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Extracts that were obtained with solvents of increasing polarity (hexane, dichloromethane, methanol, 80% methanol, and water) from the red macroalga Gracilaria domingensis were evaluated by reducing power with ferric reduction antioxidant power (FRAP) and Folin–Ciocalteu (FC) assays, lipid peroxidation inhibition by β-carotene-linoleic acid assay, and metal chelating ability based on the iron-ferrozine system. The highest antioxidant capacity was reported for the hexane (Hx) extract by the FRAP, metal chelating, and lipid peroxidation inhibition assays. An activity-guided fractionation of the Hx extract was carried out for the identification of its active constituents. The primary components were the most active antioxidant compounds. Despite the high antioxidant activities, the Hx extract was not active in the FC assay. In this assay, the activities were found in the methanol (M) and 80% methanol (80M) extracts. The FC assay is commonly used to measure the total phenolic compounds. However, no phenolic compounds were detected by GC-MS and HPLC analyses in the M and 80M extracts. Thus, non-phenolic components influenced the FC assay. The M and 80M extracts showed high content of mycosporine-like amino acids (MAAs). A fraction contained two MAAs (porphyra-334 and shinorine) (156 mg GAE·g−1) showed a similar performance to the values that were found for well-known antioxidants (BHT = 156 mg GAE·g−1 and Trolox = 166 mg GAE·g−1) and 30 times higher than those of the original extracts (~5 mg GAE·g−1) in the FC assay. Thus, MAAs contribute to the antioxidant activities that were observed in the FC assay within the studied samples. Together, these results advance our understanding of the antioxidant properties of algal extracts.

Abstract The potential of seaweed extracts in cosmetic applications have increased with novel development and market. Beneficial biological properties include the ability to struggle aging and anticancer agents. This research aimed to evaluate antioxidant, photoprotective and cytotoxic properties of extracts from beach-cast seaweed species from the Brazilian coast in order to propose an appropriate use of this sustainable resource. Analysis of antioxidant capacity, UV/VIS absorption, quantification of UV photoprotectors, total content of C, N and S, development of cosmetic creams and evaluation of the cytotoxicity activity against tumoral cells lines were performed. The highest antioxidant capacity was found in extracts of brown seaweeds, followed by red seaweeds, with the lowest activity detected in the green seaweed. Same pattern was observed for phenolic compounds. The extracts did not show cytotoxicity activity against healthy human cells. Other forms of extraction and incorporation of the extract into the base creams should be evaluated, the isolation and purification of substances could increase the efficiency of the photoprotective capacity. The species were highly promising and proved to be natural sources of antioxidants and substances with cytotoxicity activity against tumoral cells; therefore, they could be exploited as functional ingredients with specific applications for different types of industries. The application of seaweed extracts in combination with other natural ingredients can help in the design of new cosmetics against the negative effects of UV radiation, in addition to having the great advantage of not presenting toxicity to health or the environment because they are biodegradable. Graphical Abstract

Beach-cast marine algae are a potential biomass for several biofunctional products and occur in large volumes in some coastal regions due to natural current processes or drifting algae like pelagic Sargassum. Antioxidant activity and chemical composition of methanolic and aqueous extracts from fifteen beach-cast marine algae from the Brazilian Coast were evaluated. In general, the highest antioxidant activities were found in extracts from brown macroalgae followed by the extracts of red algae, and the lowest activities were detected in the green beach-cast algae. The concentrations of phenolic compounds and carbohydrates exhibited a positive correlation with the antioxidant activities of the tested extracts. To the best of our knowledge, this is one of the few worldwide studies concerning beach-cast seaweeds and antioxidant activity and related antioxidant metabolites. This study suggests that these algae are potential sources for obtaining extracts with antioxidant properties, rich in phenolic compounds and sulfated carbohydrates. Beach-cast macroalgae are unused biomass and the beneficial utilization of this biomass for prospection of natural products and functional foods is suggested.

Stressful conditions, such as mechanical damage, can significantly compromise the survival of algal beds by reducing their biomass, reproductive output, and even altering their production of defensive chemical compounds. In the present work, the effect of different intensities of trampling (no trampling, low and high trampling intensities) on reproduction, morphology, and phenolic content of Sargassum species was studied in three sites along the southwestern Atlantic Coast, Brazil, from March to October 2015. The parameters were evaluated in distinct periods (0, 90, and 180 days) after trampling, using 40- × 40-cm quadrats along transects. Trampling reduced algal reproductive biomass in two of the three studied sites (Pernambuco and Fortaleza beaches) shortly after the experimental treatment (T0). The mean thallus length was higher in trampled plots in all study sites, and the dry biomass of the individuals were higher in Pernambuco and Cigarras beaches, which also presented lower phenolic levels after damage. These results suggest a probable trade-off in resource allocation, with an immediate compromise of the individuals’ reproduction followed by a decrease in the production of defense compounds, probably due to an investment in damage repairing of vegetative portions, maximizing the individuals’ survival in the long term. Although the individuals reach larger sizes, they reproduce less and are more susceptible to other sources of stress that can compromise Sargassum spp. fitness.

In this study, we analyzed the antioxidant activity and total phenolic content of the intertidal seaweed Palisada perforata collected from different reef microhabitats (sheltered site, tide pool, plateau, and exposed site) along the coast of Pernambuco (Brazil). Both parameters were compared with the same parameters of this species grown in the laboratory under two experiments simulating temperature, salinity, and desiccation conditions found in the reef. After both experiments (temperature x salinity and desiccation), the algal photosynthetic performance was measured through chlorophyll fluorescence parameters using a pulse-amplitude modulation fluorometer to test their stress response. Palisada perforata likely underwent stress by desiccation due to tidal fluctuations rather than to temperature or salinity changes. This conclusion agrees with our observations of the plateau site´s specimens, which were exposed to both air and UV radiation during low tides and exhibited higher antioxidant activity to avoid oxidative damage. However, despite the environmental stress, the antioxidant activity remained low, suggesting that photoinhibition is a crucial protection mechanism against oxidative damage.

Every day, tons of caffeine is consumed by humans in beverages, medications or supplements, and a significant amount of this stimulant is released in domestic sewage. Once in aquatic environments caffeine interacts directly with the periphytic community, which is responsible for a significant part of primary production in aquatic ecosystems. However, the effects of exposure to caffeine are mostly unknown for both the periphyton and their predators. Aiming to comprehend the interaction between caffeine and the periphytic community, ecotoxicological experiments were performed by exposing a periphytic biofilm cultivated in the laboratory to different concentrations of caffeine, following concentrations found in domestic sewers. The impact of exposure to this contaminant was observed on the structure of the community through taxonomic evaluation, as well a set of physiological variables linked to primary production. After exposure to the highest caffeine concentration (300 µg L−1), the density of the genus Scenedesmus was severely affected, leading to an increase in cyanobacteria and diatoms. Both richness and diversity decreased after exposure, and there was lower photosynthetic activity, with light saturation point changing from 186 µmol m−2 s−1 in the control treatment to 108 µmol m−2 s−1 after exposure. Caffeine accumulation within the biofilm was also observed during the first 24 h, in the concentration of 0.14 µg /cm².

Kappaphycus alvarezii was introduced for mariculture purposes on the coast of São Paulo, southeast of Brazil, in 1995, and since then an experimental pilot cultivation has been maintained. Since it is an exotic species, the dispersion of thallus fragments, presence of reproductive structures and recruitment from spores were monitored bimonthly from November 2016 to January 2018. Fragment dispersion was analyzed on nine selected monitoring sites around the cultivation raft through visual observation and photographic records. To verify the presence of reproductive structures 40 individuals were collected randomly from the cultivation raft and analyzed under a light microscope and stereomicroscope. Reproductive structure recruitment was also evaluated using artificial substrata. The results showed that even 25 years after the introduction of K. alvarezii on the coast of São Paulo, the invasive behavior of this exotic species had not been recorded. There was no evidence of vegetative dispersion and/or establishment in the Ubatuba Bay. Reproductive structures were also not found during the monitoring period. However, we highlight the importance of permanent and systematic environmental monitoring to prevent any impact and to ensure a sustainable aquaculture. These results will contribute to the development of the cultivation of the non-native K. alvarezii in Brazil and to improving public policies of coastal management.

Sargassum species form extensive benthic beds in tropical and subtropical low intertidal and subtidal zones, acting as important drivers for marine community structure. Temperature, as one of the most important abiotic factor, affects seaweed performance and triggers changes in metabolic responses; therefore, laboratory experiments involving temperature ranges are tools for understanding seaweed engineering. The aim of this study was to assess the physiological vulnerability and sensitivity of Sargassum stenophyllum C. Martius exposed to five different temperatures by analyzing photosynthetic performance and chemical composition related to carbon and nitrogen metabolism. There were no significant differences in energy quenching between treatments, except at 35 °C, which showed decreased photochemical quenching and increased non-regulated non-photochemical quenching. Chlorophyll a and chlorophyll c at 15 °C and 35 °C exhibited lower amounts at the end of experiment. Protein content showed progressive diminution in the treatments. Total soluble carbohydrates content showed higher concentration as temperature increased. After 7 days, total amino acid content showed increase from 15 °C to 30 °C. No generalization between the amino acid patterns, although glutamine and glutamate content at 15 °C and 35 °C were reduced; and the highest values of isoleucine and leucine were detected at 35 °C. We postulated that accumulation of certain chemical compounds in S. stenophyllum results from a reallocation of carbon and nitrogen, osmoregulation responses and protection against oxidative stress. Results suggest this species’ tolerance ranges between 15 °C and 30 °C and sensitivity at 35 °C.

Macroalgae produce a large range of primary and secondary metabolites with ecological and economical importance. Studies on antioxidants from marine algae have increased notably, focusing on searching new sources of natural compounds for different applications, in which tropical species have been shown to have high potential, often improved by stressful environmental conditions during the tide cycle with periods of emersion and submersion. Therefore, in order to characterize the antioxidant activity and relate it to local environmental tide exposure, three species of brown marine algae, Canistrocarpus cervicornis, Dictyopteris delicatula, and Lobophora variegata from two beaches on the northeast coast of Brazil were studied. Dichloromethane:methanol (DCM:M) and aqueous extracts were tested for ferric reducing antioxidant power, 2,2-diphenyl-1-picrylhydrazyl, and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) antioxidant assays and total phenolic compounds. Aqueous extracts of C. cervicornis showed up to 10 times major antioxidant activity and phenolic compounds than DCM:M extracts. Different characteristic of antioxidant activity were identified among the beaches, species, and extracts, in which aqueous extracts from C. cervicornis and L. variegata showed the most promising matrices for future prospection of natural antioxidants.

is one of the most farmed algae globally. It is used almost exclusively for the carrageenan industry, although there is increasing interest in its biotechnological application as a natural product ...

In some coastal areas, large quantities of beach-cast macroalgae can accumulate and are usually considered waste and disposed of. However, due to their biofunctional and nutritional properties, they have great potential as a new source of raw materials. Increasing population growth has made the search for alternative raw materials with valuable nutritional properties urgent; here, beach-cast macroalgae could provide great potential. Our research goal was to characterize the nutritional profile of 12 beach-cast seaweed species from the Brazilian coast to assess their potential valorization. A considerable number of nutritional compounds was observed, such as ash (6.5–59.3%), total dietary fibers (22.1–65.8%), proteins (5.1–21.5%), and carbohydrates (31.4–81.0%), with an expressive abundance of minerals, free amino acids, and fatty acids. Spatoglossum schroederi and Alsidium seaforthii showed protein contents of 21.5 ± 0.2%, 19.7 ± 0.1%, and high amounts of total dietary fiber of 59.2 ± 0.4%, 61.7 ± 4.9%, respectively. The overall profile suggests that beach-cast seaweeds are suitable for nutritional and other bioeconomical purposes, to which different species with different characteristics contribute. Contamination of these seaweeds with unwanted toxic compounds like micropollutants was not studied. However, this must be considered before they are used for human consumption.

Seaweeds are a source of antioxidants and pigments, which can be used as functional ingredients for food, cosmetic, pharmaceutical, and industrial applications. As fresh seaweed has a large amount of water, it usually goes through a drying process in order to be commercialized, which facilitates transportation and storage and also increases shelf time. However, the drying procedures can change the chemical composition and antioxidant properties of seaweeds. Thus, the aim of this study was to evaluate the antioxidant properties and pigment and protein content of four Brazilian macroalgae (Gracilariopsis tenuifrons, Pterocladiella capillacea, Sargassum stenophyllum, and Ulva fasciata) suitable for use as functional bioproducts after processing with three different drying procedures (freeze-drying, oven-drying and silica-drying), using a fresh frozen treatment as control. Among the studied species, S. stenophyllum presented the highest antioxidant activity. For this species, freeze-drying was the procedure with the highest activity in the Folin-Ciocalteu and metal chelating assays, while for the ABTS, DPPH, and FRAP assays, no significant differences were observed between freeze-drying and silica-drying. Freeze-drying also showed low reduction of photosynthetic pigments in G. tenuifrons, P. capillacea, and U. fasciata and was the method that best-preserved protein content in the four species. In general, the antioxidant potential and pigment and protein content for the studied algae decreased in the following order: fresh frozen (control) > freeze-dried > silica-dried > oven-dried. Freeze-drying was the procedure that presented the lowest alteration in functional properties, as the low temperature prevents the degradation of heat-sensitive compounds. In addition, freeze-drying is a vacuum process and the absence of oxygen prevents oxidation reactions of functional ingredients.

In Brazil species of Gracilaria play a social and economic role in some poor communities of the northeastern coast. Considering that these algae are typically consumed after depigmentation and drying, little is known about the chemical composition and nutritional value after processing. In the present study dried and depigmented samples of Gracilaria birdiae (GB), Gracilaria caudata (GC), Gracilaria domingensis (GD), and a commercially available sample of G. birdiae (C-GB), provided by a local community, were studied as a source of valuable compounds and as nutritional supplements. In nutritional terms, the dietary fiber and mineral contents of the studied algae were higher than those of the traditional foods in the standard Brazilian diet. The results suggest that these algae have functional properties and consequently may be used as a source of nutraceutical. GB and GC showed a high antioxidant potential, similar to that of some staple foods (e.g., cereals and legumes), but lower than that of rich-antioxidant foods (e.g., berries and nuts). The polysaccharides from both G. birdiae samples (GB and C-GB) showed a low sulfation degree and higher yields, suggesting that they are a good source of agar. GB was also rich in mycosporine-like amino acids (MAAs), mainly porphyra-334. In contrast, C-GB contained the lowest values of MAAs and antioxidants. The reduction in these compounds may compromise the use of C-GB for other purposes such as cosmetic production. However, the sample of C-GB showed the highest potential as a source of dietary fiber and agar. In general, the analyzed species are alternatives to traditional foods and a source of valuable compounds.

The training of biologists is strongly based on a face-to-face curriculum, including numerous hands-on laboratory and field activities. This structure was abruptly changed by the 2020 pandemic, forcing us to move to emergency remote teaching (ERT). We survived and adapted, and we can now seize the opportunity to reflect on our teaching practices. How about we take advantage of what we learned in the heart of the battle and think about adopting the blended learning approach in the course of Biological Sciences at IB-USP? Just as biological and cultural evolution occur;it is only natural that our teaching practices and the teaching-learning processes also evolve. We had hits and misses with ERT, and these experiences allowed us to embrace adaptation, transforming our teaching practices. Surely, adopting the blended learning approach in a biology course, by definition, does not involve abolishing hands-on activities that foster fundamental skills and competences of the professional biologist. Therefore, we do not advocate here for a full migration to distance education (DE) or massive open online courses (MOOC), but rather to the incorporation of educational technology tools, used during the ERT, within traditional place-based teaching methods. Crucially, blended learning has the potential to improve teaching practices in higher education courses. For example, it allows each student to become an autonomous learner where they can establish their own pace of study and take an active role in the exploration of new content. As a consequence, this can increase student performance in hands-on laboratory and field activities, and other activities that are more productive in person. In blended learning, most of the content is passed on remotely, making the learning experience more enjoyable and enabling the construction of knowledge in a more collaborative, active and integrated way. In summary, it is clear that we are facing one of the greatest challenges of our era but, fortunately, we have the opportunity to combine our experiences and improve our teaching practices, while promoting social acceptance and inclusive classrooms.

In this study, we analyzed the antioxidant activity and total phenolic content of the intertidal seaweed Palisada perforata collected from different reef microhabitats (sheltered site, tide pool, plateau, and exposed site) along the coast of Pernambuco (Brazil). Both parameters were compared with the same parameters of this species grown in the laboratory under two experiments simulating temperature, salinity, and desiccation conditions found in the reef. After both experiments (temperature x salinity and desiccation), the algal photosynthetic performance was measured through chlorophyll fluorescence parameters using a pulse-amplitude modulation fluorometer to test their stress response. Palisada perforata likely underwent stress by desiccation due to tidal fluctuations rather than to temperature or salinity changes. This conclusion agrees with our observations of the plateau site´s specimens, which were exposed to both air and UV radiation during low tides and exhibited higher antioxidant activity to avoid oxidative damage. However, despite the environmental stress, the antioxidant activity remained low, suggesting that photoinhibition is a crucial protection mechanism against oxidative damage.

Periphyton has been recognized as an important element in aquatic food chains due to its role in primary production. More recently, it has been used as bioindicator of contamination in reservoirs since biofilm analysis can support in understanding the impacts of bottom-up contaminants to the reservoirs. Copper (Cu) is one of these pollutants which has been used as an algicide; it accumulates in the sediment and can be released to the water column, causing harm to various aquatic organisms, including the periphytic biofilm. In this work periphyton cultivated in the laboratory was exposed to copper, using concentrations from 0.013 to 0.15 mg Cu L−1 over 15 days under controlled conditions (temperature, light, and oxygenation). Different physical-chemical and ecological parameters were measured in order to describe the effects of Cu on the community, which included alterations in ash-free dry mass and chlorophyll concentration, as well as an earlier photosynthetically light saturation point. The results reflected different ecological behavior with modifications in the community composition and greater cyanobacteria dominance like abundance of species with mucilage as the Cu concentration increased. Furthermore, some species of diatoms were not found when the water was contaminated with Cu. This disturbance in the ecological composition of periphyton affects significantly the food chain due to the unpalatability of tolerant species and/or the bioaccumulation of Cu which may be transferred to other organisms potentially causing toxicity to primary consumers.

The genus Gracilaria is an important marine bio-resource since some members are a source of about 80% of the global production of agar. Moreover, species of Gracilaria are used in traditional medicine and human diet in many parts of the world. In this review, it was possible to verify that the number of publications concerning bioactivities for the genus has highly increased, and several promising results in the agriculture and aquaculture fields, as well as antimicrobial, cytotoxic, antioxidant, antinociceptive, anti-ulcer, antidiarrheal, anti-hyperlipidemic, antiacetylcholinesterase, and anti-inflammatory activities, have been reported. However, many bioactivity results are obtained only for the crude extracts and fractions. Phytochemical approaches are uncommon, and the chemical knowledge related to the genus is only available from nutrition, ecology, or physiology fields. The genus contains a wide variety of metabolites, such as mycosporine‑like amino acids (MAAs), agarans, lipids, steroids, diterpenes, phenolic acids, bromophenols, sulfonic acids, oxylipins, heterosides, and pigments. Several of these metabolites are bioactives and of particular interest for industrial and medical applications. In general, the genus Gracilaria has a high potential as a source of high-value compounds and extracts for several applications. However, only agar is commercially exploited. A better use of the biomass from commercial cultivation may be an important alternative for exploiting the other bioactive components. Further studies on the chemical composition and isolation of bioactives in the genus are also required.

Short-term effects of pCO2 (700–380 ppm; High carbon (HC) and Low carbon (LC), respectively) and nitrate content (50–5 µM; High nitrogen (HN) and Low nitrogen (LN), respectively on photosynthesis were investigated in Ulva rigida (Chlorophyta) under solar radiation (in-situ) and in the laboratory under artificial light (ex-situ). After six days of incubation at ambient temperature (AT), algae were subjected to a 4 °C temperature increase (AT+4 °C) for 3 d. Both in-situ and ex-situ maximal electron transport rate (ETRmax) and in situ gross photosynthesis (GP), measured by O2 evolution, presented highest values under HCHN, and lowest under HCLN, across all measuring systems. Maximal quantum yield (Fv/Fm), and ETRmax of photosystem (PS) II [ETR(II)max] and PSI [ETR(I)max], decreased under HCLN at AT+4 °C. Ex situ ETR was higher than in situ ETR. At noon, Fv/Fm decreased (indicating photoinhibition), whereas ETR(II)max and maximal non-photochemical quenching (NPQmax) increased. ETR(II)max decreased under AT+ 4 °C in contrast to Fv/Fm, photosynthetic efficiency (α ETR) and saturated irradiance (EK). Thus, U. rigida exhibited a decrease in photosynthesis under acidification, changing LN, and AT+4 °C. These results emphasize the importance of studying the interaction between environmental parameters using in-situ versus ex-situ conditions, when aiming to evaluate the impact of global change on marine macroalgae.

Macroalgae must be able to survive in conditions of different light intensities with no damage to their physiological performance or vital processes. Irradiance can stimulate the biosynthesis of certain photoprotective compounds of biotechnological interest, such as pigments and proteins. Pterocladiella capillacea is a shade-grown alga, which play a role key in the balance of marine ecosystems. In addition, it is considered one of the best sources of bacteriological agar and agarose with a wide pharmacological potential. In order to evaluate the photosensitivity in P. capillacea under 60 (control) and moderate light intensity of 300 μmol(photon) m–2 s–1, photosynthetic performance and chemical composition were assessed. P. capillacea showed photosensitivity without evidence of photodamage. The results indicate the possibility to increase a growth rate and probably infer productivity in long-term cultivation by stimulation at moderate light intensity. Increasing photosynthetic pigment and protein contents were also observed under medium light, an interesting result for functional ingredient approaches.

Crude extracts using hexane, dichloromethane, methanol, 80% methanol or water of two agarophytes (Gracilaria caudata and Gracilaria domingensis) and their phase partitions were evaluated on early growth of lettuce. Hexane, methanol, 80% methanol and aqueous extracts of G. caudata and dichloromethane and aqueous extracts of G. domingensis were biostimulants. Palmitic acid, the major compound of non-polar extracts and phase partition, showed a significant stimulant activity in the concentrations tested (ranging from 0.49 mM to 1.95 mM), increasing 83% of lettuce root length, comparing to control, at the highest concentration. The promoting effect of the aqueous extracts is probably related to the presence of agaran, a typical hydrocolloid polysaccharide from red algae, which is mostly an exclusive constituent of these extracts. The agarans of G. domingensis and G. caudata promoted an increase in lettuce root length of 60% and 40%, respectively (both at 1 mg·mL−1 of extract). Differences in the effects promoted by these two agarans are probably related to the different content of sulfate groups (higher for polysaccharide from G. domingensis). These results suggest that structural features of agaran-type polysaccharides can elicit distinct responses. To the best of our knowledge, this is the first report on the identification of compounds with biostimulating potential from Gracilaria.

We herein report the physiological and cellular changes in the brown seaweed Sargassum cymosum (C. Agardh 1820) after short- (7 days) and long-term (14 days) exposure to manganese (Mn). To accomplish this, S. cymosum segments were cultivated without metal (0 mg L −1 Mn, Control) and with Mn (10, 20, 40 and 80 mg L −1 ) during 7 and 14 days under laboratory-controlled conditions. Seaweeds had high Mn biosorption capacity. Mn treatments had higher growth rates than Control at both exposure times, but reduction in cell viability after 14 days. Photosynthetic pigments (chlorophylls a and c ) increased with Mn treatments, and changes in the composition of carotenoid profile were observed. Phenolic and flavonoid compounds also showed content reductions relative to exposure time and Mn concentration. In confocal analysis, lower autofluorescence of chloroplasts and phenolic compounds was observed. Scanning Electron Microscopy analysis indicated changes on the thallus surface of Mn treated samples, with disruption of cortical cell walls after 14 days. Transmission Electron Microscopy revealed cellular damage, with organelle disruption and disorganization of cell wall fibrils. Medium to high concentrations of Mn proved to be a metabolic stressor for S. cymosum , causing damage to organelle structure and cellular organization, while, at the same time, attenuating acclimation mechanisms for resistance against toxicity. Since this metal is not recognized as a pollutant in Brazilian coastal waters, S. cymosum is at risk for both heavy metal contamination and variations in abiotic parameters, such as salinity or pH, which could, in turn, intensify the metabolic damage to S. cymosum after long-term exposure of Mn.

This study aimed to determine the effects of cadmium (Cd) on apical segments of Pterocladiella capillacea (S. G. Gmelin) Santelices & Hommersand. For 7 days, these segments were cultivated under different salinities (25, 35 and 45 psu) and different Cd concentrations (0.17–0.70 ppm Cd). The samples were processed for light and confocal microscopy to assess photosynthetic performance, CHN levels, protein levels, as well as NADH dehydrogenase, and catalase activities. Plants cultivated at 0.70 ppm showed a reduction in the number of floridean starch grains by cytochemical analysis. Chloroplast autofluorescence decreased with cadmium exposure, while the kinetic patterns of ETR-light curves showed no significant differences among the treatments. Treatments showed variations in CNH levels, but no clear trend was observed. The content of total soluble protein and mitochondrial NADH dehydrogenase activity varied significantly, depending on the cadmium concentration and salinity levels. However, catalase activity decreased only in samples exposed to both cadmium and salinity treatments. Based on these lines of evidence, the present results showed a higher sensitivity of P. capillacea to increasing levels of cadmium exposure. When intermediate concentrations of cadmium were associated with low salinity values, its toxic effect on the model alga was intensified. Abiotic factors interfered with the physiological ability of the alga to protect itself from metal toxicity, resulting in metabolic compromise and reduction of primary productivity, i.e., photosynthesis and carbohydrate accumulation in the form of starch granules.

In recent years phytotherapy has been encouraged by Brazilian government agencies and has gained more and more credibility as a way of alternative therapy to complement allopathy. Although little explored in Brazil, seaweeds are promising marine bioresources as herbal medicine. In this context, the aim of the present study was to evaluate the antioxidant activities and reverse transcriptase inhibition (RT-HIV) of crude extracts (methanolic, aqueous, and hot aqueous) from three abundant species in Brazilian rocky shores, Sargassum vulgare (Ochrophyta), Palisada flagellifera (Rhodophyta), and Ulva fasciata (Chlorophyta), under two seasons (dry and rainy). Methanolic extracts from S. vulgare (EC50 = 18.22 ± 2.91 μg mg−1, dry), P. flagellifera (EC50 = 24.85 ± 3.13 μg mg−1, rainy), and U. fasciata (EC50 = 33.41 ± 1.53 μg mg−1, dry) showed the highest β-carotene bleaching activities, while hot aqueous extracts from S. vulgare showed the highest RT-HIV inhibition and antioxidant activities in ABTS, FRAP, and Folin-Ciocalteu assays. In general, the three macroalgae showed considerable antioxidant effects; however, only S. vulgare showed an anti-HIV potential (IC50 10.15 ± 1.77 mg mL−1 for the dry season and IC50 = 22.41 ± 5.74 μg mL−1 for rainy season). Regarding both extract yields and bioactivities, S. vulgare in the rainy season was the most promising alga. In conclusion, the studied seaweeds may be an effective alternative for Brazilian herbal medicine; additionally, seasonal studies are essential, since there were significant differences mainly for extract yields.

Practices of aquaculture production may generate potential pollutants that cause environmental pressure. In this context, a recommendation to mitigate the environmental impacts caused by aquaculture waste would be using and recycling such nutrients, considered as “pollutants,” in an eco-efficient way, with approaches such as the integrated multi-trophic aquaculture (IMTA). This system integrates the culturing of organisms with different and complementary ecosystem functions. This study aimed to investigate the ecosystem capacity of Ulva lactuca in wastewater bioremediation in an IMTA system with mussel and fish effluents. For such, three systems were set up: (1) algae cultivated with seawater, (2) algae with effluent from fish, and (3) algae with effluent from fish and mussels. Ulva lactuca proved to be a suitable species for the IMTA system with high growth and easy handling in cultivation. Algal growth rate, nutrient uptake (N and P) and O2 production increased significantly as the succession of trophic levels increased, demonstrating the high ecosystem capacity of U. lactuca for wastewater bioremediation as well as the use and recycling of eutrophication agents for biomass production. The highest absorption/removal of dissolved nitrogen occurred in the form of NH4+, a N form with the greatest metabolic advantage for photosynthetic assimilation, but toxic in high concentrations. The present IMTA system showed a balance between inputs and outputs, denoting sustainable and efficient characteristics of several ecosystem goods and services.

We report the first screening for antioxidant activity (AOX) of three dominant seaweeds from low intertidal reefs of Brazil. Sargassum furcatum, Bryothamnion triquetrum, and Osmundaria obtusiloba were extracted with dichloromethane and methanol (2:1), and AOX was measured by five UV-vis microplate spectrophotometric methods: DPPH (2,2-diphenyl-1-picryhydrazyl) and ABTS (2,2-azinobis (3-ethylbenzthiazoline-6-sulfonic acid)) free radical scavenging, metal chelating capacity, total phenolic compounds using reducing power by Folin-Ciocalteu and FRAP (ferric reducing antioxidant power). All studied species showed high AOX, even at very low extract concentrations. We can attribute these results to the stressful environment in which these seaweeds live, high hydrodynamics, air exposure during low spring tides, intense solar radiation, and other factors that may contribute to oxidative stress, featuring O. obtusiloba as a new source of natural antioxidants.

The most common Mycosporine-like Amino Acids (MAAs) in red algae (asterina-330, shinorine, palythine, palythinol, and porphyra-334) were evaluated regarding their in vitro antioxidant capacities, comparing them with synthetic (BHT and Trolox) and natural (ascorbic acid, gallic acid, p-cumaric acid, quercetin, and rutin) antioxidants. Folin-Ciocalteu, ABTS +, and FRAP assays have the same reaction mechanism of electron transfer and usually show a positive correlation. However, the antioxidant capacities for the MAAs were discrepant between these assays. While porphyra-334, shinorine, and palythine were as active as, or more active than synthetic phenolic antioxidants (Trolox and BHT) in Folin-Ciocalteu assay, the antioxidant potentials of MAAs were lower than those of the standard compounds in ABTS + and FRAP assays. The pH-dependent antioxidant power was hypothesized as an explanation for this distinct behavior and was evaluated through ABTS + assay. Alkaline pH allows antioxidant capacities similar to Trolox in ABTS + assay, supporting our hypothesis. Comparing to standard compounds, MAAs showed low activity using ORAC assay and were pro-oxidant in β-carotene/linoleic acid assay. Therefore, imino-MAAs present relevant in vitro antioxidant capacity under specific pH conditions in assays based on electron transfer.

Direct and indirect effects on ecological processes caused by natural and anthropogenic disturbances may alter the composition and relative abundance of marine benthic communities . Trampling is a source of impact that can lead to the removal of individuals, breakage or damage of structural components and alterations of physiological performance of sessile organisms, possibly affecting the population dynamics and indirectly promoting structural changes in the entire community. To better support management strategies for coastal environments and to evaluate the anthropogenic impacts on a seaweed bed dominated by species of the genus Sargassum inhabiting the subtidal rocky shores in southeastern Brazil, we used an experimental approach to assess the physiological responses of this seaweed to trampling. We applied different intensities of trampling expected during summer vacation and throughout different periods of the year and quantified the fluorescence and pigment concentration of Sargassum beds. Changes caused by trampling are reflected in the health status of Sargassum , showing a decrease in chlorophyll a fluorescence and concentration of photosynthetic pigments depending on the site where this kind of impact occurs.

Specimens previously described as Hypnea musciformis and Hypnea nigrescens in Brazil were shown to be morphological variants of a new species named Hypnea pseudomusciformis, which has been used for the production of carrageenan on the coast of Brazil. In this study, individuals of both morphological variants were collected in the field and cultivated in unialgal culture conditions. The life history of both variants was completed in 118 days. Tetrasporophytes produced tetrasporangia in 40 days. Released tetraspores germinated and 15 days later, an erect cylindrical axis developed from basal disk. At the age of 35 days, spermatangial conceptacles could be observed, and after 3 days of co-culture of male and female gametophytes, cystocarps could be observed, indicating the occurrence of fertilization. Finally, carpospores were released from cystocarps after 10 days, germinated and originated new tetrasporophytes in 15 days. When cultured, the morphological differences between the “musciformis” and “nigrescens” variants were attenuated and the life histories were the same. Furthermore, both morphological variants had different growth rates, but similar pigment content. These results corroborate that, for Brazil, specimens previously identified as H. musciformis and H. nigrescens are variants of H. pseudomusciformis, a highly plastic species.

By evaluating carotenoid content, photosynthetic pigments and changes in cellular morphology, growth rates, and photosynthetic performance, this study aimed to determine the effect of cadmium (Cd) on the development of young gametophytes of Gelidium floridanum. Plants were exposed to 7.5 and 15 μM of Cd for 7 days. Control plants showed increased formation of new filamentous thallus, increased growth rates, presence of starch grains in the cortical and subcortical cells, protein content distributed regularly throughout the cell periphery, and intense autofluorescence of chloroplasts. On the other hand, plants treated with Cd at concentrations of 7.5 and 15 μM showed few formations of new thallus with totally depigmented regions, resulting in decreased growth rates. Plants exposed to 7.5 μM Cd demonstrated alterations in the cell wall and an increase in starch grains in the cortical and subcortical cells, while plants exposed to 15 μM Cd showed changes in medullary cells with no organized distribution of protein content. The autofluorescence and structure of chloroplasts decreased, forming a thin layer on the periphery of cells. Cadmium also affected plant metabolism, as visualized by a decrease in photosynthetic pigments, in particular, phycoerythrin and phycocyanin contents, and an increase in carotenoids. This result agrees with decreased photosynthetic performance and chronic photoinhibition observed after treatment with Cd, as measured by the decrease in electron transport rate. Based on these results, it was concluded that exposure to Cd affects cell metabolism and results in significant toxicity to young gametophytes of G. floridanum.

Three macroalgal species belonging to Chlorophyta (Ulva rigida), Rhodophyta (Ellisolandia elongata) and Phaeophyceae (Heterokontophyta; Cystoseira tamariscifolia), natu- rally growing at the same shore level and representing 3 morpho-functional groups, were exposed to short-term changes in temperature under different carbon and nitrogen regimes. Experiments were conducted in outdoor tanks at 4 combinations of carbon and nitrogen levels under reduced solar radiation. In vivo chl a fluorescence parameters and pigment contents were monitored to assess diurnal physiological responses and potential for recovery. Strong fluctuations in chl a flu- orescence parameters, but not in chl a content, were observed in response to diurnal variation in solar radiation and light climate within the tanks; sensitivity varied between algal species and, in some cases, depended on the carbon and nitrogen regime. Nitrogen uptake was similarly high in U. rigida and E. elongata and lowest in C. tamariscifolia. In U. rigida and E. elongata, chl a con- centrations decreased after high-carbon treatments. Effective photosystem II quantum efficiency was reduced in all species at noon, and lowest in C. tamariscifolia. The results highlight the com- plexity of physiological short-term acclimations which were most likely linked to biochemical changes at the cellular level. Long-term experiments are required in future for more comprehen- sive investigation of the observed interactive effects of the different environmental parameters.

High levels of irradiance may affect the growth and development of photosynthetic organisms, changing concentrations of carotenoids and chlorophylls. These changes may indicate different photoprotection strategies. In this study, gametophytic apical portions of Gracilariopsis tenuifrons were cultivated under controlled laboratory conditions for 1 week, at different light irradiances: 60 (control), 600, and 1,000 μmol photons m−2 s−1. Growth rate, amount, and composition of pigments were analyzed daily. Color of seaweeds exposed to 600 and 1000 μmol photons m−2 s−1 varied along the days, from red to yellowish, suggesting a decrease in vital processes as photosynthesis and growth. However, no decrease in biomass was observed. Actually, there was an increase at growth rates for the algae kept under higher light intensities. The main registered pigments were chlorophyll a, β-carotene, and zeaxanthin. β-carotene and chlorophyll a levels were lower in algae exposed to high light intensity. In treatment exposed to 600 μmol photons m−2 s−1, this reduction was 42 and 35 %, respectively, while in those exposed to 1000 μmol photons m−2 s−1 the values were 55 and 50 % lower than the control. The lower levels of these pigments may be associated with the reduction in energy harvesting by the photosynthetic complexes-antennae, in an effort to dissipate the high excitation impinged over the photosynthesis system as a whole. For zeaxanthin levels, a 20 % increase was observed in the beginning of the experiment, which was followed by a drop to the initial levels, suggesting the role of this pigment in this alga’s photoprotection process.

The in vitro effect of cadmium (Cd) on apical segments of Pterocladiella capillacea was examined. Over a period of 7 days, the segments were cultivated with the combination of different salinities (25, 35, and 45 practical salinity units) and Cd concentrations, ranging from 0.17 to 0.70 ppm. The effects of Cd on growth rates and content of photosynthetic pigments were analyzed. In addition, metabolic profiling was performed, and samples were processed for microscopy. Serious damage to physiological performance and ultrastructure was observed under different combinations of Cd concentrations and salinity values. Elementary infrared spectroscopy revealed toxic effects registered on growth rate, photosynthetic pigments, chloroplast, and mitochondria organization, as well as changes in lipids and carbohydrates. These alterations in physiology and ultrastructure were, however, coupled to activation of such defense mechanisms as cell wall thickness, reduction of photosynthetic harvesting complex, and flavonoid. In conclusion, P. capillacea is especially sensitive to Cd stress when intermediate concentrations of this pollutant are associated with low salinity values. Such conditions resulted in metabolic compromise, reduction of primary productivity, i.e., photosynthesis, and carbohydrate accumulation in the form of starch granules. Taken together, these findings improve our understanding of the potential impact of this metal in the natural environment.

Heavy metals, such as lead, copper, cadmium, zinc, and nickel, are among the most common pollutants found in both industrial and urban effluents. High concentrations of these metals cause severe toxic effects, especially to organisms living in the aquatic ecosystem. Cadmium (Cd), lead (Pb) and copper (Cu) are the heavy metals most frequently implicated as environmental contaminants, and they have been shown to affect development, growth, photosynthesis and respiration, and morphological cell organization in seaweeds. This paper aimed to evaluate the effects of 50 μM and 100 μM of Cd, Pb and Cu on growth rates, photosynthetic pigments, biochemical parameters and ultrastructure in Gelidium floridanum . To accomplish this, apical segments of G. floridanum were individually exposed to the respective heavy metals over a period of 7 days. Plants exposed to Cd, Cu and Pb showed discoloration of thallus pigmentation, chloroplast alteration, especially degeneration of thylakoids, and decrease in photosynthetic pigments, such as chlorophyll a and phycobiliproteins, in samples treated with Cd and Cu. Moreover, cell wall thickness and the volume of plastoglobuli increased. X-ray microanalysis detected Cd, Cu and Pb absorption in the cell wall. The results indicate that Cd, Pb and Cu negatively affect metabolic performance and cell ultrastructure in G. floridanum and that Cu was more toxic than either Pb or Cd.

Chlorophyll a and carotenoids are important pigments in photosynthesis. Several studies have been published describing extraction and analysis protocols of these pigments, mainly in vascular plant species. This study standardizes an extraction and analysis protocol of these substances in Gracilaria tenuistipitata var. liui, a red seaweed. Apical portions grown in vitro were triturated in liquid nitrogen. Extracts were prepared in 1.5 mL solvent and centrifuged. Quantitative and qualitative analyses of pigments were performed by UV/visible light spectrophotometry and high performance liquid chromatography (HPLC) and HPLC coupled to mass spectrometry (HPLC-MS). The parameters assessed were: minimum biomass, best extraction solvent, and number of extraction steps. Methanol was the most efficient solvent, and 50 mg fresh biomass was the amount of sample indicated, submitted to one single extraction step. No significant differences were observed in levels of these pigments by UV-visible light spectrophotometry and HPLC. However, HPLC or HPLC-MS are required to identify the different carotenoids present in this seaweed species. Clorofila a e carotenoides são importantes pigmentos da fotossíntese. Na literatura são encontrados vários protocolos de extração e análise desses pigmentos utilizando, principalmente, plantas vasculares. O objetivo deste estudo foi padronizar uma metodologia de extração e análise dessas substâncias em uma macroalga vermelha, Gracilaria tenuistipitata var. liui. Amostras de talos gametofíticos cultivados in vitro foram trituradas em nitrogênio líquido, extraídas em 1,5 mL de solvente, centrifugadas e os pigmentos analisados quantitativamente e qualitativamente através de espectrofotometria de UV/visível, cromatografia liquida de alta eficiência (CLAE) e CLAE-acoplada a espectrometria de massas (CLAE-EM). Foram testados os parâmetros massa mínima, solvente para extração e número de extrações. Dentre os solventes testados, o metanol foi o mais eficiente, sendo 50mg de material fresco a massa mínima indicada para ser submetida a somente uma extração. Não foram encontradas diferenças significativas na quantificação desses pigmentos comparando-se os dados obtidos em espectrofotometria de UV/visível com os de CLAE. No entanto, para a identificação dos diferentes carotenoides e suas quantificações são necessárias CLAE ou CLAE-EM.

Lipid and fatty acid profiles provide nutritional information of marine algae, but the analysis of algal fatty acid composition has also been proposed as a chemotaxonomic tool. Although the total lipid (TL) content of macroalgae is usually only 1–6% dry weight (DW), much lower than in microalgae, some species can accumulate interesting long-chain polyunsaturated fatty acids (LC-PUFA) which are essential fatty acids, not produced by humans or animals, that show beneficial health effects. This study aimed to evaluate the lipid and fatty acid profiles of three Brazilian seaweeds, Sargassum vulgare (Ochrophyta), Palisada flagellifera (Rhodophyta), and Ulva fasciata (Chlorophyta) collected from the north-east of Brazil at two seasons (dry and rainy). Lipid and fatty acid profiles in the three macroalgae were stable across seasons. The total fatty acid (TFA) contents of S. vulgare and U. fasciata ranged from 1.3 to 1.5% DW, with the main fatty acids represented by palmitic and oleic acids; however, there was no large accumulation of LC-PUFA. By contrast, P. flagellifera exhibited a lower TFA content (0.8–0.9% DW), but eicosapentaenoic and arachidonic acids accounted for 15–16% and 16–20% of TFA, up to 1.5 and 1.9 mg g-1 DW, respectively. In all species, glycolipids were the most abundant lipid class (60–70%), followed by phospholipids (10–25%), and neutral lipids (10–15%). The composition of each lipid fractions demonstrated that fatty acid profiles of each lipid class were highly species-specific, and lipid profiles were indicative of tropical species. Based on these algae lipid profiles, P. flagellifera could be considered a good source of omega-3 (LC-PUFA). The seasonal stability in the lipid content and fatty acid profiles confers a strong advantage for potential exploitation of those species in the north-eastern regions of Brazil, representing a source of algal biomass with constant biochemical composition all year-round.

The red macroalga Porphyra C. Agardh is one of the most ecologically successful genera that lives in the upper intertidal zone. Biochemical, physiological, and morphological acclimation strategies allow their growth and distribution as well as a quick recuperation between tidal regimens. Studies of Porphyra are poorly developed in Chile, and management and exploitation proposals need to be supported by biological and ecophysiological approaches. This study evaluated seasonal and latitudinal physiological performances of Porphyra spp. via maximum quantum yield (F v / F m), pigments, proteins, phenolic compounds, and antioxidant activity in order to describe how algae can acclimate to their environment and to provide insights to their management and use. Sampling was done at three costal sites in Chile between 25°S and 34°S between winters 2010 and 2011. A total of four different morphotypes were identified (one in the north, one in the center, and two in the south locations) and evaluated separately. Results showed seasonal and latitudinal patterns for all ecophysiological variables studied, with a general tendency of decrease in F v / F m, pigments, and soluble proteins during spring–summer seasons accompanied by an increase in the antioxidant capacity. Latitudinal differences were observed with a tendency of higher values for ecophysiological traits in central and southern morphotypes. Phenology patterns were different between an annual population in the north location and a perennial one for central-south populations. The taxonomic clarity should be evaluated in order to better understand if there exists intraspecific (dependent on morphology) or interspecific variation.

The photoacclimation responses of the brown macroalga Sargassum cymosum were studied to determine its cytochemical and ultrastructural organization, as well as photosynthetic pigments and performance. S. cymosum was cultivated in three salinities (30, 35 and 40 psu) under four irradiation treatments: PAR-only, PAR + UVA, PAR + UVB and PAR + UVA + UVB. Plants were exposed to PAR at 70 μmol photons m(-2) s(-1), PAR + UVB at 0.35 W m(-2) and PAR +UVA at 0.70 W m(-2) for 3 h per day during 7 days in vitro. Growth rate was not significantly affected by any type of radiation or salinity. The amount of pigments in S. cymosum was significantly influenced by the interaction of salinity and radiation treatments. Compared with PAR-only, UVR treatments modified the kinetics patterns of the photosynthesis/irradiance curve. After exposure to UVR, S. cymosum increased cell wall thickness and the presence of phenolic compounds. The number of mitochondria increased, whereas the number of chloroplasts showed few changes. Although S. cymosum showed insensitivity to changes in salinity, it can be concluded that samples treated under four irradiation regimes showed structural changes, which were more evident, but not severe, under PAR + UVB treatment.

Increase of harmful radiation to the Earth’s surface due to ozone depletion results in higher exposure to harmful ultraviolet- B radiation (UV), while fluctuations in seawater salinity may alter water density, ionic concentration, nutrient uptake, and osmotic pressure. This study evaluated the effects of salinity and UV on metabolism and morphology of Acanthophora spicifera (M.Vahl) Borgesen. Water with 30 and 37 psu [g(salt) kg–1(sea water)] was used for experiments during 7 d of exposure to UV (3 h per day). We demonstrated that UV treatment predisposed, irrespective of salinity, A. spicifera to a decrease in its growth rate and cell viability, as well as affected its morphological parameters. After exposure to PAR + UVA + UVB (PAB), samples showed structural changes and damage, such as increasing cell wall thickness and chloroplast disruption. Our results indicate that UV led to dramatic metabolic changes and cellular imbalances, but more remarkable changes were seen in samples exposed to high salinity.