In Malaysia, the uses of water for domestic, commercial and industrial purposes is increasing considerably, resulting in a rapid increase in the wastewater volume and pollutants. The mariculture industries are also facing the same problems. This research focuses on the impact of shrimp farming activities on the environment. The continuing discharge of contaminants from the pond obviously shows that no concern to conform with environmental regulations and good farming practices. Therefore, an efficient treatment system must be developed to improve the water quality at low operational cost and environmentally viable. In the present study, the performance of Gracilaria changii and Gracilaria edulis as biofilters for nutrients removal from shrimp pond in a laboratory scale and outdoor environment were assessed. The outdoor experiments were conducted in an Outdoor Recirculating Culture System (ORCS). The water flow rate was 200 L/hr. In the laboratory batch culture experiments, both species demonstrated considerably high nutrient removal efficiencies for ammonium, nitrate and phosphate concentrations. The removal efficiencies were 72.5%, 58.8% and 45.9% for G. edulis, and 71%, 56.8% and 43.5% for G. changii, respectively. The mean specific growth rate (SGR) for G. edulis was 3.5 ± 1.0 % day-1, while G. changii was 3.3 ± 0.9 % day-1. As for experiments conducted in ORCS, the nutrient removal efficiencies for ammonium, nitrate and phosphate were 86.2%, 59.3% and 52.0% for G. edulis, and 78.1%, 55.5% and 65.9% for G. changii, respectively. The mean SGR for G. edulis was 3.91 ± 1.0 % day-1 and G. changii was 3.69 ± 0.6 % day-1. The removal efficiency and SGR of G. edulis and G. changii in ORCS were higher compared to the laboratory batch culture experiments. The efficiency of biosand filters (BSF) to reduce total suspended solid, turbidity and chlorophyll-a of shrimp pond water was also assessed. The results showed that total suspended solid, turbidity and chlorophyll-a concentrations decreased significantly. The BSFdepicted 70.6%, 70.0% and 60.0% efficiencies in the reduction of TSS, turbidity and chlorophyll-a, respectively. The integration of shrimp culture with G. edulis in ORCS was conducted as well, and the study proved to be successful. Results showed that shrimp and seaweed grew well in the system. The mean SGR for shrimp and G. edulis were 1.31 ± 0.76 % d-1 and 4.4 % d-1, respectively. High survival rate of shrimp (91%) was observed in the treatment unit. The design considerations, the combination of cultured species and application of G. edulis as biofilter in this study provides useful information for aquaculture field. The findings include improvement of shrimp water quality to an acceptable level that ultimately enhances shrimp and seaweeds productivity and produces an ecologically sustainable treatment and cultivation system.
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Fucoxanthin is the main carotenoid produced in brown algae as a component of the light-harvesting complex for photosynthesis and photoprotection. In contrast to the complete elucidation of the carotenoid biosynthetic pathways in red and green algae, the biosynthetic pathway of fucoxanthin in brown algae is not fully understood. Recently, two models for the fucoxanthin biosynthetic pathway have been proposed in unicellular diatoms; however, there is no such information for the pathway in brown seaweeds to date. Here, we propose a biosynthetic pathway for fucoxanthin in the brown seaweed, Ectocarpus siliculosus, derived from comparison of carotenogenic genes in its sequenced genome with those in the genomes of two diatoms, Thalassiosira pseudonana and Phaeodactylum tricornutum. Currently, fucoxanthin is receiving attention, due to its potential benefits for human health. Therefore, new knowledge regarding the medical and nutraceutical properties of fucoxanthin from brown seaweeds is also summarized here.
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Multiple health benefits have been ascribed to brown seaweeds that are used traditionally as dietary component mostly in Asia. This systematic review summarizes information on the impact of brown seaweeds or components on inflammation, and inflammation-related pathologies, such as allergies, diabetes mellitus and obesity. We focus on oral supplementation thus intending the use of brown seaweeds as food additives. Despite the great diversity of experimental systems in which distinct species and compounds were tested for their effects on inflammation and immunity, a remarkably homogeneous picture arises. The predominant effects of consumption of brown seaweeds or compounds can be classified into three categories: (1) inhibition of reactive oxygen species, known to be important drivers of inflammation; (2) regulation, i.e., in most cases inhibition of proinflammatory NF-κB signaling; (3) modulation of adaptive immune responses, in particular by interfering with T-helper cell polarization. Over the last decades, several inflammation-related diseases have increased substantially. These include allergies and autoimmune diseases as well as morbidities associated with lifestyle and aging. In this light, further development of brown seaweeds and seaweed compounds as functional foods and nutriceuticals might contribute to combat these challenges.
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The therapeutic potential of Sargassum siliquosum grown in Australian tropical waters was tested in a rat model of metabolic syndrome. Forty-eight male Wistar rats were divided into four groups of 12 rats and each group was fed a different diet for 16 weeks: corn starch diet (C); high-carbohydrate, high-fat diet (H) containing fructose, sucrose, saturated and trans fats; and C or H diets with 5% S. siliquosum mixed into the food from weeks 9 to 16 (CS and HS). Obesity, hypertension, dyslipidaemia, impaired glucose tolerance, fatty liver and left ventricular fibrosis developed in H rats. In HS rats, S. siliquosum decreased body weight (H, 547 ± 14; HS, 490 ± 16 g), fat mass (H, 248 ± 27; HS, 193 ± 19 g), abdominal fat deposition and liver fat vacuole size but did not reverse cardiovascular and liver effects. H rats showed marked changes in gut microbiota compared to C rats, while S. siliquosum supplementation increased gut microbiota belonging to the family Muribaculaceae. This selective increase in gut microbiota likely complements the prebiotic actions of the alginates. Thus, S. siliquosum may be a useful dietary additive to decrease abdominal and liver fat deposition.
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Methane (CH4) is a potent greenhouse gases (GHG) with 25 times more global warming potential than carbon dioxide (CO2) (Eckard et al., 2010; Jeyanathan et al., 2014). Emission of CH4 from livestock contributes to climate change accounting for roughly 28% of global anthropogenic CH4 emission (Beauchemin et al., 2008). Enteric CH4 production also results in a significant energy loss to the animals which amounts to 2 to 12% of the gross energy intake (Martin et al., 2010; Benchaar and Greathead, 2011; Patra, 2012). Therefore, safe and effective enteric methane mitigation strategies will have a positive contribution to both the environment and animal productivity.
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Models of benthic community dynamics for the extensively studied, shallow rocky ecosystems in eastern Canada emphasize kelp-urchin interactions. These models may bias the perception of factors and processes that structure communities, for they largely overlook the possible contribution of other seaweeds to ecosystem resilience. We examined the persistence of the annual, acidic (H2SO4), brown seaweed Desmarestia viridis in urchin barrens at two sites in Newfoundland (Canada) throughout an entire growth season (February to October). We also compared changes in epifaunal assemblages in D. viridis and other conspicuous canopy-forming seaweeds, the non-acidic conspecific Desmarestia aculeata and kelp Agarum clathratum. We show that D. viridis can form large canopies within the 2-to-8 m depth range that represent a transient community state termed “Desmarestia bed”. The annual resurgence of Desmarestia beds and continuous occurrence of D. aculeata and A. clathratum, create biological structure for major recruitment pulses in invertebrate and fish assemblages (e.g. from quasi-absent gastropods to >150 000 recruits kg−1 D. viridis). Many of these pulses phase with temperature-driven mass release of acid to the environment and die-off in D. viridis. We demonstrate experimentally that the chemical makeup of D. viridis and A. clathratum helps retard urchin grazing compared to D. aculeata and the highly consumed kelp Alaria esculenta. In light of our findings and related studies, we propose fundamental changes to the study of community shifts in shallow, rocky ecosystems in eastern Canada. In particular, we advocate the need to regard certain canopy-forming seaweeds as structuring forces interfering with top-down processes, rather than simple prey for keystone grazers. We also propose a novel, empirical model of ecological interactions for D. viridis. Overall, our study underscores the importance of studying organisms together with cross-scale environmental variability to better understand the factors and processes that shape marine communities
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The red alga Gracilaria lemaneiformis was cultivated with the scallop Chlamys farreri in an integrated multi-trophic aquaculture (IMTA) system for 42 h at Sanggou Bay, located in north China. Variation in inorganic carbon in the IMTA system was determined. The experiment included three treatments each with three replicates and three scallop monoculture systems as controls. Scallop density (399.1 ± 7.85 g per microcosm) remained the same in all treatments while seaweed density differed. The seaweed density was set at three levels (treatments 1, 2, 3) with thallus wet weights of 125.3 ± 4.72 g, 252.3 ± 7.50 g, and 378.7 ± 6.51 g per microcosm, respectively. This produced bivalve to seaweed wet weight ratios of 1:0.31, 1:0.63, and 1:0.96 for treatments 1, 2, and 3, respectively. In control groups, continuous dissolution of carbon dioxide (CO2) produced by scallops into the seawater not only caused an ongoing increase in partial pressure of CO2 (pCO2), 5.5 times higher than that of natural seawater, but also acidified seawater by 0.8 units after 42 h of culture. However, in all seaweed-scallop groups, the higher the algal density, the more CO2 was absorbed; pCO2 was lowest in treatment 3. The results suggest that a ratio of bivalve to seaweed less than 1:0.96 may produce an even stronger CO2 sink. Overall, the integrated culture of seaweed and scallop could provide an efficient and environmentally friendly means to reduce CO2 emissions from bivalve mariculture.
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In this study we investigate open-ocean macroalgae mariculture and sinking (MOS) as ocean-based carbon dioxide removal (CDR) method. Embedding a macroalgae model into an Earth system model, we simulate macroalgae mariculture in the open-ocean surface layer followed by fast sinking of the carbon-rich macroalgal biomass to the deep seafloor (depth > 3,000 m). We also test the combination of MOS with artificial upwelling (AU), which fertilizes the macroalgae by pumping nutrient-rich deeper water to the surface. The simulations are done under RCP4.5 a moderate emission pathway. When deployed globally between years 2020 and 2100, the simulated CDR potential of MOS is 270 PgC, which is further boosted by AU to 447 PgC. More than half of MOS-sequestered carbon retains in the ocean after cessation at year 2100 until year 3000. The major side effect of MOS on pelagic ecosystems is the reduction of phytoplankton net primary production (PNPP) due to the nutrient competition and canopy shading by macroalgae. MOS shrinks the mid layer oxygen minimum zones (OMZs) by reducing the organic matter export to, and remineralization in, subsurface and intermediate waters, while it creates new OMZs on the seafloor by oxygen consumption from remineralization of sunken biomass. MOS also impacts the global carbon cycle, reduces the atmospheric and terrestrial carbon reservoir when enhancing the ocean carbon reservoir. MOS also enriches the dissolved inorganic carbon in the deep ocean. Effects are mostly reversible after cessation of MOS, though recovery is not complete by year 3000. In a sensitivity experiment without remineralization of sunk MOS biomass, the entire MOS-captured carbon is permanently stored in the ocean, but the lack of remineralized nutrients causes a long-term nutrient decline in the surface layers and thus reduces PNPP. Our results suggest that MOS has a considerable potential as an ocean-based CDR method. However, MOS has inherent side effects on marine ecosystems and biogeochemistry, which will require a careful evaluation beyond this first idealized modeling study.
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The present Bulletin which includes catalogues of molluscs, prawns, stomatopods and marine algae is in continuation of the two earlier ones dealing with other groups in the Reference Collections of the Central Marine Fisheries Research Institute. Of the molluscs 366 species have been listed representing Gastropoda, Bivalvia and Cephalopoda. A good number of them is of interest to amateur conchologists; there is a fair representation of economically important species, and a few are rare or little known forms of scientific interest. Ninety-five prawn species are catalogued, the majority of which support the important prawn fisheries of the country. Among those included here is a number of hitherto unrecorded deep sea prawns from grounds discovered by exploratory trawling in recent years. The collection is a very valuable one for reference purposes in view of the great economic importance of this group.
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Caulerpa lentillifera (sea grapes) is widely consumed in South-East Asia as a low-energy food with high contents of vitamins and minerals. This study investigated dried sea grapes containing 16.6% insoluble fibre commercially produced in Vietnam as an intervention. We hypothesised that insoluble fibre is the primary metabolite that will reverse diet-induced metabolic syndrome. Male Wistar rats (n = 48) were randomly allocated to four groups in a 16 week protocol. Two groups were fed either corn starch (C) or high-carbohydrate, high-fat (H) diets for the full 16 weeks. The other two groups received C and H diets for eight weeks and then received C. lentillifera added to these diets for the final eight weeks (CCL and HCL, respectively). High-carbohydrate, high-fat diet-fed rats developed obesity, hypertension, dyslipidaemia, fatty liver disease and increased left ventricular collagen deposition. C. lentillifera supplementation in HCL rats decreased body weight, systolic blood pressure, plasma concentrations of total cholesterol and non-esterified fatty acids, inflammatory cells in heart and liver, and visceral adiposity. The Firmicutes to Bacteroidetes ratio decreased in the gut microbiota of HCL rats. Therefore, C. lentillifera attenuated cardiovascular and metabolic symptoms of metabolic syndrome in rats, possibly by preventing infiltration of inflammatory cells together with modulating gut microbiota.
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