Gracilaria Greville is a genus of seaweed that is economically explored by the cosmetic, pharmaceutical and food industries. One of the biggest problems associated with growing Gracilaria is the discharge of heavy metals into the marine environment. The absorption of heavy metals was investigated with the macroalga Gracilaria tenuistipitata Zhang et Xia, cultivated in a medium containing copper (Cu) and cadmium (Cd). In biological samples, EC50 concentrations of 1 ppm for cadmium and 0.95 ppm for copper were used. These concentrations were based on seaweed growth curves obtained over a period of six days in previous studies. ICP-AES was used to determine the amount of metal that seaweeds absorbed during this period. G. tenuistipitata was able to bioaccumulate both metals, about 17% of copper and 9% of cadmium. Basal natural levels of Cu were found in control seaweeds and in G. tenuistipitata exposed to Cd. In addition, the repertoire of other important chemical elements, as well as their concentrations, was determined for G. tenuistipitata and two other important seaweeds, G. birdiae Plastino & Oliveira and G. domingensis (Kützing) Sonder ex Dickie, collected in natural environments on the Brazilian shore.
This study evaluates the influence of depth and environmental parameters on the development of Gracilaria birdiae Plastino & Oliveira (Gracilariaceae) in an organic shrimp pond. The macroalgae was cultivated on modules placed at three depths (surface, 10 and 20 cm depth). Growth rates were measured weekly based on variation in fresh weight during 35 days. G. birdie showed the greatest productivity (35.7%) at 10 cm, followed by 20 cm (33.4%) and surface (25.3%). Average SGR values were 0.36±0.57% d-1(surface) 0.38±0.96% d-1 (10 cm) and 0.38 ±0.54% d-1(20 cm), over the study period. The biomass variation of G. birdiae showed significant difference among the three depths. The correlations generated by multiple regressions demonstrated that analyzed environmental parameters explain from 62 to 67 % of G. birdiae growth.
Gracilariales is a clade of florideophycean red macroalgae known for being the main source of agar. We present a de novo genome assembly and annotation of Gracilaria domingensis, an agarophyte alga with flattened thallus widely distributed along Central and South American Atlantic intertidal zones. In addition to structural analysis, an organizational comparison was done with other Rhodophyta genomes. The nuclear genome has 78 Mbp, with 11,437 predicted coding genes, 4,075 of which did not have hits in sequence databases. We also predicted 1,567 noncoding RNAs, distributed in 14 classes. The plastid and mitochondrion genome structures were also obtained. Genes related to agar synthesis were identified. Genes for type II galactose sulfurylases could not be found. Genes related to ascorbate synthesis were found. These results suggest an intricate connection of cell wall polysaccharide synthesis and the redox systems through the use of L‐galactose in Rhodophyta. The genome of G. domingensis should be valuable to phycological and aquacultural research, as it is the first tropical and Western Atlantic red macroalgal genome to be sequenced.
Esse estudo teve o objetivo de investigar os saberes e práticas tradicionais presentes nas atividades de extrativismo dos bancos naturais e cultivo de macroalgas marinhas no Rio Grande do Norte. O estudo foi realizado por meio de entrevistas semiestruturadas utilizando questionário composto por assuntos que abordavam questões relacionadas as práticas produtivas, aspectos sociais, manejo das macroalgas e conhecimentos referentes aos ecossistemas costeiros. Além das entrevistas, foi realizado o acompanhamento das atividades produtivas desenvolvidas pelos participantes envolvidos na pesquisa. Dentre os registros obtidos, podemos destacar os saberes tradicionais da atividade extrativista, os conhecimentos empíricos relacionados à ecologia e ciclo de vida das macroalgas. No que se refere a produção das algas cultivadas, ficou constatada que essas práticas contribuem para a diminuição da pressão exercida sobre os bancos naturais, possibilitando a manutenção e a recuperação das populações naturais de macroalgas na área estudada. Além disso, ficou evidenciado que as atividades desenvolvidas pela comunidade têm contribuído para o desenvolvimento econômico, social e ambiental da região. Em conclusão, foi possível verificar que os saberes e práticas tradicionais do extrativismo e cultivo de algas, influenciam de forma positiva na conservação dos recursos naturais, e o seu uso de forma racional é extremamente importante para a perpetuação dos saberes dessas populações tradicionais.
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