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- Effect on health status and pathogen resistance of gilthead seabream (Sparus aurata) fed with diets supplemented with Gracilaria gracilisPublication . Passos, Ricardo; Correia, Ana Patrícia; Ferreira, Inês; Pires, Pedro; Pires, Damiana; Gomes, Emma; Carmo, Beatriz do; Santos, Paulo; Simões, Marco; Afonso, Clélia; Baptista, TeresaAquaculture intensification turns the reared populations prone to disease outbreaks, leading the industry to use antibiotics and chemotherapeutics. As the industry is searching for solutions, the development of sustainable aquafeeds with immunostimulant properties is emerging. This work aimed to assess the health benefits of Gracilaria gracilis as a supplement in Sparus aurata feed as well as its protective effect in a bacterial challenge. G. gracilis supplementation improved growth performance and influenced the haematological profile, namely in the constitution of the leukocytic population and erythrocytes size. Algae powder supplementation did not compromise the hepatic antioxidant systems and intestinal health and morphology were not affected by the algal supplementations. Algal extract improved lysozyme plasmatic concentration and a 5% algae powder inclusion was able to successfully protect the fish against a Photobacterium damselae subsp. piscicida infection, granting a 95% survival. In general, a 5% G. gracilis powder diet supplementation was able to improve growth, health, and bacterial resistance in gilthead seabream.
- In vitro evaluation of the antibacterial and antioxidant activities of extracts of Gracilaria gracilis with a view into its potential use as an additive in fish feedPublication . Afonso, Clélia; Correia, Ana; Freitas, Marta; Mouga, Teresa; Baptista, TeresaFish in aquaculture systems are subject to several stressors that inhibit the immune response and potentiate the development of disease and increased mortality. The inclusion of additives in the fish diet, namely seaweeds or their extracts, that are natural sources of bioactive compounds can be an important tool for promoting the health and well-being of these animals. The present study aims at the development of sustainable and effective methodologies for the extraction of bioactive compounds of the red seaweed Gracilaria gracilis, exploring its antibacterial and antioxidant potential and considering its potential use as an additive for functional fish feeds. The yield of the extraction methods was evaluated upon the use of sequential solid–liquid extraction techniques with ethanol and water as solvents, different extraction temperatures (room temperature: 40ºC and 70ºC), and extraction time. The results demonstrated that the adoption extraction times of 30 min. at 40ºC provided higher yields. We also evaluated the antioxidant capacity and the antibacterial properties of the obtained extracts against different strains that cause fish diseases by disk diffusion and broth microdilution methods. The antioxidant activity was determined by the DPPH reducing capacity method and quantification of total polyphenols content (TPC).With these results, we can establish extraction procedures that allow the future use of G. gracilis extracts, with antibacterial and antioxidant effects in a safe and effective way.
- Identification of Gracilariaceae (Rhodophyta) of central Portugal by histological and genetic methodsPublication . Freitas, Marta V.; Simões, Marco; Valdez, Christian; Afonso, Clélia; Trindade, Beatriz G.; Correia, Ana; Baptista, Teresa; Mouga, TeresaThis study aims to identify different populations of Gracilariaceae collected from the central coast of Portugal through light microscopy, anatomical observations and genetic tools, essential approaches to correctly assign species identity. Samples were obtained from Ria de Aveiro (AV), Figueira da Foz (FFBC, FFMD), and Lagoa de Óbidos (LOBR, LOEV, LOBS). Although histological observations offered a visual representation of the characteristic pseudoparenchymatous organization, they did not allow a clear distinction among the species. The amplification of a ∼700 bp fragment of the mitochondrial cytochrome oxidase I gene, and its sequencing enabled us to assign the populations FFBC and LOBS to Gracilaria gracilis, and the populations AV, FFMD, LOBR, and LOEV to Agarophyton vermiculophyllum. This contribution will help phycologists to correctly identify the Portuguese populations of Gracilaria sensu lato at the species level, which will be crucial in ensuring that future studies and industrial exploration accurately target the correct species.
- Potential use of macroalgae Gracilaria gracilis in diets for European seabass (Dicentrarchus labrax): Health benefits from a sustainable sourcePublication . Passos, Ricardo; Correia, Ana Patrícia; Pires, Damiana; Pires, Pedro; Ferreira, Inês; Simões, Marco; Carmo, Beatriz do; Santos, Paulo; Pombo, Ana; Afonso, Clélia; Baptista, TeresaSeaweeds still possess a large undisclosed potential, mainly due to their constituent’s richness, which may have several uses for society. In aquaculture, they may play a role as an ecological sustainable aquafeed supplement to increase overall health and fight pathogenic outbreaks. This study aimed to evaluate the general health modulation that the inclusion of Gracilaria gracilis could accomplish in the diet of Dicentrarchus labrax. Dried algae at 2.5% and 5% and algal extract at 0.35% inclusion levels were supplemented to seabass diet to evaluate possible growth, haematological, immunological, antioxidant, metabolic, and intestinal morphological modulations. The supplementations did not impact growth or feed utilization, and barely affected the haematological profile and some metabolic parameters. Nevertheless, it caused a marked outcome on lysozyme, some oxidative stress biomarkers, and intestine morphology, suggesting beneficial consequences from the algal inclusion. Dried algae powder, with a 2.5% inclusion, boosted immune response, with higher plasmatic lysozyme and intestinal acid goblet cells and protected against oxidative damages by improved enzymatic and non-enzymatic responses. Thus, we provide evidence that dietary seaweed application may be a path towards a more sustainable aquaculture industry.
- New insights on the sporulation, germination, and nutritional profile of Gracilaria gracilis (Rhodophyta) grown under controlled conditionsPublication . Freitas, Marta; Mouga, Teresa; Correia, Ana; Afonso, Clélia; Baptista, TeresaThe red seaweed Gracilaria gracilis is a widely cultivated species known for its high agar content. It is also an important source of proteins, minerals, and vitamins. The chemical profile of seaweed depends on the cultivation methods used and the growing conditions to which they are exposed. Thus, two independent methods of sporulation and germination were tested upon Gracilaria gracilis grown in controlled conditions. During the tests, different substrates, culture media and incubation times were tested to induce cystocarp maturation. The results showed that cystocarp maturation and spore release were successful, with a visible volume increase and format change in the protruding cystocarps. Furthermore, the process of maturation to germination was accomplished, fulfilling the complete life cycle. In parallel, the nutritional profile of the biomass obtained was evaluated and compared with the nutritional values of biomass collected from the environment. Results showed no significant differences between wild specimens and cultivated ones in organic matter, ash content, lipid content, carbohydrates, or phycocolloid content. The present work, therefore, presents two simple alternative methods with potential applications in start-ups aimed at the cultivation of seaweed. Through these methods, it is possible to obtain biomass with nutritional characteristics similar to those obtained in the wild.
- Seasonal changes in the nutritional composition of agarophyton vermiculophyllum (Rhodophyta, Gracilariales) from the Center of PortugalPublication . Afonso, Clélia; Correia, Ana; Freitas, Marta; Baptista, Teresa; Neves, Marta; Mouga, TeresaSeaweeds exhibit high nutritional value due to a balanced concentration of proteins, vitamins and minerals, a high concentration of low digestibility polysaccharides, and reduced levels of lipids, many of which are n-3 and n-6 fatty acids. The species Agarophyton vermiculophyllum is no exception and, as such, a comprehensive study of the chemical and nutritional profile of this red seaweed was carried out for 1 year. Seasonal variations in moisture, ash, protein and amino acids content, crude fibers, ascorbic acid, agar, lipids, and the corresponding fatty acid profile, were analyzed. We found low levels of fatty acids and a high protein content, but also noticed interesting seasonal change patterns in these compounds. The present study gives insights on the environmental conditions that can lead to changes in the nutritional composition of this species, aiming, therefore, to bring new conclusions about the manipulation of environmental conditions that allow for maximizing the nutritional value of this seaweed.