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The aim of this paper is to review the multiplicity of the current uses of marine macroalgae. Seaweeds are already used in many products and for different purposes, from food products to medicine. They are a natural resource that can provide a number of compounds with beneficial bioactivities like antioxidant, anti-inflammatory, anti-aging effects, among others. Despite studies directed in prospecting for their properties and the commodities already marketed, they could, surely, be even more researched and sustainably explored.

Paalme, T.; Torn, K., and Martin, G., 2024. Variation of essential macroelement contents in two common charophyte species, Chara aspera and Chara tomentosa, inhabiting shallow brackish waters of the Baltic Sea. In: Phillips, M.R.; Al-Naemi, S., and Duarte, C.M. (eds.), Coastlines under Global Change: Proceedings from the International Coastal Symposium (ICS) 2024 (Doha, Qatar). Journal of Coastal Research, Special Issue No. 113, pp. 946-950. Charlotte (North Carolina), ISSN 0749-0208. Nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), sodium (Na), and sulfur (S) are considered essential mineral plant nutrients that contribute to growth, photosynthesis, and various metabolic and physiological processes. In this study, quantification and comparison of macronutrients in two common charophyte species, Chara aspera and C. tomentosa, collected monthly (March 2014 to March 2015) in semi-enclosed shallow Rame Bay in the NE Baltic Sea were carried out. Combustion analysis (Dumas method) and microwave plasma-atomic emission spectrometry (MP-AES) were used to determine the concentrations of mineral elements in charophytes. The main goal of this investigation was to complement the knowledge of the mineral composition of brackish water charophytes. Thus, the effects of species and season/month on mineral element content both in charophyte shoots and rhizoids were examined. Our analysis showed significant species-specific variations in macroelement content. Mg, K, P, Na, and S content was significantly higher in C. tomentosa; no statistically significant differences between species were found in N content, while Ca content was remarkably higher in C. aspera. As a rule, the elemental content in rhizoids and shoots of the same charophyte species varied considerably. The magnitude and direction of differences in macroelement content between species and shoots and rhizoids of the same species depended on the time the charophytes were collected. Seasonal variation in macroelement content could be explained by changing demands for metabolic and physiological processes at different growth phases of charophytes, as well as by the concentration and availability of these elements in the surrounding environment.

The interest in seaweeds for cosmetic, cosmeceutics, and nutricosmetics is increasing based on the demand for natural ingredients. Seaweeds offer advantages in relation to their renewable character, wide distribution, and the richness and versatility of their valuable bioactive compounds, which can be used as ingredients, as additives, and as active agents in the formulation of skin care products. Bioactive compounds, such as polyphenols, polysaccharides, proteins, peptides, amino acids, lipids, vitamins, and minerals, are responsible for the biological properties associated with seaweeds. Seaweed fractions can also offer technical features, such as thickening, gelling, emulsifying, texturizing, or moistening to develop cohesive matrices. Furthermore, the possibility of valorizing industrial waste streams and algal blooms makes them an attractive, low cost, raw and renewable material. This review presents an updated summary of the activities of different seaweed compounds and fractions based on scientific and patent literature.

da Silva, I.M.; Lobo, M.; Muipela, A.; Rocha, R.J.M., and Quintino, V., 2024. Coral reefs community structure in Pemba, Northern Mozambique: 2012 vs 2016. In: Phillips, M.R.; Al-Naemi, S., and Duarte, C.M. (eds.), Coastlines under Global Change: Proceedings from the International Coastal Symposium (ICS) 2024 (Doha, Qatar). Journal of Coastal Research, Special Issue No. 113, pp. 931-935. Charlotte (North Carolina), ISSN 0749-0208. The composition of the coral community in Pemba, Northern Mozambique, was assessed in 2012 and 2016. The composition and coral coverage were evaluated in two sites, Kaori and Wimbe, by analyzing 20-meter transects of 40 underwater photographs, each arranged along the reef crest. The coral community changed during the study period, with decreasing coverage of the reef-building coral and increasing macroalgae and soft coral. These findings suggest a potential long-term change to soft coral- or macroalgae-dominated reefs, combining climate change with anthropogenic forcing, mainly due to fishing and urban pressure. In 2019, cyclone Kenneth destroyed most of the reef, especially the ones under study. The monitoring places still didn't recover after the cyclone, which is mainly rubble, probably due to the area's extensive use of fishing nets.

Bacteria and marine macroalgae form close associations, while various bacteria affect the morphogenesis and growth of macroalgae. Hyphomonas strains exhibit normal morphogenetic activity in protoplasts of the red alga Pyropia yezoensis (nori). However, the effects of the bacteria on the growth of Pyropia from protoplast cells to regenerated thalli remain unknown. Here, we assessed the growth of P. yezoensis and Pyropia tenera using combined cultures of three Hyphomonas strains (LNM10-16, SCM-2, and LNM-9) and three algal media (artificial seawater with vitamins, artificial seawater, and natural seawater) over 7 weeks. Third week after culture, the three Hyphomonas strains showed almost similar levels of normal growth activity for both Pyropia species. However, at 7 weeks, significant differences were observed among the three Hyphomonas strains in terms of length, length-to-width ratio, and normal morphology of Pyropia thalli. LNM10-16 significantly promoted the thalli length and length-to-width ratios of both Pyropia species in artificial seawater without vitamins and natural seawater, compared with the other two Hyphomonas strains. P. yezoensis cultured in artificial seawater with vitamins showed a much higher demand for LNM10-16 in development of the thalli length than P. tenera . These results may be explained by differences in the growth activities of Hyphomonas strains and the nutrient requirements of Pyropia species. Furthermore, the bacteria were more specifically attached to the rhizoid surfaces of both species. This study is the first to reveal that Hyphomonas strains affect the growth of Pyropia species by attaching to their rhizoids.

This review delves into the burgeoning field of seaweed proteins as promising alternative sources of protein. With global demand escalating and concerns over traditional protein sources’ sustainability and ethics, seaweed emerges as a viable solution, offering a high protein content and minimal environmental impacts. Exploring the nutritional composition, extraction methods, functional properties, and potential health benefits of seaweed proteins, this review provides a comprehensive understanding. Seaweed contains essential amino acids, vitamins, minerals, and antioxidants. Its protein content ranges from 11% to 32% of dry weight, making it valuable for diverse dietary preferences, including vegetarian and vegan diets. Furthermore, this review underscores the sustainability and environmental advantages of seaweed protein production compared to traditional sources. Seaweed cultivation requires minimal resources, mitigating environmental issues like ocean acidification. As the review delves into specific seaweed types, extraction methodologies, and functional properties, it highlights the versatility of seaweed proteins in various food products, including plant-based meats, dairy alternatives, and nutritional supplements. Additionally, it discusses the potential health benefits associated with seaweed proteins, such as their unique amino acid profile and bioactive compounds. Overall, this review aims to provide insights into seaweed proteins’ potential applications and their role in addressing global protein needs sustainably.

Ecosystems around the world have experienced shifts in community state as a result of anthropogenic activities that alter important ecological feedbacks. On coral reefs, transitions to a state where fleshy macroalgae are a major space holder have often been associated with the loss of top‐down control, which frequently has been attributed to overharvesting of herbivorous fishes. However, nutrients could also facilitate the proliferation of macroalgae, but evidence for the role of this mechanism in state shifts on coral reefs is inconsistent. Here, we combine a common garden nutrient enrichment experiment with surveys of algal traits to assess potential mechanisms by which nutrient subsidies could trigger and/or maintain a regime shift to abundant macroalgae on reefs. We explored how nutrients influenced individual performance at three life stages of the frondose brown alga Turbinaria ornata , which is often a dominant fleshy macroalga on coral reefs throughout the Indo‐Pacific. Our enrichment experiment revealed that nutrients greatly increased growth and survival rates of young Turbinaria recruits during this brief life stage when they are most vulnerable to herbivory. For the juvenile stage, we found strong correlations between nutrient availability and the expression of physical defenses that deter herbivory. Additionally, reproductive investment by adults in natural populations was positively correlated with nutrient availability. Taken together, our findings provide several mechanisms by which nutrients could facilitate a persistent shift from coral to fleshy macroalgae by allowing more vulnerable recruit and juvenile life stages to escape herbivore control and by enhancing the reproductive output of adults that produce germlings that recruit locally. These results lend novel insights into bottom‐up mechanisms by which increases in nutrients can bolster the establishment and subsequent replenishment of populations of fleshy macroalgae, which can inform management strategies for conserving or restoring coral reefs.

Asparagopsis taxiformis has potent antimethanogenic activity as a feed supplement at 2 % of organic matter in in vitro bioassays. This study identified the main bioactive natural products and their effects on fermentation using rumen fluid from Bos indicus steers. Polar through to non-polar extracts (water, methanol, dichloromethane and hexane) were tested. The dichloromethane extract was most active, reducing methane production by 79 %. Bromoform was the most abundant natural product in the biomass of Asparagopsis (1723 μg g −1 dry weight [DW] biomass), followed by dibromochloromethane (15.8 μg g −1 DW), bromochloroacetic acid (9.8 μg g −1 DW) and dibromoacetic acid (0.9 μg g −1 DW). Bromoform and dibromochloromethane had the highest activity with concentrations ≥1 μM inhibiting methane production. However, only bromoform was present in sufficient quantities in the biomass at 2 % organic matter to elicit this effect. Importantly, the degradability of organic matter and volatile fatty acids were not affected at effective concentrations.

Mycosporine-like amino acids (MAAs), maximally absorbed in the wavelength region of 310–360 nm, are widely distributed in algae, phytoplankton and microorganisms, as a class of possible multi-functional compounds. In this work, based on the Web of Science, Springer, Google Scholar, and China national knowledge infrastructure (CNKI), we have summarized and analyzed the studies related to MAAs in marine macroalgae over the past 30 years (1990–2019), mainly focused on MAAs distribution, contents, and types. It was confirmed that 572 species marine macroalgae contained MAAs, namely in 45 species of Chlorophytes, 41 species of Phaeophytes, and 486 species of Rhodophytes, and they respectively belonged to 28 orders. On this basis, we established an open online database to quickly retrieve MAAs in 501 species of marine macroalgae. Furthermore, research concerning MAAs in marine macroalgae were analyzed using CiteSpace. It could easily be seen that the preparation and purification of MAAs in marine macroalgae have not been intensively studied during the past 10 years, and therefore it is necessary to strengthen the research in the preparation and purification of MAA purified standards from marine macroalgae in the future. We agreed that this process is not only interesting, but important due to the potential use of MAAs as food and cosmetics, as well as within the medicine industry.

Edible marine algae are rich in bioactive compounds and are, therefore, a source of bioavailable proteins, long chain polysaccharides that behave as low-calorie soluble fibers, metabolically necessary minerals, vitamins, polyunsaturated fatty acids, and antioxidants. Marine algae were used primarily as gelling agents and thickeners (phycocolloids) in food and pharmaceutical industries in the last century, but recent research has revealed their potential as a source of useful compounds for the pharmaceutical, medical, and cosmetic industries. The green, red, and brown algae have been shown to have useful therapeutic properties in the prevention and treatment of neurodegenerative diseases: Parkinson, Alzheimer’s, and Multiple Sclerosis, and other chronic diseases. In this review are listed and described the main components of a suitable diet for patients with these diseases. In addition, compounds derived from macroalgae and their neurophysiological activities are described.