Fish assemblages in tropical habitats like coral reefs or seagrass beds vary with natural cycles (e.g., lunar, diel or tidal) on several spatio-temporal scales. However, the dimensions of these variations are rarely being quantified despite their strong implications for ecosystem functioning and conservation of exploited stocks. Ignoring these predictable changes hinders the identification of *Manuscript Click here to view linked References structuring forces of fish assemblages and may lead to incorrect interpretations of the results and evaluation of habitats. To assess natural variation on short timescales, fish assemblages at a small tropical island (Chumbe Island, Tanzania) in the western Indo-Pacific were investigated and compared among two coastal habitats (coral reef and seagrass bed) at different lunar, diel, and tidal phases using underwater visual census methods. Results of multivariate analyses suggested two distinct fish communities in the two habitat types with the coral reef comprising a higher species richness and heterogeneity than the seagrass bed. In the coral reef, community composition and trophic diversity was influenced by all three natural cycles, while in the seagrass bed they were mainly driven by tidal phases. Mean fish densities were slightly different in the two habitat types during daytime but increased significantly in the seagrass bed during twilight hours. For the investigated habitats on Chumbe Island our results indicate that (i) through their routine migrations mobile fishes can provide important functional links between habitats, (ii) seagrass beds have lower species richness and diversity, and emphasize that (iii) fish movement governed by natural cycles can cause predictable short-term variations in fish communities.
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Planktivorous fish which limit zooplankton grazing have been predicted to increase algal biodiesel production in wastewater fed open reactors. In addition, tanks with higher algal diversity have been predicted to be more stable, more productive, and to more fully remove nutrients from wastewater. To test these predictions, we conducted a 14-week experiment in Houston, TX using twelve 2,270-L open tanks continuously supplied with wastewater. Tanks received algal composition (monocultures or diverse assemblage) and trophic (fish or no fish) treatments in a full-factorial design. Monocultures produced more algal and fatty acid methyl ester (FAME) mass than diverse tanks. More than 80% of lipids were converted to FAME indicating potentially high production for conversion to biodiesel (up to 0.9 T ha-1 y-1). Prolific algal growth lowered temperature and levels of total dissolved solids in the tanks and increased pH and dissolved oxygen compared to supply water. Algae in the tanks removed 91% of nitrate-N and 53% of phosphorus from wastewater. Monocultures were not invaded by other algal species. Fish did not affect any variables. Our results indicated that algae can be grown in open tank bioreactors using wastewater as a nutrient source. The stable productivity of monocultures suggests that this may be a viable production method to procure algal biomass for biodiesel production.
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It's Rich In Vitamins And Antioxidants, But It's Not What You Think It Is. The latest cash crop in the farm-to-table food craze doesn’t come from the land; it comes from the Long Island Sound. In spite of what you might think, this new cash crop isn’t shell-fish; it’s kelp. The superfood is loaded with vitamins, minerals, and antioxidants, and is being served up at local restaurants.
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The animal feeding industry is looking for new local sources of high quality protein in order to reduce import and ensure sustainable and environmental friendly animal production systems. Local legumes and seaweeds may be alternative sources of protein. We present in this paper the background for the ongoing Norwegian Research Council project Legumes and seaweeds as alternative protein sources for sheep (AltPro), which aims to investigate the suitability and potential of legumes and seaweeds as new and underutilized protein sources in sheep diets. The project addresses several critical aspects for the future development of the agriculture industry in Norway applicable to other European countries from an integrated social and natural scientific approach: 1. use of protein sources alternative to soya, 2. environmental, climatic, societal and economical sustainability, 3. animal health and welfare.
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Forage fish play a crucial role in marine food webs in many ecosystems (Box 1.1). These small and medium-sized pelagic species are the primary food source for many marine mammals, seabirds, and larger fish, transferring energy from plankton to larger predators. Forage fish are also important predators in marine ecosystems, feeding upon phytoplankton, zooplankton, and, in some cases, the early life stages of their predators.
Forage fish play an intermediary role in many marine ecosystems, including estuaries, shelf seas, upwelling, and open ocean systems occurring from the tropics to the Earth’s poles. They constitute the majority of prey upon which some predators depend. Such highly dependent predators may be iconic or ecologically important, while others may be commercially or recreationally valuable fish species. In some cases, highly dependent predators may include threatened or endangered species. A reduction in available prey—because of fishing, environmental conditions, or a combination of both—can have direct and lasting impacts and can fundamentally change the structure and functioning of an ecosystem.
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Today, mariculture is one of the fastest growing food production sectors, with an annual growth rate of 4-11%. This rapid growth is likely due in part to the large area of “usable land” in the ocean and the high protein food that can be produced and harvested, one of which is seaweed. (Troell, 1999; CBD, 2013). In addition, seaweed is not only a source of food, but has properties that make it an option for utilization in pharmaceuticals, biofuels, and other applications. A unique advantage of this type of systems is that growing seaweed consumes excess nutrients and CO2, two compounds believed to have ecologically dangerous impacts (Troell, 1999). With these benefits to the marine agronomy, it is not hard to see why scientists and engineers are interested farther developing this unique industry.
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The repertoire of novel biobased materials is continually expanding as they represent green alternatives to carbon-intensive fossil materials. Lipid-extracted algae (LEA) biomass is a promising feedstock for the production of a spectrum of biobased materials, such as hydrochar and biochar, electrodes in microbial fuel cells (MFCs), supercapacitors, biocomposites, biopolymers, activated carbon including N-doping, and biosorbents. By selecting appropriate process conditions, these renewable products can be designed to possess desirable properties and, at the same time, be more sustainable. Most importantly, we view LEA as a potentially significant additional source of revenue for algae biorefineries that can accelerate the commercial development of algae. The present study assesses the utilization of LEA for the production of biobased materials, their applications and sustainability profile, and future trends.
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Biological lipids derived from oleaginous microorganisms are promising precursors for renewable biofuel productions. Direct lipid extraction from wet cell-biomass is favored because it eliminates the need for costly dehydration. However, the development of a practical and scalable process for extracting lipids from wet cell-biomass is far from ready to be commercialized, instead, requiring intensive research and development to understand the lipid accessibility, mechanisms in mass transfer and establish robust lipid extraction approaches that are practical for industrial applications. This paper aims to present a critical review on lipid recovery in the context of biofuel productions with special attention to cell disruption and lipid mass transfer to support extraction from wet biomass.
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The present study evaluated the efficiency of seaweeds collected from Abu Qir Bay, Alexandria, Egypt, as a feedstock for biodiesel. A total of 15 macroalgal species were collected overall in the four seasons. The highest seasonal biomass production of 652.1 and 626.3 g m⁻² was recorded with Chaetomorpha linum and Ulva compressa in autumn and spring, respectively. While the highest annual biomass production was detected in Ulva fasciata (1056.8 g m⁻²). Lipid content varied among species, with the highest value of 14.66 % and 9.94 % dw in U. fasciata and U. compressa during spring, which resulted in the highest annual lipid productivity of 67.4 and 63.3 g m⁻², respectively. Palmitic acid (C16:0) showed the highest value among all fatty acids (1.12-19.62 mg g−¹ dw) in all studied species. The biodiesel characteristics of all algae species tested are in agreement with the values of international standards. Overall, the present study recommended U. compressa and U. fasciata as a promising biodiesel feedstock due to the relatively higher lipid productivity and FAMEs characteristics that comply with the international standards and high net energy output that reached 1.24 and 1.30 GJ ton⁻¹, respectively.
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The nutritional value and chemical changes in the lipid content of the green macroalgae, Ulva sp., were assayed in the present study. Ulva samples were collected from two stations, Ras Al-Tin (station A) and El-Muntazah (Station B) along Alexandria shore on the Mediterranean Sea, in twelve sampling periods (from January to December 2012). Each three samples of each station were plotted to represent one season. The chemical characterization of the lipid fractions was performed by gas liquid chromatography. The result showed that Ulva lipid content is relatively high (9.4±1.5 and 12.2±2.7%DW, at station A and B respectively) that can be explained by the higher pollution level at the station A. The fatty acids (FAs) of Ulva sp. lipidic extract mainly composed of palmitic, oleic and linoleic FAs. Saturated fatty acids (SFAs) represented about 50% of the total FAs (TFAs). Monounsaturated fatty acids (MUFAs) accounted for a high percent, 17.6-33.4% of TFAs. Polyunsaturated fatty acids (PUFAs) existed in a high percent in Ulva extraction reaching a maximum in winter and spring at both stations, about 38.4 and 30.5% of TFAs at station A and B, respectively. The high percent of PUFA can be attributed to the correlation between the low temperature and the degree of unsaturation. Also, the long chain fatty acids (C16 and C18) constitute more than 82% of the TFAs, which are the main components for biofuel. The results indicate that Ulva has a good potential for its use in human and animal food and health maintenance as a rich source of MUFAs and PUFA as well as in biodiesel production. Also, the wide ranges of the fatty acids indicate the possibility of manipulating the fatty acids profile through the cultivation conditions.
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Marine Agronomy Group, CAFNRM, UH-Hilo
200 W. Kawili st., HI 96720, USA
Contact: Marine.Agronomy.Group@gmail.com
Funding for this web portal is provided by the World Wildlife Fund and the University of Hawaii-Hilo.