Effects of a commercial extract of the brown alga Ascophyllum nodosum on the biomass production of Kappaphycus alvarezii (Doty) Doty ex P. C. Silva and its carrageenan yield and gel quality cultivated in Brazil

Despite of its success, the carrageenan industry has had to cope with difficulties due to epiphyte infestations and diseases known as ice-ice. Some promising results in respect of biomass production, carrageenan yield, and protection epiphytes were obtained using a powdered extract of the brown alga Ascophyllum nodosum in Kappaphycus alvarezii seedling production. This study focused on the effects of the A. nodosum extract on the treatment of K. alvarezii cultivated on commercial floating rafts not only to evaluate improvements demonstrated in vitro but also the effects on the quality of the carrageenan. The seedlings were treated in an A. nodosum extract solution and placed alongside their controls on commercial floating rafts using the tubular net technique. Daily growth rate, carrageenan yield, gel strength, and gel viscosity were obtained over 20 and/or 40 days. After 20 days, daily growth rates showed no significant difference (p?=?0.44), while the carrageenan yield was higher in samples that were treated with the A. nodosum solution (p?<?0.001). After 40 days, both daily growth rate (p?=?000.7) and carrageenan yield (p?=?0.009) were higher in treated samples; however, gel strength was higher in control samples (p?=?0.03) as viscosity was also highest in the samples which had not been treated (p?<?0.001). The use of the A. nodosum extract treatment on the cultivation in situ of K. alvarezii was positive since after 40 days when the daily growth rate and carrageenan yield increased. In spite of the negative effect on the quality of the semi-refined carrageenan, the values were within commercial standards.     

Does biofouling influence <Emphasis Type="Italic">Kappaphycus alvarezii</Emphasis> (Doty) Doty ex Silva farming production in Brazil?

The commercial cultivation of Kappaphycus alvarezii is the main source of raw material for the carrageenan industry. Brazilian commercial farming uses floating rafts that serve as substrata for fouling organisms that may affect production of the carrageenophyte seedlings. The aim of this work was to identify and quantify the biofouling on floating rafts at Sepetiba Bay, Rio de Janeiro State (23° 02′ 25″ S and 43° 53′ 39″ W), and to evaluate seedling damage caused by epibionts and endobionts. Samples were collected from August 2006 to August 2007. In each assessment, organisms contained in random sampling areas of 18 quadrats of 0.10 m² (n = 18) were removed from floating rafts. K. alvarezii seedling samples were collected to verify the presence of epibionts or endobionts (n = 30). Twenty-four taxa belonging to seven groups of animals and three groups of seaweed were found. The percentage occurrence estimated 13 dominant organisms and amphipod tubes: e.g., Chondracanthus tedii, Cladophora vagabunda, Gracilariopsis tenuifrons, Hypnea spinella, Hypnea musciformis, Hincksia mitchelliae, Spyridia spp., Ulva spp., Bowerbankia sp., Bugula neritina, Botryllus sp., Haplosclerida sp., and Perna perna. Richness, equitability, diversity, and total biomass varied significantly during the study period (p < 0.001). There was a tendency for higher biomass values in August 2007. After 6 months, epibionts (i.e., Chlorophyta, Rhodophyta, Chordata, Cnidaria and Ectoprocta) were found on K. alvarezii seedlings. Endobionts were not found in this study. The biofouling biomass was not found to have a significant effect on K. alvarezii daily growth rate, carrageenan yield, or quality (gel strength and viscosity; p > 0.05).     

Effect of the commercial extract of the brown alga Ascophyllum nodosum Mont. on Kappaphycus alvarezii (Doty) Doty ex P.C. Silva in situ submitted to lethal temperatures

Kappaphycus alvarezii is being introduced in several countries and in some of them there is a need to adapt this cultivation to periods with lethal temperatures, such as the 16–18 °C that occurs in the winter in southern Brazil. Moreover, there is the need to maintain the seedlings during this lethal temperature period. Considering the promising results obtained with the commercial powder extract of Ascophyllum nodosum (Acadian marine plant extract powder—AMPEP) treatment in the cultivation of K. alvarezii in vitro and in the sea allowing more resistance to epiphytes and increasing the growth rate and carrageenan yield, it was hypothesized that seedlings previously subjected to an AMPEP treatment could be more resilient to lethal temperatures. The daily growth rate and carrageenan yield and gel quality (gel strength and gel viscosity) of K. alvarezii in vitro previously treated with AMPEP were analyzed under temperature stress. The daily growth rates and the gel strengths of the AMPEP-treated samples were increased. In spite of the lower carrageenan yield and lower gel viscosity, the values were within the ones accepted by the carrageenan industry. Thus, the treatment of the seedlings of the K. alvarezii with AMPEP solution can be used as an alternative to lower temperature effects on crops as a preventive action for the cultivation of the seedlings in tanks and in the sea in periods of low temperatures at sea.     

<Emphasis Type="Italic">Kappaphycus alvarezii</Emphasis> (Rhodophyta,Areschougiaceae) cultivated in subtropical waters in Southern Brazil

Four strains of Kappaphycus alvarezii were cultivated in the subtropical waters of Florianópolis, Santa Catarina State, Brazil (27°29′19′′ S/48°32′28′′ W), from February 2009 to February 2010. Seaweeds were cultivated on floating raft near of mussel farms. Salinity ranged from 29 to 36 psu and temperature from 17.1 to 28.5°C. Higher growth rates (5.12–4.29% day⁻¹) were measured in summer and autumn, showing a positive correlation between growth rate and water temperature. Lower growth rates (0.54–0.32% day⁻¹) occurred in winter, resulted mainly by biomass loss. Significant differences were observed among the strains in spring and the brown tetrasporophytic strain was the only one which failed to recover, being excluded of the experiments. The effect of cultivation periods (36, 42, and 97 days) on carrageenan yield, gel strength, and viscosity were analyzed. Carrageenan yields were higher for plants kept 42 days in the sea (28%), against 25% for 36 and 97 days. There were no significant differences in carrageenan yield among the strains analyzed. Viscosity increased with the increase of cultivation period, while gel strength seemed to vary at random. Tetrasporangia and cystocarps were not observed, and lost fragments did not attach outside the raft. In general, dissolved inorganic nitrogen concentration decreased around the cultivation area as compared to the mussel farm. Results show that cultivation of K. alvarezii is technically feasible in subtropical waters and can be associated with local mussel farms, mitigating the eutrophication and, eventually, increasing the economic return of the farmers.     

The effects of selected cultivation conditions on the carrageenan characteristics of <Emphasis Type="Italic">Kappaphycus alvarezii</Emphasis> (Rhodophyta,Solieriaceae) in Ubatuba Bay,São Paulo,Brazil

The yield and the quality of carrageenan depend, among other things, on the cultivar or strain and on the cultivation and processing techniques. This work presents carrageenan yields and some properties of Kappaphycus alvarezii under selected cultivation conditions i.e. cultivation period, depth and planting density. Growth rates (GR) ranged from 5.2–7.2% day⁻¹, with the highest GR at 28 days, at 0–0.5 m depth, and planting density of 12 and 8.4 plants m⁻². Highest productivity was observed in samples after 44 and 59 day cultivation period, which were grown at 0–0.5 m depth, and a planting density of 24 plants m⁻². Carrageenan yields, iota fraction, viscosity, molecular weight and gel strength were measured. A cultivation period of 28 days during the winter had a significant higher carrageenan yield, while samples from 59 days showed a significantly higher iota fraction. Carrageenan also presented an increasing molecular weight under longer cultivation periods. A similar trend was observed for viscosity and gel strength. All samples cultivated in Brazil gave higher values when compared to a K. alvarezii commercial reference sample, with the exception of carrageenan yield values, which were lower in this study. Taking into account all parameters, the culture condition which provided the best carrageenan from a commercial perspective were 45 days of cultivation, growing at the surface, with a planting density of 12 plants m⁻². Considering that this study was performed in the least favorable season (winter), these results indicate that the site is suitable for the implementation of commercial cultivation.     

Kappaphycus alvarezii (Gigartinales, Rhodophyta) cultivated in Brazil: is it only one species?

Kappaphycus alvarezii which is endemic to the Indo-Pacific region is the main raw material for kappa carrageenan production. A seedling that was cultivated in Japan (originally from the Philippines) was introduced in a trial, for aquaculture purpose, in 1995, in São Paulo State, southeastern region of Brazil. It was later introduced in Santa Catarina State, in Southern Brazil. In 1998, another seedling that was brought from Venezuela, also originally from the Philippines, was commercially introduced at Ilha Grande Bay and later on at Sepetiba Bay, both in Rio de Janeiro State. The aim of this study was to characterize 21 samples from different farms (Rio de Janeiro and Santa Catarina States) and verify if they are K. alvarezii or other species. Based on the intergenic spacer cox2-3 sequences, phylogenetic relationships were inferred through neighbor joining, maximum likelihood, and Bayesian analyses. The topology of the trees suggests that all samples from the different farms form a monophyletic group of K. alvarezii. Statistical analysis of the cox2-3 marker calculated with median-joining network showed 38 variable positions defining 15 haplotypes for the studied samples of Kappaphycus. The most frequent K. alvarezii haplotype grouped the samples cultivated worldwide with the Brazilian samples. These results are important for better productivity and are environmentally desirable for introduction purposes since the species introduced is known and will help focusing the research on this species. This knowledge can be of assistance to the government in setting up environmental and cultivation protocols to achieve sustainability in macroalgae aquaculture.     

Evaluation of growth rate and semi‐refined carrageenan properties of tissue‐cultured Kappaphycus alvarezii (Rhodophyta,Gigartinales)

This study aimed to evaluate and compare the quality of κ‐carrageenan obtained from tissue‐cultured and field‐cultured Kappaphycus alvarezii. Carrageenan properties including yield, viscosity, gel strength and sulfate content were studied. After 60 days of cultivation, tissue‐cultured K. alvarezii showed a higher growth rate (6.3 ± 0.01% day^?1) than field‐cultured seedlings (3.4 ± 0.3% day^?1). The obtained carrageenan yield from tissue‐cultured (67.3 ± 16.4%) was higher than field‐cultured K. alvarezii (51.5 ± 21.0%). Gel viscosity of carrageenans from tissue‐cultured K. alvarezii (1280.0 ± 25.0 cP) was found significantly higher than field‐cultured samples (87.8 ± 20.9 cP). The 1.5% gel solution of tissue‐cultured and field‐cultured K. alvarezii exhibited gel strengths of 703.5 ± 14.1 and 288.3 ± 19.3 g cm^?2, respectively. The average sulfate content of carrageenans was found to be significantly different between tissue‐cultured and field‐cultured K. alvarezii with 34.2 ± 10.9 and 7.5 ± 6.7%, respectively. Tissue culture is recommended to produce high quality seedlings by providing optimized culture conditions to the seaweed. This approach can serve as an alternative way to solve the seedling shortage problems currently faced by the seaweed industry.     

Spatial and temporal variation of <Emphasis Type="Italic">Hypnea musciformis</Emphasis> carrageenan (Rhodophyta - Gigartinales) from natural beds in Rio de Janeiro State,Brazil

Hypnea musciformis (Wulfen in Jacqu.) J. V. Lamour. is a native source of kappa-carrageenan, a commercially important galactan, exploited for decades on the northeastern Brazilian coast. Further studies to obtain information about the effects of abiotic factors on the carrageenan yield and quality of specimens from the southeastern Brazilian coast (Rio de Janeiro State) are needed. In this study, the carrageenan yield and quality of H. musciformis was analyzed over a period of 1 year in populations from Rio de Janeiro state. One epiphytic population was collected at a site situated at the entrance of the Sepetiba Bay (Praia Vermelha), another in the middle of the bay (Praia Grande) and a third (Praia Rasa) in a place exposed to the open sea. An epilithic population was also collected at Praia Rasa. In the sampling period, different changes were observed in the carrageenan yield and quality (viscosity and sulphate content) of the H. musciformis (August 1994 to June 1995) at the different sites and habitats (epilithic and epiphytic). Kappa carrageenan was the only one of its type detected. Only one population showed a correlation between viscosity and degree of sulphate content. Our analyses suggest that abiotic factors, such as water movement, desiccation stress, low salinity and extreme temperatures, were the main abiotic factors that influenced the changes in carrageenan of the populations studied. Thus, for a rational use of natural beds of H. musciformis, it is desirable to estimate the changes in carrageenan and algal biomass in the place to be exploited.     

Bioremediation potential of three carrageenophytes cultivated in tanks with seawater from fish farms

Intensive fish farming discharges large amount of nutrients, the majority of which are composed of dissolved nitrogen in ammonium form, which promotes eutrophication in coastal waters. Macroalgae have been proven to effectively reduce the nutrients of fish farm effluents and at the same time increase the economic output of the aquaculture system when economically important species are utilized. In this study, the potential of three high value carrageenophytes (Kappaphycus alvarezii, Kappaphycus sp., K. striatum) to extract ammonium in fish farm effluent collected from a milkfish (Chanos chanos) fish cage was investigated. To establish economic viability of the integrated culture system, the effects of elevated total ammonia of fish farm effluent on the growth rate, phycocolloid content, and quality of these seaweeds were determined. Tank cultivation trials showed that the three carrageenophytes substantially reduced the ammonium content of the fish farm effluent (41–66% reduction efficiency) and consequently attained maximum daily growth rates of 4.41%, 2.90%, and 2.75% for K. striatum, Kappaphycus sp., and K. alvarezii, respectively. Their carrageenan content was improved. Carrageenan quality, however, was not significantly enhanced. Elevated ammonium in fish farm effluent did not adversely affect the performance of tank cultivated Kappaphycus; thus, future integration of these seaweeds in fish farms is feasible. Presented at the 6th Meeting of the Asian Pacific Society of Applied Phycology, Manila, Philippines.     

Growth rate and carrageenan analyses in four strains of <Emphasis Type="Italic">Kappaphycus alvarezii</Emphasis> (Rhodophyta,Gigartinales) farmed in the subtropical waters of São Paulo State,Brazil

Growth rate, semi-refined and refined carrageenan yields, 3,6-anhydrogalactose and sulphate contents, and gel strength were investigated in four strains of Kappaphycus alvarezii (brown, green and red tetrasporophytic strains, and one strain derived from tetraspores progeny, called G11) farmed in subtropical waters of São Paulo State, Brazil. All studied strains showed higher growth rates from February to May, decreasing from July to December. The G11 strain exhibited lower growth rates, but had semi-refined and refined carrageenan yields significantly higher than the others and similar to a commercial sample. A negative correlation between growth rate and semi-refined carrageenan yield was verified for all strains. The brown strain had the lowest content of 3,6-anhydrogalactose, while G11 and green strains showed higher values. No clear pattern of variation and no relationship were observed for sulphate and gel strength. However, all strains presented gel strength values near the one obtained from commercial sample. These results show that the carrageenan extracted from brown, green, red, and G11 strains of K. alvarezii cultured in subtropical waters of São Paulo State, Brazil with commercial potentials.     

Effect of ammonium on growth and carrageenan content in Kappaphycus alvarezii (Gigartinales,Rhodophyta)

Kappaphycus alvarezii, cultured in a region deficient in nitrogen with intermittent application of 10 mM ammonium at three-day intervals for 1 hour, attained a daily growth rate of 4.6%, which was considered to be the optimum growth rate. Under such conditions, the C/N ratio was 29 with a carrageenan content of 58% and gel strength of 45–70 g cm^–2. Gel strength of carrageenan was high when nitrogen content was high and vice versa.     

Growth rate of the carrageenophyte Kappaphycus alvarezii (Rhodophyta, Gigartinales) introduced in subtropical waters of São Paulo State, Brazil

Twenty branches of Kappaphycus alvarezii (Doty) Doty ex P. Silva produced in unialgal culture and weighing about 3 g each were transferred into the sea monthly from October 1995 to October 1996 at Ubatuba Bay, São Paulo State, Brazil (23°26.9′S, 45°0.3′W), an area with mean monthly seawater temperature from 20.3 to 28.5°C (extremes: 17.0–31.0°C). All plants were harvested after the second month and a new series of growth experiments was performed using cuttings weighing from 100 to 150 g. The cultivation experiments were carried out using a floating system. Daily growth rates were calculated based on monthly weight measurements of each individual. Small branches produced in vitro showed high survival rates when introduced into the sea during all seasons. Growth rates observed for the transplanted branches during the first and second months in the sea were higher (6.5–10.7% day‐¹) than for subsequent cuttings produced in the sea (4.5–8.2% day‐¹). The latter values are in the range reported for other regions. Seasonal variation of growth rates was clearly related to seawater temperature. These results show that the commercial cultivation of K. alvarezii is technically feasible at Ubatuba Bay using a floating raft culture method.     

Seasonal variation in growth and carrageenan yield in cultivated Kappaphycus alvarezii (Doty) Doty on the coastal waters of Ramanathapuram district,Tamil Nadu

Kappaphycus alvarezii, a kappa carrageenan yielding red seaweed, was cultivated in Indian subtropical waters on the Palk Bay side of Bay of Bengal in Ramanathapuram district, Tamil Nadu, at three different sites: Vedalai, Munaikadu, and Thonithurai, for 1 year from April 2011 to March 2012. The maximum crop yields of 416 ± 51 and 550 ± 41 FW raft^?1 were recorded at Vedalai and Munaikadu, respectively, in December 2011, whereas a maximum of 326 ± 49 FW raft^?1 was recorded at Thonithurai in April 2011. Similarly, the maximum daily growth rates (DGRs) of 4.30 ± 0.51 % and 4.92 ± 0.40 % were obtained at Vedalai and Munaikadu, respectively, in December 2011, and 3.76 ± 0.48 % was recorded at Thonithurai in April 2011. Variations in environmental parameters like seawater temperature, salinity, nitrate, and phosphate were found to influence the growth of the seaweed. The maximum carrageenan content as a percentage of dry weight was 29.30 ± 0.61 % (Vedalai), 31.00 ± 0.71 % (Munaikadu), and 29.10 ± 1.12 % (Thonithurai) in March 2012. The data on moisture content (%), clean anhydrous weed/salt ratio, and carrageenan yield obtained in this study fulfilled those of international standards. Further, the results indicated that large-scale cultivation by either NGOs or self-help groups (SHGs) may be taken up along the coastal waters for the benefit of the poverty-stricken coastal people as their livelihood, as the growth rate obtained in this study compared well with that recommended for commercial cultivation elsewhere.     

Effect of ultraviolet-B radiation on growth,photosynthetic pigments,and cell biology of <Emphasis Type="Italic">Kappaphycus alvarezii</Emphasis> (Rhodophyta,Gigartinales) macroalgae brown strain

Kappaphycus alvarezii is a seaweed of great economic importance for the extraction of kappa carrageenan from its cell walls. The most common strains are dark red, brown, yellow, and different gradations of green. It is known that ultraviolet radiation (UVR) affects macroalgae in many important ways, including reduced growth rate, reduction of primary productivity, and changes in cell biology and ultrastructure. Therefore, we examined the brown strain of K. alvarezii exposed to ultraviolet-B radiaton (UVBR) for 3 h per day during 28 days of cultivation. The control plants showed growth rates of 7.27% d⁻¹, while plants exposed to UVBR grew only 4.0% d⁻¹. Significant differences in growth rates and in phycobiliproteins between control and exposed plants were also found. Compared with control plants, phycobiliprotein contents were observed to decrease after UV-B exposure. Furthermore, the chlorophyll a (Chl a) contents decreased and showed significant differences. UVBR also caused changes in the ultrastructure of cortical and subcortical cells, which included increased thickness of the cell wall and number of plastoglobuli, reduced intracellular spaces, changes in the cell contour, and destruction of chloroplast internal organization. Reaction with Toluidine Blue showed an increase in the thickness of the cell wall, and Periodic Acid-Schiff stain showed a decrease in the number of starch grains. By the significant changes in growth rates, photosynthetic contents and ultrastructual changes observed, it is clear that UVBR negatively affects intertidal macroalgae and, by extension, their economic viability.     

Laboratory and field growth studies of commercial strains ofEucheuma denticulatum andKappaphycus alvarezii in the Philippines

Daily growth rates of 0.1 to 8.4% d^-1 for the brown form and 0.2 to 6.3% d^-1 of the green form were measured for 3 to 5-cm long branches of the tropical red seaweedKappaphycus alvarezii cultured in the laboratory. Highest growth rates were found using inexpensive enrichments such as soil water and coconut water supplemented with 0.7 mM N and 13 µM P and with a liquid fertilizer, Algafer, produced from seaweeds in the Philippines. Laboratory grown branches of bothK. alvarezii andEucheuma denticulatum transplanted to rafts in the field showed daily growth rates of 4.4 to 8.9% d^-1, as high or higher than other reported growth rates. The studies, carried out in the Philippines, demonstrate the viability and high yield of laboratory cultivars and methods to keep laboratory culture costs low.     

The commercial red seaweed <Emphasis Type="Italic">Kappaphycus alvarezii</Emphasis>—an overview on farming and environment

Commercial cultivation of the red alga Kappaphycus alvarezii (Doty) Doty has been satisfying the demand of the carrageenan industry for more than 40 years. For the past four decades, this species has been globally introduced to many maritime countries for experimental and commercial cultivation as a sustainable alternate livelihood for coastal villagers. Accompanying the introduction is an increasing concern over the species effects on the biodiversity of endemic ecosystems. The introductions of non-endemic cultivars have resulted in the adaptation of quarantine procedures to minimize bioinvasions of additional invasive species. The present review focuses on Kappaphycus farming techniques through the application of biotechnological tools, ecological interactions with endemic ecosystems, future K. alvarezii farming potentials in Asia, Africa, and the Pacific, and the challenges for prospective farmers, i.e., low raw material market value, diseases, grazing, etc. The introduction of Kappaphycus cultivation to tropical countries will continue due to the high production values realized, coastal villages searching for alternative livelihoods, and the increased global industrial demand for carrageenan.     

Effects of salinity on the growth rate,carrageenan yield,and cellular structure of <Emphasis Type="Italic">Kappaphycus alvarezii</Emphasis> (Rhodophyta,Gigartinales) cultured in vitro

Kappaphycus alvarezii was cultured in vitro under salinities ranging from 15 to 55 psu for 35 days to determine the differential effect on growth rate, carrageenan yield, and cellular structure. Plants kept in 15 psu died after 3 days, while plants cultured in 55 psu presented low growth rates during the entire experimental period (0.28% day⁻¹). Plants cultured in 25, 35, and 45 psu showed growth rates normally associated with this species (between 3% and 4% day⁻¹) and similar cellular morphology. Carrageenan yield was significantly higher in plants cultured in 25 psu in relation to the other treatments. As observed by light microscopy, plants cultured in 15 psu showed cellular turgidity and increased cell wall thickness, both consequences of hyposalinity. Chloroplasts and other membranous organelles underwent rupture and considerable disorganization in ultrastructure. Although branches from the 55 psu samples showed plasmolysis, cells were able to maintain chloroplast integrity, despite their rudimentary features. In high salinities, great concentrations of floridean starch grains were observed in subcortical cells, indicating their probable participation in osmoregulation. Based on these results, we defined the range of 25 to 45 psu as the limits of saline tolerance for K. alvarezii. While new field studies are required to confirm these results, it can be concluded that new sites, such as inactive or abandoned shrimp tanks with salinities up to 25 psu, could be considered for commercial farming.     

Effects of improved post-harvest handling on the chemical constituents and quality of carrageenan in red alga,Kappaphycus alvarezii Doty

Red alga Kappaphycus alvarezii Doty is an important commercial species widely cultivated in southeast Asian countries for its polysaccharide, kappa-carrageenan. Common post-harvest handling technique involves sun-drying of harvested seaweed on platforms at the farms. Quantity and quality of carrageenan varies depending on the duration and care taken during the post-harvest handling of the raw seaweed. In this study, dynamics of moisture content, water activity index (aw), carrageenan yield, and carrageenan quality were investigated by subjecting the seaweed to three post-harvest methods: (1) freeze-drying (FD), (2) shade-drying (SD), and (3) direct sun-drying (DSD). Seaweed dried under FD and SD produced high yield (56–58 %), superior gel strength (1,454–1,424 g cm^?2), high viscosity (57–58 cPs), and low syneresis (15–17 %). But, carrageenan extracted from DSD seaweed gave 28 % lower yield, 38 % lower gel strength, 27 % lower viscosity, and 8–9 % higher syneresis. In addition, gelling temperature and melting temperature of the DSD carrageenan were lower by 4 and 9 °C, respectively. Molecular size analyses of carrageenan extracted from seaweed dried under FD and SD contained carrageenan of 700 KDa (80 %) and 200 KDa (4–10 %). However, carrageenan extracted from DSD seaweed contained smaller carrageenan molecules, 460 KDa (55 %), 210 KDa (25 %), and <100 KDa (20 %). Further, scanning electron microscope images illustrated the severe effects of DSD on the morphology of seaweed cells. Therefore, SD technique was found to be the best post-harvest processing technique that gave quality carrageenan in a high quantity. Due to its simplicity and low cost, it is a practical approach to be practiced in southeast Asian countries.     

In vitro cultivation of three <Emphasis Type="Italic">Kappaphycus alvarezii</Emphasis> (Rhodophyta,Areschougiaceae) variants (green,red and brown) exposed to a commercial extract of the brown alga <Emphasis Type="Italic">Ascophyllum nodosum</Emphasis> (Fucaceae,Ochrophyta)

Diseases such as “ice-ice” and “goose bumps” are responsible for loss of almost 70% of infected Kappaphycus production. To improve the growth of K. alvarezii and reduce the impact of diseases, the effect of the commercial Ascophyllum nodosum extract was tested. Five grams of apical branches of each K. alvarezii variant (n = 6) were bathed at different extract concentrations (e.g., 5, 10, 15, 20, 25, and 30 g L⁻¹) for 1 hour. To test the effect of the extract on epiphytes apical tips were not cleaned. After 2 weeks, the epiphytes such as Cladophora sp. and Ulva sp. disappeared. Polysiphonia subtilissima survived but its appearance was weak. The highest K. alvarezii growth rates were observed at extract concentrations of 15 and 20 g L⁻¹ (p < 0.001), almost double the expected for a 45-day production cycle used at Sepetiba Bay, Brazil. These results show that the extract was efficient at improving the growth of K. alvarezii and reducing the presence of some epiphytes.     

Ultrastructural,morphological, and molecular characterization of Colaconema infestans (Colaconematales,Rhodophyta) and its host Kappaphycus alvarezii (Gigartinales,Rhodophyta) cultivated in the Brazilian tropical region

Endophytic and epiphytic infections have caused serious problems for Kappaphycus farmers, such as reduction in biomass production and decrease in the yield and quality of carrageenan. During environmental monitoring from January 2011 to December 2012, along Pitimbu Beach, Paraíba State, northeastern Brazil, drifting thalli of Kappaphycus alvarezii (Gigartinales, Rhodophyta) were detected with red spots, apparently caused by epiphytic/endophytic infections. Therefore, drifting thalli of K. alvarezii farmed along the northeastern Brazilian coast were cultured in the laboratory and submitted to molecular and morphological analyses to identify and characterize the causative agent and its effects on the cellular structure and ultrastructure of the host alga K. alvarezii that was found to be infected by the endophyte Colaconema infestans (Colaconematales) identified through morphological and rbcL molecular evidence. Infected thalli of K. alvarezii were processed and analyzed through light, transmission electron, and scanning electron microscopy. Alterations were observed in morphology and cellular organization, including structural changes of chloroplasts and decrease in floridean starch grains, along with increased cell wall thickness. Therefore, while no outbreak has been reported, the discovery of C. infestans infection in drifting thallus of K. alvarezii suggests a potential threat to its cultivation that should be monitored.