Showing papers on "Kappaphycus alvarezii published in 2023"

Scientific basis for the use of minimally processed homogenates of Kappaphycus alvarezii (red) and Sargassum wightii (brown) seaweeds as crop biostimulants

Abstract: Seaweed extracts act as biostimulants that boost crop- productivity, −quality and ameliorate stress. The precise constituents and mechanism behind the positive responses have still remained elusive and speculative. In-depth investigation was contemplated to reveal the metabolites that become constituent of extracts after seaweed processing and appraise whether they are present in physiologically relevant concentration at a given foliar application level. The minimally processed homogenate(s) (MPHs) of Kappaphycus alvarezii (KA) and Sargassum wightii (SW) were biochemically characterized. In two different experiments, six different formulations prepared using one or both of MPHs in proportions ranging from 0 to 100 % were assayed on tomato at three dilution levels of 0 %, 0.8 %, and 1.6 %, under well-watered and soil-moisture deficit conditions. The two MPHs differed between them with respect to composition and content. The tomato yield increased over control at 0.8 % application level under both water regimes, but also increased at higher concentrations under duress. The formulations made using only one of the two seaweed MPHs (KA:SW 0:100 and 100:0) recorded 20–31 % higher yields over control, although combined formulations using at least 60 % of either of the MPHs also produced higher yield. Both the MPHs contained gallic acid, catechin hydrate, myo-inositol, mannitol, glycine, leucine, putrescine, tyramine, IAA, canavanine, and many other reported bioactive compounds having defined roles and mode of action. At the application level of 0.8 %, many of these compounds were deduced to be present in physiologically relevant concentrations. This was inferred based on the literature cited concentrations of same compounds that elicited beneficial plant response upon exogenous application in pure form. It is implied that multiple bioactive compounds in seaweed extracts act in tandem and improve plant performance in totality, despite possible synergistic or antagonistic interactions among them. The findings prescribe a scientific basis for formulating other seaweed biostimulants and determining their optimal application doses.

Application of brown seaweed-derived agro biostimulant to the commercial farming of the red seaweed Kappaphycus alvarezii in India: Growth enhancement and production of quality raw material

Abstract: Currently global seaweed industries are facing issue with availability of raw material for processing of carrageenan due to low growth of current planting material. Use of biostimulants in seaweed cultivation is recently paid more attention due to their proven biostimulatory effect, of which, Ascophyllum marine plant extract powder (AMPEP) is a well proven biostimulant to improve the growth and quality of Kappaphycus alvarezii biomass. Hence, 500 kg of AMPEP was purchased and studied its impact on the commercial farming of K. alvarezii from April 2018 to January 2022 in India. Vegetative propagule of K. alvarezii were dipped in an AMPEP with concentration range of: 0.025, 0.05, 0.10, 0.15, 0.20 and 0.25 % for 30, 60, 90 and 120 min. Before out-planting on rafts in shallow coastal water and found that K. alvarezii responded well to a 0.1 % solution with dipping time of 60 min. The percentage of average daily growth rate (ADGR%) of AMPEP-treated plant in a 45 d grow out period was 3.50 ± 0.50 % vs a control of 1.75 ± 0.25 % for the summer and pre-monsoon months (p < 0.05) but no statistically significant differences between the treated and control plants were found during the rainy and winter seasons. Treated plants were found with low incidence of epiphytes, and disease as compared to control plants. The general appearance and health of treated Kappaphycus was good with significant differences in the yield and quality of semi-refined carrageenan (SRC) and dry weed quality (p < 0.05). The cost of AMPEP for producing of additional 1 kg of dry Kappaphycus was 0.066USD. Results of the present study is very encouraging and AMPEP can be used for the production of K. alvarezii biomass for industrial and biorefinery processing as it has been witnessed that there was 16.66 % increase in biomass production in 2021in India.

Effects of Salt Reduction and the Inclusion of Seaweed (Kappaphycus alvarezii) on the Physicochemical Properties of Chicken Patties

Abstract: This study investigates the effect of salt reduction through the inclusion of seaweed (Kappaphycus alvarezii) on the physicochemical and sensory qualities of chicken patties. A control sample (1.5% salt and without seaweed) and four chicken patty formulations were used with two levels of salt (1% and 1.5%) and two levels of seaweed (2% and 4%). Adding seaweed improves water holding capacity and minimized cooking loss in reduced-salt patties. In addition, adding seaweed decreases the shrinkage of the diameter and thickness of chicken patties (p > 0.05). However, adding seaweed made the patties darker, as shown by lower L* values (p > 0.05). Additionally, the incorporation of seaweed significantly increased (p < 0.05) the hardness, chewiness, cohesiveness, and elasticity of patties. Reduced-salt chicken patties with the addition of 2–4% of seaweed showed lower extracted water than 1.5% salt chicken patties with seaweed (p < 0.05), indicating a higher water holding capacity. The sensory evaluation showed that the chicken patty with 1.5% salt and 4% seaweed had the highest overall acceptability. However, the overall acceptability of the chicken patties with 1% salt and 4% seaweed was significantly higher (p < 0.05) than the control. In conclusion, the addition of Kappaphycus alvarezii to reduced salt patties improved textural properties with acceptable taste profiles.

Prevalence of Ice-Ice Disease in Kappaphycus spp. and Eucheuma denticulatum Farms in Sibutu, Tawi-Tawi, Philippines

Abstract: Kappaphycus spp. and Eucheuma denticulatum are commercially farmed in the world, notably in tropical countries such as Indonesia, Philippines, and Malaysia. Diseases and pests, particularly ice-ice disease, are the major hurdles in the sustainability of eucheumatoid seaweed culture. In this study, ice-ice disease prevalence in Kappaphycus and Eucheuma farms in Sibutu, Tawi-Tawi, Philippines, was assessed and compared according to species, farm depth, and time. Results revealed that in deep water farms, ice-ice disease prevalence was significantly lower in K. striatus (4.29±0.97%) than in K. alvarezii (10.53±2.64%) in July. In shallow water farms, E. denticulatum had the highest ice-ice prevalence (21.97±1.73%) significantly among the assessed seaweed species during August, and K. alvarezii had the lowest ice-ice disease occurrence (5.43±1.98%) significantly during September. In terms of depth water farm and time comparison, ice-ice disease prevalence (7.41±1.50% - 27.04±4.66%) in deep water (exceeding 2.47±0.16 m during low tide) did not differ significantly from that prevalence (11.35±1.69% - 12.91±1.93%) in shallow water farms (0.61±0.29 m during low tide) across time. This study suggests that ice-ice disease is still a prevalent and persistent problem in eucheumatoid seaweed farming.

Molecular docking approaches of biomolecules extracted from red seaweed Kappaphycus alvarezii against hemolysin protein of bioluminescence disease-causing bacteria Vibrio harveyi

Abstract: Abstract Molecular docking is suited a major approaches in structural biology and computer-assisted drug design against the protein of disease-causative agents. Marine resources are an unmatched reservoir of several natural biological products, which exhibit structural features that have not been found in a terrestrial organism. Herein, it was performed that molecular docking with various compounds/ ligand molecules identified by Gas Chromatography and Mass Spectrometry (GC-MS) analysis from the marine red seaweed Kappaphycus alvarezii extract against the hemolysin protein of bacterial disease-causing shrimp pathogen, Vibrio harveyi. Further, extracts of K. alvarezii were evaluated against V. harveyi infection during Penaeus monodon larviculture. This study correlates with various virulence factors including the hemolysin protein of V. harveyi . Among the compounds docked, an inhibitory effect was observed based on docking scores and found the highest binding affinity/inhibiting activity in Cyclotetracosane. Extract of K. alvarezii at 200 µg mL − 1 showed reductions in the V. harveyi counts that leads to a 29.70% reduction in the cumulative percentage mortality (CPM) caused by postlarvae and during larviculture. Using statistical analysis, significant differences ( p < 0.05) were observed in the growth and virulence factors of V. harveyi during shrimp larviculture trials. While considering these findings, it was determined that K. alvarezii extract can be replaced as an alternative bio-agents by protecting against V. harveyi infections and possibly other aquatic pathogenic bacteria in shrimp farming systems.

Fabrication and characterization of Kappaphycus alvarezii biomass based thin-film and its applications

Abstract: The present investigation is aimed at developing films using biomass of seaweed Kappaphycus alvarezii blended with natural additives both without glycerol (K) and with glycerol (KG) and to use the same in enhancement of shelf life of tomatoes. The natural additives used were Azadirachta indica oil (K1), A. indica leaves extract (K2), Citrus limon leaves extract (K3), A. indica gum (K4), Prunus amygdalus gum (K5), Moringa indica gum (K6) and the extract and oil of A. indica leaves (K7). The result showed that the moisture content ranged from 10.3±1.2 to 19.9±0.4 %, thickness 0.01 to 0.10 mm, and swelling index above 45 % in all the prepared films. The tensile strength and transparency were higher for K6, KG6, K and KG respectively. KG6 and K3 films showed maximum phenolic content, antioxidant and antimicrobial activity. The promising results of current investigation proved the suitability of the film in enhancing the shelf life of tomatoes to 14 days at room temperature.

Characterization of bioplastics developed from Kappaphycus alvarezii crosslinked with commercial sodium alginate

Abstract: Abstract Plastic pollution has become one of the most concerning problems globally due to excessive use of one-time use plastics. However, bioplastics could be the answer to help combat this problem as they are readily biodegradable. Development of bioplastics was done by mixing seaweed biomass into distilled water at specific ratio, using glycerol as plasticizer. Bioplastics were developed at the ratio of 100:0, 75:25, 50:50, 25:75, and 0:100 K. alvarezii to commercial sodium alginate ratio. Characterization was done based on their appearance, mechanical, thermal and permeability properties, and biodegradability. Resulted data for their appearance showed that when more K. alvarezii was in the mixture there were more colour differences in comparison to white background and the same trend for the opacity due to the natural colour of whole K. alvarezii . As for their mechanical properties, tensile strength of the bioplastics decreased from 100:0 ratio to 0:100 ratio at 7.91 ± 0.45 MPa (100:0), 6.78 ± 0.31 MPa (75:25), 5.20 ± 0.37 MPa (50:50), 4.13 ± 0.17 MPa (25:75) and 3.76 ± 0.14 MPa (0:100), respectively. Same goes for their elastic modulus at 20.93 ± 0.61 MPa (100:0), 16.47 ± 0.99 MPa (75:25), 11.42 ± 0.53 MPa (50:50), 8.78 ± 0.45 MPa (25:75) and 6.65 ± 0.32 MPa (0:100), respectively. This shows that the addition of alginate enhances the elasticity but decreases tensile strength. As a conclusion, developed seaweed-based bioplastics resulted different properties at different mixture ratio show potential to be incorporated into the market as they are a greener option to fight single-use plastic wrappings such as saran wrap, beverages and food additive packets.

Chemical composition and physicochemical properties of red seaweed (Kappaphycus alvarezii) and brown seaweed (Sargassum polycystum) from Sabah, Malaysia

Abstract: The proximate composition, amino acid composition and some physico-chemical properties of two type of seaweeds Kappaphycus alvarezii and Sargassum polycystum which widely cultivated in Sabah, Malaysia were investigated. S. polycystum showed the highest level of protein and crude fibre with 11.69% and 39.863% dry weight, respectively. Minor component was fat 0.12-0.13% in both seaweeds. As for the physicochemical properties of the seaweeds, their swelling capacity (SWC) ranged from 13.33 to 35.83 mL/g while water retention capacity (WRC), and oil retention capacity (ORC) ranged from 8.18 to10.59 g/g dry weight and 2.68 to 3.32 g/g dry weight, respectively. SWC and ORC of K. alvarezzi was higher than S. polycystum (p<0.05). Both seaweeds contained high amounts of minerals and balanced amino acid profiles. This study suggested that K. alvarezzi has high nutritional value which could be potentially used as ingredients in human food application.

The Potential and Development of Seaweed Cultivation in Lombok: A Review

Abstract: The potential area of Lombok seaweed cultivation is 5490 Ha. The area utilized is 2039.63 Ha. The purpose of this paper is to review the diversity, cultivation activities, production and potential of seaweed to be developed, specifically focusing on aspects of cultivation and production on the island of Lombok, Indonesia. Macroalgae that have been cultivated on Lombok are Kappaphycus alvarezii morphotype brown and green and Gracilaria verucosa. The decline and the amount of uncertainty in production were caused by several problems in seaweed cultivation, weather changes, limited capital for production and decreased quality of seaweed seeds. The species that have the potential to be developed are Sargassum aquifolium, Caulerpa sp., Ulva sp., Eucheuma spinosum, and Gelidium sp. Development Locations are located throughout the waters in the shape of a bay and are by the stipulated water utilization spatial plan. Developing seaweed aqua tourism and institutional arrangements related to seaweed production is necessary.

Stabilitas Dimensi dan Setting Time Bahan Cetak Anatomis Kedokteran Gigi Dari Ekstrak Natrium Alginat Rumput Laut Merah (Kappaphycus alvarezii) Dari Desa Agel, Kecamatan Jangkar, Situbondo

Abstract: Alginate impression material is important in dentistry. In its clinical application, setting time is still considered too fast, and the alginate impression material must have dimensional stability in accordance with ANSI / ADA standard specification no.18. Alginate impression material has a main component, namely sodium alginate which is produced from the seaweed extraction process. In Indonesia, there are several types of seaweed, one of which is the Kappaphycus alvarezii (K. alvarezii). The seaweed from the village of Agel Situbondo has the potential to be a source of sodium alginate and has antibacterial and antioxidant effects. The aim of this study to analyze the dimensional stability and setting time of the alginate printing material with sodium alginate extract of kappaphycus alvarezii seaweed. The study was conducted using laboratory experimental methods with post-test only control group design, there were 2 groups, namely the commercial alginate printing material control group, and the alginate printing material treatment group with sodium alginate extract from the acid method, then the FTIR test was carried out. Then the two groups were tested for setting time and dimensional stability. The results of the FTIR test of red seaweed extract showed an absorption peak that was identical to that of sodium alginate. The results of the setting time test significantly took longer for the red seaweed alginate impression material than the control group, while the dimensional stability showed the same results. Conclusion: The results of the setting time test showed that the treatment group had a longer setting time than the control group and both groups had dimensional stability according to the standard. The results of the setting time test showed that the treatment group had a longer setting time than the control group and both groups already had dimensional stability in accordance with the standard.

A Review on the Potential Anti-inflammatory Properties of Kappaphycus alvarezii

Abstract: Inflammation is significant innate mechanism of immunity in our human system. It enables our body to respond to a variety of stimuli, including ischemic, traumatic, physical, chemical, and infectious impulses. A major contributor to global health challenges and a significant driver of rising health expenditures are inflammatory disorders. Naturally occurring substances as well as its chemical structural analogues with anti-inflammatory potential have been discovered in the recent years. Marine life forms have a myriad source of natural molecules that can invoke inflammation as a defense against pathophysiology of illness. Macro and microalgae have been determined to be an undiscovered resource with pro-and anti-inflammatory compounds. Natural substances found in marine species can be employed in novel interventions as treatment modalities as anti-diabetic, anti-inflammatory, anti-bacterial, anti-viral, and antioxidant capabilities. Among these substances, Kappaphycus alvarezii is one such marine red algae that can be employed therapeutically to possess biological effects that exhibit strong anti-inflammatory activity and fewer adverse effects. The expanding desire to research marine seaweeds such as Kappaphycus alvarezii and its phytochemicals has made it possible to find novel substances with the potential to be used in healthcare in the near future. This review envisages the anti-inflammatory properties of marine algae along with phytochemicals discovered in Kappaphycus alvarezii and its biological functionalities.

Kappaphycus alvarezii flours as an ingredient for seaweed‐enriched, rice‐based, snacks: raw algae pretreatment and physical properties of the dough and snacks.

Abstract: In this work, the addition of pretreated Kappaphycus alvarezii flour to a rice-based snack formulation was proposed as an alternative to producing algae-enriched snacks adding value to this seaweed and improving the quality of the snacks. Dried algae were submitted to multiple washing cycles to allow the reduction of the natural salt concentration of the algae. After, algae were dried and milled to obtain flour. The flour was added in different concentrations (0%, 2%, 5%, and 10%) in the model formulation of rice-based dough. Rice-K. alvarezii snacks were produced by baking at 220 °C. The proximate composition of the raw and pretreated algae was determined, as well as the colour, texture, and microstructure of dough and snacks. The pretreatment efficiently allowed for a reduction of 78% of the initial content of sodium and an 85% reduction of potassium. The concentration of 5% and 10% of algae addition presented higher values of hardness and consistency of the dough and lower adhesiveness. At higher concentrations, the seaweed flour acts as a processing aid during the preparation steps of the snacks but does not influence the hardness of the final snacks. The pretreated K. alvarezii flour is an alternative for increasing the quality of rice-based snacks while preserving the algae's potential health benefits.

Organic fragments of k-carrageenan, lipids and peptides plus K-rich inorganic fraction in Kappaphycus alvarezii biomass are responsible for growth stimulus in rice plant when applied both foliar and root pathway

Abstract: Kappaphycus alvarezii seaweeds regulate plant growth and development by modifying various metabolic functions. However, the substances responsible for the effects and relationship with the application pathway are poorly understood. This study aimed to structurally characterize biomass fractions and to evaluate the structure-bioativity relationship of different concentrations applied to the leaves and roots of rice plants (Oryza sativa L.). The aqueous extracts obtained from K. alvarezii were characterized by ATR-FTIR and 13C NMR CP/MAS, and their structures were compared by chemometrics. The composition was determined by CHN elemental analysis and atomic absorption. Bioactivity in plants was evaluated by foliar application (5 %, 10 %, 15 %, 20 % and 25 %) and root application (1 %, 2 %, 3 %, 5 % and 10 %), and the dry and fresh mass and root morphology were determined. The results show that the aqueous extract (KAlv-sapL) contains CAlkyl (26 %), CAlkyl-O,N (15 %), CAlkyl-O (23 %), CAlkyl-di-O (7 %), CAromatic-H,R (6 %), CAromatic-O,N (3 %), CCOOH-H,R (17 %) and CCO (3 %), belonging to fragments of k-carrageenan, lipids, and peptides; high amounts of K, P, Ca, Mg, Fe, Mn, Zn and Cu. KAlv-sapL applied via foliar treatment at 5 % and 10 % promoted increases in root and leaf dry mass by >30 % and 10 %, respectively, and 10 % of KAlv-sapL increased the area, diameter and number of roots by 11 %, 19 % and 40 %, respectively. Root application at 3 % (KAlv-sapL) stimulated the production of fresh and dry root mass by 60 % and 28 %, respectively, and when applied at 2 %, the root area, length, number and volume increased by 30 %, 50 %, 19 % and 31 %, respectively. In addition, the application at 2 % (KAlv-sapL) promoted intense mobilization and allocation of K+ in the leaves, increasing the uptake efficiency of this nutrient. The bioactivity of Kappaphycus seaweed occurs through joint action of carrageenan, lipids and peptides, and the inorganic fraction, rich in K+ and essential nutrients.

In vivo elicitation is efficient in increasing essential oil yield with high anti-inflammatory sesquiterpene content in Varronia curassavica Jacq.

Abstract: Essential oils in plants are produced in very low concentrations and elicitation stands out among the techniques used to increase their productivity. This work evaluated the potential elicitor of salicylic acid (SA) or seaweed extract (SE) on the biomass yield, physiological parameters and essential oil production in Varronia curassavica Jacq. plants. The elicitors were applied through foliar spray in four serial applications (21, 34, 53 and 70 d after transplanting the seedlings to the pots - DAT), in concentrations of 1 mM (SA) and 5 mL L-1 (SE). The control plants were sprayed with water. Biometric measurements of plant height and number of branches were performed after 2, 3 and 4 elicitor applications. Plants were harvested at 91 DAT and biometric, biochemical and phytochemical parameters were evaluated. Application of SA resulted in increases in number of leaves (11.68%) and foliar concentrations of chlorophylls (57.67%), anthocyanins (73.80%), carotenoids (42.58%), total soluble sugars (19.48%) and essential oil (18%). The plants treated with SE had no changes in leaf biomass or essential oil production. The SA treatment increased by twice the amount of α-humulene and (E)-caryophyllene present in the essential oil while for SE treatment there was an average increase of 78.6%. It was concluded that the elicitation of V. curassavica plants by SA foliar pulverization is an efficient strategy for promoting the higher productivity of leaves and essential oil. Foliar pulverization of SA or SE modifies essential oil quality, inducing increases in the compounds of greatest interest for the pharmaceutical industry.

Understanding the mode of action of AgroGain®, a biostimulant derived from the red seaweed Kappaphycus alvarezii in the stimulation of cotyledon expansion and growth of Cucumis sativa (cucumber)

Abstract: Seaweed-based biostimulants are sustainable agriculture inputs that are known to have a multitude of beneficial effects on plant growth and productivity. This study demonstrates that Agrogain® (Product code: LBS6), a Kappaphycus alvarezii-derived biostimulant induced the expansion of cucumber cotyledons. Seven days treatment of LBS6-supplementation showed a 29.2% increase in area of expanded cotyledons, as compared to the control. LBS6-treated cotyledons also showed higher amylase activity, suggesting starch to sucrose conversion was used efficiently as an energy source during expansion. To understand the mechanisms of LBS6-induced expansion, real time gene expression analysis was carried out. This revealed that LBS6-treated cotyledons differentially modulated the expression of genes involved in cell division, cell number, cell expansion and cell size. LBS6 treatment also differentially regulated the expression of those genes involved in auxin and cytokinin metabolism. Further, foliar application of LBS6 on cucumber plants being grown under hydroponic conditions showed improved plant growth as compared to the control. The total leaf area of LBS6-sprayed plants increased by 19.1%, as compared to control. LBS6-sprayed plants efficiently regulated photosynthetic quenching by reducing loss via non-photochemical and non-regulatory quenching. LBS6 applications also modulated changes in the steady-state photosynthetic parameters of the cucumber leaves. It was demonstrated that LBS6 treatment modulated the electron and proton transport related pathways which help plants to efficiently utilize the photosynthetic radiation for optimal growth. These results provide clear evidence that bioactive compounds present in LBS6 improved the growth of cucumber plants by regulating the physiological as well as developmental pathways.

Analysis of Antimicrobial Activity of Carrageenan Extracted from Kappaphycus Alvarezii

Abstract: The abuse of synthetic antibiotics is one of the leading causes of the emergence of antibiotic-resistant microorganisms that have become the primary health concern. To overcome this resistance and counteract all the side effects of synthetic drugs, attention was diverted towards natural resources for developing antimicrobial substances. This study tests the effect of carrageenan isolated from Kappaphycus alvarezii on pathogenic bacteria. Carrageenan is a natural bioactive compound extracted from red algae. Carrageenan was extracted from K. alvarezii using hot water extraction. The antimicrobial property of carrageenan was tested using the Minimum Inhibitory Concentration and the bacterial cell growth rate. Moreover, a commercial antibacterial hand wash and anti-acne toner were used as comparative agents. Firstly, a series of concentrations were used, from 25 µg/mL to 10 mg/mL. The results showed no antimicrobial activity of carrageenan extracted from K. alvarezii using ethanol toward the strains used in this study, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa and Staphylococcus aureus. However, the carrageenan extracted exhibited a growth-boosting effect over the microorganisms used. Thus, further studies can be carried out using different carrageenan extract methods for K. alvarezii to ensure that anti-microbial compounds from K. alvarezii can be extracted during the carrageenan extraction.

Estudio de la variabilidad en el tiempo y espacio de la actividad antioxidante y composición bioquímica de Kappaphycus alvarezii en diferentes densidades de siembra

Abstract: Kappaphycus alvarezii es una de las especies de algas más cultivadas en el mundo, debido a su alto contenido de compuestos bioactivos con reportes antioxidantes y bioestimulantes. El presente estudio evaluó el efecto de las densidades de plantación sobre la composición bioquímica y antioxidante de K. alvarezii cultivada en un sistema de línea larga durante las estaciones seca y húmeda, con el fin de proporcionar una base científica para una cosecha óptima. Se midieron el contenido de humedad, cenizas, grasa, fibra, auxinas, fenoles, flavonoides, DPPH y ABTS. Los datos se analizaron mediante pruebas t, Wilcoxon, Kruskal-Wallis y ANOVA unidireccional. Los resultados mostraron un mayor contenido de grasa (2,01 % P.s), fibra bruta (5,21% P.s), contenido total de fenoles (324,09 μg GAE/g P.s) y ABTS (9,32 μg GAE/g P.s) durante la estación seca. Con respecto a la densidad de plantación, se produjo un aumento significativo del contenido en cenizas, fenoles totales y ABTS con una densidad de 10 líneas.célula-1 al mismo tiempo. Los contenidos de flavonoides, DPPH y auxina mostraron una tendencia estacional opuesta, alcanzando los niveles máximos en la estación húmeda. Este estudio aporta nueva información sobre las condiciones ambientales que pueden provocar cambios en la actividad antioxidante y la composición bioquímica de esta especie con vistas al desarrollo de bioproductos para diferentes sectores industriales como el alimentario, el farmacéutico y el de los fertilizantes en Ecuador. Palabras claves: Alga roja; Fenoles; Flavonoides; Antioxidante; Composición bioquímica; Variación estacional; densidad de siembra.

Impacts of aquaculture nutrient sources: ammonium uptake of commercially important eucheumatoids depends on phosphate levels 1

Abstract: Abstract 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 fecal waste as nutrient streams can contribute to variations in nitrogen and phosphorus levels (e.g., primarily NH 4 + and PO 4 -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 PO 4 -3 levels on NH 4 + 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 NH 4 + , representing eutrophic conditions, and 0, 0.5, 1.0, 1.5, 3.0 or 5.0 µM PO 4 -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 PO 4 -3 levels were observed. For K. alvarezii , maximum NH 4 + uptake (17.8 ± 1.6 µmol gDW -1 h -1 ) was observed at 0.5 µM PO 4 -3 and the uptake rate declined at higher PO 4 -3 levels. For K. striatus , the NH 4 + uptake increases with increasing PO 4 -3 levels, with maximum N-uptake (6.35 ± 0.9 µmol gDW -1 h -1 ) observed at 5.0 µM PO 4 -3 . For E. denticulatum, maximum NH 4 + uptake (14.6 ± 1.4 µmol gDW -1 h -1 ) was observed at 1.0 µM PO 4 -3 . Our results suggest that, among the three eucheumatoid species, the NH 4 + uptake of K. striatus persist even at high levels of PO 4 -3 . However, our results also showed that K. striatus had the lowest range of NH 4 + uptake rates. These results should be taken into consideration when incorporating eucheumatoids in IMTA system where PO 4 -3 levels significantly vary in space and time.