Digital library

  • Ecosystem-based management and models in sustainable management of coastal aquaculture

    To be successful, the complex process of ecosystem-based management requires management tools that can integrate physical, chemical and biological processes, modeling tool must function at multiple scales, be easily understood by non-scientist and above all reliably predict management alternatives. It must address specific questions about bays, lagoons or coastal oceans without the ability to predict the cumulative consequences to large marine ecosystems. 　

    This presentation discusses the concept of ecosystem modeling and focuses on two examples representing small and medium scale semi-enclosed marine ecosystems using a modified coastal ocean circulation model （Blumberg and Mellor 1987）. Xincun Lagoon in southeast Hainan Island is a 21.97km2 （ ～ 6km X ～ 4km） lagoon with a maximum depth of 10.6m and a 120m-wide outlet to the South China Sea. Xincun City, a major fishing port of ～15,000 people, is on one shore of the lagoon and the other shore is a wildlife reserve. The adjacent lagoon experienced a dramatic growth up to 230ha of fish pen aquaculture in 1996 followed by a catastrophic decline. The natural circulation in the lagoon combined with increased oxygen demand that was created by the fish pens was the likely reason for the disaster. Reducing the number of fish pens （33ha） and the advent of a pearl and macroalgae culture resulted in a more sustainable aquaculture industry and environment. Data indicated that the surface water quality did not violate China’s National Water Quality Standards, but the pens were responsible for an estimated 5,000 tonnes of organic pollutants. Fish pens reduced bottom water and sediment quality. Low quality bottom water also flowed in and out of fish pen area with the tide because of the slow turnover time （up to 90 days）. Further analysis indicated that macroalgae culture on racks and seagrasses act nutrient scrubbers and could play an important role by reducing ecosystem risk of less desirable algal blooms （Rawson, et al. 2002）. 　

    The medium scale modeling experiment was conducted on Jiaozhou Bay that is a shallow bay of ～ 400km2 with an average depth of 7m and maximum of 50m. The adjacent city is Qingdao, which is one of China’s largest ports and has a population > 2 million people. During the period of this study the bay cotained three areas of scallop aquaculture pens. Simulation experiments with two-pen stocking densities （12 individual m － 3 and 24 individuals m －3） indicated that scallops dramatically decreased the concentration of phytoplankton in the culture areas. However, the impact that scallop culture had on nutrient concentrations was small （Chen, et. al 1999）. 　A new management model system has been developed with funding from the Georgia Sea Grant Program based on the unstructured grid, finite-volume coastal ocean model （Chen et al., 2003）. This system provides a powerful management tool that allows aquaculture to be integrated into the broader context of coastal and large marine ecosystem management. Fed aquaculture does create pollution, but aquaculture is rarely the only pollution source. We must address the issue of aquaculture’s contribution to pollution and find practical solutions to these complex problems.

    Author(s): Yarish, Charles MingYuan Zhu, Lu Wang, Jim Sullivan, DaoRu Wang, Changsheng Chen, Mac Rawson

  • Edible Seaweeds of China and Their Place in the Chinese Diet

    Coastal peoples of China are consumers of seaweeds, which rank as favored “vegetables” and are introduced into several kinds of cooking methods in the same way that westerners might use onions (raw, fried, steamed, boiled, used alone, or mixed with other vegetables). Descriptions for preparation of 24 species are provided; a table gives the names of all species known to be used as food in China at this time. Although thousands of workers are involved in growing the seaweed crops of the brown alga Laminaria and the red alga Porphyra, many thousands more become part of the total activity of gathering the 74 species in 36 genera that form an important part of the Chinese diet. These numbers of species of edible algae are larger than those reported for any ethnic group in the world. This report is the first comprehensive one to appear in the west on seaweeds as food in China.

    Author(s): Bangmei Xia, Isabella Aiona Abbott

  • Effect of canopy biomass and wave exposure on growth in Laminaria hyperborea (Laminariaceae: Phaeophyta)

    Annual growth per plant and allocation of growth to the stipe were measured in 2- to 4-year-old plants of Laminaria hyperborea from five stations with different degrees of wave exposure and different amounts of canopy biomass. Low growth in plants with initial stipe lengths of less than about 40 cm suggested that the presence of canopy-forming plants suppresses growth of understorey plants, and this was supported by the high lamina growth rate of understorey plants after removal of the canopy-forming plants. Canopy biomass and wave exposure were found to exert a differential effect on the growth of the age groups examined. Average annual growth per plant in 2- to 3- year-old plants decreased with increasing canopy biomass; growth of 4 year-old plants was not significantly influenced by canopy biomass, but increased with increasing wave exposure of the sites, suggesting an influence of some factor connected with wave exposure. The allocation of annual growth to stipe and lamina was also found to be influenced by canopy biomass and wave exposure. In 2- to 3- year-old plants the amount of annual growth allocated to the stipe increased with increasing canopy biomass while a positive linear regression between allocation of growth to the stipe and wave exposure was found in 4-year-old plants. Individual measurements carried out at a wave-exposed locality showed that the maximum allocation of growth to the stipe in the intermediate-sized plants occurred simultaneously with a period of rapid stipe elongation. Thus, rapid stipe growth in L. hyperborea can be associated with high allocation of annual growth to the stipe when the plants are about to grow into the canopy-forming layer. We suggest that this is due to the combined effects of suboptimal light levels within the kelp forest and high wave exposure.

    Author(s): Kjersti Sjøtun , Stein Fredriksen , Jan Rueness

  • Effect of Dietary Seaweed Supplementation in Cows on Milk Macrominerals, Trace Elements and Heavy
 Metal Concentrations

    This study investigated the effect of seaweed supplementation in dairy cow diets on milk yield, basic composition, and mineral concentrations. Thirty-seven Icelandic cows were split into three diet treatments: control (CON, no seaweed), low seaweed (LSW, 0.75% concentrate dry matter (DM), 13–40 g/cow/day), and high seaweed (HSW, 1.5% concentrate DM, 26–158 g/cow/day). Cows were fed the same basal diet of grass silage and concentrate for a week, and then were introduced to the assigned experimental diets for 6 weeks. The seaweed mix of 91% Ascophyllum nodosum: 9% Laminaria digitata (DM basis), feed, and milk samples were collected weekly. Data were analyzed using a linear mixed effects model, with diet, week, and their interaction as fixed factors, cow ID as random factor, and the pre-treatment week data as a covariate. When compared with CON milk, LSW and HSW milk had, respectively, less Se (−1.4 and −3.1 μg/kg milk) and more I (+744 and +1649 μg/kg milk), while HSW milk also had less Cu (−11.6 μg/kg milk) and more As (+0.17 μg/kg milk) than CON milk. The minimal changes or concentrations in milk for Se, Cu, and As cannot be associated with any effects on consumer nutrition, but care should be taken when I-rich seaweed is fed to cows to avoid excessive animal I supply and milk I concentrations. 

    Author(s): Eric E. Newton, Ásta H. Pétursdóttir, Gunnar Ríkharðsson, Corentin Beaumal, Natasa Desnica, Konstantina Giannakopoulou, Darren Juniper, Partha Ray, Sokratis Stergiadis

  • Effect of different drying methods on phytochemical content and amino acid and fatty acid profiles of the green seaweed, Ulva spp.

    Green seaweeds are a potential source of proteins, minerals, fatty acids, and essential amino acids, and also often contain bioactive compounds with antioxidant activity. They have the potential to be a source of functional and nutraceutical ingredients. However, their elevated water content shortens shelf life; thus, a preservation method should be employed, such as drying. In the present article, Chilean green seaweed (Ulva spp.) was characterized and the effect of different drying methods (freeze-, vacuum-, solar-, and convective drying) on the quality of dried algae as functional ingredient, along with a description of the drying parameters for each method was evaluated. Proximate composition of fresh Ulva spp. indicated that, other than water, ash, protein, and crude fiber are the main constituents. Ulva samples also had a high amount of total dietary fiber (with an IFD/SFD ~ 1.5). The isotherm curve presented the typical type II sigmoid shape and the BET model gave the best fitting. There was a significant effect of drying method on proximate composition of dried Ulva and the convective drying the method that showed higher values for almost all parameters, except fat content. Color was not affected by drying and the typical green color was present in all samples. Total flavonoid content (TFC), total carotenoids and antioxidant capacity (DPPH and ORAC) were also higher in convective drying. In addition, other minor components with nutritional value were identified, such as essential polyunsaturated fatty acids (PUFAs with a ω3/ω6 ratio of 1:1) and amino acids. Among the different drying methods applied, convective drying (70 °C, 120 min) better retained the physicochemical parameters and antioxidant capacity of Ulva spp. 

    Author(s): Elsa Uribe, Antonio Vega-Gálvez, Vivian García, Alexis Pastén, Jéssica López, Gabriela Goñi

  • Effect of different fertilizers on the growth of Gracilaria edulis (Gmelin) silva in onshore cultivation

    Culture of agar yielding red alga Gracilaria edulis was canied out using fiberglass tanks in onshore condition under a shed with transparent roof and providing running seawater system and aeration. The seed material was pretreated for 12 hours at different concentrations of Urea, NPK, Superphosphate, Di-ammonium phosphate, Ammonium sulphate, Organic fertilizer, Organic mixture, Potash, Ammonium Chloride, Calcium nitrate, Magnesium sulphate and Ferrous sulphate. In general, the growth and biomass of cultured seaweed were found to be more in plants treated with low concentrations of these fertilizers than untreated and plants treated with higher concentrations. Data on the environmental and hydrological parameters from seaweed culture tanks were recorded.

    Author(s): Kaliaperumal, N, Ramalingam, J R

  • Effect of feeding Spirulina platensis on the growth, proximate composition and organoleptic quality of common carp, Cyprinus carpio L.

    The effect of feeding Spirulina platensis on the growth, carcass composition, organoleptic quality, digestive enzyme activity and digestibility of common carp, Cyprinus carpio L., was studied through a culture trial lasting 120 days. Four experimental diets were employed by replacing fish meal protein from the standard diet at 25%, 50%, 75% and 100% through the incorporation of Spirulina. Another diet with Spirulina as the sole source of protein was also used. The final weight gain, specific growth rate, food conversion ratio and protein efficiency ratio of common carp were not affected by Spirulina supplementation. However, the diet with Spirulina as the sole source of protein resulted in better net protein retention. The muscle RNA:DNA ratio of fish fed Spirulina diets was higher than that of fish fed control diet.

    There was no significant difference in carcass moisture and protein content in the fish fed Spirulina diets as compared to fish-meal-based control diet. The carcass ash and fat contents were positively and negatively correlated with dietary Spirulina level, respectively. Organoleptic evaluation revealed no effect of Spirulina feeding on the quality of both raw and cooked fish. The gut digestive enzyme activity did not show any definite trend with respect to Spirulina supplementation. Spirulina improved the protein digestibility of the diets.

    Author(s): M C Nandeesha, B Gangadhar, T J Varghese, P Keshavanath

  • Effect of Freshwater Washing Pretreatment on Sargassum muticum as a Feedstock for Biogas Production

    The pretreatment of seaweed by washing in freshwater is often used in seaweed biofuel research studies. However, the effect of washing seaweed prior to anaerobic digestion (AD) does not appear to have been greatly studied. This study examines washing Sargassum muticum with freshwater and its effect on ultimate and proximate analyses, salt content, methane production from anaerobic digestion, and leachate loss from ensiling. Washing with freshwater significantly (p < 0.01) increased moisture content (unwashed 85.6%, washed 89.1%) but significantly (p < 0.05) reduced ash (unwashed 32.7% dry weight dw, washed 30.6% dw) and salt content (unwashed ash containing 51.5%, washed 42.5%). The dry biomass higher heating value was significantly (p < 0.05) increased by washing due to the lower ash content (11.5 to 12.6 kJ g−1 dw). There was no significant change in the protein or lipid content, although washing increased the nitrogen content (3.85–4.77% dw). Washing significantly (p < 0.05) increased leachate losses during ensiling, with total leachate losses increasing after washing (12.7–25.2%). The methane yield from anaerobic digestion (28 days) was not statistically significantly different (p > 0.05) between unwashed (0.225 L CH4 g−1 VS) and washed samples (0.177 L CH4 g-1 VS). However, washing delayed biomethane production.

    Author(s): John J. Milledge , Birthe V. Nielsen, Manar S. Sadek, Patricia J. Harvey

  • Effect of Global Warming Scenarios on Carotenoid Pigments Gracilaria changii

    The phenomenon of global warming is anincrease in the earth's temperature due to thegreenhouseeffect where 50% of the main contributors to thegreenhouse effect are carbon dioxide (CO2). Carbondioxide is one of the ingredients needed for photosynthesis.Photosynthesis is carried out by plants that havechloroplasts. Plants in the watersare Seaweed. Gracilariachangii is a type of red seaweed (Rhodophyceae). Thedominant pigment from Gracilaria changii is carotenoids.Carotenoid serves as a light energy absorbent forphotosynthesis and serves to protect chlorophyll from lightdamage. Seeing the important role of carotenoids inGracilaria changii so that this study aims to determine theeffect of increasing temperature and carbon dioxideoncarotenoid pigments.Research on the scenario of globalwarming in this region was first carried outon alaboratory scale, many previous studies were carried outin the cultivation area.Thisstudy was conducted for 40days, seaweed that has been cleaned is put into anaquarium and given an injection of CO2. We were exposedto present-day control seawater (400 ppm pCO2) andseawater treated with CO2to simulate ocean conditionspredicted for the next 50–100 years (700 ppm, 1000 ppm,and 1300 ppm) and temperature treatment (30oC, 32oC,34oC). The research design applied in this study is aCompletelyRandomized Design consisting of ninetreatments with three replications. Data analysis used isAnalysis of Variance (ANOVA) continued by Post hocTest. The results obtained from this study there weresignificant differences (P <0.05) of carbon treatment incarotenoid pigments. The highest carotenoid pigments arefound in 700 ppm CO2injection treatment.

    Author(s): Eddy Soekendarsi, Ambo Tuwo, Sharifuddin Bin Andy Omar, Nur Indah Sari Arbit

  • Effect of growth promoters on the onshore culture of Gracilaria edu Zis (Gmelin) Silva

    Culture of agar yielding red alga Gracilaria edulis was carried out in fibreglass tanks by providing running seawater and aeration under a shed with transparent roof. The seed material was pretreated for 12 hours at different concentrations of growth promoters IAA, IBA, GA, Ascorbic acid, EDTA and Inositol. In general, more increase in growth and biomass was obtained in the plants pretreated with lower concentrations of these growth promoters.

    Author(s): Kaliaperumal, N, Ramalingam, J R, Diwakar, K, Ezhilvalavan, R

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