Search Results (36)

Massive pelagic Sargassum influxes along Caribbean coasts have created an urgent need for valorization routes for this biomass. Here, sodium alginate was extracted from Sargassum fluitans collected at Chuburná Beach, Yucatán, Mexico, using a multistep extraction involving 0.2% formaldehyde pretreatment at 4 °C and brief heating at 65–70 °C, and subsequently used to prepare calcium-crosslinked alginate nanoparticles by ionotropic gelation. To our knowledge, this is the first direct synthesis of alginate nanoparticles from non-commercial alginate extracted from pelagic S. fluitans. An extraction yield of 18.7 ± 0.05% (mean ± SD, n = 3) was obtained, and UV–Vis, FTIR, and NMR analyses confirmed the characteristic structural features of alginate. ¹H NMR revealed an M-rich composition (F_M = 0.61, F_G = 0.39; M/G = 1.54) with short guluronate blocks (N_G>1 = 2.42), whereas ¹³C NMR corroborated the presence of both β-D-mannuronic and α-L-guluronic acid residues. SEM images showed predominantly spherical-to-subspherical nanoparticles with representative dry diameters of 233–269 nm, whereas DLS measurements at 0, 24, and 72 h revealed a dominant volume-based nanoscale population with main peaks at 12.75–15.31 nm and PDI values of 0.229–0.291, indicating reasonable short-term colloidal stability at room temperature. These results demonstrate that pelagic S. fluitans can serve as a viable feedstock for the production of structurally preserved alginate and calcium-crosslinked alginate nanoparticles. The study supports converting recurrent Sargassum biomass into higher-value polysaccharide-based materials and provides a basis for future application-specific evaluation of these nanomaterials. Full article

Coastal ecosystems of the tropical Atlantic and the Mexican Caribbean have experienced recurrent massive influxes of pelagic brown macroalgae, Sargassum natans and Sargassum fluitans, generating severe environmental, social, and economic impacts. While the accumulation of this biomass poses a significant waste management challenge, it also represents an underexploited renewable resource aligned with circular economy and sustainability principles. This study investigated the valorisation of Sargassum spp. through comprehensive physicochemical characterisation and multiple value-added applications. The biomass collected in Tulum, Quintana Roo, Mexico, was analysed to determine its chemical composition, including lignin, holocellulose, α-cellulose, ash, and moisture content, using standardised methods of the Technical Association of the Pulp and Paper Industry (TAPPI). For mechanical testing, methods from the American Society for Testing and Materials (ASTM) were used. The biomass was subjected to controlled pretreatment and thermochemical conversion processes. Evaluated valorisation pathways included: (1) taxonomic identification and physicochemical characterisation, (2) polymer composites, (3) reinforcement in construction materials such as unfired clay bricks, and (4) biochar and activated carbon production for contaminant adsorption. The results demonstrated that Sargassum spp. biomass can be transformed from an environmental nuisance into a multifunctional, high-value biomaterial, providing scalable solutions that mitigate waste disposal challenges and contribute to climate and resource sustainability. Full article

Massive strandings of holopelagic Sargassum cause major ecological and economic problems, but its conversion into bioproducts offers a sustainable alternative. This study assessed the potential of holopelagic Sargassum (S. fluitans and S. natans) collected in the Caribbean as ecofriendly insecticides against the whitefly Bemisia tabaci, a major pest of tomato crops. Extracts were produced using green methods: ultrasound-assisted extraction (UAE) and ultrasound-assisted enzymatic hydrolysis (UAEH) with enzymes cocktails. Biochemical analyses revealed high mineral and polysaccharide contents, varying with the extraction technique. Extracts were tested at 1–6% (w/v) using clip-cage (adults) and leaf-dip (eggs) methods. All extracts reduced adult survival, with UAE and UAEH-P/C extracts achieving over 50% mortality at ≥4% concentration after 48 h (LD₅₀: 3.9–4.5%). Egg mortality was significant only with UAE and UAEH-P extracts at 6% (LD₅₀: 1.9–2.8%). These results suggest insecticidal activity through both ingestion and cuticle/embryo disruption. Although enzymatic extraction did not markedly enhance biochemical yields, extracts showed, for the first time, promising biocidal and ovicidal properties. This research highlights holopelagic Sargassum as a renewable source of natural insecticidal compounds, supporting sustainable management of both invasive algal biomass and agricultural pests. Full article

The massive arrival of pelagic sargassum on the Gulf of Mexico coast has become an environmental and socioeconomic challenge, generating high management costs and affecting tourism, fisheries, and coastal ecosystems. In this context, its valorization through anaerobic digestion represents a sustainable alternative for renewable energy production. This study assessed its valorization through anaerobic digestion as a renewable energy route. Pelagic sargassum (Sargassum natans/Sargassum fluitans) was collected, mechanically pretreated, and digested in batch mode using ruminal fluid as inoculum. Two inoculum:substrate ratios (2:1 and 3:1, v/v) were operated for 7 days, and daily cumulative biogas production was recorded. The 3:1 ratio reached 10.6 mL of cumulative biogas, approximately twice the 5.0 mL obtained at 2:1, and its production curve did not plateau by day 7, suggesting ongoing activity. Elemental analysis of the sargassum showed a low C/N ratio (6.9:1) and high moisture (~95%), both of which constrain performance. Boyle’s model was used to estimate theoretical CH₄ and CO₂ yields and as expected, largely overpredicted the experimental volumes because it assumes ideal conversion. These results indicate that ruminal fluid enhances early-stage biogas formation but also highlight process limitations associated with biomass quality and short retention time. Future work should include extended digestion, co-digestion strategies to adjust the C/N ratio, and full monitoring of pH, soluble COD, VFAs, and volatile solids consumption. Full article

The unprecedented influx of pelagic Sargassum represents both a serious ecological concern and a potential opportunity regarding biopolymer production. Assessing the quality, preservation status, and processing potential of these species is crucial to transforming this environmental challenge into a sustainable benefit for industrial valorization. In the present work, we investigated the alginate yields (21.2 ± 0.57% and 18.1 ± 0.11% dw) and the structural characteristics of sodium alginates extracted from Sargassum natans and Sargassum fluitans encountered drifting along Moroccan coasts, respectively. The FTIR analysis indicated that the extracted alginates from both species exhibited similar spectral profile of the commercial alginate obtained from Sigma-Aldrich. The ¹H NMR spectra of the extracted alginates displayed characteristic signals for monads M and G and diads MM, GG, and MG/GM, consistent with M/G ratios above 1, with fairly abundant heteropolymeric fractions (F_GM/F_MG) accounting for more than 52% of the polymer diads. Intrinsic and molecular weight analyses revealed differences between S. natans ([η] = 1.39 dL/g; Mw = 0.65 × 10⁻⁵ g/mol) and S. fluitans ([η] = 0.80 dL/g; Mw = 0.37 × 10⁻⁵ g/mol). Both values are comparable to commercial alginate but remarkably lower in viscosity. Consequently, alginates from these species are foreseen to form elastic, flexible, and softer gels, making them suitable for applications such as drug delivery, cancer therapy, bioactive encapsulation, controlled nutrient release, and environmental remediation. Full article

Macroalgae are valuable natural sources for bioprospection and the development of raw materials applicable to the nutrition, health, and agriculture industries. To build a basis for the sustainable use of marine organisms from the Colombian Caribbean, a preliminary study was conducted focusing on known functional compounds in two genera of macroalgae, including the species Acanthophora spicifera (Rhodophyta), Sargassum ramifolium, and Sargassum fluitans (Ochrophyta). This study included the extraction and identification of polysaccharides using ultrafiltration, nuclear magnetic resonance (¹H-NMR), Fourier-transform infrared spectroscopy (FT-IR), and size exclusion chromatography (SEC); fatty acids by gas chromatographic (GC) profiling; and phenolic composition and antioxidant activity by complementary semi-quantitative methods (ABTS, DPPH, FRAP, and ORAC assays). Carrageenan-type polysaccharides were detected in A. spicifera, while alginate and fucoidan types were found in S. ramifolium and S. fluitans; palmitic acid was the predominant fatty acid in A. spicifera and S. ramifolium, but it was not detected in S. fluitans. S. ramifolium showed the highest ABTS, DPPH, and ORAC activities and phenolic compounds, while S. fluitans exhibited the highest FRAP activity. This study contributes to the chemical knowledge on Colombian macroalgae to establish potential applications in various fields, including biomedicine, cosmetics, functional foods, and nutraceutical ingredients. Full article

This study presents the results obtained from extracting and quantifying cosmetically valuable metabolites such as phenolic compounds and mycosporine-like amino acids (MAAs) from 12 samples of marine macroalgae collected in the Colombian Caribbean Sea. Natural deep eutectic solvents (NADESs) were prepared, physicochemically tested (viscosity, surface tension, pH, and conductivity), and then compared with water as the reference solvent to quantify phenolic compounds using the Folin–Ciocalteau test. With a simple extraction assay with water and ultrasound followed by ultraviolet spectral scanning the presence of MAAs was easily determined in several of the analysed samples, and then they were identified by HPLC-DAD. Hydrochloric acid solution at 5% extracted a higher content of phenolic compounds than NADES and water. The NADES that showed the highest phenolic compound extraction yield was a mixture of betaine, glucose, and water with 1:1:5 molar ratio. Sargassum cf. ramifolium and Sargassum fluitans showed the highest contents of phenolic compounds extracted with NADES, with 29.2 and 21.9 mg GAE/g DW, respectively. The results show that NADESs are an interesting alternative for the more efficient extraction of cosmetically valuable compounds such as phenolic compounds and mycosporine-type amino acids from marine macroalgae. Full article

Since 2011, pelagic sargassum blooms (S. fluitans and S. natans) have impacted coastal communities, aquaculture, tourism, and biodiversity across the Tropical Atlantic region. Whilst the initial event is generally attributed to an anomalous North Atlantic Oscillation (2009–2010), the drivers of sargassum movement and proliferation remain unclear. This research gap is particularly evident in West Africa, where annual and seasonal sargassum variability is under-researched, and a lack of consensus exists on seasonal and annual trends. This paper addresses these gaps by (1) providing a first attempt at characterising the seasonal and annual trends of sargassum biomass in the Eastern Tropical Atlantic, through using satellite imagery to create a time-series for 2011–2022; and (2) exploring the hypothetical drivers of movement and proliferation of sargassum for this area, through assessing its co-variation with potential drivers including atmospheric, oceanic, and policy, establishing a historical timeline of events. The time-series analysis reveals an annual biomass peak in September and a second peak between March and May. The exploration of potential drivers reveals that alongside sea surface temperature there are multiple factors that could be influencing sargassum biomass, and that further research is necessary to clarify primary and secondary drivers. The results contribute to understanding drivers, impacts, and predictions of sargassum blooms in the Eastern Tropical Atlantic. We anticipate that our findings will enable sargassum-affected areas to better anticipate the size and timing of sargassum events in West Africa and offer researchers a new perspective on possible drivers of proliferation within the wider Tropical Atlantic region. Full article

Since 2011, countries across the tropical Atlantic have experienced severe influxes of the seaweed species Sargassum natans and Sargassum fluitans (henceforth, “sargassum”), with nearshore and onshore ecological, economic and social impacts locally and regionally. Not all affected countries have had the same response to this emergent environmental challenge. Here, we explore the first ten years of policies produced in response to sargassum influx risk across islands in the Wider Caribbean Region, considering the variation in form, content and aim of sargassum adaptation policies. This assessment of the variation in Caribbean adaptation policies allows lessons to be identified for rapid adaptation to emergent environmental challenges. We find that several countries have no national policy for sargassum adaptation, and many subnational island jurisdictions have no island-specific policies. Whilst there is increasing anecdotal evidence of private and local adaptations taking place to address sargassum influx events, there remains significant scope for government leadership and resource support in adapting to this emergent threat. The lesson is that private adaptations to emergent threats may be quicker to develop and execute than policy adaptation, but longer-term, larger-scale adaptations depend on evidence-based, widely supported government policies with clear avenues of funding. Full article

In Caribbean islands, the washing ashore of tons of pelagic Sargassum spp., consisting of two species Sargassum fluitans and Sargassum natans, has been regularly occurring since 2011. As green lubrication is a growing trend in the tribology industry, biochar is a promising alternative. Sargassum biochars, produced from Sargassum pelagic algae, are therefore being studied as solid lubricants. This study aims to explore their potential applications. Biochars from brown algae were pyrolyzed at 400 °C and then annealed at different temperatures (from 600 °C to 1500 °C). The Raman spectra collected on the different biochars showed that there was a structural organization of the biochars as the temperature increased. The tribologic properties of the biochars were studied and compared to a solid lubricant reference (exfoliated graphite). Raman spectroscopy analysis revealed a progressive structural reorganization with increasing temperature, leading to a 58% reduction in the coefficient of friction. The morphology and the structure of the tribofilm are investigated by profilometry, scanning electron microscopy, and Raman microspectrometry. Overall, these results can be considered as a first step for utilizing the biochar derived from brown algae Sargassum sp. as an additive in the lubricant industry, for the purpose of emission reduction. Full article

This study deals with the efficacy of extracts of Sargassum natans and Sargassum fluitans, an invasive brown algae present in Guadeloupe, as novel and environmentally friendly corrosion inhibitors for iron in 1 mol L⁻¹ hydrochloric acid solutions. Six different Sargassum extracts (SE) were obtained using Soxhlet extraction with ethyl acetate, acetone, and ethanol, respectively, as solvents; cold successive maceration with chloroform and methanol, respectively; and microwave-assisted extraction with water. Subsequent electrochemical analysis showed that extracts from ethanol and ethyl acetate exhibited remarkable inhibition efficiencies of, respectively, 72.6% and 70.2%, but the better one was the extract of the cold maceration from chloroform with an inhibition efficiency of 92.0%. These findings allow us to focus on the chloroform extract (SEd) in order to see the change happening during the corrosion process via SEM and EDX analyses. Also, NMR analysis was conducted to identify the main chemicals responsible for the anticorrosion effect. The successful demonstration of the corrosion inhibitor effectiveness of extracts of Sargassum natans and fluitans suggests a potentially valuable use for this invasive biomass. These encouraging results warrant further investigation to identify and elucidate the active inhibitors in these extracts to deepen our understanding of their mechanisms for corrosion prevention and potentially expand their utility as an environmentally conscious approach to corrosion control. Full article

The spread of sargassum on beaches in Africa, Brazil, Central America, and the Caribbean has increased to become a social, environmental, and economic problem. In recent years, the presence of biomass on the coasts of the Mexican Caribbean has been recorded as ≈2360 m³ Km⁻¹, reaching up to 200 m wide in the northern part of the coasts. Its removal from the coast and, later, the continent is one of the strategies implemented to mitigate its impact on land. Several studies have reported the seasonality of and geographic variation in sorbed metals in sargasso. However, it is unknown whether these metals can mobilize or remain in sargassum tissue once they reach accumulation sites. This study included seawater, sargassum tissue as a consortium, and S. natans and S. fluitans, as well as the leachate generated in the process of degradation per se and percolated by rain. Of the 10 metals evaluated (As, B, Fe, Zn, Mn, Cd, Al, Ni, Cu, and Pb for water, tissue, and leachate), only B is recurrent in water from the north of the Mexican Caribbean, in addition to traces of Al and Fe. Meanwhile, in tissue, the results coincide with those of previous studies, where As is recurrent, although its concentration varies with the mentioned variability. The leachate showed that four to eight metals of those present in the tissue were detected, including As, Fe, and Al, which represent a potential impact on coastal systems and infiltration into shallow water table areas. Full article

The self-assembled monolayers (SAMs) process is one of the techniques used for the production of ultra-thin layers. The present work is therefore devoted to the study of the inhibition of zinc corrosion in a marine environment rich in H₂S by SAMs based on Sargassum fluitans III. The protective effect of crude extracts of Sargassum fluitans on the surface of zinc using the SAMs process was evaluated by gravimetry and impedance on two different sites after three months of exposure. The formation of SAMs was characterized by FTIR, and the corrosion products formed on the surfaces were analyzed by XRD. The results obtained show that SAMs based on Sargassum fluitans III effectively inhibit zinc corrosion. Full article

The movement and biomass fluctuations of sargassum across the Tropical Atlantic have profound implications when influxes reach the Eastern Caribbean. These influxes have cross-cutting impacts across ecological, economic, and social systems. The objective of this work is to quantify sargassum biomass accumulation in the Eastern Caribbean, accounting for the spatial variability in sea surface temperature and morphotype diversity. A parallel implementation of a climatological drifter-based model was used to simulate advection of sargassum across the model domain. After determining the trajectory of virtual sargassum particles, Monte Carlo simulations using 1000 realizations were run to quantify biomass accumulations along these tracks. For simulations with a single morphotype, the biomass accumulation as predicted by the model effectively reproduced the seasonal distributions of sargassum for the simulated period (May 2017 to August 2017). The model closely approximated an observed increase during the period from May to July 2017, followed by a subsequent decline in sargassum abundance. A major factor that led to the discrepancy between the simulated and observed biomass accumulation is the occlusion of the optical satellite signal from cloud cover, which led to underestimates of sargassum abundance. The mean maximum growth rate required to reproduce the observed sargassum biomass was 0.05 day⁻¹, which is consistent with other published experimental and computational studies that have reported similar growth rates for sargassum populations under comparable environmental conditions. An innovative aspect of this study was the investigation of the biomass dynamics of the three dominant morphotypes found in the study area. The results from these simulations show that the accumulation of the fastest growing morphotype, Sargassum fluitans var. fluitans, closely approximates the profiles of the overall prediction with a single morphotype. Full article

Since 2011, massive new strandings of holopelagic Sargassum have been reported on the coasts of the Caribbean, northern Brazil, Guiana, and West Africa, causing severe economic and ecological damage. Three common morphotypes (S. fluitans III, S. natans I, and S. natans VIII) were identified as responsible for these catastrophic events, with dominance shifts between them over time. However, the taxonomic status of these holopelagic Sargassum morphotypes remains unclear. Using an integrative taxonomy framework, combining a morphological study and molecular analyses, this study aimed to clarify their taxonomic status. Morphological analyses of 54 characters revealed no intermediate form between the three morphotypes, with the overall shape, nature of the axis, and size and shape of blades and vesicles being the most discriminating. An analysis of mitochondrial (IGS, cox2, cox3, mt16S rRNA, and nad6) and plastid (rbcL) markers confirmed the genetic divergence among the three morphotypes, with a lower level of divergence between the two S. natans morphotypes. Without additional molecular characterization, these morphotypes cannot be classified as three distinct species. However, due to their distinct morphological characteristics and sympatry within drifting aggregations, a revision of holopelagic species names is proposed, with Sargassum fluitans var. fluitans (for S. fluitans III), Sargassum natans var. natans (for S. natans I), and S. natans var. wingei (for S. natans VIII). This revision provides necessary clarity on the species involved in inundations of the tropical Atlantic. Full article