The Green Revolution boosted agricultural production approximately 2.5 times and was associated with an approximately 40% price reduction in the cost of food (MA, 2005). Following on the euphoria of this success there has been increasing pressure to diversify production and to improve the planet’s environment (Hubert et al., 2010). Successful realization of this pressure will require better soil management. However, current conditions are very different from what they were 50 years ago. The success of the Green Revolution came at the expense of the natural capital, such that 18 of the 24 currently acknowledged ecosystem services have been impaired. Although soils have aided climate regulation by sequestering an estimated 2 Gt carbon (C) per annum from fossil fuel burning, they have lost part of their capacity to regulate hydrological fluxes and nutrient cycles and therefore to support plant production. The soils of the earth are now being asked to produce 70% more food over the next 35 years, while also producing biofuels, regulating climate through further C sequestration, and helping to conserve biodiversity. However, the other side of this coin is the declining amount of land remaining available for conversion to agroecosystems and the increased cost of energy, which has led to a substantial increase in the price of fertilizers. Further, world sources of phosphorus (P) are being rapidly depleted and the toxic effects of pesticides are now forcing the replacement of these former pillars of intensive agriculture with new technical options. Agriculture now needs to sustain high levels of production while preserving or restoring the natural capital of the soil. Maintenance of an appropriate level of soil biodiversity is critical to achieving this goal, but in order to protect the soil resource and optimize its long-term use, new land use practices are needed to be developed, based on much greater understanding of the factors controlling its functioning. This article summarizes the current knowledge of the composition and taxonomic richness of the soil biota. It then examines the participation of the soil biota in the major soil functions and discusses ways to reconcile the conservation and/or improvement of this natural capital with the production of critical ecosystem goods and services.
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We evaluated the potential of three seaweed species (Ulva pertusa, Saccharina japonica, Gracilariopsis chorda) as biofilters for effluents from black rockfish (Sebastes schlegeli) tanks. The experiments consisted of a fish monoculture system and a fish-seaweed integrated system under identical physical conditions. All species efficiently removed NH 4 + , NO 3 – + NO 2 – , and PO 4 3– from the fish tank effluents. Of the three species evaluated, U. pertusa showed the highest biofil-tering efficiency for NH 4 + (>80%). In contrast to U. pertusa and G. chorda, S. japonica showed a relatively higher prefer-ence for NO 3 – + NO 2 – than for NH 4 + . These results suggest that seaweeds may select nitrogen sources fitting their storage capacity. Therefore, standard fish farm effluents should establish a total nitrogen concentration that includes both NO 3 – and NH 4 + , and the selection of a biofilter seaweed species should be made with consideration of the N forms expelled in effluent. The biofiltering efficiency for PO 4 3– was highest in G. chorda (38.1%) and lowest in S. japonica (20.2%). In all species, tissue N and P contents rapidly increased over the initial values. The data for tissue N and P contents, and C : N and N : P ratios, indicate that neither N nor P was limiting. This suggests that the three species serve as biofilters by stor-ing large amounts of nutrients. These results provide valuable information for selecting optimal seaweed species in fish-seaweed integrated systems and allow land-based integrated aquaculture system operators to understand the behavior of integrated cultures sufficiently for the results herein to be extrapolated to larger-scale cultures.
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‘Biogas’ is the word used to denote the mixtures of methane and carbon dioxide produced by bacterial action, in vitro, on various organic substrates. In vitro’, because similar mixtures of methane and carbon dioxide are formed by essentially the same bacterial actions in the gut of animals (in particular the rumen and similar organs of the herbivore gut; see previous papers) and in decaying vegetation in marshes and river beds.
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Although Lobophora belongs to a marine algal family (Dictyotaceae) that produces a large array of secondary metabolites, it has received little atten- tion compared to other genera, such as Dictyota, in terms of natural compounds isolation and character- ization. However, metabolites produced by Lobo- phora species have been found to exhibit a wide array of bioactivities including pharmacological (e.g. antibacterial, antiviral, antioxidant, antitumoral), pes- ticidal, and ecological. This review aims to report the state-of-the-art of the natural products isolated from Lobophora species (Dictyotales, Phaeophyceae) and their associated bioactivities. All bioactivities docu- mented in the literature are reported, therefore including studies for which pure active substances were described, as well as studies limited to extracts or fractions. From the early 1980s until today, 49 scientific works have been published on Lobophora chemistry and bioactivity, among which 40 have reported bioactivities. Only six studies, however, have identified, characterized and tested no less than 23 bioactive pure compounds (three C21 polyunsaturated alcohols, three fatty-acids, a macrolactone, 11 polyke- tides, a few sulfated polysaccharides, three sulfolipids, a tocopherol derivative). The present review intends to raise awareness of chemists and biologists given the recent significant taxonomic progress of this brown algal genus, which holds a promising plethora of natural products yet to be discovered with ecological and pharmacological properties.
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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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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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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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The secondary metabolites of seaweed Ulva fasciata and Hypnea musciformis,collected form southeast and southwest coast of India. were tested for biotoxicity potential. Both species bowed potent activity in antibacterial, brine shrimp cytotoxicity, larvicidal, antifouling and ichthyotoxicity assays.
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Wastewater and activated sludge present a major challenge worldwide. Wastewater generated from large and small-scale industries, laundries, human residential areas and other sources is emerging as a main problem in sanitation and maintenance of smart/green cities. During the last decade, different technologies and processes have been developed to recycle and purify the wastewater. Currently, identification and fundamental consid- eration of development of more advanced microbial-based technologies that enable wastewater treatment and simultaneous resource recovery to produce bioenergy, biofuels and other value-added compounds (organic acids, fatty acids, bioplastics, bio-pesticides, bio-surfactants and bio-flocculants etc.) became an emerging topic. In the last several decades, significant development of bioprocesses and techniques for the extraction and recovery of mentioned valuable molecules and compounds from wastewater, waste biomass or sludge has been made. This review presents different microbial-based process routes related to resource recovery and wastewater application for the production of value-added products and bioenergy. Current process limitations and insights for future research to promote more efficient and sustainable routes for this under-utilized and continually growing waste stream are also discussed.
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The growing world population demands an in- crease in animal protein production. Seaweed may be a valu- able source of protein for animal feed. However, a biorefinery approach aimed at cascading valorisation of both protein and non-protein seaweed constituents is required to realise an eco- nomically feasible value chain. In this study, such a biorefinery approach is presented for the green seaweed Ulva lactuca containing 225 g protein (N × 4.6) kg−1 dry mat- ter (DM). The sugars in the biomass were solubilised by hot water treatment followed by enzymatic hydrolysis and centri- fugation resulting in a sugar-rich hydrolysate (38.8 g L−1 sugars) containing glucose, rhamnose and xylose, and a protein-enriched (343 g kg−1 in DM) extracted fraction. This extracted fraction was characterised for use in animal feed, as compared to U. lactuca biomass. Based on the content of essential amino acids and the in vitro N (85 %) and organic matter (90 %) digestibility, the extracted fraction seems a promising protein source in diets for monogastric animals with improved characteristics as compared to the intact U. lactuca. The gas production test indicated a moderate rumen fermentation of U. lactuca and the extracted frac- tion, about similar to that of alfalfa. Reduction of the high content of minerals and trace elements may be required to allow a high inclusion level of U. lactuca products in animal diets. The hydrolysate was used suc- cessfully for the production of acetone, butanol, ethanol and 1,2-propanediol by clostridial fermentation, and the rhamnose fermentation pattern was studied.
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Marine Agronomy Group, CAFNRM, UH-Hilo
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