Seaweed farming is often depicted as a sustainable form of aquaculture, contributing to poverty reduction and financial revenues in producer countries. However, farms may negatively affect seagrasses and associated organisms (e.g. invertebrate macrofauna) with possible effects on the flow of ecosystem goods and services to coastal societies. The present study investigates the influence of a seaweed farm, and the farmed seaweed Eucheuma denticulatum in particular, on fishery catches using a traditional fishing method (“madema” basket traps) in Chwaka bay (Zanzibar, Tanzania). The results suggest that a seaweed farm, compared to a seagrass bed, had no influence on catch per unit effort (no. of individuals per catch, or catch weight) or no. of species per catch, but significantly affected catch composition (i.e. how much that was caught of which species). The two species contributing most to differences between the sites were two economically important species; the herbivorous seagrass rabbit fish Siganus sutor, which was more common in the seaweed site and is known to graze on the farmed algae; and the benthic invertebrate feeder chloral wrasse Cheilinus chlorourus, more common in the seagrass site. Compared to vegetation-free bottoms, however, the catches were 3−7 times higher, and consisted of a different set of species (ANOSIM global R > 0.4). As traps placed close to the seaweeds fished three times more fish than traps placed on sand patches within the seaweed farm, the overall pattern is attributed to the presence of submerged vegetation, whether seagrass or seaweed, probably as shelter and/or food for fish. However, qualitative differences in terms of spatial and temporal dynamics between seagrass beds with and without seaweed farms, in combination with other factors such as institutional arrangements, indicate that seaweed farms cannot substitute seagrass beds as fishing grounds.
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The contemporary uses of seaweed in Ireland are many and various. Seaweed is gathered as food, processed and used as fertiliser, forms an ingredient in many cosmetics and spa treatments, and is the subject of biotechnological and pharmaceutical research.
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A variety of microorganisms can evolve H2 according to the following equation:2H+ + 2e +z H2. These include strict or facultative anaerobic bacteria, aerobic bacteria, blue-green and green algae. In aerobic bacteria and in blue-green algae H2 formations are restricted to N2-fixing species. Strict and facultative anaerobic bacteria as well as green algae (Chlamydomonas, Scenedesmus, Chlorella) form the gas only under O2 exclusion in the cultures. There is no clearcut demonstration for Hrformation by mosses, ferns and higher plants. Lists of the Hrforming organisms are compiled in Mortenson and Chen I and Schlegel and Schneider2. Since the redox potential of the couple 2H+ /H2 is -413 mV at pH 7.0, a low potential reductant is required for H2-formation to proceed in the cells. The reaction is also enzyme mediated. Cells may contain 3 clearly distinguishable enzymes catalyzing either uptake or evolution of H2 under physiological conditions (for a more detailed account and the references see Bothe and Eisbrenner3).
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Photosynthetic bacteria utilize hydrogen as electron donor for autotrophic CO2 assimilation. Many of these organisms also evolve hydrogen under dark anaerobic conditions and, in large quantities, anaerobically in the light in the absence of ammonia and molecular nitrogen. Hydrogen photoproduction in photosynthetic bacteria is largely or completely associated with the action of nitrogenase. It is not inhibited by CO, an inhibitor of hydrogenase and is dependent on ATP. The conventional hydrogenase catalyzes the reversible reaction H2⇄2H++2e-.It seems however that in photosynthetic bacteria this enzyme catalyzes mainly hydrogen uptake in vivo. It has been suggested that a function of hydrogenase is to reutilize the hydrogen which is evolved as a byproduct of the nitrogenase reaction, retaining reducing equivalents for N2 or CO2 reduction1. In contrast to aerobic bacteria, energy conservation in a Knallgas reaction is not possible for photosynthetic bacteria growing anaerobically in the light2.
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Inhibition of angiotensin-I-converting enzyme (ACE-I), renin, and dipeptidyl peptidase-IV (DPP-IV) plays a key role in the treatment of hypertension and type-2 diabetes. The aim of this study was to isolate and characterize novel ACE-I, renin, and DPP-IV inhibitory peptides from a papain hydrolysate of bovine serum albumin (BSA). BSA was obtained from whole bovine blood and hydrolyzed with the food-grade enzyme papain. The generated hydrolysate was further purified using ultrafiltration and high performance liquid chromatography (HPLC), and a number of novel bioactive peptides were identified using de novo peptide sequencing. These included SLR, YY, ER, and FR which inhibited the activity of the enzyme ACE-I by half at a concentration of 0.17 ± 0.02, 0.18 ± 0.04, 0.27 ± 0.01, and 0.42 ± 0.02 mM, respectively. In addition, the 1 kDa fraction of the papain hydrolysate was assessed for antihypertensive activity in vivo using spontaneously hypertensive rats (SHRs) and reduced sys- tolic blood pressure over a 24 h period when compared with the control (p b 0.001). Results demonstrated the potential of bovine serum albumin as a source of bioactive peptides with health-promoting properties and poten- tial for use as functional food ingredients.
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The Ecological Status of subtidal benthic communities within a commercial kelp farm on the southwest coast of Ireland was not impacted by macroalgal cultivation. Additionally, there was no effect on the biomass of Zostera marina, a key habitat under the EU Habitats Directive and OSPAR Commission. However, sediment grain size and total organic matter (TOM) were influenced by abiotic and biotic aspects of the farm. A temporal effect on univariate and multivariate species data, Infaunal Quality Index (IQI) and Z. marina biomass was observed. This effect was likely a community response to high storm disturbance in winter 2013/14.
The use of IQI to assess the impact of macroalgal cultivation on benthic communities is a novel approach. This study supports a view that environmental impacts of macroalgal cultivation are relatively benign compared to other forms of aquaculture. Further research must be conducted to understand all interactions between aqua- culture activities and the environment.
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Seaweeds contain a considerable amount of micronutrients and plant growth hormones like auxins, gibberellins, cytokinins, and betaines etc. which are supposed to help plant growth and also in seed germination. The extracts of seaweeds have proved itself as a highly effective and eco- friendly pesticide against various crop pests. This chapter provides an overview of the varieties of seaweeds, their ecology and their utilization worldwide. The main concept of this chapter delves into the possible utilization of selected seaweeds in agriculture. The various forms of seaweeds such as seaweed extract (SWE), compost, mulch etc. and their applications as bio-stimulators, growth promoters, crop protection, soil conditioner, and stabilizer are discussed.
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Seaweeds or marine macroalgae are rich in diverse compounds like lipids, proteins, carbohydrates, phytohormones, amino acids, osmoprotectants, antimicrobial compounds and minerals. Their potential for agricultural applications is used since antiquity, but recent demands of organic farming and organic food stimulated much the application of organic treatments like seaweed extracts in agriculture. The benefits of seaweeds application in agricultural field are numerous and diverse such as stimulation of seed germination, enhancement of health and growth of plants namely shoot and root elongation, improved water and nutrient uptake, frost and saline resistance, biocontrol and resistance toward phytopathogenic organisms, remediation of pollutants of contaminated soil and fertilization. In this review, scientific progress in this field was collected and critically assessed to lay grounds for further investigations and applications.
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Seaweeds—or marine macroalgae—notably brown seaweeds in the class Phaeophyceae, contain fucoidan. Fucoidan designates a group of certain fucose-containing sulfated polysaccharides (FCSPs) that have a backbone built of (1→3)-linked α-l-fucopyranosyl or of alternating (1→3)- and (1→4)-linked α-l-fucopyranosyl residues, but also include sulfated galactofucans with backbones built of (1→6)-β-d-galacto- and/or (1→2)-β-d-mannopyranosyl units with fucose or fuco-oligosaccharide branching, and/or glucuronic acid, xylose or glucose substitutions. These FCSPs offer several potentially beneficial bioactive functions for humans. The bioactive properties may vary depending on the source of seaweed, the compositional and structural traits, the content (charge density), distribution, and bonding of the sulfate substitutions, and the purity of the FCSP product. The preservation of the structural integrity of the FCSP molecules essentially depends on the extraction methodology which has a crucial, but partly overlooked, significance for obtaining the relevant structural features required for specific biological activities and for elucidating structure-function relations. The aim of this review is to provide information on the most recent developments in the chemistry of fucoidan/FCSPs emphasizing the significance of different extraction techniques for the structural composition and biological activity with particular focus on sulfate groups.
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Two experiments were performed in the Bekaa plain in Lebanon to evaluate the feasibility of integrating aquaculture with established agriculture production in order to increase water productivity. Both experiments consisted of four plant management treatments: 1) Aquaculture effluent irrigation and no fertilizer; 2) aquaculture effluent irrigation and inorganic fertilizer; 3) well water irrigation and no fertilization; and 4) well water irrigation with inorganic fertilizer. In the first experiment, tilapia growth and radish production using aquaculture effluent were evaluated. All fish survived and grew, and radish production was improved by irrigating with aquaculture effluent. In the second experiment, maize (Zea mays) in large plots was irrigated with aquaculture effluent. Irrigation with effluent water improved maize production and improved soil nitrogen availability. In both experiments, fish production improved water value index and water use efficiency. Results suggest that aquaculture effluent can supplant inorganic fertilizers and could actually yield better crop production.
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