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Dispersal of reproductive propagules determines recruitment patterns and connectivity among populations and can influence how populations respond to major disturbance events. Dispersal distributions can depend on propagule release strategies. For instance, the bull kelp, Nereocystis luetkeana, can release propagules (spores) from two heights in the water column ("bimodal release"): at the water surface, directly from the reproductive tissues (sori) on the kelp's blades, and near the seafloor after the sori abscise and sink through the water column. N. luetkeana is a foundation species that occurs from central California to Alaska and is experiencing unprecedented levels of population declines near its southern range limit. We know little of the kelp's dispersal distributions, which could influence population recovery and restoration. Here, we quantify how bimodal spore release heights affect dispersal outcomes based on a numerical model specifically designed for N. luetkeana. The model incorporates oceanographic conditions typical of the species' coastal range and kelp biological traits. With bimodal release heights, 34% of spores are predicted to settle within 10 m of the parental alga and 60% are predicted to disperse beyond 100 m. As an annual species, bimodal release heights can facilitate the local regeneration of adults within a source kelp forest while also supporting connectivity among multiple forests within broader bull kelp metapopulations. To leverage this pattern of bimodal spore dispersal in bull kelp restoration management, directing resources toward strategically located focal populations that can seed other ones could amplify the scale of recovery.

Energy security is a critical global challenge in the transition to sustainable development. Anaerobic digestion (AD) offers a promising renewable energy solution that mitigates environmental impacts. Algae, as biomass feedstock, have shown significant potential for bioenergy production; however, their complex chemical composition poses challenges to the efficiency of the AD process. To address these limitations, various pretreatment methods have been applied to enhance biogas production. In this study, we performed a comprehensive meta‐analysis to evaluate the effects of different pretreatments on methane (CH₄) yields from both microalgae and macroalgae. Our results demonstrate that biological, physical, and combined chemical–physical pretreatments significantly improve CH₄ production in microalgae, with increases of up to 141%, 125%, and 151%, respectively. For macroalgae, physical pretreatments were the most effective, leading to a 129% increase in CH₄ yield. We also estimate that utilizing just 10% of the global algal biomass production (3.6 Mt) could generate over 5.5 TWh y−1 of energy. This potential could be doubled with the application of appropriate pretreatment strategies. These findings highlight the role of algae in advancing renewable energy production and contribute to the growing body of knowledge on optimizing AD processes for cleaner energy generation. [ABSTRACT FROM AUTHOR]

The development of trait‐based approaches has accelerated our understanding of how communities assemble, respond to environmental change and may best be managed in the Anthropocene. Understanding the magnitude and pattern of interspecific variability forms a critical underpinning of trait‐based approaches while exploring intraspecific variability can identify the potential of species to adapt to changing environmental drivers. Our work is motivated by the critical need for a novel conceptual framework for understanding the functional ecology of macroalgae, as the current paradigm is still mired in functional group models developed in the 1980s.Our objective was to quantify interspecific and intraspecific functional trait variability in three common and morphologically diverse species of tropical marine macroalgae by exploring traits relating to the ecological functions of resource acquisition, resistance to herbivory, and resistance to physical disturbance and the trade‐offs between them.We quantified intraspecific and interspecific variability of 11 functional traits for three common and morphologically diverse species of tropical macroalgae from five fringing reefs of Mo'orea, French Polynesia that were likely to capture a wide range of environmental variability. Differences in traits among species and sites were determined with PERMANOVA, visualised with non‐metric multidimensional scaling, and trade‐offs between pairs of traits explored with correlation. Finally, spatial patterns among select traits across all species were quantified.Species clustered together in distinctly different trait spaces driven by trade‐offs among suites of functional traits. Two of three species had considerable intraspecific variability, though this variability occurred at different scales, while one clustered tightly. Exploration of individual traits across species and sites revealed trade‐offs between two strategies for resource acquisition, growing tall and strong versus investing in large surface area.Synthesis. We captured novel patterns of interspecific and intraspecific variability for tropical marine macroalgae. We found fundamental differences in traits between species that may represent ecological strategies while considerable intraspecific variability demonstrates a wide range in abilities to respond to environmental drivers. Overall, our work provides novel insights into intra and interspecific trait variation that form an essential underpinning for using a trait‐based framework in a taxon that is increasingly dominant on tropical reefs. [ABSTRACT FROM AUTHOR]

Dyes are mainly used in textile industries, owing to their usability they produce huge quantity of wastewater. Implication of best treatment technology for the treatment of textile wastewater is a concern globally. In this study, spent macroalgae Keppaphycus alvarezii was collected and converted into biochar at a temperature of 350 °C for removal of eosin yellow dye. The batch adsorption experiments were carried out by altering factors such as initial dye concentration, temperature, pH, contact time, and biochar dosage. At an initial dye concentration of 100 ppm, a contact time of 60 min, a temperature of 30 °C, a biochar dosage of 0.4 g, and a pH of 7, the best dye removal efficiency was 90.3%. In the first, second, third, and fourth regeneration cycles, the desorption efficiency of NaOH elutant is 81.24, 74.46, 62.36, and 51.23%, respectively. With the Freundlich isotherm model, the adsorption process followed pseudo-second order kinetics, according to the adsorption isotherm and kinetics studies. [ABSTRACT FROM AUTHOR]

Dakhla Bay is a paralic environment distinguished by various potentialities, including fishing, aquaculture, and tourism. However, the development of these human activities can lead to negative impacts on this environment, posing a threat to human health. This situation requires special attention to the environment and the implementation of a program for the protection and preservation of this ecosystem. This study aims to identify solutions to protect the marine environment from cadmium contamination by the macroalgae Gracilaria gracilis. The results of cadmium analyses in different compartments of Dakhla Bay, including bivalve molluscs, seawater, sediment, and macroalgae, indicate a difference in cadmium accumulation across the various studied compartments. The highest levels of cadmium are noted in macroalgae, with concentrations ranging from a minimum of 0.9 mg/kg fresh weight in the summer of 2019 to a maximum of approximately 2.55 mg/kg fresh weight recorded during the summer of 2022 at the Lassargua station. In comparison, bivalve molluscs such as Perna perna showed Cd levels ranging from 0.2 mg/kg to 1.4 mg/kg fresh weight at the same station. The sediment samples revealed average Cd levels ranging from 0.02 to 1.39 mg/kg dry weight in samples collected from Lassargua, while seawater concentrations were recorded at approximately 0.65 µg/L. The decontamination of cadmium by the macroalgae Gracilaria gracilis without impacting the quality of the algae has been well confirmed. Indeed, cadmium levels noted in macroalgae remain below the thresholds set by the regulations in force. In conclusion, the results of this study encourage the use of algocultures in Dakhla Bay to protect its ecosystem from various types of pollution. [ABSTRACT FROM AUTHOR]

Seaweeds or marine algae with their three main taxa are recognized as a potential pot for numerous products. This has been imperative to valorize their components at an industrial scale in the context of the sustainability goals of the United Nations (UN). Biorefinery approaches have been attempted for several decades to produce bioactive, biofuels, fine chemicals, and nutritional products from seaweeds. However, with the recent UN goals, climatic changes, and the global economic situation, it is essential to assess all the production processes involved concerning several factors. Numerous steps are performed following algae collection, including optimization of downstream processing (e.g., drying, extraction, and purification), in addition to suitable preservation to maintain products' integrity till their usage. Moreover, breakthroughs in biotechnologies and the biological sciences are also targeted to achieve the goals of the blue circular bioeconomy which focuses on renewable resources of foods, drug discovery, and energy, while preserving the ocean ecosystem. Hence, the current article provided new insights into the various processes to valorize marine algae in the frame of circular bioeconomy and sustainability concepts. [ABSTRACT FROM AUTHOR]

Genomic resources have yielded unprecedented insights into ecological and evolutionary processes, not to mention their importance in economic and conservation management of specific organisms. However, the field of macroalgal genomics is hampered by difficulties in the isolation of suitable DNA. Even when DNA that appears high quality by standard metrics has been isolated, such samples may not perform well during the sequencing process. We here have compared Oxford Nanopore long‐read sequencing results for three species of macroalgae to those of nonmacroalgal species and determined that when using macroalgal samples, sequencing activity declined rapidly, resulting in reduced sequencing yield. Chemical analysis of macroalgal DNA that would be considered suitable for sequencing revealed that DNA derived from dried macroalgae was enriched for polyphenol–DNA adducts (DNA with large polyphenols chemically attached to it), which may have led to sequencing inhibition. Of note, we observed the strongest evidence of sequencing inhibition and reduced sequence output when using samples dried using silica gel—suggesting that such storage approaches may not be appropriate for samples destined for Oxford Nanopore sequencing. Our findings have wide‐ranging implications for the generation of genomic resources from macroalgae and suggest a need to develop new storage methods that are more amenable to Oxford Nanopore sequencing or to use fresh flash‐frozen tissue wherever possible for genome sequencing. [ABSTRACT FROM AUTHOR]

Featured Application: The concept of this investigation aimed to formulate a beer enriched with functional ingredients originating from sea macroalgae Fucus virsoides. Marine macroalgae are organisms rich in bioactive compounds such as polysaccharides, polyphenols, and various minerals. Macroalgae are increasingly being added to the human diet precisely because they contain useful compounds that can also be used in the pharmaceutical industry. Previous research describes their addition to meat products, yogurt, bread, and baby food. However, data on the addition of algae to beer have been scarce. The goal of this work was to produce beer with the addition of brown macroalgae (Fucus virsoides) from the Adriatic Sea. In addition, the basic physical–chemical parameters (color, pH, ethanol, extract, and polyphenols) were determined. The most important premise is the transfer of selenium (Se) to beer, since Se is deficient in human food chain. The transfer of different metals, namely, S (sulfur), Mg (magnesium), P (phosphorus), K (potassium), Ca (calcium), Cr (chromium), Mn (manganese), Fe (iron), Co (cobalt), Ni (nickel), Cu (copper), Zn (zinc), As (arsenic), Se (selenium), Mo (molybdenum), Cd (cadmium), Hg (mercury), and Pb (lead), from algae to beer was determined using inductively coupled plasma–mass spectrometry (ICP−MS). The results, however, were not satisfactory regarding metal transfer. In particular, Se was detected in beer, but other metals such as As, Cd, and Pb were not. Alga addition contributed to extract values, and the original extract reached 14.3 °P in wort with alga addition, as opposed to 12.8 °P in the control sample. Such high extract content, however, resulted in beer with low alcohol content, <4% v/v for both beers. This could be explained by the high levels of unfermentable extract. pH values showed statistical difference between samples, meaning that the addition of algae significantly affected the pH value of beer, reducing acidity by almost 5%. [ABSTRACT FROM AUTHOR]

Promoting resilience is highly relevant to preserving biodiversity and ecosystem functioning. For coral reefs, parrotfish protection emerged as a mainstream action for reversing the degradation experienced by these systems. The rationale is that restoring their populations will increase grazing activity and reinforce control of fast‐growing macroalgae, facilitating coral cover recovery. A lack of a link between parrotfish trends and macroalgae and coral cover trends at a large scale has, however, often been the case. Suggesting more complex underlying dynamics that should be reexamined. In this review, we discuss how lumping parrotfish species as if they were functionally redundant may obscure trends. And how a lack of appreciation of other functions around the parrotfish paradigm, specifically bioerosion, may have unforeseen and potentially adverse effects on degraded reefs. We show that bioerosion responded more directly and quickly to spatial and temporal changes in parrotfish assemblages than macroalgae consumption, arguably due to the varying vulnerability among Caribbean parrotfishes to fisheries and habitat loss. For highly degraded reefs, positive changes in parrotfish populations could hence compromise the remaining coral skeleton structures and the reef framework, further accentuating reef degradation, where increases in macroalgae consumption could not necessarily compensate for higher rates of bioerosion. [ABSTRACT FROM AUTHOR]

Macroalgae (Ulva fasciata, Gracilaria corticata, and Sargassum wightii) were collected from the marine environment and used as the substrate for lactic acid production. These macroalgae were pretreated with hydrochloric acid (0.2 to 0.4 N) for various times (20 to 60 min). Additionally, the algal hydrolysate was incubated with cellulase for 24 h at 30 ± 1 °C to achieve enzymatic saccharification. Proximate analysis of these macroalgae was performed, and the yield was high in G. corticata. The G. corticata hydrolysate was composed of 10.01 ± 0.12% ash content, 1.25 ± 0.2% total fat, 10.2 ± 0.1% crude protein, 9.2 ± 0.2% moisture content, and a higher level of total carbohydrate (69.33 ± 1.5%) than the other two macroalgae. In G. corticata, the enzymatic treatment showed the maximum reducing sugar (33.5 ± 2.3%) relative to the other macroalgal hydrolysates and was considered for optimization of lactic acid production. Lactobacillus acidophilus (MTCC447) utilized pretreated G. corticata hydrolysate (enriched with 5% yeast extract), and maximum lactic acid yield was achieved after 72 h, 30 °C incubation temperature, and 6% inoculum (1 x 108 CFU/mL) in static culture condition. Batch fermentation was performed in the 1-L bioreactor at room temperature (30 °C) for 96 h. Lactic acid production was maximum within 72 h and the pH value was depleted. The present finding indicates that G. corticata could be used as a substrate for lactic acid production. [ABSTRACT FROM AUTHOR]

Artificial Light at Night (ALAN) is an emerging global stressor that is likely to interact with other stressors such as warming, affecting habitat‐forming species and ecological functions. Seaweeds are dominant habitat‐forming species in temperate marine ecosystems, where they support primary productivity and diverse ecological communities. Warming is a major stressor affecting seaweed forests, but effects of ALAN on seaweeds are largely unknown. We manipulated ALAN (0 lx vs. 25 lx at night) and temperature (ambient vs. +1.54°C warming) to test their independent and interactive effects on the survival, growth (biomass, total‐, blade‐ and stipe‐length) and function (photosynthesis, primary productivity and respiration) on the juveniles of two habitat‐forming seaweeds, the kelp Ecklonia radiata and the fucoid Sargassum sp. Warming significantly increased Ecklonia mortality; however, ALAN did not affect mortality. ALAN had positive effects on Ecklonia biomass, total and blade growth rates and gross primary productivity; however, warming largely counterbalanced these effects. We found no significant effects of warming or ALAN on Ecklonia photosynthetic yield, stipe length, net primary productivity or respiration rates. We found no effects of ALAN or warming on Sargassum for any of the measured variables. Synthesis. Our findings indicate that ALAN can have positive effects on seaweed growth and functioning, but such effects are likely species‐specific and can be counterbalanced by warming, suggesting an antagonistic interaction between these global stressors. These findings can help us to predict and manage the effects of these stressors on seaweeds, which underpin coastal biodiversity. [ABSTRACT FROM AUTHOR]

Crustose coralline algae (CCA) from the genus Titanoderma are reported to induce high levels of coral larval settlement across a wide diversity of species. Consequently, Titanoderma is a promising taxon to cultivate in aquaculture facilities for application in coral reef restoration projects. However, knowledge on the optimum conditions to promote growth and reproduction in Titanoderma is limited. To investigate this, we cultured adult fragments of Titanoderma sp. at two temperatures (27.5 or 30 °C) and two light levels (mean maximum midday irradiance of 10 or 40 µmol photons m−2 s−1) on three different tile materials (CaCO3, concrete, or PVC). We found that the combination of 27.5 °C and 40 µmol photons m−2 s−1 were best for adult fragment growth. Greater number of conceptacles were formed under higher light intensities, while temperature did not have an influence. Sporeling settlement and subsequent growth into juveniles were only evident at 40 µmol photons m−2 s−1, with substantially higher recruitment on substrates made of concrete. These results provide important insights for developing optimal conditions to cultivate Titanoderma sp. in aquaculture facilities to support reef restoration projects using sexually produced corals. [ABSTRACT FROM AUTHOR]

Interest in farming kelps has grown beyond using kelp for food, feed or biofuels. There is considerable interest in generating biomass from seaweed for use in bioplastics and other products that would substitute for petroleum-derived products. For these uses to be viable, large amounts of biomass are needed. Very large kelp farms can be expensive to build and maintain, leading to the need to optimize the biomass per unit area. Although close spacing of growlines can lead to poor growth, a viable approach may be to grow two species of kelps together: one that hangs down and one that is buoyant, growing up. This system would increase the spacing in three dimensions. In Alaska, Saccharina latissima is commonly grown hanging down from longlines. One of the buoyant Alaskan kelps is Nereocystis luetkeana. Because there are commercial uses for wild-harvested Nereocystis in Alaska, we undertook a preliminary trial in Kodiak, Alaska, that grew both Saccharina and Nereocystis in the same longline array. Closely spaced lines were seeded the first week of February 2023 and set at 3 m below the surface. The arrays were harvested in late June 2023. Total yields were greatest on the combined arrays, followed by the Nereocystis only and Saccharina only arrays. Despite having 45% fewer grow-lines, the total yield of the Nereocystis on the combined arrays was statistically similar to the Nereocystis only arrays. These results may have significance for large scale macroalgal production. [ABSTRACT FROM AUTHOR]

Seaweeds are important primary producers in marine ecosystems and often play keystone and significant structural roles in their communities. After almost a century of research, seaweed functional ecology has emerged as a key approach in seaweed biology with applications in environmental monitoring and rocky shore communities. Several models and functional groups have been proposed to compare and understand seaweed morphology, physiology, and ecology, but there is no consensus on preferred approaches, adequate model usage, and terminology. To address this problem and to provide a comprehensive model synopsis, we conducted a literature review on seaweed functional ecology research from 1934 to 2023. We selected the works that proposed general models for the functional ecology of seaweeds and the papers that tested them. We evaluated each model's strengths, limitations, and scope of application. We also identified the common issues in testing seaweed functional models and suggested a glossary to promote unified and clear terminology. We present hypotheses and classification tables, application flowcharts, and visual aids for each model. We show that most functional models remain untested but are nonetheless often used. After reviewing close to 90 years of research on seaweed functional ecology, we conclude the review by providing new perspectives and highlighting the open questions of the field. [ABSTRACT FROM AUTHOR]

In the economically important red macroalga Pyropia, carbohydrates and proteins contents are usually used to evaluate the nutritional status and commercial value. As main component elements of carbohydrates and proteins, C, N and S contents can be the suitable indicators. However, efficient and nondestructive estimation of these elements have not been well established in macroalgae, which is definitely needed in high-throughput phenotyping and selective breeding. In the current study, hyperspectral imaging was used to estimate the C, N and S contents in thalli of Pyropia yesoensis. Based on spectral information acquired by two hyperspectral cameras with range of 400 nm to 1700 nm, two machine learning methods, partial least squares regression (PLSR) and support vector machine regression (SVR), were performed to establish prediction models following different preprocessing methods. The result showed that SVR model following Savitzky-Golay (S-G) smoothing preprocessing performed the best for N content with excellent accuracy (RTest2 = 0.94, RMSE = 0.331, MAPE = 5.47%, RPD = 3.44). Both of PLSR and SVR models could not yet meet satisfactory prediction for C and S content with RTest2 < 0.4 and RPD < 1.5. Further validation on field samples corroborated accuracy and robustness of the optimal estimation model for N. This study demonstrates that hyperspectral imaging is effective for estimating N contents of P.yesoensis thalli. It unveils the capability of hyperspectral imaging with machine learning models for estimating macroelement contents in macroalgae thalli, and offers a convenient, non-destructive, and effective method for the phenotyping and selective breeding of macroalgae. [ABSTRACT FROM AUTHOR]

Marine forests are key providers of ecosystem services globally with increasing recognition of their relevance in the context of climate adaptation and mitigation. Along the Southeast Pacific, these forests sustain productive and intricate trophic webs, serving as crucial sustenance for coastal systems and subsidies for deeper habitats. This study aimed to estimate the contribution of Lessonia trabeculata to the local blue carbon pathways within the southern sector of the largest coastal protected area in Peru, Reserva Nacional San Fernando (RNSF). By integrating remote sensing, scientific diving, and the traditional knowledge of artisanal divers, we conducted a comprehensive assessment and conservative estimates of carbon captured by these forests during the austral winter of 2021 using the least destructive assessment methods. We conservatively estimated ~1300 t C captured as standing stock by L. trabeculata in the southern sector of RNSF. Said biomass-held carbon assimilation would annually release ~1300 t C m2 y-1 as detritus, of which, once exported could potentially yield to ~130 t C m2 y-1 sequestered in deep-sea sediments. Detrital productivity of L. trabeculata was calculated for the first time in Peru, along with the social and environmental cost of emissions equivalent to the amount of carbon captured (855.8k US$) and potentially removed by the standing stock (85.7k US$). In addition, we present an overview of the conservation state of the kelp population in the coastal protected area, along with allometric equations for estimating biomass based on biometric measurements easily attainable underwater. This study represents the continuation of a pioneering effort towards the understanding of blue carbon in marine forests of Peru. Our study contributes to advancing the understanding and management of these ecosystems in the face of climate challenges. The implications for the rapidly growing blue carbon field in the region's socioecological context are further discussed. [ABSTRACT FROM AUTHOR]

A screening protocol was developed and applied to isolate and select cultivars of freshwater filamentous macroalgae for year-round monoculture cultivation and nutrient bioremediation of primary municipal wastewater. The screening protocol is a step-by-step guide to identify robust cultivars which possess key attributes of competitive dominance, high biomass productivity and bioremediation performance under local seasonal and extreme conditions. Forty-four mixed samples of freshwater filamentous macroalgae were collected during summer and winter from a range of local aquatic environments. Eleven isolated cultivars were grown in primary treated municipal wastewater and their biomass productivity and bioremediation performance under local ambient (summer and winter), extreme summer (max. summer) and winter (min. winter) conditions were assessed. Extreme conditions proved to be an important determining factor for cultivar selection as biomass productivity and bioremediation performance significantly declined under min. winter conditions. However, biomass productivity was not directly related to bioremediation performance, as cultivars with low growth rates maintained high nutrient removal rates under min. winter conditions. Top performing cultivars were Klebsormidium sp. (KLEB B) which reduced total ammoniacal-N concentrations by 99.9% to 0.01 mg L-1 (± 0.01 SE), Oedogonium sp. (OEDO D) which reduced nitrate-N concentrations by 90.2% to 0.08 mg L-1 (± 0.7 SE) and Rhizoclonium sp. which reduced phosphate concentrations by 98.7% to 0.02 mg L-1 (± 0.01 SE). Based on overall biomass productivity and bioremediation performance across seasonal and extreme conditions Klebsormidium sp. (KLEB B), Stigeoclonium sp. (STIG A) and Ulothrix sp. were identified as top performing cultivars suitable for the nutrient bioremediation of primary municipal wastewater. [ABSTRACT FROM AUTHOR]

Aquaculture plays a substantial role in providing high-quality food globally, as fish serve as a source of protein, minerals, and polyunsaturated fatty acids for human health. Consequently, aquaculture production is steadily increasing. However, there are some challenges including high expense of commercial feed, aquatic pollution, diseases, misuse of antibiotics, and safety of food fish for human health that are concerns for the achievement of sustainable aquaculture production. Therefore, there is a need to explore more options to address these problems. The use of aquatic plants in aquaculture could be the best way to solve these problems and develop sustainable aquaculture production. Aquatic plants, including algae, submerged plants, floating-leaf plants, and emergent plants, offer nutritionally enriched options used in aquaculture as direct feed or feed ingredients. Recent observations indicate that various forms of algae (e.g., nanoparticles, extracts, and pigments) have emerged as promising feed additives in aquaculture. Their application has demonstrated a notable enhancement in the growth performance and survival rates of fishes. This review summarizes the uses of aquatic plants in aquaculture, including (1) direct feeding of fish, (2) use as feed ingredients for fish feed, (3) reduction of water pollution through phytoremediation to improve water quality, and (4) serving as a therapeutic source for disease management. In addition, this article emphasizes the potential of different aquatic plants to solve various problems, including those posed by climate change, in achieving a safe and sustainable aquatic production. [ABSTRACT FROM AUTHOR]

Macroalgae are known as abundant sources of phytochemicals, which offer a plethora of beneficial biological properties. Besides being the most notable classes of compounds found in macroalgae, phlorotannins, bromophenols, and terpenoids comprise some of the most relevant for their biological properties. Phlorotannins, mainly prevalent in brown algae and structurally characterized as complex polyphenolic compounds derived from phloroglucinol units, possess robust antioxidant, anti-inflammatory, antitumor, and cytotoxic activities, modulated by factors such as the degree of polymerization and environmental conditions. Bromophenols, halogenated compounds found in algae and other marine organisms, exhibit significant antioxidant and antiviral properties. Their diverse structures and bromination patterns contribute to their potential as therapeutic and chemical defense agents. Pigments (chemically described as primary terpenoids) play a critical role in light absorption and energy transfer in macroalgae and are divided into three main groups: (i) carotenoids, which are primarily found in brown algae and provide photoprotective and antioxidant benefits; (ii) chlorophylls, known for facilitating the conversion of light into biological energy; and (iii) phycobilins, which are mostly found in red algae and play important roles in light absorption and energy transfer, besides providing remarkable health benefits. Finally, secondary terpenoids, which are particularly abundant in red algae (e.g., the Rhodomelaceae family) are central to cellular interactions and exhibit significant antioxidant, antimicrobial, antidiabetic, and anti-inflammatory properties. This study represents a detailed analysis of the biosynthesis, structural diversity, and biological activities of these macroalgae metabolites, emphasizing their potential biological properties. [ABSTRACT FROM AUTHOR]

Dynamic models of sugar kelp (Saccharina latissima) growth are used to estimate the production potential of seaweed aquaculture in many regions around the world. These models do not currently account for the existence of S. latissima ecotypes that are adapted to regional environmental conditions, particularly temperature. We tested the hypothesis that recalibrating the temperature parameters of a dynamic energy budget model using literature data for S. latissima from regions with a similar climate to the region of interest would result in more accurate predictions than using a general species‐wide temperature response curve. Calibrating the model using data from warm regions significantly improved model accuracy for kelp cultivation at the southern end of the species range (Rhode Island, USA) in cases where the original parameters underestimated growth but resulted in drastic overestimates when heavy frond erosion occurred. In Trømso, Norway, a cold parameterization produced extremely accurate predictions: the model predicted a final frond length of 88.2 cm, compared with the observed length of 87.5 (±4.70) cm. Our results demonstrate that recalibrating temperature response curves allows one model to be applied to kelp aquaculture in different regions, an important step toward the prediction of S. latissima productivity over large areas. [ABSTRACT FROM AUTHOR]

Seaweeds are the most phylogenetically diverse group of multicellular organisms and rank foremost among marine keystone species. Due to their taxonomic diversity and functional importance, previous studies have classified seaweeds into functional groups based on qualitative or semi-quantitative traits, such as seaweed form, anatomy, and thickness. Despite the widespread use of seaweed functional groups from basic marine ecology to coastal monitoring, it is not known how accurate such morphology-based proposals are in grouping seaweeds by their form. To address this uncertainty at the foundations of seaweed biology, we surveyed and gathered all available data on seaweed forms using PRISMA protocols. We used the surface area to volume ratio (SA:V), a quantitative and universal measure of seaweed form, to assess the distribution and diversity of seaweed morphology across 99 species from three phyla. We show that seaweed surface area to volume ratio values span 3.64 orders of magnitude and follow a continuous and exponential distribution, without any significant gaps or clusters. We also tested current functional group schemes based on morphology and anatomy and showed that only 30% to 38% of their groups showed any significant pairwise differences in morphology. Our results challenge the basis of the current functional group approach in seaweed biology and suggest that a trait-based framework based on quantitative and continuous measures of seaweed form could provide a simpler and more accurate alternative to functionally assess seaweed ecology and physiology, as well as its implications for coastal ecosystem management. [ABSTRACT FROM AUTHOR]

This study investigates the biomass production and growth strategies of the relict seagrass Zostera marina, a species sensitive to high temperatures, within the Venice Lagoon (Italy). Monthly data collected from January to December 2019 and November 2020 to October 2021 in a single station in proximity of one lagoon port-entrance, along with seasonal data from 2018 and 2021 for the whole lagoon, were analyzed in conjunction with environmental parameters and macroalgal presence. The objective was to understand the impact of climate changes, particularly rising water temperatures, on the cover, standing crop and net primary production of Z. marina and the effect of the MoSE gate closures designed to protect Venice from high-water events. Despite expectations of a decline due to temperature increase and reduced water exchange, our findings reveal a notable adaptability of Z. marina, with increases in both cover and biomass. This resilience suggests that Z. marina can counteract environmental challenges, making this study relevant for broader ecological and conservation contexts beyond the Venice Lagoon. [ABSTRACT FROM AUTHOR]

Crop monitoring is a fundamental practice in seaweed aquaculture. Seaweeds are vulnerable to several threats such as ice-ice disease (IID) causing a whitening of the thallus due to depigmentation. Crop condition assessment is important for minimizing yield losses and improving the biosecurity of seaweed farms. The recent influence of modern technology has resulted in the development of precision aquaculture. The present study focuses on the exploitation of spectral reflectance in the visible and near-infrared regions for characterizing the crop condition of two of the most cultivated Eucheumatoids species: Kappaphycus alvareezi and Eucheuma denticulatum. In particular, the influence of spectral resolution is examined towards discriminating: (a) species and morphotypes, (b) different levels of seaweed health (i.e., from healthy to completely depigmented) and (c) depigmented from silted specimens (thallus covered by a thin layer of sediment). Two spectral libraries were built at different spectral resolutions (5 and 45 spectral bands) using in situ data. In addition, proximal multispectral imagery using a drone-based sensor was utilised. At each experimental scenario, the spectral data were classified using a Random Forest algorithm for crop condition identification. The results showed good discrimination (83–99% overall accuracy) for crop conditions and morphotypes regardless of spectral resolution. According to the importance scores of the hyperspectral data, useful wavelengths were identified for discriminating healthy seaweeds from seaweeds with varying symptoms of IID (i.e., thalli whitening). These wavelengths assisted in selecting a set of vegetation indices for testing their ability to improve crop condition characterisation. Specifically, five vegetation indices (the RBNDVI, GLI, Hue, Green–Red ratio and NGRDI) were found to improve classification accuracy, making them recommended for seaweed health monitoring. Image-based classification demonstrated that multispectral library data can be extended to photomosaics to assess seaweed conditions on a broad scale. The results of this study suggest that proximal sensing is a first step towards effective seaweed crop monitoring, enhancing yield and contributing to aquaculture biosecurity. [ABSTRACT FROM AUTHOR]

Marine-derived nutrients and bioactive compounds may offer a myriad of biological benefits, such as anticancer and anti-inflammatory properties, and technological potential, enhancing food quality as additives. Their role in the sustainable development of food technology is fundamental, especially in advancing the knowledge of functional foods and related technologies. Algae are considered one of the major sources of marine-derived ingredients and the subject of several recent studies. Despite their potential, the translation of marine ingredients' potential into a marine-based competitiveness of the food industry faces hurdles in the extraction process and operational systems scale-up that the industry needs to tackle. The complexity of marine matrices with diverse compounds and solubilities adds complexity to extraction processes and may lead to low yields or bioactivity loss. Contaminants, like heavy metals and pesticide residues in marine organisms, require rigorous purification processes for product safety. The use of biorefinery systems in marine-based ingredients' production, particularly cascade processes, offers zero-waste solutions, contributing to the blue economy and aligning with UN sustainability goals. Sustainability assessment tools are critical for evaluating marine-based food production's environmental, social, and economic impacts. A continued exploration and collaboration are essential for the future, fostering innovation and sustainability to create a resilient, equitable, and eco-friendly food system. [ABSTRACT FROM AUTHOR]

Sugar kelp (Saccharina latissma) has many nutritional benefits and has been identified as a rich source of fibre, vitamins, and antioxidants. However, it is not regularly consumed in the Western world, and the sensory perception of foods containing sugar kelp must be investigated to increase acceptance in North America. This study evaluated consumers' (n = 99) sensory perception of couscous with increasing amounts of sugar kelp (0% (control), 4%, 6%, 8%, and 10% wt/wt). Furthermore, consumers' purchase intent, liking, and emotional response to couscous with added sugar kelp was evaluated with and without nutritional information. Sugar kelp at 6% incorporation did not impact the consumers' liking scores ("Like Slightly" on the hedonic scale), but at 8% the consumers' liking significantly decreased ("Neither Like nor Dislike"). The 8% and 10% levels of sugar kelp addition led to astringency, bitter, hard, brackish, fishy, and chewy attributes being perceived by the consumers. The consumers identified they preferred samples that had soft, savoury, salty, and bland flavours and disliked samples that were brackish and gritty. The nutritional information did not increase overall liking scores, purchase intent, or emotional response. However, the inclusion of sugar kelp in the couscous did lead to an increased selection of positive emotions like happy, joyful, pleasant, and enthusiastic. Overall, the consumers were interested in foods containing seaweed and believed they were nutritious. The results indicated that sugar kelp could be added to couscous up to 6% wt/wt without impacting overall liking. [ABSTRACT FROM AUTHOR]

Low-cost and green preparation of efficient sorbents is critical to the removal of organic contaminants during water treatment. In this study, the co-pyrolysis of macroalgae and oyster shell was designed to synthesize nitrogen-doped porous biochars for sorption removal of atrazine from water. Oyster shell played a significant role in opening pores in macroalgae-derived biochars, resulting in the surface area of the macroalgae (Enteromorpha prolifera and Ulva lactuca) and oyster shell co-pyrolyzed carbonaceous as high as 1501.80 m2 g−1 and 1067.18 m2 g−1, the pore volume reached 1.04 cm3 g−1 and 0.93 cm3 g−1, and O/C decreased to 0.09 and 0.08, respectively. The sorption capacity of atrazine to nitrogen-doped porous biochars (the Enteromorpha prolifera, Ulva lactuca and oyster shell co-pyrolyzed carbonaceous) reached 312.06 mg g−1 and 340.52 mg g−1. Pore-filling, hydrogen bonding, π-π or p-π stacking and electrostatic interaction dominated the multilayer sorption process. Moreover, the nitrogen-doped porous biochars showed great performance in cyclic reusability, and the Enteromorpha prolifera, Ulva lactuca and oyster shell co-pyrolyzed carbonaceous sorption capacity still reached 246.13 mg g−1 and 255.97 mg g−1, respectively. Thus, this study suggested that it is feasible and efficient to remove organic contaminants with the nitrogen-doped porous biochars co-pyrolyzed from macroalgae and oyster shell, providing a potential green resource utilization of aquatic wastes for environmental remediation. Highlights: Nitrogen-doped porous biochars (NPBs) were derived from natural wastes. Oyster shell enhanced the micropore and mesopore structures of NPBs. Physical sorption dominated atrazine sorption onto the NPBs. [ABSTRACT FROM AUTHOR]

Kelp forests are productive and biodiverse ecosystems with high ecological, cultural, and economic importance. However, the high sensitivity of kelp to water temperature means that these ecosystems are vulnerable to marine heatwaves (MHWs), especially at the equatorward edge of their range. To date, few laboratory studies have compared the effects of MHWs of different durations or intensities on kelp, and it is difficult to determine these effects from naturally occurring MHWs in the field. We exposed juvenile sporophytes of the giant kelp Macrocystis pyrifera from Wellington, Aotearoa New Zealand to simulated MHWs three or six weeks in duration, at temperatures of 18°C, 20°C, and 22°C, corresponding to 2, 4, and 6°C above local mean summer temperatures. While all MHW treatments reduced mean kelp growth rates by over 30% relative to 16°C controls, the 22°C treatments had much more severe and wide-ranging effects, including rapid blade erosion, reduced chlorophyll fluorescence, tissue bleaching, increased δ13C values, andmortality. Nonetheless, sporophytes had some ability to recover from heat stress; within the 18°C treatment, mean relative growth rates neared or exceeded those within the control treatment within three weeks after MHWs concluded. These results support the findings of previous studies which indicate that M. pyrifera sporophytes experience a key physiological tipping point around 20°C. Additionally, our findings suggest that juvenile M. pyrifera from the Wellington population could be relatively resilient toMHWs if temperatures remain at sub-lethal levels. However, if averageMHWintensities and durations continue to increase over time, survival and recruitment of juvenile kelp could be adversely affected, thus threatening the long-term persistence of giant kelp forests near the warm edge of their range in New Zealand. [ABSTRACT FROM AUTHOR]

Most deep-ocean life relies on organic carbon from the surface ocean. While settling primary production rapidly attenuates in the water column, pulses of organic material can be quickly transported to depth in the form of food falls. One example of fresh material that can reach great depths across the tropical Atlantic Ocean and Caribbean Sea is the pelagic macroalgae Sargassum. However, little is known about the deep-ocean organisms able to use this food source. Here, we encountered the isopod Bathyopsurus nybelini at depths 5002–6288 m in the Puerto Rico Trench and Mid-Cayman Spreading Center using the Deep Submergence Vehicle Alvin. In most of the 32 observations, the isopods carried fronds of Sargassum. Through an integrative suite of morphological, DNA sequencing, and microbiological approaches, we show that this species is adapted to feed on Sargassum by using a specialized swimming stroke, having serrated and grinding mouthparts, and containing a gut microbiome that provides a dietary contribution through the degradation of macroalgal polysaccharides and fixing nitrogen. The isopod's physiological, morphological, and ecological adaptations demonstrate that vertical deposition of Sargassum is a direct trophic link between the surface and deep ocean and that some deep-sea organisms are poised to use this material. [ABSTRACT FROM AUTHOR]

The experiment was to investigate the effects of three species of macroalgae on the growth performance, physiology and biochemistry index of juvenile largemouth bass. A total of 360 juvenile largemouth bass with an initial body weight of (6.04±0.03) g were randomly divided into four groups with three replicates per group and 30 perca per replicate. Group C (Control Group) was fed a basic diet, while Groups T1, T2, and T3 were fed the basic diet supplemented with 5% Gracilaria lemaneiformis powder, 5% Asparagopsis taxiformis powder, and 5% Sargassum powder, respectively, with each group's diet being isonitrogenous and isocaloric. The experiment lasted for 57 days. The results showed that compared to Group C, the feed intake rate and feed coefficient of all experimental groups was significantly increased (P<0.05), and the protein deposition rate and fat deposition rate of Groups T2 and T3 were significantly decreased (P<0.05). The whole fish moisture content of Groups T2 and T3 was significantly increased (P<0.05), while the crude protein and crude fat concentrations were significantly decreased (P<0.05). The crude fat content in the liver of Groups T2 and T3 was significantly decreased (P<0.05). The study shows that the diet with 5% Gracilaria lemaneiformis powder, Asparagopsis taxiformis powder, and Sargassum powder respectively does not affect the growth of juvenile largemouth bass, but can improve its feeding rate and reduce the crude fat of the whole body and liver, and overall effect of juvenile largemouth bass supplemented with Sargassum powder feed is the best. [ABSTRACT FROM AUTHOR]

In human body, free radicals cause oxidative stress which is reported to be the main reason of many life style human diseases. This stress induced by the imbalance of antioxidants and oxidants. Many deadly diseases induced by oxidative stress as it forms the root cause of several degenerative changes in the cells and tissues. Nucleic acids, lipids and proteins in our body are demaged by this stress, made changes to cellular functions and lead to apoptosis or necrosis. Antioxidants have an important role in protection human body from oxidative damages and prevention of many chronic diseases, for example, diabetes, cardiovascular disease, aging, even diseases related to the nervous system. Currently, the exploration of natural antioxidants is trends in the pharmaceutical industries because synthetic antioxidants are reported to cause major side effects. Antioxidants of natural origin are considered safe and highly effective. These substances are abundant in many medicinal herbs including algae, fungi, plants and animals. Among them, seaweed is believed to be a potential source of medicinal herbs capable of synthesizing compounds with good biological activity. Off these, macroalgae, including red, brown, and green macroalgae, are considered a natural source of antioxidant components that can provide a valuable contribution to the innovation of pharmaceutical and industrial fields. Since algal products' antioxidant properties and nutritional benefits have been increasingly recognized, their properties as antioxidants require further investigative studies. This review provides information on various aspects of antioxidants, including algal sources containing antioxidants, the chemical composition of macroalgae, and antioxidant components, as well as their benefits to human health. [ABSTRACT FROM AUTHOR]

Macroalgae are a natural oceanic resource of inexhaustible abundance for the biomass energy industry with growth rates that are three to four times greater than those of terrestrial plants. The objective of this study was to evaluate the sustainability of macroalgae as biomass for biorefining through two investigations. Firstly, the deposition of macroalgae was sampled through 28 collections on seven beaches in the city of Maceió, Brazil, over a two-year period using a zigzag sampling method, covering a deposition area of 135,000 m2. From this, it was estimated that daily collection would yield 5.03 t/ha of dry biomass. Secondly, the calorific values of macroalgal biomass energy and pellet compounds were calculated. The lower calorific value (8.82 MJ/kg) found from a compound of 13 species analyzed was similar to that of the main biomass used in Brazil to obtain energy, i.e., sugarcane bagasse, which has been evaluated as 8.91 MJ/kg. Macroalgal biomass in the form of condensed energy pellets was found to have a higher calorific value of 20.18 MJ/kg, i.e., 1.2% greater than the average for terrestrial biomass pellets. Based on the results obtained, it was observed that macroalgal biomass has the possibility of becoming a new renewable feedstock with potential for bioenergy. The estimates for the deposition of biomass show possibilities for producing biofuels from marine algal raw material, which provides scope for creating another sustainable alternative for global energy issues with a reduction in environmental problems. [ABSTRACT FROM AUTHOR]

Macroalgae are beneficial for consumers and producers due to their high productivity, their chemical composition and their efficient cultivation without additional feed. Asia dominates global macroalgae production, while European production is still marginal and mainly based on wild harvesting in the North Atlantic. The European Commission has launched initiatives to promote the sustainable production, safe consumption and innovative use of macroalgae products in European regional seas, including the Mediterranean Sea. A variety of coastal and seabed types and a wide range of environmental conditions make the Mediterranean a hotspot of marine biodiversity while providing good conditions for the cultivation of macroalgae. The aim of this paper is to compare the global macroalgae production and macroalgae production in the Mediterranean Sea, focussing on the cultivation of edible macroalgae. The paper also discusses the limitations and possibilities of macroalgae production in the region. Macroalgae production is one of the most promising sectors of the blue economy in the Mediterranean. The production of edible macroalgae suitable for human consumption has great potential, considering future population growth and related food security and health issues, as well as the additional ecosystem benefits of macroalgae production. [ABSTRACT FROM AUTHOR]

This study used a meta-analytic approach to evaluate the effects of dietary supplementation with seaweed on milk yield, milk composition, nutrient digestibility, ruminal fermentation, and enteric methane (CH4) emissions of dairy cows. Data used in statistical analyses were obtained from 23 peer-reviewed scientific articles. Effect size was assessed using weighted mean differences (WMD) between seaweed-supplemented and control treatments. Dietary supplementation with seaweed decreased (p < 0.05) dry matter intake, milk protein content, milk urea nitrogen, and somatic cell count. In contrast, milk fat content, milk lactose content, and milk iodine increased (p < 0.05) in response to dietary supplementation with seaweed. Dietary supplementation with seaweed did not affect (p > 0.05) nutrient digestibility, total volatile fatty acids, acetate, and propionate. Dietary supplementation with seaweeds increased (p < 0.05) ruminal pH and ruminal concentration of butyrate and valerate. In contrast, lower (p < 0.05) ruminal ammonia nitrogen concentration, acetate/propionate ratio, daily CH4 emission, CH4 yield, and CH4 intensity were observed in response to dietary supplementation with seaweeds. In conclusion, dietary supplementation with seaweed modifies milk composition, improves ruminal fermentation, and decreases enteric methane emissions without negatively affecting milk yield or feed efficiency. [ABSTRACT FROM AUTHOR]

Fuentes-Agueda, S.A.; Gallegos, M.E., and Mandujano, M.C., 2024. Spatial and temporal changes in the demography of Caulerpa paspaloides along a distance gradient. Journal of Coastal Research, 40(5), 952–961. Charlotte (North Carolina), ISSN 0749-0208. It has been proposed that Caulerpa species have greater abundances and growth rates near mangroves than offshore. The main purpose of this study was to observe the demographic differences in Caulerpa paspaloides in three different sites of Los Petenes, Campeche, Mexico (adjacent to the mangroves, at an intermediate distance to the mangroves and offshore). For the demographical census, the number of complete and incomplete fronds, stolons, their diameter, and dry biomass was registered in May, August, and December 2013 and February 2014 for each site. Also, 100 complete fronds in May and December were marked; they were collected in June and February based on growth data obtained through the marked fronds and calculable dry biomass population growth rate (k). Significant differences were found between the abundance of structures between sites and months. The offshore population had the biggest biomass and highest average stolon diameter, whereas the intermediate site has the highest number of complete and incomplete fronds. However, no significant differences in the number of stolons were found. The values of fitness (k) obtained from the analysis of the biomass were 2.06 in summer and 0.68 in winter adjacent to the mangroves, intermediate distance was 1.57 and 1.26, and distance to offshore was 1.56 and 0, respectively. For marked fronds, the fitness (k) was 1.78 for the first site, 1.89 at the intermediate site, and 1.67 offshore. Reduction in C. paspaloides fitness suggests that the species has seasonal growth and reproduction. Also, the most important parameters related to C. paspaloides biomass were salinity and nutrients (total phosphorus and dissolved inorganic nitrogen in column water). The greatest growth rates in biomass were observed close to the mangroves, suggesting that living close to the mangrove has positive effects on the growth of C. paspaloides. [ABSTRACT FROM AUTHOR]

Sea hares are cryptic, herbivorous sea slugs present on many coral reefs worldwide. Although they are known to consume high quantities of macroalgae, they are rarely considered or quantified in assessing algal suppression. Their role as algal suppressors is not well understood, therefore this study sought to quantify sea hare herbivory on the abundant red algal genus Laurencia. The sea hares Aplysia dactylomela, Dolabella auricularia and Dolabella sp. were collected and used in herbivory trials in aquaria at Heron Island on the Southern Great Barrier Reef to quantify their rate of consumption. A. dactylomela consumed 76.9 g partially dried weight of Laurencia per 24-h, which was significantly more than the other species, with D. auricularia consuming an average of 22.5 g and Dolabella sp. consuming 37.4 g partially dried weight. Consumption of Laurencia by A. dactylomela increased with body size, with the exception of the smallest animals, which ate up to 12.5 times their body weight. D. auricularia consumed significantly more algae than was lost in control tanks. Although we observed Dolabella sp. feeding on Laurencia, the amount consumed was not significantly different to loss of algae in control tanks. The rate of herbivory on Laurencia by A. dactylomela is comparable or greater than that of more commonly studied reef herbivores such as fishes and urchins, which suggests that they may contribute to algal suppression on coral reefs and further studies are warranted to evaluate their possible role in coral-algal phase shift dynamics. [ABSTRACT FROM AUTHOR]

The Chengjiang biota, a Burgess Shale‐type Lagerstätte in eastern Yunnan, South China (Cambrian Series 2, Stage 3), provides valuable information regarding the origin and early evolution of metazoans, and complex marine ecosystems. Although the major animal phyla in the Chengjiang biota have been extensively studied, macroalgae have received comparatively little attention. Here, we establish new taxa Yunnanospirellus typica and Y. elegans, describe five genera and six species (Tawuia sp., Morania fragmenta, Liulingjitaenia alloplecta, Longfengshania stipitata, Lo. spheria and Paralongfengshania sicyoides) not previously reported in the Chengjiang biota, and elucidate the pith structure of Enteromophites intestinalis. With 13 genera and 17 species now recorded, macroalgae rank fourth in species‐level biodiversity in the Chengjiang biota (behind Euarthropoda, Porifera and Priapulida). Macroalgae account for 71.57% of total abundance, far more than all other animal phyla in the Chengjiang biota. Fuxianospira is the most dominant genus, accounting for 52.01% of all macroalgae specimens. Unattached (floating, planktonic or drifting) forms dominate (eight attached; nine unattached species). The high diversity of attached macroalgae indicates that the macroalgal communities adapted to the Proterozoic firm substrate (probably covered by microbial mats) persisted from the Ediacaran to the early Cambrian, providing compelling evidence for the existence of firm substrate during this time. Meanwhile, the blooming of unattached macroalgae in the Chengjiang biota suggests that other niches were also rich in macroalgae. Unattached macroalgae might have provided oxygen and energy to metazoans, eventually leading to ecological expansion in the upper and middle water column of the early Cambrian seas. [ABSTRACT FROM AUTHOR]

The sustainable meeting of the global quest for ruminant intensification dictates the need to identify alternative, eco-friendly, and safe feed ingredients. In this sense, macroalgae offer a new paradigm in sustainable ruminant feed supply. This study aimed to investigate the potential of sub-Antarctic macroalgae, including Lessonia flavicans, Macrocystis pyrifera, Gigartina skottbergii, and Ulva Lactuca, regarding their chemical composition, in vitro gas production, and CH4 production. A completely randomized design consisted of a 96 h (h) incubation that included four different species and a control (alfalfa hay) with buffered rumen fluid. In vitro total gas, fermentation characteristics, and CH4 production were evaluated. The highest and the lowest crude protein (CP) contents were for U. lactuca (185.9 g/kg) and G. skottsbergi (86 g/kg), respectively (p < 0.0001). All macroalage had lower levels of natural detergent fiber (NDF) and acid detergent fiber (ADF) compared to alfalfa hay (p < 0.0001). The highest potential of gas production (b) was for M. pyriphera (162.8 mL gas/g DM), followed by alfalfa (119.3 mL gas/g DM). However, G. skottsbergi and M. pyriphera showed the highest dry matter degradability at 96 h (68.49 and 67.62 mg/100 mg, respectively; p < 0.0001) and microbial crude protein (679.8 and 669.8 mg/g, respectively, p < 0.0001). All four tested algae produced lower amounts of methane compared to alfalfa hay (p < 0.0001). After 24 h of incubation, M. pyriphera, L. flavicons, G. skottsbergi, and U. lactuca reduced CH4 by 99.7%, 98.6%, 92.9%, and 79.8%, respectively, when compared with the control. Also, all tested algae had lower (p = 0.0001) CH4 production (ml CH4/g Dry matter degradability, DMD) than alfalfa hay. The current results suggest that M. pyriphera and L. flavicons are promising feed additives for ruminants with eco-friendly production and acceptable CP content and DMD that could effectively mitigate CH4 emissions. Overall, these findings suggest that macroalgae hold promise as a substitute feed source for sustaining ruminant production at the onset of global warming. [ABSTRACT FROM AUTHOR]

Seabirds are important vectors for nutrient transfer across ecosystem boundaries. In this seasonal study, we evaluate the impact of an Arctic colony (Alkhornet, Svalbard) of Black-legged Kittiwakes (Rissa tridactyla) and Brünnich's Guillemots (Uria lomvia) on stream nutrient concentrations and fluxes, as well as utilization by coastal biota. Water samples from seabird-impacted and control streams were collected regularly throughout the melt season (June–September) for nutrient and organic carbon analysis. Stable carbon and nitrogen isotope analysis (δ13C and δ15N) was used to assess whether seabird-derived nitrogen (N) could be traced into filamentous stream algae and marine algae as well as consumers (amphipods). Concentrations of nitrate (NO3−) and nitrite (NO2−) peaked in July at 9200 µg N L−1 in seabird-impacted streams, 70 times higher than for control streams. Mean concentrations of phosphate (PO43−) in seabird-impacted streams were 21.9 µg P L−1, tenfold higher than in controls. Areal fluxes from seabird-impacted study catchments of NO3− + NO2− and PO43− had estimated ranges of 400–2100 kg N km−2 and 15–70 kg P km−2, respectively. Higher δ15N was found in all biota collected from seabird-impacted sites, indicating utilization of seabird-derived nitrogen. Acrosiphonia sp. from seabird-impacted sites had higher δ15N values (20–23‰ vs. 3–6‰) and lower C:N ratios (10.9 vs. 14.3) than specimens collected from control sites, indicating reliance on seabird-derived nitrogen sources and potentially higher N-availability at seabird-impacted nearshore sites. Our study demonstrates how marine nutrients brought onshore by seabirds also can return to the ocean and be utilized by nearshore primary producers and consumers. [ABSTRACT FROM AUTHOR]

Qatar and other Gulf States have a diverse range of marine vegetation that is adapted to the stressful environmental conditions of seawater. The industrial wastewater produced by oil and gas activities adds further detrimental conditions for marine aquatic photosynthetic organisms on the Qatari coastlines. Thus, these organisms experience severe stress from both seawater and industrial wastewater. This review discusses the biodiversity in seawater around Qatar, as well as remediation methods and metabolic pathways to reduce the negative impacts of heavy metals and petroleum hydrocarbons produced during these activities. The role of microorganisms that are adjacent to or associated with these aquatic marine organisms is discussed. Exudates that are released by plant roots enhance the role of microorganisms to degrade organic pollutants and immobilize heavy metals. Seaweeds may have other roles such as biosorption and nutrient uptake of extra essential elements to avoid or reduce eutrophication in marine environments. Special attention is paid to mangrove forests and their roles in remediating shores polluted by industrial wastewater. Seagrasses (Halodule uninervis, Halophila ovalis, and Thalassia hemprichii) can be used as promising candidates for phytoremediation or bioindicators for pollution status. Some genera among seaweeds that have proven efficient in accumulating the most common heavy metals found in gas activities and biodegradation of petroleum hydrocarbons are discussed. [ABSTRACT FROM AUTHOR]

Macroalgae and phytoplankton support the base of highly productive nearshore ecosystems in cold-temperate regions. To better understand their relative importance to nearshore food webs, this study considered four regions in the northern Gulf of Alaska where three indicator consumers were collected, filter-feeding mussels (Mytilus trossulus), pelagic-feeding Black Rockfish (Sebastes melanops), and benthic-feeding Kelp Greenling (Hexagrammos decagrammus). The study objectives were to (1) estimate the proportional contributions of macroalgal and phytoplankton organic matter using carbon and nitrogen stable isotopes, (2) determine if macroalgal use affected consumer growth using annual growth rings in shells or otoliths, and (3) describe changes in organic matter use and growth during the Pacific Marine Heatwave (PMH; 2014–2016) in one consumer, mussels. Macroalgae were the major organic matter source (> 60%) to the diet for all three consumers. The relationships between macroalgal contribution and growth were neutral for both fish species and significantly positive for mussels. During the PMH, mussels had a drop (> 10%) in macroalgal contributions and grew 45% less than in other time periods. Simultaneously, the relationship between macroalgal contribution and mussel growth was strongest during the PMH, explaining 48% variation compared to 3–12% before or after the PMH. Collectively, the results suggest that macroalgae is likely more important to cold-temperate nearshore food webs than phytoplankton. Management actions aimed at conserving and expanding macroalgae are likely to benefit nearshore food webs under all climate scenarios and especially during marine heatwaves. [ABSTRACT FROM AUTHOR]

Extensive use of dyes by the textile industries poses a serious threat to the aquatic flora and fauna. Low‐cost bio‐sorbent derived from marine red, Gracilaria verrucosa (RAC), and green macroalgae, Enteromorpha intestinalis (GAC) have been used for effective removal of unsafe Malachite Green (MG) dye. Batch study was conducted to determine the different bio‐sorption parameters such as biochar dosage, pH, initial concentration of MG, and contact time including MG bio‐sorption capacities. The physicochemical characterization results show the presence of lower crystallite sizes, and active functional groups such as carbonyl, hydroxyl, carboxyl, sulfate and amine with the mesoporous morphology of the algal biochar. The FT‐IR, XRD and SEM analyses were also performed to characterize the structural investigation of adsorbents. The kinetics of adsorption such as pseudo‐first‐order and pseudo‐second‐order were analyzed and pseudo‐second‐order confirms about the nature of process to be chemisorption. The bio‐sorption test for 20 mg/L of initial MG at an equilibrium time of 90 min by RAC showed maximum removal efficiency of about 97.49% at pH 8 whereas GAC showed a removal efficiency of 93.37% at pH10. Thus, marine macroalgae RAC and GAC can be a substitute for the commercially available adsorbents for degradation of dyes from textile effluents. [ABSTRACT FROM AUTHOR]

According to European Union guidelines, the assessment of the ecological status of Transitional Water Systems (TWSs) should be based on the monitoring of biological communities rather than physico-chemical parameters and pollutants. Macrophytes, including aquatic angiosperms and macroalgae, are organisms that respond more quickly to environmental changes by varying the structure and biomass of their assemblages. There are several ecological indices based on macrophytes, among them the Macrophyte Quality Index (MaQI), which has been intercalibrated with water and sediment parameters, nutrient concentrations, and pollutants and is used to determine the ecological status of Italian TWSs. In the Venice Lagoon, it was applied to 87 stations, showing a significant score increase over the last ten years of monitoring (2011–2021) due to progressive lagoon environmental recovery. The dominant taxa assemblages, previously dominated by Ulvaceae, were replaced by species of higher ecological value, with an increase in the number and distribution of sensitive species, as well as the spread and cover of aquatic angiosperms. The rise in the Ecological Quality Ratio (EQR) determined by the MaQI confirms the key role of macrophyte monitoring in detecting environmental changes in TWSs. In fact, a simple check of the presence or absence of aquatic angiosperms and sensitive species is sufficient for an initial rapid assessment of the ecological status of these environments. [ABSTRACT FROM AUTHOR]

Rabbit meat production faces challenges due to the prevalence of gastrointestinal diseases in rabbits, exacerbated by restrictions on antibiotic use in European animal production. Marine macroalgae, rich in bioactive compounds such as soluble polysaccharides, represent promising solutions to this problem. However, research on the effects of macroalgae and the underlying mechanisms in rabbits is limited, especially in commercial settings. This study aimed to evaluate the impact of Saccharina latissima (dehydrated) and Ulva lactuca (dehydrated and hydrolyzed extract) on rabbit on growth performance and gut health in a commercial farm context. A total of 96 litters (8 rabbits/litter) of crossbred rabbits weaned at 33 days of age were randomly assigned to 4 experimental groups (control, Saccharina latissima dehydrated, Ulva lactuca dehydrated and Ulva lactuca hydrolyzed extract; 24 replicates/treatment) and monitored from weaning to slaughter at 61 days of age. The key indicators of gut health were assessed 14 days post-weaning by counting coccidia, isolating specific microflora and examining histological samples. Additionally, the relevant intestinal markers (microbiome composition, mucin content and gene expression related to immune response and tight junction proteins) were determined in order to elucidate the potential mechanisms involved. The inclusion of macroalgae in the diet did not influence growth performance of the animals. S. latissima had a positive effect in reducing coccidia counts (p = 0.10) and improving mucosal morphology (p < 0.001), which can possibly be attributed to modulation of the microbiota and improved mucosal functionality. Ulva lactuca had a favorable effect on gut tight junction proteins (p < 0.001), enhancing intestinal barrier function. These findings suggest the potential of macroalgae to modify the intestinal microbiome by reducing the presence of inflammatory bacteria. Further research is warranted to elucidate the mechanisms involved and optimize macroalgae supplementation in rabbit nutrition for enhanced gut health. [ABSTRACT FROM AUTHOR]

Waters polluted with Pb and Cd have a negative impact on the environment. Padina australis grows abundantly on the coast of Palang Subdistrict, Tuban, and the local community consumes it. Macroalgae as food must be free of metal contamination. This study aims to determine the impact of Pb and Cd bioaccumulation on P. australis. Sampling was conducted at two stations, including Station I, Panyuran Village, and Station II, Glodog Village. Analysis of Pb and Cd metal levels using Atomic Absorption Spectrophotometry (AAS). Analysis of protein content using the Kjeldahl method. The data obtained was analyzed with Principle Component Analysis (PCA). The results of the analysis of Pb and Cd levels in P. australis at station II, which are 0.200 ± 0.028 and 0.021 ± 0.004 mg.kg-1 higher than station I, which are 0.194 ± 0.015 and 0.010 ± 0.001 mg.kg-1. The protein content of P. australis at station I was 4.713 ± 0.508 mg.kg-1, and at station II was 5.900 ± 0.928 mg.kg-1. This shows that P. australis is still considered good for consumption even though it has been polluted and contains Pb and Cd metals. P. australis can tolerate and does not experience severe physiological damage so it has the potential as a heavy metal phytoremediator. [ABSTRACT FROM AUTHOR]

Dakhla Bay is a paralic environment distinguished by various potentialities, including fishing, aquaculture, and tourism. However, the development of these human activities can lead to negative impacts on this environment, posing a threat to human health. This situation requires special attention to the environment and the implementation of a program for the protection and preservation of this ecosystem. This study aims to identify solutions to protect the marine environment from cadmium contamination by the macroalgae Gracilaria gracilis. The results of cadmium analyses in different compartments of Dakhla Bay, including bivalve molluscs, seawater, sediment, and macroalgae, indicate a difference in cadmium accumulation across the various studied compartments. The highest levels of cadmium are noted in macroalgae, with concentrations ranging from a minimum of 0.9 mg/kg fresh weight in the summer of 2019 to a maximum of approximately 2.55 mg/kg fresh weight recorded during the summer of 2022 at the Lassargua station. In comparison, bivalve molluscs such as Perna perna showed Cd levels ranging from 0.2 mg/kg to 1.4 mg/kg fresh weight at the same station. The sediment samples revealed average Cd levels ranging from 0.02 to 1.39 mg/kg dry weight in samples collected from Lassargua, while seawater concentrations were recorded at approximately 0.65 μg/L. The decontamination of cadmium by the macroalgae Gracilaria gracilis without impacting the quality of the algae has been well confirmed. Indeed, cadmium levels noted in macroalgae remain below the thresholds set by the regulations in force. In conclusion, the results of this study encourage the use of algocultures in Dakhla Bay to protect its ecosystem from various types of pollution.

Macroalgae (Ulva fasciata, Gracilaria corticata, and Sargassum wightii) were collected from the marine environment and used as the substrate for lactic acid production. These macroalgae were pretreated with hydrochloric acid (0.2 to 0.4 N) for various times (20 to 60 min). Additionally, the algal hydrolysate was incubated with cellulase for 24 h at 30 ± 1 °C to achieve enzymatic saccharification. Proximate analysis of these macroalgae was performed, and the yield was high in G. corticata. The G. corticata hydrolysate was composed of 10.01 ± 0.12% ash content, 1.25 ± 0.2% total fat, 10.2 ± 0.1% crude protein, 9.2 ± 0.2% moisture content, and a higher level of total carbohydrate (69.33 ± 1.5%) than the other two macroalgae. In G. corticata, the enzymatic treatment showed the maximum reducing sugar (33.5 ± 2.3%) relative to the other macroalgal hydrolysates and was considered for optimization of lactic acid production. Lactobacillus acidophilus (MTCC447) utilized pretreated G. corticata hydrolysate (enriched with 5% yeast extract), and maximum lactic acid yield was achieved after 72 h, 30 °C incubation temperature, and 6% inoculum (1×108 CFU/mL) in static culture condition. Batch fermentation was performed in the 1-L bioreactor at room temperature (30 °C) for 96 h. Lactic acid production was maximum within 72 h and the pH value was depleted. The present finding indicates that G. corticata could be used as a substrate for lactic acid production.

Abstract Background Kelps are not only ecologically important, being primary producers and habitat forming species, they also hold substantial economic potential. Expansion of the kelp cultivation industry raises the interest for genetic improvement of kelp for cultivation, as well as concerns about genetic introgression from cultivated to wild populations. Thus, increased understanding of population genetics in natural kelp populations is crucial. Genotyping-by-sequencing (GBS) is a powerful tool for studying population genetics. Here, using Saccharina latissima (sugar kelp) as our study species, we characterize the population genetics at a fine geographic scale, while also investigating the influence of marker type (biallelic SNPs versus multi-allelic short read-backed haplotypes) and minor allele count (MAC) thresholds on estimated population genetic metrics. Results We examined 150 sporophytes from 10 locations within a small area in Mid-Norway. Employing GBS, we detected 20,710 bi-allelic SNPs and 42,264 haplotype alleles at 20,297 high quality GBS loci. We used both marker types as well as two MAC filtering thresholds (3 and 15) in the analyses. Overall, higher genetic diversity, more outbreeding and stronger substructure was estimated using haplotypes compared to SNPs, and with MAC 15 compared to MAC 3. The population displayed high genetic diversity (H E ranging from 0.18–0.37) and significant outbreeding (F IS ≤ − 0.076). Construction of a genomic relationship matrix, however, revealed a few close relatives within sampling locations. The connectivity between sampling locations was high (F ST ≤ 0.09), but subtle, yet significant, genetic substructure was detected, even between sampling locations separated by less than 2 km. Isolation-by-distance was significant and explained 15% of the genetic variation, while incorporation of predicted currents in an “isolation-by-oceanography” model explained a larger proportion (~ 27%). Conclusion The studied population is diverse, significantly outbred and exhibits high connectivity, partly due to local currents. The use of genome-wide markers combined with permutation testing provides high statistical power to detect subtle population substructure and inbreeding or outbreeding. Short haplotypes extracted from GBS data and removal of rare alleles enhances the resolution. Careful consideration of marker type and filtering thresholds is crucial when comparing independent studies, as they profoundly influence numerical estimates of population genetic metrics.

Abstract Seaweeds are the most phylogenetically diverse group of multicellular organisms and rank foremost among marine keystone species. Due to their taxonomic diversity and functional importance, previous studies have classified seaweeds into functional groups based on qualitative or semi-quantitative traits, such as seaweed form, anatomy, and thickness. Despite the widespread use of seaweed functional groups from basic marine ecology to coastal monitoring, it is not known how accurate such morphology-based proposals are in grouping seaweeds by their form. To address this uncertainty at the foundations of seaweed biology, we surveyed and gathered all available data on seaweed forms using PRISMA protocols. We used the surface area to volume ratio (SA:V), a quantitative and universal measure of seaweed form, to assess the distribution and diversity of seaweed morphology across 99 species from three phyla. We show that seaweed surface area to volume ratio values span 3.64 orders of magnitude and follow a continuous and exponential distribution, without any significant gaps or clusters. We also tested current functional group schemes based on morphology and anatomy and showed that only 30% to 38% of their groups showed any significant pairwise differences in morphology. Our results challenge the basis of the current functional group approach in seaweed biology and suggest that a trait-based framework based on quantitative and continuous measures of seaweed form could provide a simpler and more accurate alternative to functionally assess seaweed ecology and physiology, as well as its implications for coastal ecosystem management.

Abstract Low-cost and green preparation of efficient sorbents is critical to the removal of organic contaminants during water treatment. In this study, the co-pyrolysis of macroalgae and oyster shell was designed to synthesize nitrogen-doped porous biochars for sorption removal of atrazine from water. Oyster shell played a significant role in opening pores in macroalgae-derived biochars, resulting in the surface area of the macroalgae (Enteromorpha prolifera and Ulva lactuca) and oyster shell co-pyrolyzed carbonaceous as high as 1501.80 m2 g−1 and 1067.18 m2 g−1, the pore volume reached 1.04 cm3 g−1 and 0.93 cm3 g−1, and O/C decreased to 0.09 and 0.08, respectively. The sorption capacity of atrazine to nitrogen-doped porous biochars (the Enteromorpha prolifera, Ulva lactuca and oyster shell co-pyrolyzed carbonaceous) reached 312.06 mg g−1 and 340.52 mg g−1. Pore-filling, hydrogen bonding, π-π or p-π stacking and electrostatic interaction dominated the multilayer sorption process. Moreover, the nitrogen-doped porous biochars showed great performance in cyclic reusability, and the Enteromorpha prolifera, Ulva lactuca and oyster shell co-pyrolyzed carbonaceous sorption capacity still reached 246.13 mg g−1 and 255.97 mg g−1, respectively. Thus, this study suggested that it is feasible and efficient to remove organic contaminants with the nitrogen-doped porous biochars co-pyrolyzed from macroalgae and oyster shell, providing a potential green resource utilization of aquatic wastes for environmental remediation. Graphical Abstract

Seaweed aquaculture is becoming increasingly important as the global seaweed market is set to exceed £20 billion by 2030, leaving natural populations at risk of overexploitation. Fucoids, such as Fucus serratus, are intertidal seaweeds hand-harvested for their use in agricultural, pharmaceutical, and biomedical industries. Despite many aspects of the biology of fucoids being well researched, there have been very few studies on their aquaculture. In this study, we grew F. serratus biomass from gamete life stages in the Queen’s University Marine Laboratory for 8 months and monitored their growth, amino acid and phenolic contents in a subtidal field trial. Gametes of F. serratus were successfully fertilized in vitro and attached to substrata: Tiles (mesocosm) and Dyneema Twine (subtidal). The growth of F. serratus on each substrate was monitored for 6 months in the laboratory facility with juveniles reaching 2–4 mm in length. The juveniles on twine were then deployed at the Strangford Lough test site and growth was compared against the juveniles on tiles after an additional two months. Prior to field deployment, individuals grown on tiles were significantly longer (~17%) than those on twine growing to ~3 cm, however, after the two-month deployment, the twine thalli grew significantly longer than those on the tiles (~33%) reaching ~6 cm in length. Subtidal F. serratus grown on twine had significantly higher amino acid content, whereas the phenolic content was significantly lower (~62 mg PGE g−1) than seaweed grown on the tiles (~128 mgPGE g−1). Growing F. serratus successfully in subtidal areas is highly important for providing sustainably sourced biomass to reduce reliance on wild harvesting. Further, cultivating in the subtidal zone will help to avoid competition for space from other aquaculture industries operating in the intertidal zone.