The increasing levels of contamination in coastal regions by toxic metal pollutants have been directly related to anthropic action of disorganized population growth and development of industrial activities. Among the toxic metals, cadmium (Cd) has been identified as highly available in the environment and easily absorbed by diverse organisms. This study examined the effect of Cd on physiological performance of the red macroalga Bostrychia radicans from two mangrove locations (non-polluted and polluted). Bostrychia radicans exhibited deleterious responses on physiological performance with different levels of response depending on the area of origin and Cd dosage, with higher susceptibility for algae from reduced polluted areas. Additionally, our results showed that B. radicans could be recommended as a potential bioindicator of Cd pollution with photosynthesis parameters and pigment content as biological toxicity descriptors.

We found that an innovative nursery approach, where Lessonia corrugata seeded spools were cultivated by spinning to increase the water motion relative to non-spinning spools, had higher growth in both the nursery and at-sea stages. Using this method, we compared the at-sea growth of sporophytes cultivated on spinning spools at different depths (1 m, 3 m, 5 m) and seasons (timing of out-planting). Finally, we compared the at-sea growth of sporophytes cultivated on spinning spools vs. non-spinning sporophytes at 3-m depth. In the nursery, sporophytes on spinning spools developed significantly faster than those on non-spinning spools: blade length was 4.6 and 2.5 cm, and holdfast area was 0.10 and 0.03 cm 2 for spinning and non-spinning spools, respectively. At-sea L. corrugata in spring had significantly greater biomass production at 3 m and 5 m (3.0 kg m −1 and 2.4 kg m −1 , respectively) and up to 96% survival. In summer, 100% of deployed kelps died at all depths. Growth was faster at 5 m (0.3 ± 0.06 kg m −1 ) in autumn and at 3 and 5 m (1.1 ± 0.1 kg m −1 and 0.8 ± 0.1 kg m −1 , respectively) in winter. At sea, sporophytes from the spinning spools grew significantly 60% larger, and survival was ~ 3 times greater over 3 months than sporophytes from non-spinning. Overall, this study shows that spinning seeded spools in the nursery improves the growth at sea, spring is the best season for out-planting L. corrugata , and 3 or 5 m depth is best for production.

Kelp forests provide vital ecosystem services such as carbon storage and cycling, and understanding primary production dynamics regarding seasonal and spatial variations is essential. We conducted surveys at three sites in southeast Tasmania, Australia, that had different levels of water motion, across four seasons to determine seasonal primary production and carbon storage as living biomass for kelp beds of Lessonia corrugata (Order Laminariales). We quantified blade growth, erosion rates, and the variation in population density and estimated both the net biomass accumulation (NBA) per square meter and the carbon standing stock. We observed a significant difference in blade growth and erosion rates between seasons and sites. Spring had the highest growth rate (0.02 g C · blade-1 · d-1 ) and NBA (1.62 g C · m-2 · d-1 ), while summer had the highest blade erosion (0.01 g C · blade-1 · d-1 ), with a negative NBA (-1.18 g C · m-2 · d-1 ). Sites exhibiting lower blade erosion rates demonstrated notably greater NBA than sites with elevated erosion rates. The sites with the highest water motion had the slowest erosion rates. Moreover, the most wave-exposed site had the densest populations, resulting in the highest NBA and a greater standing stock. Our results reveal a strong seasonal and water motion influence on carbon dynamics in L. corrugata populations. This knowledge is important for understanding the dynamics of the carbon cycle in coastal regions.

Lessonia (order Laminariales) is a kelp genus restricted to the temperate southern hemisphere, where species form dense forests from the low intertidal to 25 m depth at wave exposed sites. Lessonia spp. are among the most harvested kelps globally due to their importance in providing raw materials for food, cosmetics, bioactive and biomedical industries. Over-harvesting of natural beds can negatively affect Lessonia populations and the many species that depend on these habitats, including commercially important fish and molluscs, but good harvest management plans reduce these impacts on natural Lessonia stocks. However, the increasing demand for raw materials will likely only be met by aquaculture for which Lessonia shows high potential in pilot scale studies undertaken in Chile, New Zealand, and Australia. In this concise review, we highlight the current knowledge of Lessonia spp. taxonomy and distribution, life history, ecology and ecosystem services, wild harvest, aquaculture, and commercial applications. We discuss future research directions.

Antioxidant potential, carbohydrate content, ash, minerals, proteins, and amino acids of Kappaphycus alvarezii farmed along the São Paulo coast, Brazil, were evaluated to support the best use of four strains and new applications with added value. Ash content ranged from 25.60 to 11.65%. Mineral contents varied from 10,130.90 ± 1,613.78 mg (100 g) −1 DW (summer 2018) to 12,561.20 ± 2,190.72 mg (100 g) −1 DW (summer 2017), and the highest mineral contents occurred in the green strain. Carbohydrate levels varied from 122.92 ± 15.11 mg g −1 DW (summer 2017) to 231.79 ± 16.86 mg g −1 DW (winter 2017), and the highest carbohydrate value was observed in the G11 strain. The highest protein amount was observed in the brown strain with 8.79 mg (100 g) −1 DW. The highest antioxidant potential of K. alvarezii was in spring 2017 for the brown strain. Total phenolic content ranged from 41.77 ± 15.41 to 366.58 ± 109.17 mg GAE g −1 DW, DPPH activity ranged from 13.29 ± 1.20 to 61.07 ± 3.43%, FRAP ranged from 58.73 ± 3.96 to 105.54 ± 6.60%, and ABTS varied from 95.29 ± 4.31 to 112.52 ± 1.41%. Therefore, nutritional and antioxidant properties of K. alvarezii varied according to strains and seasons, with the best result in the spring of 2017. In summer and autumn of 2017, the green strain had better nutritional and antioxidant profiles, whereas in the winter of 2017 and spring of 2017 it was the G11 strain and in the summer of 2018 it was the red strain.

Numerical modelling development for capillary barrier investigation considering unsaturated soil–geotextile interface has been studied and evaluated in recent years. Most engineering constructions involving geomaterials and geotextiles application, such as reinforced walls, slopes, embankments, and roads, require understanding the hydraulic performance of those systems for design purposes (capillary barrier, drainage, filtration, etc.). Considering that the hydraulic behavior of those materials is directly dependent on their saturated–unsaturated state over time, unsaturated principles should be applied for their long-term evaluation. This paper presents a 1D (one-dimensional) numerical analysis of an unsaturated system composed of soil and gravel layers separated by a geotextile in a column laterally impermeable (2.0 m). A non-woven geotextile was applied considering different soil types from the literature, such as silty sand, sandy, compacted residual silty, bimodal, and compacted residual sandy soils. A SEEP/W finite element numerical model was developed to perform transient analyses through the system to evaluate its hydraulic performance in terms of capillary barrier formation considering different geomaterials combinations in different hydraulic conditions. A significant influence of geotextile hydraulic conductivity and water flow rate were verified on the capillary barrier effect. Also noticed were the different height and duration of capillary barrier formation for different soil profiles. A design chart-table was proposed to evaluate soil–geotextile performance in terms of capillary barrier for new geotechnical designs. Finally, it could be inferred that fine-grained soils demonstrated to develop higher and longer water column (positive pore pressure) compared to coarse-grained soils, independently of their initial suction.

Seaweed cultivation is gaining interest world-wide for both food and non-food applications. Global seaweed aquaculture production currently exceeds 32 Mt WW per annum but is dominated (86% of total) by Asian countries. To meet future demand for seaweed products, regions beyond Asia with aquaculture production potential are being explored. The goal of this study was to assess the suitability of the native kelp Macrocystis pyrifera (Phaeophyceae, Laminariales), for aquaculture in Tasmania, south-eastern Australia. M. pyrifera was cultivated on seeded twine on loops (1 – 5 m depth) along 100-m longlines at two sites (Okehampton Bay and Great Taylor Bay) from April-November 2020. Temporal and spatial variability in (1) yield (kg m -1 , WW), (2) biofouling (% coverage), and (3) biochemical composition (including proximate composition, fatty acids, dietary minerals, heavy metal profiling, C, N, H, S concentrations and C:N ratio, antioxidants (phenolic compounds), and pigments (Chl- a , Chl- c , fucoxanthin)) was compared amongst the two cultivation sites, at two depths (1 and 5 m) from harvests between July – November 2020. Yield (kg m -1 , WW) did not significantly change across harvest times, but was greater at a depth of 1 m compared to 5 m. Biofouling on the kelp blades increased significantly in early spring (September). The biochemical composition of the cultured biomass varied over time, between sites and with depth for most of the compounds analysed. Higher lipid, protein and ash content was reported for cultures cultivated at Okehampton Bay compared to Great Taylor Bay and at 5 m compared to 1 m depth, and levels of these macronutrients decreased during the harvest period. The iodine content was slightly above the tolerable content for dried seaweed products in Australia and New Zealand. The combined results of yield, biofouling, and biochemical composition suggest that, for an April deployment at the sites investigated, M. pyrifera should be harvested in July-August (mid to late winter) to optimise yield and quality of the cultured kelp biomass. These findings provide a better understanding of the variation in growth and quality of cultivated M. pyrifera biomass in the region, and inform future management and development of kelp aquaculture in south-eastern Australia and in a global context.

Kappaphycus alvarezii 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 with biological properties. This cultivated species produces different strains with distinct chemical and physiological properties. Despite this, K. alvarezii has been marketed as a single biomass. The aim of this study was to evaluate differences in antioxidant capacities among green, red, brown and G11 strains of K. alvarezii cultivated in southeastern Brazil, assessed by Folin-Ciocalteu reducing potential, DPPH, ABTS and FRAP assay methods. Methanolic and aqueous extracts yielded from 2.67% to 3.43% and 26.25% to 32.90%, respectively. Nevertheless, methanolic extracts showed higher total phenolic content (40.80 mg GAE 100 g(-1) DW to 58.49 mg GAE 100 g(-1) DW) than aqueous ones (7.77 mg GAE 100 g(-1) DW to 12.51 mg GAE 100 g(-1) DW), and a similar trend was found for DPPH (7.15% to 31.21%), for ABTS (60.29% to 100.39%), and for FRAP (27.24% to 95.95%). Antioxidant activity of aqueous extracts was lower than 17% for all spectrophotometric assays. The green strain had the highest index of antioxidant capacity, suggesting that this strain may be suitable as a natural source of antioxidants. This is the first report evaluating antioxidant potential of four strains of K. alvarezii, supporting the need for further research to identify and select for its value as a viable natural antioxidant source.

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.

Abstract 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.

Aquaculture is one of the fastest growing agricultural activity in the last decades due to its great potential for expansion, which has not been explored yet.However, it is interesting that this growth should be directed toward a conscious production that aims the sustainability of production, taking advantage of ecosystem goods and services that may favor the attainment of this objective.Marine Integrated Multi-Trophic Aquaculture (IMTA) is an alternative to achieve this goal.The production is based on the recycling and reuse of resources, which makes IMTA aligns higher aquaculture productivity with a lower ecological footprint.The aim of this work was to understand the interactions between the open water integrated cultivation of the red macroalgae Gracilariopsis tenuifrons and the mussel Perna perna in the cove of Mar Virado, in the Ubatuba city.In the Chapter 1, we tested techniques for growing macroalgae strains under semi-controlled conditions that aims to maintain healthy seeding with a low maintenance cost.They were tested for algal densities of culture (gram of algae per liter of culture medium) and we used a cheapest source of nutrients, the commercial Forth® 30-10-10 orchid fertilizer.Gracilariopsis tenuifrons showed preference for 1 g.L -1 density cultivation and showed good results for the use of orchid fertilizer.The algae also showed good results for growth rates, with rates higher than 6 %.day -1 .In Chapter 2, an open water integrated cultivation was carried out between the macroalgae G. tenuifrons and the mussel P. perna, with the aim to character the environment of a marine farm in relation to its interactions between the integrated cultivation of mussels and the macroalgae and the environmental factors.The macroalgae were cultivated at different points of the marine mussel farm, in these places we measured biotic and abiotic parameters such as nutrient concentration, velocity and direction of water flow, solar irradiance temperature and growth rates of macroalgae.The chemical algal composition at each culture point was also analyzed.The results showed that there is a difference in the growth of macroalgae at different points, where the nutrient flow from the mussels was higher, with higher growth rates and a higher concentration of compounds in the algal material such as proteins, pigments and carbohydrates.Thus, the knowledge of the dynamics of the integrated crop area is good for a better production.

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.

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.