Natural Bioactive Compounds from Macroalgae and Microalgae for the Treatment of Alzheimer's Disease: A Review.

Neuroinflammation, toxic protein aggregation, oxidative stress, and mitochondrial dysfunction are key pathways in neurodegenerative diseases like Alzheimer's disease (AD). Targeting these mechanisms with antioxidants, anti-inflammatory compounds, and inhibitors of Aß formation and aggregation is crucial for treatment. Marine algae are rich sources of bioactive compounds, including carbohydrates, phenolics, fatty acids, phycobiliproteins, carotenoids, fatty acids, and vitamins. In recent years, they have attracted interest from the pharmaceutical and nutraceutical industries due to their exceptional biological activities, which include anti-inflammation, antioxidant, anticancer, and anti-apoptosis properties. Multiple lines of evidence have unveiled the potential neuroprotective effects of these multifunctional algal compounds for application in treating and managing AD. This article will provide insight into the molecular mechanisms underlying the neuroprotective effects of bioactive compounds derived from algae based on in vitro and in vivo models of neuroinflammation and AD. We will also discuss their potential as disease-modifying and symptomatic treatment strategies for AD.

The potential climate benefits of seaweed farming in temperate waters.

Seaweed farming is widely promoted as an approach to mitigating climate change despite limited data on carbon removal pathways and uncertainty around benefits and risks at operational scales. We explored the feasibility of climate change mitigation from seaweed farming by constructing five scenarios spanning a range of industry development in coastal British Columbia, Canada, a temperate region identified as highly suitable for seaweed farming. Depending on growth rates and the fate of farmed seaweed, our scenarios sequestered or avoided between 0.20 and 8.2 Tg CO2e year-1, equivalent to 0.3% and 13% of annual greenhouse gas emissions in BC, respectively. Realisation of climate benefits required seaweed-based products to replace existing, more emissions-intensive products, as marine sequestration was relatively inefficient. Such products were also key to reducing the monetary cost of climate benefits, with product values exceeding production costs in only one of the scenarios we examined. However, model estimates have large uncertainties dominated by seaweed production and emissions avoided, making these key priorities for future research. Our results show that seaweed farming could make an economically feasible contribute to Canada's climate goals if markets for value-added seaweed based products are developed. Moreover, our model demonstrates the possibility for farmers, regulators, and researchers to accurately quantify the climate benefits of seaweed farming in their regional contexts.

Application of Artificial Neural Network and Genetic Algorithm Modeling for In Vitro Regeneration of Seaweed Seedling Production.

Marine macro-algae, commonly known as "seaweed," are used in everyday commodity products worldwide for food, feed, and biostimulant for plants and animals and continue to be one of the conspicuous components of world aquaculture production. However, the application of ANN in seaweeds remains limited. Here, we described how to perform ANN-based machine learning modeling and GA-based optimization to enhance seedling production for implications on commercial farming. The critical steps from seaweed seedling explant preparation, selection of independent variables for laboratory culture, formulating experimental design, executing ANN Modelling, and implementing optimization algorithm are described.

Microbacterium algihabitans sp. nov., Microbacterium phycohabitans sp. nov., and Microbacterium galbum sp. nov., isolated from dried beach seaweeds.

Three actinobacterial strains, KSW2-21T, KSW2-29T and KSW4-17T, were isolated from dried seaweeds collected around Gwakji Beach in Jeju, Republic of Korea. Their taxonomic positions were determined based on genomic, physiological and morphological characteristics. The isolates were Gram-positive, aerobic, non-motile, rod-shaped bacteria characterized by the following chemotaxonomic features: ornithine as the cell wall diamino acid, the N-glycolyl type of murein, MK-11 as the predominant menaquinone, polar lipids including diphosphatidylglycerol, phosphatidylglycerol, two unidentified glycolipids and four unidentified phospholipids, with anteiso-C15 : 0, iso-C16 : 0 and anteiso-C17 : 0 as the the major fatty acids. The 16S rRNA gene phylogeny showed that the novel strains formed three distinct sublines within the genus Microbacterium. Strain KSW4-17T formed a tight cluster with the type strain of Microbacterium hydrothermale, while strains KSW2-21T and KSW2-29T occupied distinct positions between the type strains of M. hydrothermale and Microbacterium testaceum. Strains KSW4-17T and KSW2-29T showed 99.9 % rRNA gene sequence similarity to M. hydrothermale CGMCC 1.12512T, while strain KSW2-21T revealed 99.4 % 16S rRNA gene sequence similarity to the type strains of M. hydrothermale and M. testaceum. The genome sizes and genomic G+C contents of the three isolates ranged from 3.44 to 3.74 Mbp and from 70.3 to 70.8 mol%, respectively. The phylogenomic tree based on 92 core gene sequences exhibited similar topologies to the 16S rRNA gene phylogeny. The comparison of overall genomic relatedness indices, such as average nucleotide indentity and digital DNA-DNA hybridization, supported that the isolates represent three new species of the genus Microbacterium. Based on the results obtained here, Microbacterium algihabitans sp. nov. (type strain, KSW2-21T=KACC 23322T=DSM 116381T), Microbacterium phycohabitans sp. nov. (type strain KSW2-29T=KACC 22350T=NBRC 115221T) and Microbacterium galbum sp. nov. (type strain, KSW4-17T=KACC 23323T=DSM 116383T) are proposed.

From Sea Water to Salt Crystals: An Onsite Investigation of Microplastics in a Conventional Sea Salt Farming System.

This study investigated microplastic (MP) contamination in conventional sea salt farming systems. Various crude sea salt samples (n = 22) that were traditionally produced were collected from salt farms and local vendors. Salt water (n = 15), macroalgae (n = 6), and clay of pond floors (n = 6) were collected from ponds subjected to different production (stabilization, evaporation, and concentration and crystallization concentration) processes. All samples were analyzed for MP abundance and characteristics. The potential sources of MP contamination in the salt were also investigated. The mean abundance of MPs in the salt water and clay of pond floor increased progressively throughout the production process and reached its highest level in the concentration and crystallization ponds (7400 MP particles/m3 in salt water and 19,336 MP particles/m2 in the clay of the pond floor). A maximum of 26,500 MP particles/kg of macroalgal material indicated the potential sink of MPs on the surface of the algae. Approximately 34-2377 MP particles/kg salt were found in the crude sea salt samples. However, the mean abundance (378 MP particles/kg of salt) indicated nonsignificant impacts of different harvesting processes on MP contamination. Most MP size distributions, shapes and polymer types in the salts were similar to those found in the salt water, macroalgae and clay of the pond floor. Approximately 99% of the MPs were fragments that were suspected to be decomposed from larger plastic debris and plastic machinery and tools used at the salt farm. Similar patterns of polymer distribution, in which PP > PE > PET > PS, were found for all samples studied.

Aquatic Antagonists: Seaweed Dermatitis (Lyngbya majuscula).

The cyanobacterium Lyngbya majuscula grows in marine and estuarine environments across the world and produces many biologically active compounds. Direct contact with L majuscula and its dermatoxins can cause seaweed dermatitis, which manifests as a papulovesicular eruption. As oceans warm, L majuscula will bloom more frequently; therefore, public awareness of L majuscula and seaweed dermatitis in oceanside communities can help promote precautions that can reduce the risk for exposure. This article describes the irritants that lead to dermatitis, clinical presentation, and prevention and management of seaweed dermatitis.

Dilute acid-assisted microbubbles-mediated ozonolysis of Eucheuma denticulatum phycocolloid for biobased L-lactic acid production.

Biobased L-lactic acid (L-LA) appeals to industries; however, existing technologies are plagued by limited productivity and high energy consumption. This study established an integrated process for producing macroalgae-based L-LA from Eucheuma denticulatum phycocolloid (EDP). Dilute acid-assisted microbubbles-mediated ozonolysis (DAMMO) was selected for the ozonolysis of EDP to optimize D-galactose recovery. Through single-factor optimization of DAMMO treatment, a maximum D-galactose recovery efficiency (59.10 %) was achieved using 0.15 M H2SO4 at 80 °C for 75 min. Fermentation with 3 % (w/v) mixed microbial cells (Bacillus coagulans ATCC 7050 and Lactobacillus acidophilus-14) and fermented residues achieved a 97.67 % L-LA yield. Additionally, this culture approach was further evaluated in repeated-batch fermentation and showed an average L-LA yield of 93.30 %, providing a feasible concept for macroalgae-based L-LA production.

Effects of seaweed fertilizer application on crops' yield and quality in field conditions in China-A meta-analysis.

Seaweed fertilizer, formulated primarily with seaweed extract as its main ingredient, has been extensively studied and found to significantly improve nutrient use efficiency, increase crop yield and quality, and enhance soil properties under field conditions. This growing body of evidence shows that seaweed fertilizer is a suitable option for sustainable agriculture in China. However, a comprehensive and quantitative analysis of the overall effects of seaweed fertilizer application in China is lacking. To address this gap, we conducted a meta-analysis of relevant studies on the effects of seaweed fertilizers under field conditions in China with MetaWin and SPSS software. Our analysis examined the effects of seaweed fertilizers on crop yield, quality, and growth under different preparation methods, application techniques, and regions. Our results showed that the application of seaweed fertilizer led to a significant average increase in crop yield of 15.17% compared with the control treatments. Root & tuber crops exhibited the most pronounced response, with a yield boost of 21.19%. Moreover, seaweed fertilizer application significantly improved crop quality, with elevations in the sugar-acid ratio (38.32%) vitamin C (18.07%), starch (19.65%), and protein (11.45%). In addition, plant growth parameters such as height, stem thickness, root weight, and leaf area showed significant enhancement with seaweed fertilizer use. The yield-increasing effect of seaweed fertilizers varied depending on their preparation and use method, climate, and soil of application location. Our study provides fundamental reference data for the efficient and scientific application of seaweed fertilizers in agricultural practices.

[Sargassum seaweed assaults the French West Indies]. / Algues sargasses à l'assaut des Antilles.

SARGASSUM SEAWEED AS SAULTS THE FRENCH WEST INDIES. Since 2011, Martinique and the islands of Guadeloupe have been affected by repeated groundings, culminating in an exceptional wave in 2018. While the sargassum ( Sargassum natans and S. fluitans ) involved in these phenomena are neither toxic nor urticating, indirect toxicity linked to the presence of microorganisms and heavy metals (arsenic, mercury, etc.) in sargassum clusters has been described. Similarly, after a 24 to 48 hours stay on the shore, sargassum algae enter a putrefaction cycle responsible to produce hydrogen sulfide (H2S) and ammonia (NH3). The acute toxicity of these gases is well known. However, very few data are available on the clinical effects of prolonged exposure to low doses of H2S and NH3. Our team has recently described the syndromic features of chronic exposure, supposing for deleterious effects on the cardiovascular, respiratory and neurological systems.

ALGUES SARGASSES À L'ASSAUT DES ANTILLES. Depuis 2011, la Martinique et les îles de la Guadeloupe sont touchées par des échouements à répétition d'algues sargasses qui ont culminé avec une vague exceptionnelle en 2018. Si les sargasses (Sargassum natans et S. fluitans) impliquées dans ces phénomènes ne sont ni toxiques ni urticantes, une toxicité indirecte liée à la présence de micro-organismes et de métaux lourds (arsenic, mercure…) dans les amas de sargasses est décrite. De même, après un séjour de vingt-quatre à quarante-huit heures sur le littoral, les algues sargasses entrent dans un cycle de putréfaction responsable de la production d'hydrogène sulfuré (H2S) et d'ammoniac (NH3). La toxicité aiguë de ces gaz est bien connue. Il existe en revanche très peu de données disponibles sur les effets cliniques d'une exposition prolongée à de faibles doses d'H2S ou NH3. Notre équipe a récemment décrit le tableau syndromique de l'exposition chronique et suppose des effets délétères sur le système cardiovasculaire, respiratoire et neurologique.

Molecular identification of Halomonas AZ07 and its multifunctional enzymatic activities to degrade Pyropia yezoensis under high-temperature condition.

BACKGROUND: Pyropia yezoensis a commercially important red seaweed species, is susceptible to various microorganisms infections, among which bacterial infections are the most prominent ones. Pyropia yezoensis is often affected by harmful bacterial communities under high temperatures that can lead to its degradation and economic losses. The current study aimed to explore Pyropia yezoensis-associated microbiota and further identify potential isolates, which can degrade Pyropia yezoensis under high-temperature conditions. METHODS AND RESULTS: The 16S rRNA gene sequencing was used to identify the agarolytic bacterial species. The results showed that Chromohalobacter sp. strain AZ6, Pseudoalteromonas sp. strain AZ, Psychrobacter sp. strain AZ3, Vibrio sp. strain AZ, and Halomonas sp. strain AZ07 exhibited algicidal properties as these strains were more abundant at high temperature (25 °C). Among the five isolated strains, the potential isolate Halomonas sp. strain AZ07 showed high production of agarolytic enzymes, including lipase, protease, cellulase, and amylase. This study confirmed that the isolated strain could produce these four different enzymes. The strain Halomonas AZ07 was co-treated with Pyropia yezoensis cells under two different temperature environments, including 13 °C and 25 °C. The degradation of Pyropia yezoensis occurred at the optimum temperature of 25 °C and effectively degraded their cell wall, proteins, lipids, and carbohydrates. CONCLUSION: The successful cultivation of Pyropia yezoensis in coastal farm environments is dependent on specific temperature and environmental factors, and lower temperatures have been observed to be particularly beneficial for the survival and growth of Pyropia yezoensis. The temperature below 13 °C was confirmed to be the best niche for the symbiotic relationship of microbiota associated with Pyropia yezoensis for its growth, development, and production.

From micro to mesoscale: Understanding the influence of macroalgal communities on Ostreopsis Schmidt blooms.

Harmful Algal Blooms (HABs) are increasing in temperate areas, and the growth rates of benthic harmful dinoflagellates may be favoured in the context of global climate change. Benthic dinoflagellates, including species belonging to the Ostreopsis Schmidt genus, are known to develop on the surface of macroalgae and different macroalgal morphotypes and communities could host higher or lower cell abundances. The physical structure of the macroalgal substrate at the small scale (cm, microhabitat scale) and the structural complexity of the macroalgal community at the medium scale (few m, mesohabitat scale) could play a relevant role in bloom facilitation: the hypothesis that Ostreopsis species could be associated with macroalgal turfs and shrubs, structurally less complex communities than canopy-forming macroalgae, is especially under discussion and, if confirmed, could link bloom occurrence to regime shifts in temperate ecosystems. The present study, performed in two locations of the Ligurian Sea (Rochambeau, France and Vernazzola, Italy) aimed at understanding marine vegetation's role at the micro and mesohabitat scales in controlling the distribution and abundance of Ostreopsis. The abundance of the microalgal cells was quantified at different spatial scales, from cm to a few m, on different macroalgal species and communities, including artificial substrates, to tease apart the micro and mesohabitat effects. The results obtained show a high spatio-temporal variability, potentially hiding habitat-related patterns. The substrate's preferences diminish when cell abundances are very high, as in the case of Rochambeau, while in presence of moderate cell abundances as in Vernazzola or the first phases of blooms, it is possible to appreciate differences in abundances among substrates (in our study, Dictyota fasciola (Roth) Lamouroux supporting higher abundances). Our results open new research topics such as the study of blooms at a larger scale (macrohabitat) and testing different sampling methods to standardise the cells' abundances independently on the substrate.

Strong, anti-swelling, and biodegradable seaweed-based straws with surface mineralized CaCO3 armor.

While the extensive utilization of disposable plastic straws has resulted in significant environmental issues such as microplastics and soil and ocean pollution, the quest for alternative straws for versatile use remains a formidable challenge. Here, drawing inspiration from naturally water-resistant materials such as bones and sea urchins, we have developed seaweed-based straws with significantly improved water resistance and mechanical strength via in-situ mineralization of CaCO3 on their surfaces. Specifically, the COO- groups on the G (α-L-guluronate) blocks of alginate were employed to establish a robust cross-linked network, while the COO- groups on the M (ß-D-mannuronate) blocks attracted free Ca2+ through electrostatic forces, thereby promoting CaCO3 nucleation. This effectively prevents COOH groups from hydrating, reducing swelling, and results in the fabrication of nano- to micron-sized CaCO3 particles that reinforce the structure without compromising the cross-linked network. Compared with the control group, the S5% sample (prepared with 5 % Na2CO3 solution) exhibited a 102 % increase in water contact angle, a 35 % decrease in swelling degree, and a 35.5 % and 37.5 % increase in ultimate flexural and tensile stress, respectively. Furthermore, the potential use of these straws as a waste for heavy metal adsorption was investigated, addressing environmental concerns while demonstrating economic feasibility.

Application of MALDI-MS for characterization of fucoidan hydrolysates and screening of endo-fucoidanase activity.

Brown macroalgae synthesize large amounts of fucoidans, sulfated fucose-containing polysaccharides, in the ocean. Fucoidans are of importance for their recently discovered contribution to marine carbon dioxide sequestration and due to their potential applications in biotechnology and biomedicine. However, fucoidans have high intra- and intermolecular diversity that challenges assignment of structure to biological function and the development of applications. Fucoidan-active enzymes may be used to simplify this diversity by producing defined oligosaccharides more applicable for structural refinement, characterization, and structure to function assignment for example via bioassays. In this study, we combined MALDI mass spectrometry with biocatalysis to show that the endo-fucoidanases P5AFcnA and Wv323 can produce defined oligosaccharide structures directly from unrefined macroalgal biomass. P5AFcnA released oligosaccharides from seven commercial fucoidan extracts in addition to unrefined biomass of three macroalgae species indicating a broadly applicable approach reproducible across 10 species. Both MALDI-TOF/TOF and AP-MALDI-Orbitrap systems were used, demonstrating that the approach is not instrument-specific and exploiting their combined high-throughput and high-resolution capabilities. Overall, the combination of MALDI-MS and endo-fucoidanase assays offers high-throughput evaluation of fucoidan samples and also enables extraction of defined oligosaccharides of known structure from unrefined seaweed biomass.

Development of a New Binary Matrix for the Comprehensive Analysis of Lipids and Pigments in Micro- and Macroalgae Using MALDI-ToF/ToF Mass Spectrometry.

While edible algae might seem low in fat, the lipids they contain are crucial for good health and preventing chronic diseases. This study introduces a binary matrix to analyze all the polar lipids in both macroalgae (Wakame-Undaria pinnatifida, Dulse-Palmaria palmata, and Nori-Porphyra spp.) and microalgae (Spirulina-Arthrospira platensis, and Chlorella-Chlorella vulgaris) using matrix-assisted laser desorption ionization mass spectrometry (MALDI-MS). The key lies in a new dual matrix made by combining equimolar amounts of 1,5-diaminonaphthalene (DAN) and 9-aminoacridine (9AA). This combination solves the limitations of single matrices: 9AA is suitable for sulfur-containing lipids and acidic phospholipids, while DAN excels as an electron-transfer secondary reaction matrix for intact chlorophylls and their derivatives. By employing the equimolar binary matrix, a wider range of algal lipids, including free fatty acids, phospholipids, glycolipids, pigments, and even rare arsenosugarphospholipids were successfully detected, overcoming drawbacks related to ion suppression from readily ionizable lipids. The resulting mass spectra exhibited a good signal-to-noise ratio at a lower laser fluence and minimized background noise. This improvement stems from the binary matrix's ability to mitigate in-source decay effects, a phenomenon often encountered for certain matrices. Consequently, the data obtained are more reliable, facilitating a faster and more comprehensive exploration of algal lipidomes using high-throughput MALDI-MS/MS analysis.

Supplementation of Seaweed Extracts to the Diet Reduces Symptoms of Alzheimer's Disease in the APPswePS1ΔE9 Mouse Model.

We previously demonstrated that diet supplementation with seaweed Sargassum fusiforme (S. fusiforme) prevented AD-related pathology in a mouse model of Alzheimer's Disease (AD). Here, we tested a lipid extract of seaweed Himanthalia elongata (H. elongata) and a supercritical fluid (SCF) extract of S. fusiforme that is free of excess inorganic arsenic. Diet supplementation with H. elongata extract prevented cognitive deterioration in APPswePS1ΔE9 mice. Similar trends were observed for the S. fusiforme SCF extract. The cerebral amyloid-ß plaque load remained unaffected. However, IHC analysis revealed that both extracts lowered glial markers in the brains of APPswePS1ΔE9 mice. While cerebellar cholesterol concentrations remained unaffected, both extracts increased desmosterol, an endogenous LXR agonist with anti-inflammatory properties. Both extracts increased cholesterol efflux, and particularly, H. elongata extract decreased the production of pro-inflammatory cytokines in LPS-stimulated THP-1-derived macrophages. Additionally, our findings suggest a reduction of AD-associated phosphorylated tau and promotion of early oligodendrocyte differentiation by H. elongata. RNA sequencing on the hippocampus of one-week-treated APPswePS1ΔE9 mice revealed effects of H. elongata on, amongst others, acetylcholine and synaptogenesis signaling pathways. In conclusion, extracts of H. elongata and S. fusiforme show potential to reduce AD-related pathology in APPswePS1ΔE9 mice. Increasing desmosterol concentrations may contribute to these effects by dampening neuroinflammation.

The effect of agar from the seaweed Gracilaria fisheri on properties of biodegradable starch foam.

This work focuses on the potential of agar from the seaweed Gracilaria fisheri to modify the properties of starch foam. The effects of different ratios of glycerol and agar on the properties of starch foams were investigated. All formulations used in this study produced easy-to-handle, smooth, single-use foam trays with no visible cracks. The addition of agar slightly affected the off-white color of the foam but red and yellow color values significantly decreased with increments of agar content. As the agar content was increased, the foam became less dense. A foam produced at a glycerol:agar ratio of 3:7 exhibited the highest values of flexural stress at maximum load (3.23 MPa), modulus (194.46 MPa) and hardness (97.50), and the highest temperature at maximum weight loss (Tmax) (337 °C). Therefore, starch foam modified with agar from Gracilaria fisheri showed suitable physical, mechanical and thermal properties for food packaging, and could possibly be used in the place of expanded polystyrene (EPS) foam.

Investigation into the fabrication of plant-based simulant connective tissue utilizing algae polysaccharide-derived hydrogel.

Connective tissue is an important component of meat products that provides support to animal muscles. Hydrogels are considered a promising alternative to connective tissues and simulate actual products by adjusting the gel texture and mouthfeel. This study used soybean protein isolate (SPI), corn starch (CS), konjac glucomannan (KGM), and seaweed powder (SP) as raw materials to examine the effect of different added SP and KGM concentrations on the gel texture. The G' of the gel increased five-fold when the SP and KGM concentration was increased from 1 % to 3 %. The results of mechanical property tests showed that with the addition of SP, the gel hardness increased from 316.00 g to 1827.23 g and the tensile strength increased from 0.027 MPa to 0.089 MPa. Sensory evaluation showed that the samples with 2 % SP and KGM presented the highest overall acceptability score and the most significant similarity to real connective tissue. The connective tissue simulants exhibited excellent water-holding capacity (>90 %), significantly increasing their juiciness. SEM indicated that 2 % KGM addition improved gel network structure stability. The results demonstrate the potential of seaweed polysaccharide-derived hydrogels as connective tissue mimics. This provides a new strategy for the preparation of high mechanical strength hydrogels and lays the foundation for structural diversification of plant-based meat.

Diverse inorganic carbon uptake strategies in Antarctic seaweeds: Revealing species-specific responses and implications for Ocean Acidification.

Seaweeds are important components of coastal benthic ecosystems along the Western Antarctic Peninsula (WAP), providing refuge, food, and habitat for numerous associated species. Despite their crucial role, the WAP is among the regions most affected by global climate change, potentially impacting the ecology and physiology of seaweeds. Elevated atmospheric CO2 concentrations have led to increased dissolved inorganic carbon (Ci) with consequent declines in oceanic pH and alterations in seawater carbonate chemistry, known as Ocean Acidification (OA). Seaweeds possess diverse strategies for Ci uptake, including CO2 concentrating mechanisms (CCMs), which may distinctly respond to changes in Ci concentrations. Conversely, some seaweeds do not operate CCMs (non-CCM species) and rely solely on CO2. Nevertheless, our understanding of the status and functionality of Ci uptake strategies in Antarctic seaweeds remains limited. Here, we investigated the Ci uptake strategies of seaweeds along a depth gradient in the WAP. Carbon isotope signatures (δ13C) and pH drift assays were used as indicators of the presence or absence of CCMs. Our results reveal variability in CCM occurrence among algal phyla and depths ranging from 0 to 20 m. However, this response was species specific. Among red seaweeds, the majority relied solely on CO2 as an exogenous Ci source, with a high percentage of non-CCM species. Green seaweeds exhibited depth-dependent variations in CCM status, with the proportion of non-CCM species increasing at greater depths. Conversely, brown seaweeds exhibited a higher prevalence of CCM species, even in deep waters, indicating the use of CO2 and HCO3-. Our results are similar to those observed in temperate and tropical regions, indicating that the potential impacts of OA on Antarctic seaweeds will be species specific. Additionally, OA may potentially increase the abundance of non-CCM species relative to those with CCMs.

Seasonal effects of fish, seaweed and abalone cultures on dissolved organic matter and carbon sequestration potential in Sansha Bay, China.

Coastal bays serve as undeniable dissolved organic matter (DOM) reactors and the role of prevalent mariculture in DOM cycling deserves investigation. This study, based on four seasonal field samplings and a laboratory incubation experiment, examined the source and seasonal dynamics of DOM and fluorescent dissolved organic matter (FDOM) in the seawater of fish (Larimichthys crocea, LC), seaweed (Gracilaria lemaneiformis, GL) and abalone (Haliotis sp., HA) culturing zones in Sansha Bay, China. Using three-dimensional fluorescence spectroscopy coupled with parallel factor analysis (EEMs-PARAFAC), three fluorescent components were identified, i.e. protein-like C1, protein-like C2, and humic-like C3. Our results showed that mariculture activities dominated the DOM pool by seasonal generating abundant DOM with lower aromaticity and humification degrees. Accounting for 40-95 % of total fluorescent components, C1 (Ex/Em = 300/340 nm) was regarded the same as D1 (Ex/Em = 300/335 nm) identified in a 180-day degradation experiments of G. lemaneiformis detritus, indicating that the cultured seaweed modulated DOM through the seasonal production of C1. In addition, the incubation experiment revealed that 0.7 % of the total carbon content of seaweed detritus could be preserved as recalcitrant dissolved organic carbon (RDOC). However, fish culture appeared to contribute to liable DOC and protein-like C2, exerting a substantial impact on DOM during winter but making a negligible contribution to carbon sequestration, while abalone culture might promote the potential export and sequestration of seaweed-derived carbon to the ocean. Our results highlight the influences of mariculture activities, especially seaweed culture, in shaping DOM pool in coastal bays. These findings can provide reference for future studies on the carbon accounting of mariculture.

The Effect of Sargassum fusiforme and Fucus vesiculosus on Continuous Glucose Levels in Overweight Patients with Type 2 Diabetes Mellitus: A Feasibility Randomized, Double-Blind, Placebo-Controlled Trial.

BACKGROUND: Brown seaweed is promising for the treatment of type 2 diabetes mellitus (T2DM). Its bioactive constituents can positively affect plasma glucose homeostasis in healthy humans. We investigated the effect of the brown seaweeds Sargassum (S.) fusiforme and Fucus (F.) vesiculosus in their natural form on glucose regulation in patients with T2DM. METHODS: We conducted a randomized, double-blind, placebo-controlled pilot trial. Thirty-six participants with T2DM received, on a daily basis, either 5 g of dried S. fusiforme, 5 g of dried F. vesiculosus, or 0.5 g of dried Porphyra (control) for 5 weeks, alongside regular treatment. The primary outcome was the between-group difference in the change in weekly average blood glucose levels (continuous glucose monitoring). The secondary outcomes were the changes in anthropometrics, plasma lipid levels, and dietary intake. The data were analyzed using a linear mixed-effects model. RESULTS: The change in weekly average glucose levels was 8.2 ± 2.1 to 9.0 ± 0.7 mmol/L (p = 0.2) in the S. fusiforme group (n = 12) and 10.1 ± 3.3 to 9.2 ± 0.7 mmol/L (p = 0.9) in the F. vesiculosus group (n = 10). The between-group difference was non-significant. Similarly, no between-group differences were observed for the changes in the secondary outcomes. DISCUSSION: A daily intake of 5 g of fresh, dried S. fusiforme or F. vesiculosus alongside regular treatment had no differential effect on weekly average blood glucose levels in T2DM.