Mariculture has recently been adopted in many parts of coastal East Africa as a source of income and employment to many women and heartbroken fishermen who are the main victim of dwindling wild stock of aquatic resources. The sea cucumber (Holothuria scabra) has for long time been collected and sold as export marine product. Macroalgae (Eucheuma denticulatum and Kappaphycus alvarezii) are the common cultured seaweed species that provide hope for future increase in mariculture production. An experiment was conducted along the intertidal lagoon of Unguja Ukuu village in Zanzibar to assess the survival and growth performance of sea cucumber (H. scabra) in two separate pens under co-cultured systems with E. denticulatum and K. alvarezii. Juvenile sea cucumber H. scabra with mean weight (± se) of 67.18 ± 2.06 were integrated with the two common commercial seaweed in pen system for 10 weeks. The results revealed that the growth rate and survival of H. scabra, E. denticulatum and K. alvarezii were better under integration system. The growth of H. scabra was higher (1.038 g d-1) in pen systems co-cultured with K. alvarezii compared to 0.898 gd-1 in pen systems co-culture with E. denticulatum. Survival rate of H. scabra was higher (76%) in the pen systems co-cultured with E. denticulatum compared to that (70%) observed in pen systems co-cultured with K. alvarezii. The results suggest that the best integration of sea cucumber and macroalgae is between H. scabra and K. alvarezii. However, reliable source of H. scabra juvenile is essential for the future expansion of pen co-culture system.
Digital library
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The spread of organisms to new environments is one of the major drivers of speciation, since it exposes them to novel suites of environmental pressures (Mayr 1942). Recently, however, human activity has greatly accelerated the spread of organisms to new environments and altered ecosystem conditions in ways that often benefit these newcomers at the expense of pre-existing biota (Palumbi 2001). Although most research has focused on terrestrial species introductions, a recent meta-analysis determined that marine species introductions currently outpace them tenfold (Sorte et al. 2010).
Numbers of introduced marine species have increased exponentially in the last 200 years, and rates of introductions continue to increase due to trade, climate change and various other anthropogenic disturbances (Ruiz et al. 2000, Raitsos et al. 2010). It is harder to quantify the number or rate of marine algal introductions, as they are often overlooked or even encouraged (Inderjit et al. 2006). Despite representing a minority of reported marine species introductions, alien macroalgae can have profound economic and ecological impacts on existing systems (Schaffelke et al. 2006, Schaffelke & Hewitt 2007). Prevention of these impacts necessarily involves identification not only of algal species likely to become invaders but also of attributes that contribute to the invasiveness of potential nuisance algae (Anderson 2007). It is worth noting that many successful introduced algae have not been observed to negatively impact their new environments and so are not considered invasive (Boudouresque & Verlaque 2002); these cases are not pertinent to this review.
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The biomass production and biochemical properties of marine and freshwater species of green macroalgae (multicellular algae), cultivated in outdoor conditions, were evaluated to assess the potential conversion into high-energy liquid biofuels, specifically biocrude and biodiesel and the value of these products. Biomass productivities were typically two times higher for marine macroalgae (8.5–11.9 g m2 d1, dry weight) than for freshwater macroalgae (3.4–5.1 g m2 d1, dry weight). The biochemical compositions of the species were also distinct, with higher ash content (25.5–36.6%) in marine macroalgae and higher calorific value (15.8– 16.4 MJ kg1) in freshwater macroalgae. Lipid content was highest for freshwater Oedogonium and marine Derbe- sia. Lipids are a critical organic component for biocrude production by hydrothermal liquefaction (HTL) and the theoretical biocrude yield was therefore highest for Oedogonium (17.7%, dry weight) and Derbesia (16.2%, dry weight). Theoretical biocrude yields were also higher than biodiesel yields for all species due to the conversion of the whole organic component of biomass, including the predominant carbohydrate fraction. However, all marine species had higher biomass productivities and therefore had higher projected biocrude productivities than freshwater species, up to 7.1 t of biocrude ha1 yr1 for Derbesia. The projected value of the six macroalgae was increased by 45–77% (up to US$7700 ha1 yr1) through the extraction of protein prior to the conversion of the residual biomass to biocrude. This study highlights the importance of optimizing biomass productivities for high-energy fuels and targeting additional coproducts to increase value.
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This study compares the environmental performances of two protein sources for aquafeed production: Brazilian soy protein and Norwegian seaweed protein concentrates. The efficiency and sustainability of these two production systems are assessed using a comparative material and substance flow analysis accounting for the transfers of primary energy and phosphorus. The primary energy and phosphorus demand of 1 t of soy protein concentrate is compared to 2 t seaweed protein concentrate to assess commodities with similar protein contents. The primary energy consumption of the latter protein source (172,133 MJ) is found 11.68 times larger than for the soy-based concentrate (14,733 MJ). However, the seaweed protein energy requirement can be reduced to 34,010 MJ if secondary heat from a local waste incineration plant is used to dry the biomass during the late-spring harvest. The seaweed system out- performed the soy system regarding mineral phosphorus consumption since 1 t of soy protein requires 25.75 kg mineral phosphorus while 2 t of seaweed protein require as little as 0.008 kg input. These results indicate that substituting soy protein with seaweed protein in aquafeed leads to an environmental trade- off. The seaweed value chain produces proteins with near zero mineral phosphorus consumption by using naturally occurring marine phosphorus while the soy value-chain produces proteins for roughly 1/ 12th of the primary energy required by seaweed. Based on the current production technology, the seaweed value-chain will require extensive innovation and economies of scale to become energy competitive. Further research should investigate the predictive environmental impacts of a fully developed seaweed protein concentrate value-chain and account for the background emissions and multi-functionality in each system.
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Desiccation stress can determine the upper distribution limits and may enhance the uptake of nitrate and ammonium of eulittoral algal species. Upper shore species may exhibit greater stimulation of nitrate uptake following desiccation and achieve maximum uptake at higher desiccation levels. The objective of this study was to determine whether Porphyra species from different vertical elevations respond differently to the desiccation stress, in terms of growth and nitrate uptake. A eulittoral species (Porphyra umbilicalis) and a sublittoral species (P. amplissima) were compared in the present study. Samples were exposed to air for 0, 30 min (40 10% water loss) and 2 h (90 5% water loss), after an initial 4 h light period every day. Desiccation was more stressful to the sublittoral species, Porphyra amplissima, than to the eulittoral species, P. umbilicalis. When tissues were exposed for 2 h daily, P. amplissima lost weight over a 24 h day, while the growth rate of P. umbilicalis dropped by only 30% compared with that of continuously submerged blades. Nitrate uptake rate of sublittoral P. amplissima was only 73% (40 10% water loss) and 62% (90 5% water loss) of that of continuously sub-merged tissue. Nitrate uptake rates of P. umbilicalis were not significantly affected by desiccation. These results suggest that species in the eulittoral zone, which have longer exposure times, have a higher time-use efficiency than the sublittoral species in terms of nitrate uptake. This indicates a possible correlation between nitrate uptake and observed vertical distribu-tion patterns.
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Background
Porphyra yezoensis Ueda is one of the most important edible seaweed, with a dimorphic life cycle which consists of gametophyte as macroscopical blade and sporophyte as microscopic filamentous. Conspicuous differences exist in the two generations, such as morphology, cell structure, biochemistry, physiology, and so on. The developmental process of Porphyra yezoensis has been studied thoroughly, but the mechanism is still ambiguous and few studies on genetic expression have been carried out.
In this study, the suppression subtractive hybridization (SSH) method conducted to generate large-scale expressed sequence tags (EST) is designed to identify gene candidates related to the morphological and physiological differences between the gametophytic and sporophytic generations of Porphyra yezoensis Ueda.
Findings
Each 300 clones of sporophyte and gametophyte cells were dipped onto the membrane for hybridization. The result of dot-blot suggested there were 222 positive clones in gametophyte library and 236 positive clones in sporophyte library. 383 positive clones of strongest signals had been sequenced, and 191 EST sequences of gametophyte and 192 of sporophyte were obtained.
A total of 196 genes were obtained, within which 104 genes were identified from the gametophyte and 92 from the sporophyte. Thirty-nine genes of the gametophyte and 62 genes of the sporophyte showed sequence similarity to those genes with known or putative functions which were classified according to their putative biological roles and molecular functions. The GO annotation showed about 58% of the cellular component of sporophyte and gametophyte cells were mainly located in cytoplasm and nucleus. The special genes were located in Golgi apparatus, and high expression in plastid, ribosome and endoplasmic reticulum. The main biological functions of gametophyte cells contributed to DNA repair/replication, carbohydrate metabolism, transport and transcription, especially in response to heat and oxidative stress. The sporophyte cell expresses more genes in transcription, transport, carbohydrate metabolism, particularly in signal transduction, DNA and protein modification, protein and nucleotide metabolism. Four genes are expressed on both gametophyte and sporophyte cells and eighteen genes have not been annotated.
Conclusion
According to the information of GO annotation, the gametophyte tends to growth and self- protection while the sporophyte tends to be more active in development. Interpretation of the differentially expressed genes revealed new insights into the molecular processes of the generation alternation of Porphyra yezoensis. Further investigation are needed due to insufficiency of functional genes research and indeterminancy of the functions of many sequences.
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Dunaliella salina and Dunaliella bardawil are well known for carotenogenesis, the overproduction of carotenoids, under stress conditions. The effect of high light (HL) and low light (LL) on the growth, morphology, photosynthetic efficiency, and the β-carotene and zeaxanthin production of D. salina CCAP 19/18 and D. bardawil was investigated and compared. Both strains showed similar growth kinetics under LL growth condition, but D. salina CCAP 19/18 was faster. As the light intensity increased, D. salina CCAP 19/18 cells were elongated and D. bardawil cells became larger. Both strains showed decrease of the maximum quantum yield of PSII (Fv/Fm) and election transport rate (ETR) under HL growth condition and D. salina CCAP 19/18 was less liable to the light stress. Both strains had about 1.8 and 5 times difference in the O2 evolution rate at LL and HL conditions, respectively. The β-carotene and zeaxanthin production were increased as the light intensity increased in both strains. D. bardawil was more sensitive to light intensity than D. salina CCAP 19/18. The possible application of D. salina CCAP 19/18 as a carotenogenic strain will be discussed.
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Background: The hydrolysis of seaweed polysaccharides is the rate limiting step in anaerobic digestion (AD) of seaweeds. Seven different microbial inocula and a mixture of these (inoculum 8) were therefore compared intriplicate, each grown over four weeks in static culture for the ability to degrade Laminaria hyperborea seaweed and produce methane through AD.
Results: All the inocula could degrade L. hyperborea and produce methane to some extent. However, an inoculum of slurry from a human sewage anaerobic digester, one of rumen contents from seaweed-eating North Ronald say sheep and inoculum 8 used most seaweed volatile solids (VS) (means ranged between 59 and 68% used), suggesting that these each had efficient seaweed polysaccharide digesting bacteria. The human sewage inoculum, an inoculum of anaerobic marine mud mixed with rotting seaweed and inoculum 8 all developed to give higher volumes of methane (means between 41 and 62.5 ml g-1of seaweed VS by week four), compared to other inocula (means between 3.5 and 27.5 ml g-1VS). Inoculum 8 also gave the highest acetate production (6.5 mmol g-1VS) ina single-stage fermenter AD system and produced most methane (8.4 mL mmol acetate-1) in phase II of a two-stage AD system.
Conclusions: Overall inoculum 8 was found to be the most efficient inoculum for AD of seaweed. The study therefore showed that selection and inclusion of efficient polysaccharide hydrolysing bacteria and methanogenic archaea in an inoculum offer increased methane productivity in AD ofL. hyperborea. This inoculum will now beingtested in larger scale (10L) continuously stirred reactors optimised for feed rate and retention time to determinemaximum methane production under single-stage and two-stage AD systems
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This document contains food additive specification monographs, analytical methods, and other information prepared at the eighty-second meeting of the Joint FAO/WHO Expert Committee on Food Additives (JECFA), which was held in Geneva, Switzerland, 7 - 16 June 2016. The specification monographs provide information on the identity and purity of food additives used directly in foods or in food production. The main three objectives of these specifications are to identify the food additive that has be en subjected to testing for safety, to ensure that the additives are of the quality required for use in food or in processing and to reflect and encourage good manufacturing practice. This publication and other documents produced by JECFA contain information that is useful to all those who work with or are interested in food additives and their safe use in food.
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Warming of the planet has accelerated in recent years and is predicted to continue over the next 50 to 100 yr. Evidence of responses to present warming in marine ecosystems include Shifts in the geographic range of species as well as in the composition of pelagic and demersal fish, benthic and intertidal assemblages, Here we provide a review of the changes, in geographic distributions and population abundance of species detected on rocky shores of the NE Atlantic over the last 60 yr. This period encompassed the warm 1950s, a colder period between 1963 and the late 1980s and the recent period of accelerating warming to levels above those of the 1950s. The likely consequences of these responses are then explored. To do this, a summary of the dynamic balance between grazers, macroalgae and barnacles in structuring mid-shore communities is given before outlining experimental work on interactions between key components of rocky shore communities. Modelling and quantitative forecasting were used to predict changes in community composition and dynamics in a warmer world and their consequences for ecosystem functioning discussed. We then identify areas that need further work before making a case for the use of rocky shore species not just as inexpensive indicators of change offshore, but as tractable models to explore the direct and indirect effects of climate change in marine and coastal ecosystems, We also provide a societal perspective emphasising the value of long-term Studies in informing adaptation to climate change.
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