to 2.5 mg/mL. Protein precursors were identified in a subfraction (Fr1) enriched in antibacterial peptides using liquid chromatography–tandem mass spectrometry (LC–MS/MS) with database searches. Identified peptides came from different precursors such as a protein similar to ubiquitin, histones, a hypothetical leucine rich repeat protein and a ribosomal protein. These proteins might be associated with the innate immune defences in S. longicruris. Peptidic sequences were chemically synthesized and their bioactivity confirmed, suggesting that activity probably results from synergies between peptides. This is the first time that antibacterial peptides originating from algal protein hydrolysates were isolated and characterized.

Assessment of the Antioxidant and Antibacterial Activities of Three Species of Edible Seaweeds

Extraction of secondary metabolites from St. Lawrence Estuary edible seaweeds – Saccharina longicruris, Ascophyllum nodosum and Ulva lactuca – was carried out by pressurized liquid extraction using ethanol. The antioxidant potential of extracts was evaluated through DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging, oxygen radical absorbance capacity and ferric reducing antioxidant power assays, and the antibacterial activity was tested against food spoilage bacteria: Escherichia coli, Micrococcus luteus and Brochothrix thermosphacta. Of all seaweed extracts, A. nodosum exhibited the highest phenolic and carotenoid contents, 50.2 mg GAE/g and 85 μg/g, respectively. A. nodosum also displayed the best DPPH scavenging activity, EC50 10.4 μg/mL, and best capacity to reduce ferric ion, 677.2 μmol TE/g dry weight at a concentration of 100 μg/mL. U. lactuca extracts showed the highest growth inhibition of E. coli, 69.5%; M. luteus, 61.4%; and B. thermosphacta, 21.4%. These findings suggest a high potential of St. Lawrence Estuary seaweed extracts for application in the food industry. Practical Applications Food producers, food industries, governments and consumers are aware of the importance to look into effective preventive measures in food quality and food safety fields. The decay of foods is caused by physical, chemical and biological factors, which leads to the loss of the organoleptic characteristics and consumer safety. Natural extracts combining both antioxidant and antibacterial activities can be used for further applications in reducing food spoilage and prolonging food shelf life. The majority of natural extracts could be approved as Generally Recognized As Safe (GRAS). St. Lawrence Estuary seaweed extracts possess high potential for application in the food industry using pressurized liquid extraction (PLE) method, which was selected for extraction efficiency purposes. In addition, production of seaweeds extracts using approved food-grade ethanol solvent by PLE method involves, on an industrial scale, cost savings.

Profiling phlorotannins in brown macroalgae by liquid chromatography-high resolution mass spectrometry.

Phlorotannins, phenolic compounds produced exclusively by Phaeophyceae (brown algae), have recently been associated with a wide variety of beneficial bioactivities. Several studies have measured the total phenolic content in extracts from various species, but little characterisation of individual phlorotannin components has been demonstrated. The purpose of this study was to develop a liquid chromatography-mass spectrometry (LC-MS) based method for rapid profiling of phlorotannins in brown algae. Phlorotannin-enriched extracts from five phaeophyceaen species were analysed by ultrahigh-pressure liquid chromatography (UHPLC) operating in hydrophilic interaction liquid chromatography (HILIC) mode combined with high resolution mass spectrometry (HRMS). The method was optimised using an extract of Fucus vesiculosus; separation was achieved in less than 15 min. The basic mobile phase enhanced negative-ion electrospray ionisation (ESI), and generated multiply charged ions that allowed detection of high molecular weight phlorotannins. The phlorotannin profiles of Pelvetia canaliculata, Fucus spiralis, F. vesiculosus, Ascophyllum nodosum and Saccharina longicruris differed significantly. Fucus vesiculosus yielded a high abundance of low molecular weight (< 1200 Da) phlorotannins, while P. canaliculata exhibited a more evenly distributed profile, with moderate degrees of polymerisation ranging from 3 to 49. HRMS enabled the identification of phlorotannins with masses up to 6000 Da using a combination of accurate mass and ¹³C isotopic patterns. The UHPLC-HRMS method described was successful in rapidly profiling phlorotannins in brown seaweeds based on their degree of polymerisation. HILIC was demonstrated to be an effective separation mode, particularly for low molecular weight phlorotannins.

Spatial and temporal variation in grazing damage by the gastropod Lacuna vincta in Nova Scotian kelp beds

AB Aquatic Biology Contact the journal Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections AB 13:163-173 (2011) - DOI: https://doi.org/10.3354/ab00366 Spatial and temporal variation in grazing damage by the gastropod Lacuna vincta in Nova Scotian kelp beds Kira A. Krumhansl*, Robert E. Scheibling Department of Biology, Dalhousie University, Halifax, Nova Scotia B3H 4J1, Canada *Email: kira.krumhansl@dal.ca ABSTRACT: Population increases of the gastropod Lacuna vincta have been associated with significant damage to kelp blades and decreases in kelp biomass in subtidal kelp beds off Nova Scotia, Canada. We measured the total level and along-blade distribution of grazing damage by Lacuna vincta on the dominant kelp species at 5 sites in Nova Scotia, Canada, over a 15 mo period. Grazing was typically low or absent in the basal regions of blades, consistent with seasonal fluctuations in growth and physical properties of blade tissues. Grazing was largely concentrated in middle and distal sections, although this distribution varied with site exposure and over time. The cover of the invasive bryozoan Membranipora membranacea on the surface of kelp blades did not have a strong effect on grazing by L. vincta. The total level of grazing damage (max. 1% of blade area for Saccharina longicruris and 1.5% for Laminaria digitata) varied seasonally, with peaks in September at some sites. Spatial variation was driven in part by a negative relationship with site exposure. In a field experiment, simulated grazing damage that exceeded a threshold value of 0.5 to 1.0% of blade area caused a significant increase in blade loss during a period of heavy wave action due to a passing hurricane. Our results show that direct reductions in kelp biomass through grazing by L. vincta are relatively small, but can indirectly lead to significant losses of kelp biomass during large wave events. KEY WORDS: Lacuna vincta · Laminaria digitata · Saccharina longicruris · Grazing · ­Mesograzers · Kelp beds · Detritus · Membranipora membranacea Full text in pdf format PreviousNextCite this article as: Krumhansl KA, Scheibling RE (2011) Spatial and temporal variation in grazing damage by the gastropod Lacuna vincta in Nova Scotian kelp beds. Aquat Biol 13:163-173. https://doi.org/10.3354/ab00366 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in AB Vol. 13, No. 2. Online publication date: September 06, 2011 Print ISSN: 1864-7782; Online ISSN: 1864-7790 Copyright © 2011 Inter-Research.

Grazing damage and encrustation by an invasive bryozoan reduce the ability of kelps to withstand breakage by waves

Increased breakage of macroalgal fronds during large wave events can significantly reduce canopy cover and biomass. We examined the effects of encrustation by the invasive bryozoan Membranipora membranacea and damage by the snail Lacuna vincta on the ability of kelp blades (Saccharina longicruris, Laminaria digitata, and Laminaria complanata) to withstand wave forces. Using standard materials testing procedures, we documented significant reductions in the maximum stress before breakage, toughness, and extensibility of blade material following bryozoan encrustation. Histological sections of blade tissue indicated a significant degradation of the outer layers of cells following prolonged encrustation by M. membranacea as a likely cause of weakening. Full-thickness perforations and partial-thickness grazing scars also reduced blade strength, suggesting that grazing damage can initiate cracks that lead to blade breakage. Our findings provide a mechanistic link between the damaging effects of mesograzers and encrusting bryozoa on their algal hosts and the export of detrital material from subtidal kelp beds.

Kelp distribution in the northwest Atlantic Ocean under a changing climate

Warming of the planet has accelerated in recent years and is predicted to continue over the next century. Environmental consequences include increasing water temperatures, and evidence of ecological responses to current warming in marine coastal ecosystems is found in poleward shifts in the geographic range of species as well as changes in the composition of nearshore benthic communities. Most evidence has, however, been obtained from intertidal studies, but similar shifts should be occurring for subtidal communities as well, especially for the ecologically important kelp species that provide both food and shelter to a multitude of organisms. Kelp may be particularly vulnerable to climate change due to their cold-water affinities and limited dispersal ability. A major biogeographic transition occurs along northwest Atlantic shores of Canada between subarctic and boreal zones where major shifts can be seen in the composition of kelp assemblages of Alaria esculenta, Laminaria digitata, Saccharina longicruris and Saccharina latissima. Here we review the historic and recent distribution and abundance of these species and find no evidence of changes in the past century. However, sparse coverage of data, inconsistent methodology and a lack of adequate time series prevent us from concluding that no changes have occurred, especially with respect to natural variation and anthropogenic alteration. These shortcomings illustrate the need for identifying sentinel species and sites for studies dedicated to the specific questions of climate-induced changes in kelp abundance and distribution. We suggest that a combination of traditional and modern tools (e.g., benthic surveys and climate model forecasting, respectively) offers the best path forward.

Detrital production in Nova Scotian kelp beds: patterns and processes

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 421:67-82 (2011) - DOI: https://doi.org/10.3354/meps08905 Detrital production in Nova Scotian kelp beds: patterns and processes Kira A. Krumhansl1,*, Robert E. Scheibling1 1Department of Biology, Dalhousie University, Halifax, Nova Scotia B3H 4J1, Canada *Email: kira.krumhansl@dal.ca ABSTRACT: Connectivity via the transport of detrital material from areas of high to low productivity may be an important determinant of secondary productivity and biodiversity in receiving communities. On the Atlantic coast of Nova Scotia, detritus exported from subtidal kelp beds contributes to food webs in communities inhabiting deeper waters offshore. To estimate the amount of energy available via this pathway, we measured rates of detrital production via erosion of kelp blades in kelp beds at 5 sites varying in wave exposure. Specifically, we measured productivity and erosion of the 2 dominant species of kelp, Laminaria digitata and Saccharina longicruris, over 16 mo. We also examined the effect of environmental and biological factors on erosion rates, including temperature, wave exposure, grazing by snails and cover by the invasive bryozoan Membranipora membranacea. We observed clear seasonal and spatial patterns in productivity, with the highest production in spring. Erosion rate was highly variable across sites and seasons, and was strongly related to the cover of M. membranacea and the intensity of snail grazing at the distal end of kelp blades. Both factors cause tissue degradation, abrasions and perforations that weaken blades. Erosion rate was also positively related to water temperature and site exposure. Annual detrital production from the erosion of kelp blades increased linearly with kelp bed biomass, and ranged from 0.5 to 1.71 kg dry weight m–2 (150–513 g C m–2) across sites. These rates equal or exceed annual phytoplankton production off the Atlantic coast of Nova Scotia and estimates of detrital production in seagrass beds in North America. KEY WORDS: Detritus · Grazing · Invasive species · Kelp bed · Laminaria digitata · Membranipora membranacea · Productivity · Saccharina longicruris Full text in pdf format Supplementary material PreviousNextCite this article as: Krumhansl KA, Scheibling RE (2011) Detrital production in Nova Scotian kelp beds: patterns and processes. Mar Ecol Prog Ser 421:67-82. https://doi.org/10.3354/meps08905 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 421. Online publication date: January 17, 2011 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2011 Inter-Research.

Population dynamics of a nonindigenous epiphytic bryozoan Membranipora membranacea in the western North Atlantic: effects of kelp substrate

AB Aquatic Biology Contact the journal Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections AB 8:83-94 (2009) - DOI: https://doi.org/10.3354/ab00208 Population dynamics of a nonindigenous epiphytic bryozoan Membranipora membranacea in the western North Atlantic: effects of kelp substrate Megan I. Saunders*, Anna Metaxas Department of Oceanography, Dalhousie University, Halifax, Nova Scotia, B3H 4J1, Canada *Email: msaunders@dal.ca ABSTRACT: In rocky subtidal ecosystems of the western North Atlantic, the nonindigenous epiphytic bryozoan Membranipora membranacea facilitates the introduction of other nonindigenous benthic species by defoliating kelps. Susceptibility to infestation by the bryozoan varies among kelp species, although the causes of this variability are not known. We monitored the percent cover of the bryozoan on Saccharina longicruris, Laminaria digitata, and Agarum clathratum, at 2 to 3 depths within 3 sites over 15 mo in 2005 to 2006. To infer mechanisms of observed differences in cover, we examined patterns of colony settlement and abundance, size-frequency distributions, and the proportion of plants with overwintering bryozoans on the respective kelp species. We also quantified the distributions and abundances of kelps before and after a major defoliation event in the fall of 2006. During the peak in abundance in fall, the highest percent cover of the bryozoan was consistently observed on L. digitata, which was achieved by colonies attaining larger sizes. The lowest cover and abundance were observed on A. clathratum, a pattern that we attributed to lower recruitment. Following an outbreak of the bryozoan in the fall of 2006, defoliation of the kelp bed was due to losses of individuals of S. longicruris, and to a lesser extent, A. clathratum, but not to losses of L. digitata, which increased in abundance at 1 location. Our results suggest that differences in the abundance of this introduced species among its algal hosts arise as a result of both differential settlement and survival. In turn, differential susceptibility among hosts to infestation may result in alteration of the algal community structure. KEY WORDS: Invasive species · Kelp beds · Rocky subtidal ecosystems · Epibiota · Bryozoa · Membranipora membranacea · Western North Atlantic Full text in pdf format PreviousNextCite this article as: Saunders MI, Metaxas A (2009) Population dynamics of a nonindigenous epiphytic bryozoan Membranipora membranacea in the western North Atlantic: effects of kelp substrate. Aquat Biol 8:83-94. https://doi.org/10.3354/ab00208 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in AB Vol. 8, No. 1. Online publication date: December 28, 2009 Print ISSN: 1864-7782; Online ISSN: 1864-7790 Copyright © 2009 Inter-Research.

Fatty acids tracers for native and invasive macroalgae in an experimental food web

We assessed the potential of fatty acid (FA) markers for tracing primary production from an invasive green alga (Codium fragile ssp. fragile) and a native kelp (Saccharina longicruris) through 2 trophic levels in an experimental food web: a primary consumer, the green sea urchin Strongylo- centrotus droebachiensis, and 2 secondary consumers, the native rock crab Cancer irroratus and invasive green crab Carcinus maenas. Sea urchins fed the 2 algal species had distinct gonadal FA compositions, and contained markers of each alga. Crabs of each species were then fed the gonads of sea urchins which had been fed either S. longicruris or C. fragile, and their hepatopancreases were analyzed. We were able to distinguish crabs of both species with C. fragile at the base of the food chain using the marker FAs 16:3n-3 and 18:3n-3. The overall FA composition of the hepatopancreas differed with diet in the green crab but not the rock crab. Our results suggest that 16:3n-3 may be a useful marker for tracing C. fragile production in grazers and some secondary consumers in rocky subtidal habitats in the Northwest Atlantic, but signal attenuation with each trophic transfer will limit the utility of this approach in higher consumers.

Temperature-mediated outbreak dynamics of the invasive bryozoan Membranipora membranacea in Nova Scotian kelp beds

We used underwater videography to examine seasonal and interannual patterns in the cover (on kelp) of the encrusting epiphytic bryo- zoan Membranipora membranacea, and associated changes in the structure and abundance of native kelp (Saccharina longicruris) populations, at 2 sites on the Atlantic coast of Nova Scotia and over 4 to 11 yr since initial introduction of this invasive species around 1992. We show that (1) changes in the cover of M. membranacea on kelp, and in the cover of kelp on the seabed, are reciprocal and seasonal; (2) ther- mal history during the summer/fall period of bryo- zoan colony growth explains a large proportion (83%) of the interannual variation in peak cover of M. membranacea on kelp; and (3) annual decreases in kelp cover and blade size are related to the degree of infestation by M. membranacea, and not to wave action alone. Particularly severe outbreaks of M. membranacea, resulting in extensive defoliation of kelp beds, occurred in 1993, 1997 and 1999. Our field observations indicate that recurrent seasonal outbreaks of this invasive bryozoan can have a devastating effect on native kelp populations in Nova Scotia, which, in turn, facilitates the establish- ment and growth of the invasive green alga Codium fragile ssp. fragile.

The potential for seaweed resource development in subarctic Canada; Nunavik, Ungava Bay

Ungava Bay is ice covered 6–7 months of the year and evidence of ice scouring of seaweeds is extensive in the intertidal and shallow subtidal. Maximum tidal amplitudes of 16 m, among the highest in Canadian waters, compound this impact. Despite this level of annual perturbation, very extensive and dense beds of fucoids in the intertidal and laminarians in the subtidal are common on the western shores of Ungava Bay. Ground surveys of 24 intertidal stations combined with satellite images delineated 82,000 tons standing crop of Fucus vesiculosus and Fucus evanescens in Payne Bay, of which 36,000 tons were considered harvestable. Subtidally, kelp cover reached peak biomass at 5–10 m consisting of three primary species, Saccharina longicruris, Laminaria digitata, and Laminaria solidungula. In the area of Payne Bay, kelp beds of 100 ha were common, averaging 9–12 kg m−2 wet weight. The productivity of brown algae at these latitudes has been assumed to be low relative to southern latitudes. Direct measurement of lineal growth indicates productivity is intermediate between arctic and temperate populations. The potential for medium level industrial harvest exists under conservative management strategies within the constraints of subarctic logistics.

Characterization of polysaccharides extracted from brown seaweeds

The structural characteristics of polysaccharides extracted from Quebec’s seaweed have not been fully established to date. Ascophyllum nodosum, Fucus vesiculosus and Saccharina longicruris were studied in this research. The seaweeds were treated with selective solvents to extract laminaran and fucoidan in mixture (fraction A), fucoidan (fraction B), and alginate (fraction C). Analyses were performed to determine their content in sulphates, total sugars and uronic acids. H NMR was additionally performed on alginate extract. Results showed that the laminaran extracted from S. longicruris contained 99.1% of the total sugars while the extracts from A. nodosum and F. vesiculosus contained 89.6% and 84.1%, respectively. The fucoidan found in fractions A and B was shown to have different structures. F. vesiculosus and S. longicruris showed important variations in terms of total sugars, uronic acids and molecular weight of polysaccharide. A. nodosum, on the other hand, had a more stable composition, with the exception of the polysaccharide molecular weight. Alginate from S. longicruris had the lowest molecular weight (106.6 kDa) with a F MM blocks proportion of 0.07 and F GG blocks of 0.25. Their characterization will lead to a better understanding of their functional characteristics and promote the exploitation of this natural resource.