Sundried and powdered Sargassum wigluii was treated with 1 % HcI, 1 % NaOH and 10% formalin and fresh material of the same species with different concentrations of formalin, 140%, with a view to assessing the effect of chemical pre-Ireatment on the yield and viscosity of the algin content. The study indicates that high yield and viscosity of the product could be obtained by pre-treating the fresh a1ginophytes with 1-5% formalin.
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Ocean acidification (OA) is expected to reduce the calcification rates of marine organisms, yet we have little understanding of how OA will manifest within dynamic, real-world systems. Natural CO2, alkalinity, and salinity gradients can significantly alter local carbonate chemistry, and thereby create a range of susceptibility for different ecosystems to OA. As such, there is a need to characterize this natural variability of seawater carbonate chemistry, especially within coastal ecosystems. Since 2009, carbonate chemistry data have been collected on the Florida Reef Tract (FRT). During periods of heightened productivity, there is a net uptake of total CO2 (TCO2) which increases aragonite saturation state (Varag) values on inshore patch reefs of the upper FRT. These waters can exhibit greater Varag than what has been modeled for the tropical surface ocean during preindustrial times, with mean (6 std. error) Varag-values in spring = 4.69 (60.101). Conversely, Varag-values on offshore reefs generally represent oceanic carbonate chemistries consistent with present day tropical surface ocean conditions. This gradient is opposite from what has been reported for other reef environments. We hypothesize this pattern is caused by the photosynthetic uptake of TCO2 mainly by seagrasses and, to a lesser extent, macroalgae in the inshore waters of the FRT. These inshore reef habitats are therefore potential acidification refugia that are defined not only in a spatial sense, but also in time; coinciding with seasonal productivity dynamics. Coral reefs located within or immediately downstream of seagrass beds may find refuge from OA.
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The nutritional values of protein concentrates (PCs) isolated from two subtropical red seaweeds, Hypnea charoides Lamouroux and H. japonica Tanaka, were evaluated in growing rats. The protein quality of the two seaweed PCs was determined by comparing the net protein ratio (NPR), true protein digestibility (TD), nitrogen balance (NB), biological value (BV), net protein utilization (NPU) and utilizable protein (UP) of the two seaweed PCs diet groups with those of the casein control group.
There were no significant differences of NPR and BV in all diet groups. Although the values of TD (ranged from 90.5 to 90.6%), NB (ranged from 108 to 113 mg rat−1 day−1), NPU (ranged from 80.1 to 81.3%) and UP (ranged from 80.1 to 81.3%) of these two PCs were significantly lower than those of the casein control, they were comparable to those of other common plant PCs. The growth performance of rats fed the two PCs diets was satisfactory and both PCs had no adverse effect on the weight of their major organs. Together with their good protein quality as mentioned above, the PCs from the two red seaweeds under study could be a potential alternative protein source for human nutrition.
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The observed high biomass of Sargassum species and other fleshy macroalgae on nearshore coral reefs in the Great Barrier Reef (Australia) raises the concern that this may be a sign of a phase shift from hard coral to dominance by algae, thus indicating the degradation of these reefs. Nearshore reefs are, due to their geographical position, exposed to inputs of nutrients and particles from mainland run-off. This study estimated the limiting and optimum nutrient concentrations for the growth of Sargassum baccularia under continuous supply of ammonium and phosphate. To assess the nutrient situation in the field, critical and subsistence levels of tissue nutrients as determined in cultures were compared with field tissue nutrient levels, and a 'mini budget' was estimated that compares nutrient requirements with nutrient supply. The growth rates of S. baccularia almost doubled within the narrow window of substrate concentrations from 3 mu M ammonium plus 0.3 mu M phosphate to 5 mu M ammonium plus 0.5 mu M phosphate. Lower and, unexpectedly, higher nutrient concentrations resulted in reduced growth rates. Field thalli of S. baccularia were always sufficiently supplied with N and P to show positive growth rates. However, field growth was both N- and P-limited, particularly in austral summer, when fast growth of S. baccularia occurs. This was indicated by tissue N and P concentrations that fell below the respective critical nutrient values, and estimated nutrient demands that exceeded the nutrients available from the water column. We suggest that if land-derived nutrient inputs increased, S. baccularia would become nutrient-sufficient, especially during the summer wet season. This may increase the competitive potential of this species to colonise larger areas on the nearshore reefs.
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Aquaculture continues to be the fastest-growing food production sector with great potential to meet projected protein needs. The scientific and business communities are responding to the challenges and opportunities inherent in the growing aquaculture sector with research efforts generating novel technologies that mirror the diversity of the industry. In genetics and breeding, the pace of advancement and innovation has been increasing exponentially.
The number of breeding programmes, diversity of species, target traits and efficiency and sophistication of techniques applied continues to expand and advance. However, the pace of scientific development has at times outdistanced our ability to analyze risks and benefits, develop appropriate culture and containment technologies, educate and communicate, and reach policy and regulatory consensus. Now, more than ever, efforts must be made for society to accurately analyze and understand risks, to capture opportunities to raise healthier aquatic organisms faster with less environmental impact, while improving economic stability and providing associated social benefits. Disease outbreaks continue to constrain aquaculture sustainability. Improvements in aquatic animal and plant health are coming from new technologies, improved management strategies and better understanding of the genetic and physiological basis of immunity. Vaccine development is benefiting from better specific antigen determination, more efficacious adjuvants and enhanced vaccine delivery.
Traditional diagnostic technologies and newer methods have greatly improved speed, specificity and sensitivity. Research on improving oral delivery and disease management strategies that focus on prevention offer opportunities for improved control of pathogens and parasites in the future, obviating the use of antibiotics and chemotherapeutants. An important key to culture of any fed species is the development of sustainable, cost-effective and nutritionally complete feeds, along with efficient feed management systems. Current research is focusing on improved understanding of nutritional requirements, nutrient availabilities and cost-effective formulations designed to maximize food conversion efficiency. Continuing cost pressures and the acute need to find additional protein and lipid sources to augment limited fishmeal and fish oil supplies is driving an increased understanding of how different nutrients are utilized and how to use increasing amounts of terrestrial ingredients. New sources of proteins and lipids from algae and microbes can offer alternatives, as cost efficiencies improve.
Use of enzymes, probiotics and prebiotics, phytogenic compounds and organic acids are being shown to change gut microflora and improve health, digestibility and performance. Improved pelleting and extrusion technologies allow the production of top-quality feeds. Advancements in production systems, including recirculation technologies, cages and integrated multi-trophic aquaculture, are also contributing to industry expansion and sustainability. All of these production system technologies are benefitting from expanding information and communication systems which are enabling advances in every stage of production. These and other examples suggest some of the benefits that future scientific-based innovation will contribute towards meeting increasing food demands, while improving social, environmental and financial sustainability of the global aquaculture industry.
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Since 2011, Dr. Charles Yarish and colleagues have experimented with growing seaweed on long lines at the head of New York's Bronx River Estuary, along with ribbed mussels suspended from a raft. They have raised a summer crop of the native red seaweed, Gracilaria tikvahiae, that grew up to 16.5% a day in July and a winter crop of sugar kelp, Saccharina latissima, that grew up to 8 feet in six months. Yarish says he has been surprised by the profigious growth in an area with low salinity and an overload of "a suite of nutrients" from a nearby waste water treatment plant and non-point runoff from the land and river.
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Offshore grown macroalgae biomass could provide a sustainable feedstock for biorefineries. However, tools to assess its potential for producing biofuels, food and chemicals are limited. In this work, we determined the net annual primary productivity (NPP) for Ulva sp. (Chlorophyta), using a single layer cultivation in a shallow, coastal site in Israel. We also evaluated the implied potential bioethanol production under literature based conversion rates. Overall, the daily growth rate of Ulva sp. was 4.5 ± 1.1%, corresponding to an annual average productivity of 5.8 ± 1.5 gDW m2 day1 . In comparison, laboratory experiments showed that under nutrients saturation conditions Ulva sp. daily growth rate achieved 33 ± 6%. The average NPP of Ulva sp. offshore was 838 ± 201 g C m2 year1 , which is higher than the global average of 290 g C m2 year1 NPP estimated for terrestrial biomass in the Middle East. These results position Ulva sp. at the high end of potential crops for bioenergy under the prevailing conditions of the Eastern Mediterranean Sea. We found that with 90% confidence, with the respect to the conversion distribution, the annual ethanol production from Ulva sp. biomass, grown in a layer reactor is 229.5 g ethanol m2 year1 .This translates to an energy density of 5.74 MJ m2 year1 and power density of 0.18 W m2 . Growth intensification, to the rates observed at the laboratory conditions, with currently reported conversion yields, could increase, with 90% confidence, the annual ethanol production density of Ulva sp. to 1735 g ethanol m2 year1 , which translates to an energy density of 43.5 MJ m2 year1 and a power density 1.36 W m2 . Based on the measured NPP, we estimated the size of offshore area allocation required to provide biomass for bioethanol sufficient to replace 5–100% of oil used in transportation in Israel. We also performed a sensitivity analysis on the biomass productivity, national CO2 emissions reduction, ethanol potential, feedstock costs and sizes of the required allocated areas.
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Response surface methodology was used to determine the effects of the solvent pH, the temperature of extraction, and the duration of extraction on the yield, purity, molecular weight, viscosity, and total metal content of ulvan extracted from U. ohnoi. Quadratic models identified the optimised responses for yield (72.6%) purity (68.2% w/w), molecular weight (92.9 kDa), viscosity (491.1 s), and total metal content (~0 mg/kg). These responses occurred between a solvent pH of 2.2–4.0, an extraction temperature of 61.3–90.0 °C, and an extraction duration of 55.0–90.0 min. The overall desirability of the ulvan product was determined using a Derringer's desirability function, which identified a solvent pH of 2.92, an extraction temperature of 90 °C, and an extraction duration of 90 min. These extraction conditions minimise the requirement for downstream purification and are suitable for upscaling the extraction of a high quality ulvan product.
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Microalgae have become imperative for biological wastewater treatment. Its capability in biological purification of wastewaters from different origins while utilizing wastewater as the substrate for growth has manifest great potentials as a sustainable and economical wastewater treatment method. The wastewater grown microalgae have also been remarked in research to be a significant source of valueadded bioproducts and biomaterial. This paper highlights the multifaceted roles of microalgae in wastewater treatment from the extent of microalgal bioremediation function to environmental amelioration with the involvement of microalgal biomass productivity and carbon dioxide fixation. Besides, the uptake mechanism of microalgae in wastewater treatment was discussed in detail with illustrations for a comprehensive understanding of the removal process of undesirable substances. The performance of different microalgae species in the uptake of various substances was studied and summarized in this review. The correlation of microalgal treatment efficacy with various algal strain types and the bioreactors harnessed for cultivation systems was also discussed. Studies on the alternatives to conventional wastewater treatment processes and the integration of microalgae with accordant wastewater treatment methods are presented. Current research on the biological and technical approaches for the modification of algae-based wastewater system and the maximization of biomass production is also reviewed and discussed. The last portion of the review is dedicated to the assertion of challenges and future perspectives on the development of microalgae-based wastewater treatment technology. This review serves as a useful and informative reference for readers regarding the multifaceted roles of microalgae in the application of wastewater biotreatment with detailed discussion on the uptake mechanism.
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We address the question of whether seaweed zonation can be characterized in terms of light absorption, pigmentation, photosynthetic parameters, photoinhibition, and thallus structure. Based on 32 seaweed species from the Pacific coast of southern Chile, intertidal assemblages exhibited higher light requirements for photosynthesis (Ek) and lower thallus light absorptances than subtidal algae. Ek values were lower than the highest measured irradiances at the corresponding natural depths, suggesting that photosynthesis in these organisms could potentially occur at lower depths. During summer, 1% of photosynthetically active radiation (PAR) reached a depth of 23 m, while UVB and UV-A wavelengths were completely attenuated at <3 and 6 m, respectively. Overall, the photobiological adaptations were associated with depth, morphology, and taxonomic group. Photoinhibition was similar in algae from different depths, although recovery was higher in upper littoral algae than in infra- and sublittoral species. The characteristics conferring competitive abilities in light use and light stress tolerance were not, or only partially, related to the classical Littler form-function model. The filamentous and foliose forms were able to acclimate rapidly to changing light and physical stress in the supralittoral zone. For infralittoral kelps living in a highly dynamic environment, higher cross-sectional area and enhanced in vivo light absorption were coupled with morphological features (e.g. massive thallus) that are advantageous in withstanding e.g. water movement. By contrast, the rapid physiological adjustments that allow algae to endure solar stress (e.g. photochemical down-regulation) were strongly dependent on the position on the shore but not on gross morphology.
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Marine Agronomy Group, CAFNRM, UH-Hilo
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