Intertidal fucoid algae function as ecosystem engineers across temperate marine regions. In this investigation we assess the function of the alga dominating rocky reefs in temperate Australia and New Zealand, Hormosira banksii. Invertebrate and algal species assemblages were examined within areas of full H. banksii canopy, areas where it was naturally patchy or absent (within its potential range on the shore) and areas where the intact canopy was experimentally disturbed. Differences in its species assemblage were detected between areas with natural variation in H. banksii cover (full, patchy, absent), with defined species associated with areas of full cover. Differences were also detected between experimentally manipulated and naturally patchy areas of canopy cover. Species richness declined strongly following canopy manipulations, and did not recover even twelve months after initial sampling. Both light intensity and temperature were buffered by full canopies compared to patchy canopies and exposed rock. This study allows us to predict the consequences to the intertidal community due to the loss of canopy cover, which may result from a range of disturbances such as trampling, storm damage, sand burial and prolonged exposure to extreme temperature, and further allow for improved management of this key autogenic ecosystem engineer.

The decline of fossil fuels, the increase of greenhouse gases and the global demand for energy are driving the search for alternative energy sources. Anaerobic digestion is a promising technology because it can convert organic biomass into biogas. As the climate warms, there is an increase in biomass of plant origin in water bodies, and ecosystems are unable to clean themselves. This work aims to show that macroalgae and aquatic plants can be an excellent raw material for biogas production. By mixing them with co-substrates such as cattle manure, higher biogas and methane yields can be obtained. When Cladophora glomerata and Zostera marina macroalgae are mixed with cattle manure, the biogas yield is up to 458.8 mL/gVS and 397.9 mL/gVS, respectively. Methane concentration remained high and reached 62.4%–64.1%. The obtained research results show the high energy value of biogas and the energy potential of biomass. Macroalgae increased the energy potential of biogas to 22.9 MJ/m3, and the energy potential of biomass reached 2.40 MJ/Kg. Due to its high energy value, biogas produced from the considered substrates can be an excellent alter-native to fossil fuels. Integrating aquatic macroalgae into anaerobic digestion is a promising approach for a waste-free marine and freshwater system.

Some current systematized reviews of macroalgae are concise and descriptive, but it is important to conduct these of a larger number of taxa to facilitate visualizations of the types of primordial research, relevant methods, and areas of opportunity. The aim was to elaborate the state of the art in the taxonomic knowledge of Dictyota based on a systematized review of the generated information since its original description (1809 to 2023). We conducted a search for names and literature in different databases, followed by a temporal analysis (by century and bidecadal). To date, a total of 313 names have been registered for Dictyota; 108 are accepted names. The largest number of registered taxonomic names (207) was found for the 19th century, derived from large expeditions. Our analysis of literature involved 318 publications, 89 of which corresponded to alpha taxonomy, 187 to beta, and 42 to gamma. We determined that the trend in taxonomic works is integrative in nature because they include other disciplines to explain aspects that go beyond taxonomic description. Our analysis suggests that extensive reviews and monographic approaches are still required to achieve a better understanding of the genus. The effort in integrative taxonomy must be intensified, which allow improve the systematic of Dictyota.

: Seaweeds are among the most important biomass feedstocks for the production of third generation biofuels. They are also efficient in carbon sequestration during growth, and produce a variety of high value chemicals. Given these characteristics together with the relatively high carbohydrate content, seaweeds have been discussed as an ideal means for CO2 capture and biofuel production. Though third generation biofuels have emerged as some of the best alternatives to fossil fuels, there is currently no large-scale production or mainstream use of such liquid fuels due to the many technical challenges and high production costs. The present study describes the concept of coastal marine biorefineries as the most cost-effective and sustainable approach for biofuel production from sea-weeds as well as atmospheric carbon capture and storage (CCS). The suggested refinery system makes use of marine resources, namely seawater, seaweed, and marine microorganisms. Firstly, extensive screening of the current literature was performed to determine which technologies would enable the emergence of such a novel biorefinery system and its merits over conventional refineries. Secondly, the study investigates various scenarios assessing the potential of seaweeds as a means of carbon sequestration. We demonstrate that the removal of 100 Gigatons of excess CO2 using seaweed farms can be achieved in around 4 months to less than 12 years depending on the area under cultivation and the seaweed species. The total bioethanol that could be generated from the harvested biomass is around 8 trillion litres. In addition, high-value chemicals (HVC) that could potentially be recovered from the process represent a considerable op-portunity with multi-billion-dollar commercial value. Overall, coastal marine biorefineries have strong potential for a sustainable green economy and rep-resent a rapid approach for climate change mitigation.

In the past decades, one of the most widely reported phenomena on Caribbean reefs is the general fall in coral cover and rise in macroalgae. Reefs with low coral cover and high macroalgal abun-dances are often presumed to provide poorer ecosystem functions and services. In this study, we assessed the condition of coral reefs on the Caribbean Coast of Costa Rica and determined how eight key ecosystem metrics varied in response to differential coral and fleshy macroalgae covers. Most reefs surveyed had high fleshy macroalgae and low live coral covers, with an average (± SD) of 31 ± 28% and 14 ± 13% per site. We found that the rugosity, urchin density, fish richness, total fish biomass, large fish density, and the potential fishery value of the reef were higher in sites with low fleshy macroalgae covers (>10%). The value of many of the ecosystem metrics estimated for coral reefs of the region appears to be lower than what’s been reported for other areas in the Caribbean, which may be related to the high macroalgae covers found on the reefs. Our results concur with the prevailing paradigm that an increase in macroalgae abundance could reduce the ecosystem services provided by coral reefs.

The cosmetic industry recognizes the importance of natural sources for functional active constit-uents in meeting consumer expectations for safer and more sustainable beauty care products. Ma-rine macroalgae have emerged as promising resources, offering diverse bioactive constituents with potential applications in cosmetics. In this study, we investigated the biochemical profile of Padina boergesenii, a marine macroalga, using various methods to assess its potential as a cosmetic ingre-dient. The Fourier Transform Infrared (FTIR) analysis revealed the presence of distinct bioactive functional groups associated with numerous skin-beneficial compounds. Furthermore, the ethanolic and methanolic extracts of P. boergesenii were subjected to Gas Chromatography-Mass Spectrom-etry (GC-MS) analysis, which identified a total of six and fifteen significant phytocompounds, re-spectively. Additionally, a comprehensive phytochemical profiling of P. boergesenii was performed using High-Resolution Liquid Chromatography-Mass Spectrometry Quadrupole Time-of-Flight (HRLCMS-Q-TOF), highlighting the presence of various terpenoids, alkaloids, peptides, fatty acids, derivatives, and coumarins with potential cosmetic applications. To further assess its potential as a cosmetic ingredient, P. boergesenii was subjected to several additional estimations. Pigment estima-tion revealed the presence of specific pigments, while the determination of total phenol content and total protein content highlighted the richness of these bioactive components. The antioxidant analysis using the DPPH method demonstrated the antioxidant potential of P. boergesenii extracts, suggesting their ability to combat oxidative stress-related skin damage. Moreover, the tyrosinase inhibition assay indicated the inhibitory effect of P. boergesenii extracts on tyrosinase activity, which is relevant for addressing hyperpigmentation concerns. Furthermore, the elemental composition of P. boergesenii was evaluated using Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-AES), revealing that silicon (Si) exhibited the highest concentration among the measured elements, while copper (Cu) displayed the lowest concentration. Additionally, HRLCMS-Q-TOF analysis was employed to quantify 21 amino acids, with aspartic acid exhibiting the highest con-centration (2034.99 nmol/mL), and tyrosine demonstrating the lowest concentration (233.26 nmol/mL). The accuracy of all the measured elements and amino acids was deemed acceptable. Taken together, the findings of this study highlight the potential of P. boergesenii as an effective ingredient for enhancing skin health. The incorporation of seaweed-based bioactive components, such as P. boergesenii, into cosmetic products is increasingly common due to their beneficial effects on the skin. Further exploration of the potential applications of P. boergesenii in the cosmetics in-dustry is warranted to harness its valuable bioactive properties.

Marine macroalgae have garnered significant attention in the field of cosmeceutical research due to their rich abundance of bioactive compounds. These compounds offer remarkable skin benefits without inducing any adverse effects on human health, such as cytotoxicity, reproductive toxicity, genotoxicity, mutagenicity, or carcinogenicity. Among the various bioactive compounds found in brown algae, phenolic compounds exhibit diverse chemical structures and are present in high concentrations. In addition to phenolic compounds, brown algae also contain terpenoids, bro-mophenols, mycosporine amino acids (MAAs), and flavonoids, with the well-studied poly-phenol compound, phlorotannin, being particularly prominent. Marine macroalgae further possess an array of pigments derived from their natural pigmentation, including chlorophylls, carotenoids (such as fucoxanthin and β-carotene), phycobiliproteins (such as phycoerythrin and phycocyanin), and melanin. These pigments have been extensively investigated for their potential cos-meceutical applications. The phenolic compounds and pigments derived from marine macroalgae have been thoroughly studied for their beneficial effects on the skin, including skin whitening, moisturizing, photoprotection, anti-aging, anti-wrinkle, anti-melanogenic, and anti-oxidant properties. This comprehensive review aims to explore the extraction, characterization, and skin cosmetic effects of phenolic compounds and pigments derived from marine macroalgae, as documented in the existing literature, thereby enhancing our understanding of their therapeutic potential.

The extraction method for simultaneously analyzing fatty acids (Myristic acid, cis-Palmitvaccenic acid, Palmitic acid, Palmitic-9,9-d2 acid, Oleic acid, Stearic acid and Stearic-2,2-d2 acid) related to biodiesel fuel in large algae was developed. The introduction of trimethylaminoethyl (TMAE) derivatives into the hydroxyl group (-OH) functional group of the analyte was able to improve ionization and obtain high sensitivity. Liquid Chromatography (LC) was used to investigate the optimal mobile phase composition and flow rate for the separation of five derived fatty acids. In this study, a solid phase extraction (SPE) column was introduced for efficient extraction of fatty acids, and the optimal conditions for SPE were set by comparing the recovery rate according to the solvent for each step (loading, washing, and elution) of SPE from macroalgae.

The red seaweed Asparagopsis armata exhibits a strong invasive behaviour and is included in the list of the “Worst invasive alien species threatening biodiversity in Europe”. This seaweed has been shown to produce a large diversity of halogenated compounds with effective biological effects, deeply affecting rockpool species. Therefore, the present study aimed to investigate the biochemical responses to sublethal concentrations of Asparagopsis armata exudate on two coastal organisms, the marine snail Gibbula umbilicalis and the rockpool shrimp Palaemon elegans. Antioxidant defences superoxide dismutase (SOD) and glutathione-S-transferase (GST), oxidative damage endpoints lipid peroxidation (LPO) and DNA damage, the neuronal parameter acetylcholinesterase (AChE), as well as the fatty acid profile were evaluated. Results revealed different metabolic responses between species, indicating that A. armata exudate affected the organisms through different pathways. Despite previous studies indicating that the exudate effected G. umbilicalis’ survival and behaviour, this does not seem to result from oxidative stress or addressed neurotoxicity. On the other hand, for P. elegans, an inhibition of AChE and the decrease of antioxidant capacity concomitant with the increase of LPO, suggests neurotoxicity and oxidative stress as mechanisms of exudate toxicity for this species. For fatty acids, there were different profile changes between species, also more pronounced for P. elegans with a general increase in PUFA with exudate exposure, which commonly means a defence mechanism protecting from membrane disruption. Nonetheless, the omega-3 PUFAs ARA and DPA were increased in both invertebrates, indicating a common mechanism regulation of inflammation and immunity responses to this stress. This work provides further insight on the mechanisms of invertebrate response and tolerance to an expanding coastal environmental stress as is the marine invader A. armata.