The fatty acid (FA) compositions of ten seaweeds representative of Chlorophyta, Rhodophyta, and Ochrophyta from Kuwait in the Arabian Gulf region were determined and are discussed in the context of their potential nutritional perspectives for seaweed valorization. All the seaweeds had higher saturated fatty acid (SFA) and lower monounsaturated (MUFA) and polyunsaturated fatty acid (PUFA) contents than those typical of tropical environments. Palmitic, myristic, stearic, oleic, linoleic, α-linolenic, and stearidonic acids were the major FAs detected. Arachidonic, eicosapentaenoic, and docosahexaenoic acids were detected in minor amounts. Conserved fatty acid patterns revealed phylogenetic relationships among phyla, classes, and orders matching the molecular phylogenies at higher taxonomic ranks. Hierarchical clustering analyses clearly segregated different seaweeds (except Codium papillatum and Iyengaria stellata) into distinct groups based on their FA signatures. All but one species (Chondria sp.) had health-beneficial n6/n3 PUFAs (0.33:1–2.94:1) and atherogenic (0.80–2.52) and thrombogenic indices (0.61–5.17). However, low PUFA/SFA contents in most of the species (except Ulva spp.) may limit their utilization in the formulation of PUFA-rich functional foods. Ulva spp. had substantially high PUFAs with PUFA/SFA > 0.4, n6/n3 (0.33–0.66) and atherogenic (0.80–1.15) and thrombogenic indices (0.49–0.72), providing substantial potential for their utilization in food and feed applications.
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Nonindigenous marine species continue to be one of the foremost threats to marine biodiversity. As an update to a 2007 review of the impacts of introduced macroalgae, we assessed 142 additional publications to describe species’ impacts as well as to appraise information on the mechanisms of impact. Only 10% of the currently known nonindigenous macroalgal species were subjects of ecological impact studies, with changed community composition as the most commonly reported effect. Economic impacts were rarely published. Recent research has focused on the impacts of introduced macroalgal assemblages: red algal introductions to the Hawaiian Islands and turf algae in the Mediterranean. Several general issues were apparent. First, many publications included nonsignificant results of statistical analyses but did not report associated power. As many of the studies also had low effect and sample size, the potential for type II errors is considerable. Second, there was no widely accepted framework to categorize and compare impacts between studies. Information in this updated review was still too sparse to identify general patterns and mechanisms of impact. This is a critical knowledge gap as rates of introductions and hence impacts of nonindigenous macroalgae are expected to accelerate with climate change and increasing global trade connectivity.
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Poverty, hunger and malnutrition affect millions of people across the globe; of these, 25 percent live in sub-Saharan Africa. The challenge is to find suitable and sustainable technologies which ensure them physical, social and economic access to sufficient, safe and nutritious food at all times: a situation referred to as food security. Many scholars, researchers, development agencies and policy-makers argue that aquaculture, the farming of marine organisms including fish, contributes to food security in many parts of the world including sub-Saharan Africa. A range of methodologies exist which assess the prevalence and extent of food insecurity. However, little is known about the extent to which aquaculture contributes to alleviating poverty and hunger.
This study surveys different methods which could be used to determine the contribution of aquaculture to improving food security. It focuses on four main essential components of food security, namely: stability of food supply, increased availability of food, improved access to supplies and more effective food utilization. Findings indicate that physical, dietary and economic indicators are widely used to achieve this goal. However, because of the complexity and extent of global food insecurity, it is unlikely that, of the methodologies surveyed, a single one can ever accurately quantify the contribution of a given technology, such as aquaculture, to food security. Further research is needed to address this issue. Perhaps a combination of indicators currently used into a methodology could be a starting point.
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The magnitude and character of nitrogen fixation in Sargassum communities was studied for three different species, S. fluitans Borgesen, S. natans J. Meyen and S. filipendula C. Agardh. Nitrogen fixation activity was measured using the acetylene reduction technique. The character of epiphytic populations on the surface of Sargassum was investigated by scanning electron microscopy. All three species of Sargassum exhibited the potential for high levels of acetylene reduction. Mean rates of up to 7.1 μmol C2H4 produced·g−1 (Sargassum dry wt.)·h−1 were observed at one location. Nitrogen fixation activity was strongly light dependent. Saturation light intensity for nitrogen fixation was low, i.e. < 100 μE·m−2·s−1, and no photoinhibition was observed under full sunlight intensity (i.e. photon flux of ≈ 2000 μE·m−2·s−1). Results indicated that cyanobacteria were responsible for nitrogen fixation. Both Calothrix and LPP type cyanobacteria were commonly represented on the surface of the Sargassum. Activity associated with the benthic species S. filipendula exhibited significant seasonal variability. Nitrogen fixation activity in pelagic samples was variable but high throughout the year. The contribution of nitrogen fixation to the nitrogen budget of Sargassum communities appears to be particularly pronounced in the pelagic environment.
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Differences in ash behavior during hydrothermal treatment were identified based on multivariate data analysis of literature information on 29 different feedstock. In addition, the solubility of individual ele- ments was evaluated based on a smaller data set. As a result two different groups were distinguished based on char ash content and ash yield. Virgin terrestrial and aquatic biomass, such as different types of wood and algae, in addition to herbaceous and agricultural biomass, bark, brewer’s spent grain, com- post and faecal waste showed lower char ash content than municipal solid wastes, anaerobic digestion residues and municipal and industrial sludge. Lower char ash content also correlated with lower ash yield indicating differences in chemical composition and ash solubility. Further evaluation of available data showed that ash in industrial sludge mainly contained anthropogenic Al, Fe and P or Ca and Si with low solubility during hydrothermal treatment. Char from corn stover, miscanthus, switch grass, rice hulls, olive, artichoke and orange wastes and empty fruit bunch had generally higher contents of K, Mg, S and Si than industrial sludge although differences existed within the group. In the future information on ash behavior should be used for enhancing the fuel properties of char based on feedstock type and hydrother- mal treatment conditions.
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Sargassum macrocarpum is a rich source of anti-inflammatory compounds. Recently, one of the compounds, tuberatolide B, has been reported as a functional anti-inflammatory additive for foods and nutraceuticals. The artificial seeding, growth and maturation of S. macrocarpum were investigated from May 2018 to September 2019. Indoor culture experiments for induction of egg release were conducted at temperatures of 17, 20, 23, and 26°C and irradiances of 0, 10, 20, 40, and 80 μmol photons m-2 s-1 under 14 : 10 h (L : D) photoperiod. Within a given treatment combination, higher temperatures and irradiance levels favoured the maturation of receptacles in S. macrocarpum. Using artificial temperature and irradiance control, thalli matured one month earlier than thalli in nature. Under natural condition, receptacle formation began in April, and the eggs were released in June and July. The release of eggs from the receptacles was promoted at 17-20°C and 40-80 μmol photons m-2 s-1, and the fastest growth of germlings occuring at 15-17°C and 40 μmol photons m-2 s-1. For mature thalli, 300 g wet-weight was sufficient to seed 100 m of seed string. Thalli grew to 10.5 ± 2.6 cm in length at a density of 6.7 ± 3.3 individuals m-1 after 1 year of cultivation, from germination. This study demonstrates that it is possible to cultivate S. macrocarpum for the production of anti-inflammatory products.
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Artificial seawater prepared with simplified recipes was found suitable for maintaining seaweeds of commercial importance under laboratory conditions. The suitability of this artificial seawater formulation studied by gain or loss of wet weight of seaweeds incubated, showed 15.5% increase in specific growth rate in the case of Gracilaria corticata and 18% increase in the case of Ulva lactuca. However, Gracilaria edulis showed 14% decrease over the control. Physicochemical characteristics of artificial seawater were compared with these of natural seawater.
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Giant kelp (aka macro algae) are among the most prolific producers of biomass, growing in enormous underwater forests up and down the west coast of North America. For years kelp have been eyed as a source of biofuels. On November 24, 2015, one San Diego company received an award from the Department of Energy’s (DOE) Advanced Research Projects Agency-Energy (ARPA-E) to give their unique cultivation technology a run at producing biocrude from seaweed.
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Green seaweeds of the genus Ulva are rich in the bioactive sulfated polysaccharide ulvan. Herein we characterise ulvan from Ulva species collected from the Bay of Plenty, Aotearoa New Zealand. Using standardised procedures, we quantified, characterised, and compared ulvans from blade (U. australis, U. rigida, U. sp. B, and Ulva sp.) and filamentous (U. flexuosa, U. compressa, U. prolifera, and U. ralfsii) Ulva species. There were distinct differences in composition and structure of ulvans between morphologies. Ulvan isolated from blade species had higher yields (14.0–19.3 %) and iduronic acid content (IdoA = 7− 18 mol%), and lower molecular weight (Mw = 190− 254 kDa) and storage moduli (G’ = 0.1–6.6 Pa) than filamentous species (yield = 7.2–14.6 %; IdoA = 4− 7 mol%; Mw = 260− 406 kDa; G’ = 22.7–74.2 Pa). These results highlight the variability of the physicochemical properties of ulvan from different Ulva sources, and identifies a morphology-based division within the genus Ulva.
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Chinese aquaculture has employed a balanced ecosystem approach for freshwater aquaculture for several thousand years. Utilizing species that feed at different levels of the food web has permitted China to have the largest freshwater aquaculture production in the world. This production has proved to be sustainable in the long run because there is balance in this system. This concept is just starting to be thought of for broader aquaculture, including marine operations at sea or on land, and fishery communities around the world.
The National Oceanic and Atmospheric Administration has developed a Sustainable Fisheries Implementation Plan that recognizes three key elements - fisheries, aquaculture and coastal communities - for obtaining sustained production of seafood in the United States. The concepts of carrying capacity for biological activities in a hydrographic system; ecological balance between primary producers, primary and secondary consumers; and nutrient flows in ecosystems are essential elements for the future development of world aquaculture and fisheries.
This chapter documents the present status of selected polyculture systems being employed by the aquaculture industry, provides examples of balanced ecosystem approaches to aquaculture and fisheries, and examines the question of how to develop models for maximizing the production of seafood through fisheries and aquaculture working in harmony to minimize environmental impacts.
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