This review provides a systematic overview of the spatial and temporal variations in the content of biomolecular constituents of Saccharina latissima on the basis of 34 currently available scientific studies containing primary measurements. We demonstrate the potential revenue of seaweed production and biorefinery systems by compiling a product portfolio of high-value extract products. An investigation into the endogenous rhythms and extrinsic factors that impact the biomolecular composition of S. latissima is presented, and key performance factors for optimizing seaweed production are identified. Besides the provisioning ecosystem service, we highlight the contribution of green-engineered seaweed production systems to the mitigation of the ongoing and historical anthropogenic disturbances of the climate balance and nutrient flows. We conclude that there are risks of mismanagement, and we stress the importance and necessity of creating an adaptive ecosystem-based management framework within a triple-helix partnership for balancing the utilization of ecosystem services and long-term resilience of aquatic environment.
Digital library
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The results of studies conducted on the anaerobic digestion of the giant brown kelp - Macrocystis pyrifera - in laboratory-scale digesters are presented. Untreated raw kelp sustains a stable fermentation under conventional mesophilic operating conditions with a methane yield of 4.5 SCF/lb votaile solids (VS) of organic matter added and a reduction in organic matter of 50%. A materials and energy balanace presented for the kelp biomethanation process shows that 100 pounds of wet kelp as harvested and drained of physical water yields 25 SCF of methane with an energy recovery efficiency of 55.5%. The major biodegradable components of kelp are mannitol and algin, and the refractory components are cellulose and protein. The anaerobic fermentation of kelp was demonstrated as nonlimited by nitrogen or phosphorus. A stable fermentation can be developed with undiluted kelp feed or a kelp feed diluted with seawater. Thermophilic digestion of kelp exhibited unstable performance and lower yields than mesophilic digestion. Inocula derived from anaerobic marine environments did not show better performance than an inoculum derived from a mixture of effluents from domestic sewage sludge and municipal solid waste digesters. Higher methane yields may be possible through post-treatment and recycle of refractory effluent solids. Preliminary studies presented show that heat treatment alone and under acid and alkaline conditions increases the biodegradability of the digested ungasified solids.
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The brown seaweed Sargassum wightii Greville ex J. Agardh 1848 was collected from Pamban (south east coast of Tamilnadu, India; Latitude 9o18’N and Longitude 79o12’ E) and extracted with different solvents such as acetone, ethanol, benzene and chloroform in a soxhlet apparatus. The antibacterial activity of the extracts were tested against natural pathogens isolated from housefly (Musca domestica Linnaeus 1758), such as Staphylococcus aureus, Enterococcus faecalis, Bacillus cereus, Micrococcus luteus, Pseudomonas aeruginosa and Escherichia coli respectively. The extracts were also subjected to alpha amylase inhibitory, anti-inflammatory and antioxidant activities following standard protocols. Ethanol extract exerted high inhibitory effect on all the microbes and was assertive against B. cereus (14.2 mm). Potential and significant (p<0.05) alpha amylase inhibition was observed in the chloroform extract (81.24±8.063%). The benzene extract had significantly (p<0.05) higher antioxidant activity (74.44±3.27%) and the antiinflammatory activity was comparatively higher in the acetone extract (65.5±1.21%). However, the control drugs exhibited better activity than all the tested extracts. The qualitative phytochemistry showed the presence of flavonoids, pholobatannins, phenolic compounds, aromatic acids and xanthoproteins. The Fourier transform infra-red (FT-IR) spectrum contained eight major peaks which confirmed the presence of amino, keto, fluoro alkane group and aromatic compounds in the extracts which could be responsible for the bioactivity.
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Marine resources have tremendous potential for developing high-value biomaterials. The last decade has seen an increasing number of biomaterials that originate from marine organisms. This field is rapidly evolving. Marine biomaterials experience several periods of discovery and development ranging from coralline bone graft to polysaccharide-based biomaterials. The latter are represented by chitin and chitosan, marine-derived collagen, and composites of different organisms of marine origin. The diversity of marine natural products, their properties and applications are discussed thoroughly in the present review. These materials are easily available and possess excellent biocompatibility, biodegradability and potent bioactive characteristics. Important applications of marine biomaterials include medical applications, antimicrobial agents, drug delivery agents, anticoagulants, rehabilitation of diseases such as cardiovascular diseases, bone diseases and diabetes, as well as comestible, cosmetic and industrial applications.
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Biomass productivity was quantified for the marine macroalga Derbesia tenuissima cultivated outdoors at seven stocking densities from 0.25 to 8 g L−1 for 5 weeks. Total lipids and fatty acid quantity and quality was measured from samples that were freeze-dried, dried by oven (75 °C), food dehydrator (60 °C), or outdoor in the sun (40 °C) or shade (38 °C). Stocking densities of 0.25 to 2 g L−1 yielded the highest biomass productivities (>20 g dry weight m−2 day−1) with no effect on total lipid quantity (11 %), or fatty acid quantity (5.3 %) or quality at any density tested. However, there was an interactive effect of stocking density and drying technique, with a decrease of up to 40 % in polyunsaturated fatty acids in sun-dried compared to freeze-dried biomass. Notably, while fatty acid and biomass productivity may be inseparable in macroalgae, cultivation conditions have a sig- nificant carryover effect in the post-harvest delivery of high- quality bio-oils.
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- Recent research indicates that more powerful technologies are now needed to keep global warming below 2°C1 – and avoid irreversible climate change. This is echoed by warnings from both the United Nations Framework Convention on Climate Change (UNFCCC) and the International Energy Agency (IEA).
- There is therefore an urgent need for carbon-negative solutions such as Bio-CCS – the only largescale technology that can remove CO2 from the atmosphere. Bio-CCS combines sustainable biomass conversion with CO2 Capture and Storage (CCS) – e.g. in biofuels and bioenergy production – and is already being deployed at industrial scale in the U.S.2 .
- Use of biofuels and bioenergy is steadily increasing in the European Union (EU) due to targets for renewable energy sources and certain biofuels production routes could provide “low-hanging fruits” for early, low-cost CCS deployment.
- A recent study indicated that, globally, Bio-CCS could remove 10 billion tonnes of CO2 from the atmosphere every year by 20503 using available sustainable biomass – equivalent to a third of all current global energy-related emissions. In Europe, Bio-CCS could remove 800 million tonnes of CO2 from the atmosphere every year by 20503 using available sustainable biomass – equivalent to over 50% of current emissions from the EU power sector. This is in addition to any emissions reductions achieved by replacing fossil fuels with that biomass.
- Bio-CCS could ultimately result in industry sectors whose overall emissions are below zero, which could then offset emissions in other sectors where reductions are more difficult to attain.
The following actions are therefore urgently required at EU level:
- As for other low-carbon technologies, establish economic incentives to enable the large-scale deployment of Bio-CCS – in particular, reward negative emissions via the capture and storage of biogenic CO2 under the EU Emissions Trading Scheme, in the same way as for fossil CCS.
- Identify and incentivise the clustering of small-scale biogenic emission sources with other emission sources in order to achieve economies of scale for CO2 transport and storage.
- Undertake R&D to determine the costs of the various Bio-CCS routes, including additional costs induced by corrosion and other technology challenges when co-firing with high biomass percentages in existing boilers.
- Establish dedicated funding for R&D and pilot projects to further develop and prove advanced technologies.
- Address issues specific to Bio-CCS deployment (e.g. accelerate deployment of advanced biomass conversion processes) and establish an EU roadmap towards 2050.
- In addition, establish additional non-ETS measures to enable EU CCS demonstration projects to take Final Investment Decision (FID) and provide security for long-term investment.
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Net primary production (NPP) is influenced by disturbance-driven fluctuations in foliar standing crop (FSC) and resource-driven fluctuations in rates of recruitment and growth, yet most studies of NPP have focused primarily on factors influencing growth. We quantified NPP, FSC, recruitment, and growth rate for the giant kelp, Macrocystis pyrifera, at three kelp forests in southern California, USA, over a 54-month period and determined the relative roles of FSC, recruitment, and growth rate in contributing to variation in annual NPP. Net primary production averaged between 0.42 and 2.38 kg dry massm2 yr1 at the three sites. The initial FSC present at the beginning of the growth year and the recruitment of new plants during the year explained 63% and 21% of the interannual variation observed in NPP, respectively. The previous year’s NPP and disturbance from waves collectively accounted for 80% of the interannual variation in initial FSC. No correlation was found between annual growth rate (i.e., the amount of new kelp mass produced per unit of existing kelp mass) and annual NPP (i.e., the amount of new kelp mass produced per unit area of ocean bottom), largely because annual growth rate was consistent compared to initial FSC and recruitment, which fluctuated greatly among years and sites. Although growth rate was a poor predictor of variation in annual NPP, it was principally responsible for the high mean values observed for NPP by Macrocystis. These high mean values reflected rapid growth (average of ;2% per day) of a relatively small standing crop (maximum annual mean¼444 g dry mass/m2 ) that replaced itself approximately seven times per year. Disturbance-driven variability in FSC may be generally important in explaining variation in NPP, yet it is rarely examined because cycles of disturbance and recovery occur over timescales of decades or more in many systems. Considerable insight into how variation in FSC drives variation in NPP may be gained by studying systems such as giant kelp forests that are characterized by frequent disturbance and rapid rates of growth and recruitment.
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Seasonality in biomass production of Sargassum baccularia (Mertens) C. Agardh and Sargassum binderi Sonder ex 1. G. Agardh was analysed based on quarterly destructive sampling using a line transect-quadrat method from January 1995 to April 1996. Biomass for both Sargassum species showed an unimodal pattern. S. baccularia attained high biomass during January 1995 (520.23 g wet weight m-2, 47.88 g dry weight m-2 , 13.35 g ash-free dry weight m-2) and July 1995 (501.98 g wet weight m-2, 64.92 g dry weight m-2, 14.00 g ash-free dry weight m-2). S. binderi attained the highest biomass in April 1996 (656.13 g wet weight m-2, 80.81 g dry weight m-2, 15.25 g ash-free dry weight m-2) with another high value recorded in July 1995 (429.28 g wet weight m-2, 54.30 g dry weight m-2, 11.20 g ash-free dry weight m-2). Both Sargassum species recorded the lowest biomass in January 1996 (S. baccularia: 76.14 g wet weight m-2 , 9.97 g dry weight m-2, 1.97 g ash-free dry weight m-2 ; S. binderi: 68.21 g wet weight m-2, 8.36 g dry weight m-2, 1.68 g ash-free dry weight m-2). Biomass for both Sargassum species was strongly correlated to the thallus length. The population of both Sargassum species consisted mainly of young plants with 96% of the S. baccularia population and 89% of the S. binderi population being shorter than 199 mm. Both Sargassum populations recorded low percentage of fertility. The most important factor that controlled the biomass production and reproduction for both Sargassum species was rainfall.
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This presentation by Klaus Lüning discusses ways to cultivate seaweed, the development of seaweed, and the pros/cons that come along with seaweed cultivation.
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Massive strandings of the pelagic brown algae Sargassum have occurred in the Caribbean, and to a lesser extent, in western Africa, almost every year since 2011. These events have major environmental, health, and economic im- pacts in the affected countries. Once on the shore, Sargassum is mechanically harvested and disposed of in land- fills. Existing commercial applications of other brown algae indicate that the pelagic Sargassum could constitute a valuable feedstock for potential valorisation. However, limited data on the composition of this Sargassum biomass was available to inform on possible application through pyrolysis or enzymatic fractionation of this feedstock. To fill this gap, we conducted a detailed comparative biochemical and elemental analysis of three pelagic Sargassum morphotypes identified so far as forming Atlantic blooms: Sargassum natans I (SnI), S. fluitans III (Sf), and S. natans VIII (SnVIII). Our results showed that SnVIII accumulated a lower quantity of metals and metalloids compared to SnI and Sf, but it contained higher amounts of phenolics and non-cellulosic polysaccharides. SnVIII also had more of the carbon storage compound mannitol. No differences in the content and composition of the cell wall polysac- charide alginate were identified among the three morphotypes. In addition, enzymatic saccharification of SnI produced more sugars compared to SnVIII and Sf. Due to high content of arsenic, the use of pelagic Sargassum is not recommended for nutritional purposes. In addition, low yields of alginate extracted from this biomass, compared with brown algae used for industrial production, limit its use as viable source of commercial alginates. Further work is needed to establish routes for future valorisation of pelagic Sargassum biomass.
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