Nutrients removed by Kappaphycus alvarezii (Rhodophyta, Solieriaceae) in integrated cultivation with fishes in re-circulating water

The potential of the red alga Kappaphycus alvarezii to remove nutrients was tested to treat effluents of Trachinotus carolinus fish cultivation, and the production of carrageenan in this condition was analyzed. Experiments were conducted in four tanks of 8000 L with approximately 1200 fishes of 30 g each integrated with three tanks of 100 L with 700 g of K. alvarezii, as initial biomass per tank. Seawater was re-circulated between tanks with seaweed and with fish. As a control, three tanks with seawater circulating in an open system were utilized. Seawater samples were collected daily for 10 days and concentrations of nitrate, nitrite, ammonium and phosphate were determined in the inflow and outflow water of the tanks. Significant differences between both collecting points were considered as nutrient removal by the seaweed. Growth rates and carrageenan yields were also analyzed in seaweed cultivated in seawater and in effluents. Growth rates of seaweed cultivated in tanks were lower than those obtained in open sea and in laboratory cultivation. Effluents had concentrations of nitrate and nitrite ca. 100 times higher than in the control. Maximum values of nutrient removal on effluents were: nitrate = 18.2%; nitrite = 50.8%; ammonium = 70.5% and phosphate = 26.8%. All plants survived throughout the experimental period, but some developed “ice–ice”, a disease associated with physiological stress. After the experimental period, some plants selected and cultivated in open sea presented higher growth rates in 40 days, indicating nutrient storage. No significant differences between carrageenan yields of K. alvarezii cultivated in seawater and in the effluents were observed. Our results show that K. alvarezii can be utilized as a biofilter for fish cultivation effluents, reducing the eutrophication process and can also be processed for carrageenan production, which provides an additional benefit to the fisheries.     

长心卡帕藻四分孢子发育成配子体的形态建成观察

2007年11月到2009年4月在海南黎安,以养殖多年的红褐色长心卡帕藻为材料,跟踪观察了四分孢子形成、释放、萌发以及配子体苗形态建成过程。结果表明,（1）该长心卡帕藻被确定为四分孢子体,四分孢子形成和释放主要发生在夏季和秋季（2008年4月到2008年10月）。（2）人工诱导可促使四分孢子萌发并形成胚苗,胚苗色泽出现明显分化,有红褐色、黄绿色、深绿色、黄绿—红嵌合等不同类型。（3）四分孢子萌发率达到87.1%±7.2%,培养皿内胚苗平均日生长率为（6.3±1.1） %/d,在四分孢子萌发10 d左右假根出现并于培养30 d左右消失。（4）胚苗经过约5个月实验室培养发育成的配子体苗达到了下海挂养程度大小,在海上培养初期配子体苗日生长率大多在10 %/d以上,最高可达21.2 %/d,但随着藻体长大生长速率逐渐下降。经过4个多月海上挂养栽培,获得了藻枝形态、粗细、疏密程度和生长速率等差异明显的多种配子体,部分配子体活力和抗逆性比其母本有显著增加。     

Biochemical comparison of lectins among three different color strains of the red alga Kappaphycus?alvarezii

The red alga Kappaphycus alvarezii is economically important as an edible species and as a source of carrageenan, and has been extensively cultivated in many tropical countries. For this species, different color strains, which differ from each another in growth rate and carrageenan content, have been reported for decades. In this study, lectins from brown, red, and green strains of K. alvarezii cultivated in Vietnam were isolated and characterized for evaluation of their biochemical properties and contents. The results showed that each color strain contained in common the three lectins, named KAA-1, KAA-2, and KAA-3, which shared the hapten-inhibition profile of hemagglutination, 20 N-terminal amino acid sequence, and equivalent molecular mass within a range of 28,016 ± 1.2 to 28,021 ± 1.8 Da, but differed in their yields, with the highest yield of KAA-2. These properties of the three isolectins were also comparable among the three different color strains. However, the sum of the yields of the three isolectins decreased in the order: red (21.4 mg) to green (15.9 mg) to brown strains (15.1 mg), from 500 g fresh alga. Thus, this algal species can be a good source of useful lectins, irrespective of color strain.     

麒麟菜与贝类混养体系净化富营养化海水的研究

研究了热带亚热带类型双壳贝类沟纹巴非蛤(Paphia exarata Philippi) 和热带大型海藻异枝麒麟菜 (Kappaphycus striatum Schmitz) 净化富营养化海水的效果。发现沟纹巴非蛤和麒麟菜混养能有效地清除富营养化水体中的N、P和chla。影响综合评价指标、N清除率、P清除率和chla清除率的因素均为麒麟菜﹥贝;其中麒麟菜对各指标的影响均为极显著(P﹤0.01);贝对N清除率、chla清除率的影响为极显著(P﹤0.01),对综合评价指标、P清除率有一定影响,但不显著。最佳混养组合为：麒麟菜养殖量6Kg/m3、沟纹巴非蛤养殖量60只/m3（40g±2g/只）。     

异技麒麟菜对海水中氮、磷吸收的初步研究

在实验室条件下,设置四种不同营养盐浓度环境,分析异枝麒麟菜对氮、磷的去除效果。结果表明麒麟菜对海水中无机氮的去除率为89.5%～92.0%,对磷酸盐的去除率为79.6%～81.8%,对无机氮的吸收速率最高达到0.26μmol(/g·h),对磷酸盐的吸收速率最高达到0.009μmol(/g·h)。说明麒麟菜对氮、磷的吸收效果很明显,吸收速率随氮、磷浓度的升高而增大,对海水有很好的净化作用。     

Chemical Characterization,Temperature Stability,and Enzymatic Studies on Edible Marine Algae Kappaphycus alvarezii (Doty)

Antioxidant activity of the marine alga Kappaphycus alvarezii was investigated. Methanol, acetone, petroleum ether, aqueous methanol, ethyl acetate, and chloroform extracts (1 mg/mL) of K. alvarezii were tested for their 2, 2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity. The values were compared with those of Vitamin C and butylated hydroxytoluene (BHT). Extracts showing positive results, when tested for DPPH free radical scavenging, were examined for dose effect, in-vivo hydrogen peroxide (H₂O₂) and hydroxyl radical scavenging assays. All extracts showed dose-dependent DPPH scavenging and significant hydroxyl radical scavenging activities (> 82.6%). The acetone, aqueous methanol, and methanol extracts of K. alvarezii showed the highest scavenging activity. Ethyl acetate extract showed a moderate activity of 62.9%. In the DPPH method, petroleum ether and hexane extracts showed less activity with IC₅₀ values of 118.58 ± 8.94 and 116.25 ± 7.14 μg/mL, respectively. Acetone, methanol, and ethyl acetate extracts exhibited IC₅₀ values of 57.32 ± 1.07, 61.31 ± 0.67, and 79.50 ± 1.59 μg/mL, respectively. K. alvarezii showed higher antioxidant activity in both in vitro and in vivo studies. Proton NMR studies revealed signals in the region 0.5 to 2.0 ppm suggesting the presence of steroidal identity in the extracts.     

长心卡帕藻切段培养的初步研究

研究了长心卡帕藻（ Kappaphycus alvarezii）外植体切段的适宜生长温度以及诱导温度、切断长度、切段方式（与藻体纵轴呈90°横切、与藻体纵轴呈45°斜切）等因子对芽发生的影响。结果显示,在试验范围内,长心卡帕藻外植体切段的适宜生长温度为15～25℃,最适温度为20℃。诱导温度、切断长度、切段方式3种因子对外植体切段的出芽效果都存在显著影响,且各因子交互影响差异极其显著（P〈0．01）,较高的培养温度对于出芽具有明显的促进作用,25℃下试验组个体平均出芽数均高于20℃（P〈0．01）;横切可促进外植体切段出芽,相同切段长度下,横切试验组个体平均出芽数均大于斜切试验组（P〈0．01）;短切段有助于提高出芽的数量,在相同切段方式下,1cm切段组个体平均出芽数显著优于3cm和5cm切段组（P〈0．01）;25℃、1cm、横切为长心卡帕藻最优出芽诱导条件,个体平均出芽数最高,达到平均1．50个。不同切段长度对芽的发生部位具有明显的影响,1cm和3cm切段组均为切面的髓部再生芽,而5cm切段组则包括切面的髓部再生芽和非切面的皮层新生芽。     

Assessment of rocky reef fish assemblages close to seaweed farming

The seaweed Kappaphycus alvarezii (Doty) Doty ex P. C. Silva, a red algal species, is the main global source of Kappa carrageenan. The introduction of such exotic species in regions outside their original locale can change the community structure of the areas into which they are introduced. The possible influence of seaweed farming on the rocky reef fish assemblage was assessed in Paraty, Brazil. The reef fish assemblage in the seaweed farming area was compared before and after the commencement of farming with two undisturbed control areas. Among the ten species ranked as the most frequently occurring in each area, eight were the same. The fish community structure close to the seaweed farming area did not change from that of the control areas, over the months of the study. Neither the fish diversity and richness indices, nor the total average abundance among areas was significantly altered. The average abundance of the different trophic groups varied over time in both the farm and control areas, revealing similar patterns. These results suggest that K. alvarezii can be cultivated up to at least 50 m from a rocky coast without altering the fish community structure of the surrounding waters.     

The Economics of Kappaphycus Seaweed Cultivation in Developing Countries: A Comparative Analysis of Farming Systems

The farming of the red seaweed Kappaphycus alvarezii and related species as raw material for the hydrocolloid carrageenan rapidly spread from the Philippines in the late 1960s to Indonesia, Tanzania, and other tropical countries around the world. Although numerous studies have documented positive socioeconomic impacts for seaweed farming, factors such as diseases and distance to export markets have led to an uneven development of the industry. Using standard budgeting techniques, this study adapted production and market data from a FAO-led global review of seaweed farming to develop comparative enterprise budgets for eight farming systems in six countries (Indonesia, the Philippines, Tanzania, India, Solomon Islands, and Mexico). Although the basic technology package is the same across countries, the study revealed large differences in the economic performance of systems due to wide variations in farm prices and the scale of operations. Although seaweed farming is a suitable activity for small-scale producers, a minimum of 2,000 m of cultures lines are still necessary to ensure adequate economic returns. Greater farming plots may be needed if farm prices are well below the average farm prices paid in Indonesia and the Philippines. Policy recommendations are made to improve the economic potential of underperforming systems.     

A Correlation of Rapid Cardy Meter Sap Test and ICP Spectrometry of Dry Tissue for Measuring Potassium (K+) Concentrations in Pak Choi (Brassica Rapa Chinensis Group)

Nutritional status of vegetable crops is often monitored by analysis of dried plant tissues, which is costly and often time consuming. Two greenhouse trials were conducted, at the University of Hawaii at Manoa, Magoon facilities, to evaluate the portable cardy ion meter (CIM) in determining potassium (K⁺) status in fresh petiole sap of pak choi as compared with standard laboratory methods. In the first greenhouse trial, three algae species (Gracilaria salicornia, Kappaphycus alvarezii, and Eucheuma denticulatum) were used to apply five rates of K⁺ (0, 84, 168,252, and 336 kg.ha^?1). The pak choi was directly seeded into 4 L pots and was grown in peat moss. In the second greenhouse trial, K+ was provided through Eucheuma denticulatum and potassium nitrate (KNO₃) at five rates (0,112, 168, 224, 280, and 336 kg.ha^?1) in peat moss and soil media. At harvest, K⁺ concentrations in fresh petiole sap were analyzed immediately with CIM and the dried samples were analyzed by inductively coupled plasma spectroscopy (ICP) measurement. The results showed increase in leaf K+ content at higher rates and the maximum concentration of leaf K⁺ at 4500–5300 mg/L for sap and 8–9% for tissue was obtained when K⁺ was provided between 224 and 284 kg.ha^?1. There was a close correlation between the CIM readings and the ICP method (r = 0.8048 and 0.8314) from the first and second GH results, respectively. The results suggest that the CIM could be used for the rapid monitoring of the relative K⁺ status of plants. The data further suggested 4500–5000 mg K/L for fresh petiole sap and 7.5% K⁺ in tissue as critical levels for K⁺ concentration in pak choi.