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Eucheumatoid cultivation is an important alternative livelihood for small-scale farmers in coastal areas in east Malaysia. Over the last 50 years, the same clones of the red eucheumatoid Kappaphycus alvarezii and Kappaphycus striatus have been vegetatively propagated for cultivation resulting in low genetic diversity. This has made the cultivars more vulnerable to pests and diseases, which has been further exacerbated by climate change. There is an urgent need, therefore, to develop new cultivars that are resilient to pests and diseases, as well as environmental change. In this study, wild eucheumatoids were collected from four regions in Semporna, East Malaysia: Kerindingan, Sibuhun, Sebangkat and Omadal. These eucheumatoids were then grown at a commercial seaweed farm in Silungun, Semporna using two methods: i) tie-tie and ii) basket net for 60 days and their performance was evaluated based on growth and survival rates. A higher mean specific growth rate (SGR) was recorded by wild-collected Kappaphycus spp. (2.15 ± 1.90% day−1) and Eucheuma denticulatum (2.83 ± 3.27% day−1) when tie-tie was used. However, survival of the wild-collected eucheumatoids was better with the basket net, which led to a reduction in grazing and prevented detachment from culture lines. Of 212 original individuals, 72 survived throughout the study, despite the prevalence of pests and ice-ice disease. Of these, 46.15% Kappaphycus spp. and 50.75% E. denticulatum survived when cultivated using the basket net and 17.20% Kappaphycus spp. and 30.77% E. denticulatum survived when cultivated using tie-tie. The mean SGR and survival rate were significantly correlated with temperature, salinity, pH, current velocity and rainfall (p < 0.05). The surviving wild-collected Kappaphycus spp. and E. denticulatum have the potential to be developed into new cultivars for possible commercial use. [ABSTRACT FROM AUTHOR]

Eucheumatoid seaweeds, encompassing the genera Kappaphycus and Eucheuma, are widely cultivated globally, particularly in tropical regions. However, ice-ice disease (IID) poses a significant challenge to their production, causing substantial economic losses. This study aimed to elucidate the factors contributing to IID in eucheumatoid seaweeds, focusing on the perspectives of seaweed farmers in Sibutu, Tawi-Tawi, Philippines. A mixed methods approach was employed, utilizing both one-to-one interviews (n = 96) and focus group discussions. The majority of the interviewed farmers were male, aged between 31 and 60 years, with extensive experience (11‒25 years) in seaweed cultivation. Notably, all participants possessed a familiarity with IID since childhood. Farmers described IID as a pathological condition affecting eucheumatoid seaweeds, characterized by the emergence of white and soft areas on the seaweed thalli. The initial stages of the disease manifest as a pale discolouration of the thalli and the presence of epiphytes or debris. Several environmental factors were identified by the farmers as contributing to IID incidence, including high or low water temperatures, low salinity (particularly after heavy rainfall), stagnant water currents, nutrient deficiencies, inadequate seedling quality, and poor farm management practices. Additionally, deepwater (nearshore) farms were reported to be more susceptible to IID. Farmers noted that easterly winds could exacerbate the disease by facilitating the infestation of epiphytes on the seaweed. Furthermore, the prevalence of IID was observed to be highest during the dry and hot season. Kappaphycus striatus was identified by the farmers as being more susceptible to IID compared with K. alvarezii and Eucheuma denticulatum. The negative impact of IID on farmers' livelihoods was also highlighted. Some mitigation strategies employed by the farmers included the application of inorganic nutrient enrichments (e.g. ammonium phosphate (16–20-0, N-P-K) and complete (14–14-14, N-P-K) fertilizers), frequent relocation of infected seaweed to different farms, and the cultivation of more IID-resistant species. Highlights: Farmers defined ice-ice disease as an anomaly in eucheumatoid seaweeds that showed white and soft thalli. Ice-ice disease is linked to unfavourable water parameters, nutrient deficiencies and poor seedling quality and management. Kappaphycus striatus is more prone to ice-ice disease than K. alvarezii and Eucheuma denticulatum. [ABSTRACT FROM AUTHOR]

The red alga Kappaphycus alvarezii (Rhodophyta) is one of the most cultivated species in the world. Extracts obtained from Kappaphycus (KAlv-sap) have been shown to promote plant growth as well as defense against abiotic stresses. The present study aimed to examine the regulation of photosynthesis and the genetic and metabolic mechanisms resulting from foliar and root application of KAlv-sap in rice plants (Oryza sativa). KAlv-sap was obtained from fresh algae cultivated in the bay of Ilha Grande, Paraty, Brazil, and previously well characterized. Experiments were performed using applications at 21 and 24 days after germination (DAG) with four treatments: control (without KAlv-sap); two foliar application treatments with 2% and 10% KAlv-sap (2% K-sapF and 10% KAlv-sapF, respectively); and root application treatment with 2% KAlv-sap (2% KAlv-sapR). Both foliar and root applications of KAlv-sap promoted improved photosynthetic efficiency transport and adaptive response to the stress, at least until 27 DAG. KAlv-sap application increased the uptake of N and K, leading to an increase in N-NO3- and amino-N. Such conditions promote increases in biomass production, growth, and root development. Root application of KAlv-sap stimulated the growth of plants at later times compared to foliar application and, in both cases, the pathways of action include the regulation of redox homeostasis. The results shed light on the pathways of action stimulated by aqueous extracts of Kappaphycus, contributing to the improvement of the agricultural bioinputs. [ABSTRACT FROM AUTHOR]

Since its initial report in the Philippines in 1981, ice-ice disease (IID) remains a substantial threat to the sustainability of eucheumatoid seaweed production. However, comprehensive investigations into the prevalence, intensity, and potential relationships with physicochemical and meteorological parameters are limited, particularly in open-sea farms. This is the first study to conduct a 12-month monitoring of IID prevalence and intensity in eucheumatoid seaweed farms in Tawi-Tawi, Philippines. The research aimed to elucidate seasonal variations and potential associations with physicochemical and meteorological parameters. The findings revealed significant seasonal variations in IID prevalence, with a higher incidence observed during the dry season compared to the wet season. Additionally, deep-water farms exhibited significantly higher prevalence and ice-ice spot numbers per bundle compared to shallow-water farms. Furthermore, Kappaphycus striatus displayed a significantly greater ice-ice spot length per bundle compared to K. alvarezii. Notably, no interaction effects were observed among season, species, and depth. Interestingly, while no correlations were found between ice-ice disease and most measured physicochemical and meteorological parameters (temperature, salinity, pH, water current velocity, wind speed) or nutrient concentrations (phosphate, nitrate, nitrite), an inverse correlation (p < 0.05) emerged between ammonium levels and IID intensity parameters (number and length of ice-ice spot per bundle). Moreover, a positive correlation was observed between monthly rainfall and IID intensity. These findings offer valuable insights into the dynamics of IID in open-sea eucheumatoid seaweed (Kappaphycus) farming, highlighting the influence of seasonality, depth, and species susceptibility, as well as the relationship between IID severity and ammonium levels and rainfall. [ABSTRACT FROM AUTHOR]

Pollution caused by petroleum-based plastics, especially single-use food packaging, has become a global problem. In order to offer sustainable alternatives to traditional plastic, it is important to explore the use of new biodegradable plastic materials made from renewable sources. Bioplastics made from seaweed extracts, such as carrageenan and alginate, show promise as viable options. However, these phycocolloids are expensive and require a lengthy extraction process. This report presents the development of bioplastics using the entire biomass of a red seaweed (Kappaphycus sp.). The initial focus of the study was to optimize the concentration of the main ingredients, which included biomass and glycerol (plasticizer agent). The concentration range that was tested included a biomass-to-water ratio of 1:50 to 1:90 and a plasticizer concentration of 1% to 5% (v/v). Subsequently, bioplastics were created by incorporating natural dye extracts from butterfly pea flower (Clitoria ternatea), bougainvillea flower (Bougainvillea glabra), and dragon fruit peel (Hylocereus polyrhizus) using a casting method at the selected optimum concentrations. The resulting bioplastics were then characterized for their physicochemical properties (including shelf-life and biodegradability), and antimicrobial activity using standard methods. The study successfully developed bioplastics with a thickness of less than 100 µm and a moisture content below 40%. Within the tested range, the most optimal concentrations were a biomass-to-water ratio of 1:50 to 1:60 and 1% glycerol, based on factors such as tensile strength (TS), water vapor transmission rate (WVTR), elasticity, appearance, shelf-life, and biodegradability. All of the bioplastics completely degraded during a soil burial test within 13-15 days. The inclusion of brightly coloured plant extracts increased the bioplastics' antioxidant properties by more than 10% in scavenging activity. Furthermore, the dyed bioplastics had a shelf-life that was 20-30% longer. While these biomass bioplastics have lower tensile strength, elasticity, and water vapor permeation rate (<10 MPa, <30 MPa, and >2 g m-2 h-1, respectively), they show potential for applications where high tensile strength is not required, such as food packaging or wrapping. [ABSTRACT FROM AUTHOR]

The process of domestication of the seaweed Kappaphycus alvarezii (Doty) L.M. Liao (Rhodophyta) has been taking place since 1995 and 1996 with the introduction of a brown tetrasporophyte and a pale brown gametophyte (originated from tetraspore progeny cultivated in laboratory) in the Experimental Marine Farm of the Fisheries Institute, Ubatuba Bay, São Paulo State, Brazil. From both original strains, 12 new color strains were generated, but only 8 strains have survived. However, new strains with brown color were not observed during the monitoring period. From 2013 to 2022, the occurrence of spontaneous color strains and data of temperature, salinity and water transparency were recorded on the cultivation site. For data analysis, a binary logistic regression model was used to identify the significant association between the presence of generation of the new strains of K. alvarezii (outcome variable) and abiotic data (predictors), and Receiver Operating Characteristic Curve (ROC curve) was used to investigate the probability of giving rise to new strains. Results showed that temperature was significant (p-value = 0.025) for generation of new color strains of K. alvarezii. According to the temperature range (18.3 to 31.8 ºC) used in the model, the probabilities to originate a new strain was 7.6% in temperature of 15 °C and 0.01% at 33 ºC. The occurrence of new strains of K. alvarezii may contribute to the selection of new cultivars for local mariculture. [ABSTRACT FROM AUTHOR]

In an integrated multitrophic aquaculture (IMTA) system, seaweeds serve as extractive species that utilize excess nutrients, thereby reducing the risk of eutrophication and promoting sustainable aquaculture. However, the use of excessive fish feeds and the resultant faecal waste as nutrient streams can contribute to variations in nitrogen and phosphorus levels (e.g., primarily NH4+ and PO4−3) in the surrounding area and this may impact the physiology of the integrated seaweeds, particularly on how these species take up inorganic nutrients. In this study, the effect of different PO4−3 levels on NH4+ uptake of the three commercially important eucheumatoids Kappaphycus alvarezii, Kappaphycus striatus and Eucheuma denticulatum was examined under laboratory conditions. Seaweed thalli (n = 4) were incubated in seawater media containing 30 µM NH4+, and 0, 0.5, 1.0, 1.5, 3.0 or 5.0 µM PO4−3 for 1 h under a saturating light level of 116 ± 7.13 µmol photons m−2 s−1 inside a temperature-controlled laboratory. Species-specific responses to PO4−3 levels were observed. For K. alvarezii, maximum NH4+ uptake (17.8 ± 1.6 µmol gDW−1 h−1) was observed at 0.5 µM PO4−3 and the uptake rate declined at higher PO4−3 levels. For K. striatus, NH4+ uptake increased with increasing PO4−3 levels, with maximum N uptake (6.35 ± 0.9 µmol gDW−1 h−1) observed at 5.0 µM PO4−3. For E. denticulatum, maximum NH4+ uptake (14.6 ± 1.4 µmol gDW−1 h−1) was observed at 1.0 µM PO4−3. Our results suggest that among the three eucheumatoid species, the NH4+ uptake of K. striatus persists even at high levels of PO4−3. However, our results also showed that K. striatus had the lowest range of NH4+ uptake rates. These results should be taken into consideration when incorporating eucheumatoids in the IMTA system, where PO4−3levels significantly vary in space and time. [ABSTRACT FROM AUTHOR]

A phyco-biostimulant from the brown alga Ascophyllum nodosum has been widely used in agricultural crops for decades. However, it was recently discovered that the same extract can be successfully applied in the micropropagation and field cultivation stages of eucheumatoids. The present study tested the efficacy of an alkali extract from A. nodosum (aka AMPEP) on Kappaphycus alvarezii with the aim of enhancing daily growth rate, as well as to mitigate the prevalence of ice-ice disease and macro-epiphytes, using three different seeding methods (i.e., double-looping DL, tubular-netting TN and ribbon tying RT, vis-à-vis water quality parameters. Seedlings were dipped in soluble extract powder made up to 1 g L−1 AMPEP for 1 h prior to out-planting in the sea. A total of three growth cycles, each of 45 days, from November—June (representing the dry months) were followed. The daily growth rate (% increase in fwt day−1) and prevalence (%) of ice-ice disease and macro-epiphytes were measured and correlated with the prevailing water conditions at the experimental site. The average DGR ranged from 0.10—3.8, 0.7—2.6, and 0.03—3.6% day−1 for DL, TN and RT, respectively, for AMPEP-treated K. alvarezii, while the control showed a range of average growth from -0.2—3.8, 0.2—2.6, -1.0—4.0% day−1, respectively. Negative DGRs were obtained in DL (-0.2%) and RT (-1.0%) from May—June. Using a factorial set up of ANOVA, the seeding method and growth cycle had significant interactions (p < 0.01); however, no significant interaction was found between AMPEP and the seeding method. During November—January, the three seeding methods did not influence DGR; however, a significant effect was found in January–March. Using Tukey's HSD, DL and RT were significantly different from TN, but no significant differences between RT and DL were recorded. The effects of AMPEP on DGR were only significant from May—June (p < 0.05). Growth rates, ice-ice disease and macro-epiphyte (ME) incidence correlated significantly with sea surface temperature (SST) and salinity but not with pH. This study clearly demonstrated the effects of increased temperature and salinity on Kappaphycus growth rates, ice-ice disease and macro-epiphyte incidence at certain growth cycles (months). [ABSTRACT FROM AUTHOR]

Since its initial report in the Philippines in 1981, ice-ice disease (IID) remains a substantial threat to the sustainability of eucheumatoid seaweed production. However, comprehensive investigations into the prevalence, intensity, and potential relationships with physicochemical and meteorological parameters are limited, particularly in open-sea farms. This is the first study to conduct a 12-month monitoring of IID prevalence and intensity in eucheumatoid seaweed farms in Tawi-Tawi, Philippines. The research aimed to elucidate seasonal variations and potential associations with physicochemical and meteorological parameters. The findings revealed significant seasonal variations in IID prevalence, with a higher incidence observed during the dry season compared to the wet season. Additionally, deep-water farms exhibited significantly higher prevalence and ice-ice spot numbers per bundle compared to shallow-water farms. Furthermore, Kappaphycus striatus displayed a significantly greater ice-ice spot length per bundle compared to K. alvarezii. Notably, no interaction effects were observed among season, species, and depth. Interestingly, while no correlations were found between ice-ice disease and most measured physicochemical and meteorological parameters (temperature, salinity, pH, water current velocity, wind speed) or nutrient concentrations (phosphate, nitrate, nitrite), an inverse correlation (p < 0.05) emerged between ammonium levels and IID intensity parameters (number and length of ice-ice spot per bundle). Moreover, a positive correlation was observed between monthly rainfall and IID intensity. These findings offer valuable insights into the dynamics of IID in open-sea eucheumatoid seaweed (Kappaphycus) farming, highlighting the influence of seasonality, depth, and species susceptibility, as well as the relationship between IID severity and ammonium levels and rainfall.

Three Kappaphycus species (Kappaphycus striatus, Kappaphycus alvarezii, and Kappaphycus malesianus) were cultivated using two cultivation methods (longline and off-bottom) at four maturity stages with an interval of 20 days. The study was performed to evaluate the effects of cultivation type and maturity stages (0, 20, 40, and 60 days) on the arsenic (As) species concentration and carrageenan content in the seaweeds. It was found that As species concentration in Kappaphycus spp. grown using longline cultivation technique followed the order arsenate [As(V)] > dimethylarsenic acid (DMA) > arsenite [As(III)] > monomethylarsenic acid (MMA), and in off-bottom was DMA > As(III) > MMA > As(V). The principal component analysis (PCA) models for longline and off-bottom cultivations exhibited dominance of carrageenan content over As species concentration at 40 days of growth period of Kappaphycus spp. Among the cultivation techniques, longline datasets were inclined heavily towards carrageenan content vector, which was negatively correlated to the As species concentration in the PCA. The Kappaphycus spp. grown until 40 days using longline cultivation provided a high carrageenan content with less influence of As species contamination. These findings can impact the seaweed industry, where the farmers can attain sustainable yield of carrageenan that have less risk of rejection by the food safety authorities for As species contamination. [ABSTRACT FROM AUTHOR]

The aquaculture of Kappaphycus alvarezii (Kappaphycus hereafter) seaweed has rapidly expanded among coastal communities in Indonesia due to its relatively simple farming process, low capital costs and short production cycles. This species is mainly cultivated for its carrageenan content used as a gelling agent in the food industry. To further assist producers in improving cultivation management and providing quantitative information about the yield, a novel approach involving remote sensing techniques was tested. In this study, multispectral images obtained from a drone (Unoccupied Aerial Vehicle, UAV) were processed to estimate the fresh and carrageenan weights of Kappaphycus at a cultivation site in South Sulawesi. The UAV imagery was geometrically and radiometrically corrected, and the resulting orthomosaics were used for detecting and classifying Kappaphycus using a random forest algorithm. The classification results were combined with in situ measurements of Kappaphycus fresh weight and carrageenan content using empirical relations between the area and weight of fresh seaweed/carrageenan. This approach allowed quantifying seaweed biometry and biochemistry at single cultivation lines and cultivation plot scales. Fresh seaweed and carrageenan weights were estimated for different dates within three distinct cultivation cycles, and the daily growth rate for each cycle was derived. Data were upscaled to a small family-scale farm and a large-scale leader farm and compared with previous estimations. To our knowledge, this study provides, for the first time, an estimation of yield at the scale of cultivation lines by exploiting the very high spatial resolution of drone data. Overall, the use of UAV remote sensing proved to be a promising approach for seaweed monitoring, opening the way to precision aquaculture of Kappaphycus. [ABSTRACT FROM AUTHOR]

The present work was performed to evaluate the levels of phytochemical constituents and the antioxidant and antibacterial properties of marine red seaweed (Kappaphycus alvarezii) and seagrass (Cymodocea serrulata). Quantitative phytochemical analysis, antioxidant activity and antimicrobial activity against five potential pathogenic bacteria was investigated. In each case, we found the presence of flavonoids, tannins, phenolic compounds, glycosides, steroids, carbohydrates and ashes. Alkaloids were only found in K. alvarezii, though they were not found in C. serrulata. The antimicrobial properties of both K. alvarezii and C. serrulata chloroform extracts were found to be antagonistically effective against the Gram-positive bacteria Bacillus subtilis and the Gram-negative bacteria Vibrio parahaemolyticus, Vibrio alginolyticus, Vibrio harveyi and Klebsiella pneumoniae. GC-MS analysis revealed the presence of 94 bioactive compounds in K. alvarezii and 104 bioactive compounds in C. serrulata, including phenol, decane, dodecane, hexadecane, vanillin, heptadecane, diphenylamine, benzophenone, octadecanoic acid, dotriaconate, benzene, phytol, butanoic acid and 2-hydroxyl-ethyl ether, which all played important roles in antioxidant and antibacterial activities. Thus, in view of the results, both K. alvarezii and C. serrulata could be considered to be sources of ingredients with appreciable nutritional and medicinal value. [ABSTRACT FROM AUTHOR]

We report the presence of Kappaphycus cf. striatus growing in a mangrove stand in Buan, Siasi, Philippines. These plants might have originated from the wild or nearby extensive seaweed farming areas. This is the first account of wild Kappaphycus growing in a mangrove habitat and exhibiting adaptive strategies to avoid desiccation stress. These seaweeds formed scars on their thalli tips and displayed a dense morphology to reduce the surface area exposed to air. This report provides new insights into the capacity of Kappaphycus to adapt to adverse environmental conditions which could improve their chances of survival in a changing climate but could also pose a threat to other ecosystems and natural biota. [ABSTRACT FROM AUTHOR]

Graphical Abstract

The present work was performed to evaluate the levels of phytochemical constituents and the antioxidant and antibacterial properties of marine red seaweed (Kappaphycus alvarezii) and seagrass (Cymodocea serrulata). Quantitative phytochemical analysis, antioxidant activity and antimicrobial activity against five potential pathogenic bacteria was investigated. In each case, we found the presence of flavonoids, tannins, phenolic compounds, glycosides, steroids, carbohydrates and ashes. Alkaloids were only found in K. alvarezii, though they were not found in C. serrulata. The antimicrobial properties of both K. alvarezii and C. serrulata chloroform extracts were found to be antagonistically effective against the Gram-positive bacteria Bacillus subtilis and the Gram-negative bacteria Vibrio parahaemolyticus, Vibrio alginolyticus, Vibrio harveyi and Klebsiella pneumoniae. GC-MS analysis revealed the presence of 94 bioactive compounds in K. alvarezii and 104 bioactive compounds in C. serrulata, including phenol, decane, dodecane, hexadecane, vanillin, heptadecane, diphenylamine, benzophenone, octadecanoic acid, dotriaconate, benzene, phytol, butanoic acid and 2-hydroxyl-ethyl ether, which all played important roles in antioxidant and antibacterial activities. Thus, in view of the results, both K. alvarezii and C. serrulata could be considered to be sources of ingredients with appreciable nutritional and medicinal value.

In India, abiotic stress, particularly drought, is known to affect sugarcane cultivation. Among various management strategies, application of biostimulants, especially those from seaweeds, offer promising results in containing yield loss due to drought stress. Here, we tested the efficacy of Sea6 liquid biostimulant formulation LBS6 in field condition along with conventional management practices for comparison purpose using two popular commercial varieties of sugarcane (Co 86032 and Co 0212). Drought stress imposed during formative phase of the crop and foliar application of sea6 liquid formulation was applied at 60, 90 and 120 days after planting (DAP). The effect of liquid formulation on mitigating drought stress was assessed by studying the growth, physiological, yield and yield traits at important pheno-phases of the crop. Results showed that, in Co 86032 shoot population of control was 100.5×103 ha-1 and drought was 85.1×103 ha-1 with mean reduction of 15.5% over control. Drought stress induced 11.4, 12.4, 9.8 and 5.0% reduction in plant height, leaf area index (LAI), chlorophyll content (SPAD value) and photochemical efficiency, respectively. In Co 0212, drought induced 10.15, 9.4, 10.5, 9.5 and 5.1% reduction in shoot population, plant height, LAI, SPAD value and photochemical efficiency, respectively. Under drought condition, in Co 86032, foliar application of KCl (2.5%) and seaweed extract LBS6(2 mL L-1) was observed comparatively higher cane yield of 92.9 t ha-1 and 89.5 t ha-1, with 18 and 16.5% yield improvement over untreated drought plot, respectively. In Co 0212, foliar application of KCl (2.5%) and seaweed extract LBS6 (2 mL L-1) recorded 99 and 93.5 t ha-1 with 18.5% and 15.2% yield improvement over untreated drought plot, respectively. Among the two varieties, Co 0212 performed better under drought situation with KCl (2.5%) spray demonstrating better physiological efficiency under stress, closely followed by of sea6 formulation LBS6 (2 mL L-1). Further, the drought management practices did not affect the juice quality parameters in both the tested varieties. [ABSTRACT FROM AUTHOR]

Studies have shown that cultivars of the carrageenophytes Kappaphycus and Eucheuma are clones of a limited number of strains originally domesticated from wild populations. For the development and selection of new cultivars, it is important that a comprehensive record of available variants exists. This study was conducted to provide up-to-date analysis and compilation of the current state of cultivars as the last list of cultivars was compiled nearly a decade ago. The present study analyzed the cox2–3 spacer and cox1 (1356 bp) genetic diversity of cultivars collected from 2019 to 2020 from the east coast of Sabah where the seaweed farms are concentrated. These data were compared with cultivars reported from 2010 to 2012 to assess changes, if any, to the gene pool of farmed eucheumatoid in Malaysia. Kappaphycus alvarezii, K. striatus, and K. malesianus are currently cultivated while Eucheuma denticulatum is no longer an important cultivar compared to a decade ago, probably due to its lower price. Analysis of the cox2–3 spacer revealed a new haplotype, LBT10, and, by including published GenBank data, a further four previously unnamed haplotypes were recognized from Sabah. This study confirms that there is a limited gene pool within cultivars in Malaysia and suggests the need for new or genetically diverse cultivars which can adapt to a changing environment, to ensure a more sustainable carrageenan industry. [ABSTRACT FROM AUTHOR]

Kappaphycus alvarezii seaweed extract (KSWE) is known to enhance crop productivity and impart stress tolerance. Close to one quarter of foliar spray applied to maize falls on the soil, either as drift or from leaf as drip. It was hypothesized that the drift spray would profoundly influence soil microbes under stress. An experiment was conducted with five treatments, with or without KSWE application at critical stages of maize grown under soil moisture stress and compared with an irrigated control. An Illumina platform was employed for the analysis of the V3–V4 region of 16S rRNA gene from the soil metagenome. A total of 345,552 operational taxonomic units were generated which were classified into 55 phyla, 152 classes, 240 orders, 305 families and 593 genera. Shannon’s index and Shannon’s equitability indicated increased soil bacterial diversity after multiple KSWE applications under conditions of abiotic duress. The abundance of the genera Alicyclobacillus, Anaerolinea, Bacillus, Balneimonas, Nitrospira, Rubrobacter and Steroidobacter decreased (49–79%) under drought imposed at the V5,10 and 15 stages of maize over the irrigated control, while it significantly improved when followed by KSWE application under drought. Flavobacterium, Nitrosomonas, Nitrosovibrio, Rubrobacter genera and several other bacterial taxa which are important for plant growth promotion and nutrient cycling were found to be enriched by KSWE application under drought conditions. Treatments having enriched microbial abundance due to KSWE application under stress recorded higher soil enzymatic activities and plant cob yield, suggesting the contribution of altered soil ecology mediated by KSWE as one of the reasons for improvement of yield. [ABSTRACT FROM AUTHOR]

Seemingly unabated global demands for raw materials of red seaweeds for k-carrageenan have expanded commercial cultivation of Kappaphycus alvarezii in the extended areas of the tropics. However, this has also increased speculations of negative environmental effects of K. alvarezii cultivation on the native marine biota. In the present investigation the native seaweed diversity was studied from 2018–2019 in four months interval within the intertidal regions of 19 islands of the Gulf of Mannar. Data gathered were divided in to two categories, i.e. islands near to cultivation sites (2–8 km away) and far from cultivation sites (30–70 km away) revealed occurrence of 113 and 122 seaweed species respectively. Significance differences were observed only in percentage cover (F = 6.505; p = 0.013) and species richness (F = 10.312; p = 0.002) in between the two group of islands. Simpson diversity and Shannon Weaver indices were in the range of 0.870—0.884 and 2.554—2.707 respectively and no significant differences recorded between the two group of islands (p > 0.05). A Bray–Curtis Similarity index (95%) indicated a homogenous distribution of seaweed diversity. Dictyota dichotoma, Halimeda gracilis, Padina pavonica, Sargassum polycystum and Turbinaria ornata were the most common species in both groups of islands. The present study confirmed that commercial farming of K. alvarezii did not affect the native seaweeds diversity in the islands of the Gulf of Mannar. [ABSTRACT FROM AUTHOR]

Ulva lactuca is one of the macro-epiphytes of farmed seaweeds Kappaphycus spp. and Eucheuma denticulatum in Tawi-Tawi, southern Philippines, especially during the summer season, which affects the growth and health of farmed seaweeds. In this study, the abundance of culturable heterotrophic marine bacteria from U. lactuca associated with farmed seaweeds Kappaphycus spp. and E. denticulatum was investigated in the seaweed farms of Tongsibalo, Sibutu, Tawi-Tawi, southern Philippines, using serial dilution procedure. Results revealed that the average bacterial counts obtained from U. lactuca associated with Kappaphycus alvarezii, K. striatus, and E. denticulatum were 2.48 x 1010 CFU g-1, 1.14 x 1012 CFU g-1, and 1.32 x 1011 CFU g-1, respectively. In addition, agardigesting bacteria were observed from U. lactuca samples associated with K. alvarezii and K. striatus manifested by the depression and liquefaction of the marine agar after 2-3 days which were suspected as pathogenic bacteria causing ice-ice disease. Therefore, U. lactuca may serve as a vector for these potential pathogens to farmed seaweeds. [ABSTRACT FROM AUTHOR]

The impact of cottonii (COT, Kappaphycus alvarezii) and spinosum (SPI, Eucheuma denticulatum) flour (1–10% w/w) on rheological properties of wheat (WHE) and quality of bread was investigated. Wheat-COT and WHE-SPI had higher water absorption capacities, dough development times, dough stabilities and farinograph quality numbers than WHE dough. Extensograms of composite dough were largely similar to those of WHE at the same incubation times. Dough energy decreased whereas elasticity ratio (ratio of maximum resistance to extensibility) increased when incubation time was increased from 45 to 135 min. Wheat-COT and WHE-SPI had lower pasting temperatures but higher peak, final, breakdown and setback viscosities than WHE flour. Specific volume of bread containing COT (5% w/w) or SPI (7.5% w/w) was not different (p > 0.05) from that of WHE bread. Crumb texture properties of these composite breads were also largely similar to those of WHE bread. The physical properties of WHE dough and bread were influenced by gluten, whereas those of WHE-COT and WHE-SPI were influenced by gluten in addition to κ-carrageenan in COT and ι-carrageenan in SPI. Protein, ash and dietary fibre contents increased (p < 0.05) whereas carbohydrate content of bread decreased (p < 0.05) when WHE was replaced with COT or SPI (5% w/w). [ABSTRACT FROM AUTHOR]

Kappaphycus spp. and Eucheuma spp. are two economically significant seaweed species cultivated globally due to their carrageenan content with numerous commercial applications. They are mainly cultivated in the Philippines, Indonesia, Malaysia, and Tanzania. The culture of these seaweeds also provides income sources for many coastal dwellers. In 2018, the total global production from these seaweeds was about 11 million tonnes. One of the primary problems that affect seaweed production is the incidence of ice-ice disease. In this article, we reviewed the reported scientific journals on the ice-ice disease of two commercially cultured seaweed species (Kappaphycus spp. and Eucheuma spp.), focusing mainly on causes, occurrence, and control measures. The ice-ice disease is caused by both abiotic and biotic factors manifested by the presence of white and soft parts in the infected seaweeds. The occurrence of this disease varies from species, places, and seasons. Control measures may include proper farm management, polyculture with other seaweeds, pre-soaking with antibacterial substances and nutrient enrichment before out-planting, and possibly using genetic engineering. [ABSTRACT FROM AUTHOR]

Biostimulants derived from Kappaphycus alvarezii are renowned for sustainable agricultural enhancement, yet the exploration of numerous other tropical algae remains uncharted. This study aimed to unravel the metabolite diversity, bioactivities, and potential plant biostimulant properties of extracts derived from Kappaphycus alvarezii (KAE), Gracilaria debilis (GDE), and Sargassum cinctum (SCE). Two-year field trials showcased a significant boost in maize grain yields, indicating the biostimulant potential of each extract. Application of 7.5 % seaweed extract concentration substantially increased grain yields by 32 %, 29 %, and 31 % over the control for KAE, GDE, and SCE in the first-year trial and by 31 %, 28 %, and 32 % in the second year. Even a lower concentration of 2.5 % resulted in an increase in grain yield over the control. High-resolution chromatographic techniques coupled with tandem mass spectrometry (MS/MS) revealed 198, 202, and 191 compounds in KAE, GDE, and SCE, respectively. GC–MS profiling further unveiled 23, 21, and 12 metabolites, respectively. The extracts from red and brown seaweeds harbored distinct metabolites with low similarities to each other. These extracts contained a spectrum of compounds, including glycerol, glycine, valine, ellagic acid, cromakalim, genistein, 1,4-β-d-glucan, polyamines, n1-acetylspermine, mannose, propionic acid, benzoic acid, glycine, coumaric acid, hydroxycinnamic acids, and resveratrol. These compounds, known for their potent bio-stimulatory properties in various crops when applied exogenously in pure forms. This study transcends the conventional understanding of seaweed extract efficacy by shedding light on lesser-known metabolites which might have potential biostimulant roles. In contrast to the well-established components traditionally associated with seaweed extracts, this exploration highlights the need to test the biological activities of several other overlooked compounds spanning diverse classes. • The research highlights the biostimulant potential of three tropical seaweed extracts. • Seaweed extracts from K. alvarezii (KAE), G. debilis (GDE), and S. cinctum (SCE). • 7.5 % seaweed extracts increases maize yields by 29–32 %. • Metabolites in KAE, GDE, and SCE through HR-MS: 198, 202, and 191; GC–MS: 23, 21 and 12, respectively. • Many metabolites have known bioactivities at ultralow concentrations. [ABSTRACT FROM AUTHOR]

The main aim of the present study was to determine the effects of a seaweed-based biostimulant's supplementation on the growth of Chlorella variabilis. A liquid extract from Kappaphycus alvarezii (K-sap) was prepared and supplemented in the growth medium from 0.2 to 5% concentrations. The supplementation of K-sap increased the growth and photosynthetic performance of C. variabilis. Addition of 0.4% K-sap increased the biomass production by about 59% compared to the control culture. The highest lipid and neutral lipid productivities were observed in 0.6% K-sap-supplemented culture, which were around 50 and 100% higher than that of the control culture, respectively. Addition of 1% K-sap increased the carbohydrate accumulation in the cells by about 50%. These results suggest that the supplementation of a seaweed-based biostimulant effectively enhances the growth and biofuel potential of microalgae. [ABSTRACT FROM AUTHOR]

The composition of the bacterial community of carrageenophyte-attached and planktonic bacteria was studied in two bays of Vietnam with contrasting anthropogenic inputs to assess their role as ecological indicators. Clear differences (~73% dissimilarity) between carrageenophyte-attached bacteria and bacterioplankton were detected in terms of genus composition: mainly Agaribacter, Ruegeria, Alteromonas, the Pir4 lineage and Vibrio for the carrageenophytes and Candidatus Actinomarina, HIMB 11, NS groups and SAR clades for the bacterioplankton. The copiotrophic nature, potential for complex-polymer degradation, and ability to form and defend biofilms were common features inferred for the carrageenophyte-attached microbiome. Significant differences between the bays were detected in the concentration of most inorganic nutrients. More eutrophic conditions and presumptive wastewater pollution in Cam Ranh (CR) bay were primarily indicated by the dominance of Rubripirellula, Leptobacterium, Hypnocyclicus and Porphyrobacter and their correlations with phosphate. In terms of bacterioplankton, the influence of intensive aquaculture in CR bay was suggested by the dominance of the NS5 and NS4 marine groups, the SUP05 cluster, Flavobacteriaceae unclassified and SAR 11 clade III as well as their strong correlations with ammonium and phosphate. The link between silicate and other inorganic nutrients suggests freshwater input in CR bay. Arenicellaceae unclassified and Formosa were also potential indicators of eutrophication. Operational taxonomic units (OTUs) of Marinagarivorans, Cobetia, Vibrio, Alteromonas and Pseudoalteromonas were typical of the carrageenophytes showing ice-ice disease symptoms. Vibrio and Alteromonas were also common among healthy macroalgae, and differences at the OTU level suggested potential succession of species from the healthy to the diseased state. The probable beneficial roles of some bacteria, such as Ruegeria, Cutibacterium and unidentified members of the family Rhizobiaceae, were discussed. This study provides pioneering insights into the bacterial community composition of carrageenophytes and highlights their ecological value as strong indicators of the sources of organic matter, anthropogenic impacts and health status of marine systems.

The high losses in shrimp production due to mortality caused by Vibrio opportunistic pathogens still constitute a significant challenge in the shrimp industry. Synbiotic feed supplementation appears to be a promising control strategy to maintain healthy shrimp stock. In this study, the effects of synbiotic-containing prebiotic seaweeds Kappaphycus alvarezii and Spirulina sp. as well as probiotic Halomonas alkaliphila were evaluated on the survival, growth, and vibriosis of Litopenaeus vannamei during the post-larval stage. Five different feeds were tested: commercial feed, prebiotics K. alvarezii and Spirulina sp.-supplemented feed, and synbiotic-supplemented feed using K. alvarezii, Spirulina sp. and probiotic H. alkaliphila with different concentrations of 108, 109, and 1010 CFU.kg−1. Following 14 days after the feeding test, the highest shrimp survival (91.46 ± 0.05%) was obtained in the treatment group fed with synbiotic-supplemented feed containing 0.375% K. alvarezii, 0.125% Spirulina sp., and H. alkaliphila at 109 CFU.kg−1 (p < 0.05). A 7-day challenge test against opportunistic bacteria Vibrio harveyii was then performed using three treatment groups: (1) synbiotic, containing 0.375% K. alvarezii, 0.125% Spirulina sp., and H. alkaliphila at 109 CFU.kg−1; (2) prebiotic, with 0.375% K. alvarezii, 0.125% Spirulina sp.; and (3) control, using commercial feed. The highest shrimp survival of (79.9 ± 0.05%) was found in the synbiotic treatment group, followed by the prebiotic and control treatment groups (p < 0.05). Overall results suggested that synbiotic-supplemented feed containing 0.375% K. alvarezii, 0.125% Spirulina sp., and H. alkaliphila at 109 CFU.kg−1 significantly improved shrimp survival even when challenged with V. harveyii. Thus, this synbiotic can be potentially applied as an alternative biocontrol strategy against vibriosis in intensive shrimp post-larval culture. [ABSTRACT FROM AUTHOR]

Farming of eucheumatoid seaweeds is a widespread, promising activity and an important livelihood option in many tropical coastal areas as for example in East Africa, Western Indian Ocean (WIO). Compared to other types of aquaculture, seaweed farming has generally low impact on the environment. Nonetheless, there are potential direct or indirect negative effects of seaweed farming, such as introduction of alien species and changes in local environmental conditions. Although farming has been practiced in this region during several decades, the knowledge concerning the actual environmental impacts from faming non-native eucheumatoid haplotypes and consequently how to manage farming activities to mitigate those is highly limited. In this review, we provide a summary of the current scientific knowledge of potential direct and indirect negative environmental effects linked to eucheumatoid seaweed farming such as alterations of benthic macrophyte habitats and loss of native biodiversity. Furthermore, we highlight knowledge gaps that are of importance to address in the near future, e.g., large-scale ecosystem effects and farms as potential vectors of pathogens. We also provide a number of feasible management recommendations to be implemented for a continued development of environmentally sustainable seaweed farming practices in the WIO region, which includes spatial planning of farms to avoid sensitive areas and farming of native haplotypes of eucheumatoids instead of introduced specimens. [ABSTRACT FROM AUTHOR]

Indonesia is the world largest producer of the red seaweeds Kappaphycus and Eucheuma; however, this country is facing significant challenges such as disease outbreaks, epiphyte infestations and a loss in seedling quality. Biosecurity practices have been widely adopted in other aquaculture sectors and when enforced can help to limit the introduction and spread of diseases and pests. To assess current capacity for biosecurity in seaweed aquaculture in Indonesia, a systematic analysis of policy frameworks including legislation, regulatory tools, and national standards was conducted. Biosecurity themes and risks were used to evaluate current national biosecurity content. The results identified major challenges faced by the industry in order to implement biosecurity policies in practice. Barriers to implementation included unspecific reference to the seaweed aquaculture sector, limited variety of approaches to biosecurity, limited use of up-to-date scientific evidence, insufficient guidance for the use of precaution and insufficient inclusion of specific biosecurity hazards. In general, although national regulations are currently under revision, current policies indicate a lack of clarity where biosecurity is included. Six recommendations are suggested to incorporate proactive biosecurity actions into current frameworks, with the aim of improving the health and sustainability of the seaweed aquaculture sector in Indonesia. [ABSTRACT FROM AUTHOR]

A global shortfall in protein supply from capture fisheries has motivated the Malaysian government to revise its aquaculture strategy, focusing on three commodities: seaweed, fish and marine shrimp. However, the performance of the Malaysian aquaculture sector, particularly seaweed production, is poorly documented. This is the first empirical study to undertake a value chain analysis (VCA) of the Malaysian seaweed sector using stakeholder perceptions and secondary data that encompass members of seaweed farming cooperatives (the Semporna Area Farmers' Association and the governments' flagship Seaweed Cluster Project). Fieldwork was conducted between April and June 2015 among seaweed stakeholders involved in the value chain using a mixed methods approach—in-depth interviews with key informants, focus group discussions, household surveys, personal observation and secondary data. Qualitative and quantitative data were collected from both upstream (seaweed farming, marketing structure and the Malaysian Good Aquaculture Practices [MyGAP] certification programme) and downstream (seaweed processing) activities involving farmers, intermediaries/middlemen (buyers), processors and officials. Kappaphycus spp. was sold in two forms: (1) dried seaweed to be used as raw materials in carrageenan processing (approximately 90% of total harvest) and (2) fresh seaweed to be used as a source of seedlings (approximately 10% of total harvest). The value chain ended with the carrageenan form, which is exported to international markets. The price of dried seaweed varied according to a combination of seaweed quality, the strength of farmer's relationships with intermediaries and processors and in response to demand from the carrageenan industry. The prices obtained by Malaysian farmers for dried seaweed and carrageenan remained low, US$ 0.60 and US$ 4.43 per kg, respectively, despite efforts by the government to enhance the value chain by imposing seaweed standards (via MyGAP) for farm management, dried seaweed and semi-refined carrageenan. The VCA was a useful tool to identify and map the market, with the results providing a better understanding of the seaweed sector, which could be helpful in supporting further aquaculture development in Malaysia. [ABSTRACT FROM AUTHOR]

A detailed understanding of physiological and reproductive processes in seaweeds has repeatedly proven to be an essential pre-requisite in the successful development of a sustainable industry. The prime example of this was the classical discovery of the "conchocelis"-phase of Pyropia (Porphyra) by Kathleen Mary Drew-Baker in 1949. Such elegant research proved to be pivotal to the development of a globally important "nori" industry which transitioned from the simple provision of the enhanced surface area of the substrata for spore settlement to the sophisticated, mechanized and computerized operations in modern hatcheries supplied by seedling banks of selected species and their cultivars. All of the pre-requisite knowledge was acquired through intensive applied research. However, not all solutions need to be high-tech; problems caused by epiphytes and contaminants have been achieved by exposing Pyropia nets periodically and was found to be effective. This protocol was achieved based on fundamental observations by farmers which were then complemented and refined by laboratory trials. Techniques must be adapted for site-specific differences, as abiotic factors such as water current and movement, surface seawater temperature, light regime and photoperiod, nutrients dispersion and water quality are interrelated, either positively or negatively, influencing seaweed productivity and the end-use of the biomass. Unfortunately, positive techniques that have been shown in vitro/silica can prove to be impractical once attempted at large-scale cultivation and/or the return on investment is not justified by the commercial value of the resultant seaweed biomass. This chapter presents a summary of how the judicious application of knowledge based on the eco-physiological processes of common seaweed species from tropical and cold-waters can assist the future development and scale-up of the global seaweed industry. [ABSTRACT FROM AUTHOR]

A preliminary survey of the economic seaweed exploitation in Madagascar was published in 1998. The present study is an update of the situation after the large scale development of Eucheumatoid cultivation in this country. It represents a floristic survey and it includes more seaweed species than previously described. The economic impact of this new and promising source of income on the local population is also discussed. [ABSTRACT FROM AUTHOR]

Kappaphycus alvarezii is a species of red algae, and one of the most important carrageenan sources for food, cosmetic, and pharmaceutical industries. It is commercially cultivated in the eastern part of Malaysia. Although K. alvarezii is rich in nutrients, it is limited in its integration into Malaysian food products. Therefore, the present work was conducted to investigate the quality characteristics, sensorial attributes, and antioxidant activity of K. alvarezii in Malaysian food products. Seaweed puree (SP) from K. alvarezii at 10%, 20% and 30% concentrations were prepared in the formulations of fish sausages, flat rice noodles and yellow alkaline noodles. Proximate analysis, physicochemical analysis, microbial count, total phenolic content (TPC), sensory evaluation, and consumer acceptance survey of the formulated food were conducted. The incorporation of K. alvarezii significantly increased the fibre, moisture, and ash content in formulated foods. In addition, the TPC content of K. alvarezii food also significantly increased up to 42 mg GAE/100 g. The presence of SP in food at higher concentration decreased the microbial counts. Sensory analysis confirmed that only fish sausages added with SP was overall acceptable as compared to control. Based on customer survey, functional foods that are "research proven" were the most preferred. In conclusion, K. alvarezii has the potential to be incorporated in Malaysian food products and developed as functional food. [ABSTRACT FROM AUTHOR]

: Kappaphycus is a commercially important edible red alga widely cultivated for carrageenan production. Here, we aimed to investigate the anti-obesity mechanism of Kappaphycus alvarezii by comparing the effects of whole seaweed (T), extracted native κ-carrageenan (CGN), and the leftover fraction sans-carrageenan (SCGN) supplementations (5%, w/w) on diet-induced obese C57BL/6J mice. A high-fat diet induced both a raised body fat percentage and serum cholesterol level, increased adipocytes size, abnormal levels of adipocytokines, and promoted gut dysbiosis. Our results showed that, overall, both CGN and SCGN were more effective in reversing obesity and related metabolic syndromes to normal levels than T. Furthermore, these findings suggested that CGN- and SCGN-modulated gut dysbiosis induced by a high-fat diet, which may play an influencing role in adiponectin dysregulation. Our data also showed some evidence that CGN and SCGN have distinct effects on selected genes involved in lipid metabolism. In conclusion, both κ-carrageenan and SCGN have novel anti-obesity potential with possible different mechanisms of action [ABSTRACT FROM AUTHOR]