ABSTRACT The growth in the number of molecular sequences produced in recent years has provided valuable contributions to the knowledge diversity of red algae (Rhodophyta) in Brazil. However, many works indicate that there is still much to be studied. Here, we highlight the importance of compiling all these data to evidence possible taxonomic and geographic knowledge gaps in red algae through molecular data. So, this study presents a scientometric analysis of the molecular studies carried out on red algae in Brazil, based on the analysis of DNA sequences available in the public database GenBank. Our results demonstrated an increase in published papers from 1994 to 2020, corresponding to 165 studies analyzed. A huge disparity in the production of knowledge was observed, with the southeastern region concentrating the researchers responsible for most of the published studies, with emphasis on those in the University of São Paulo (USP). Bahia and São Paulo states stand out with the highest observed taxonomic richness, respectively. We also could identify the taxonomic groups with more molecular data generated, the sequence number deposited per institution since 1994, the main markers used, the regions that require a greater collection effort, and where the researchers who study red algae in the country are.

Abstract Measurements of the marine carbonate system on tropical and subtropical continental margins are poorly distributed in space and time, with many uncertainties persisting regarding the role of carbon exchanges at the ocean-atmosphere interface in these areas. To calculate sea-to-air CO 2 fluxes in Marine Ecoregions along the Brazilian continental margin (4°N to 34°S), we used data from the Surface Ocean CO 2 Atlas (SOCAT v2020), collected up to 400 km from the coast, at the surface (5 m), between 1991 and 2018, with the aim of investigating the role of ecoregions as potential sinks or sources of atmospheric CO 2. The temperature and salinity of seawater presented variability in the north-south direction mainly because of the broad latitudinal range, reflecting typical patterns of tropical (T = 27.4°C ±1.49; S = 36.4 ±1.91) and subtropical waters (T = 22.8°C ±3.41; S = 35 ±2.91), in addition to the greater or lesser influence of river inputs in each ecoregion. The pCO 2 values in the surface waters varied from 121.81 (Amazon) to 478.92 μatm (Eastern), differing significantly between ecoregions and showing an expected decadal increasing trend, both in the atmosphere and in the seawater. The calculated values of CO 2 fluxes showed non-homogeneous spatio-temporal variations, from -24.37 mmol m-2 d-1 (Rio Grande) to 9.87 mmol m- 2 d-1 (Southeastern). Throughout the analyzed time series, we observed that the Northeast, Amazon and Eastern ecoregions acted predominantly as sources of CO 2 and the Southeastern ecoregions and, mainly, Rio Grande, acted predominantly as sinks of atmospheric CO 2.

Resumo Scrippsiella acuminata é um complexo de espécies que pode causar condições anóxicas na coluna d’água durante florações. Este estudo teve como objetivo analisar a ocorrência e distribuição de Scrippsiella cf. acuminata ao longo do gradiente estuarino do rio Paraguaçu, a partir de coletas bimestrais (março de 2018 a março de 2019) realizadas em 12 pontos amostrais. Variáveis ambientais foram medidas in situ, e amostras de água foram coletadas para análise de nutrientes inorgânicos dissolvidos e densidade de células fitoplanctônicas. Em cada ponto, as amostras foram coletadas para análise da composição das espécies e preservadas com formaldeído com concentração final de 4%. S. cf. acuminata ocorreu em todo o gradiente estuarino (salinidade 0,1–38,9), exceto em julho, coincidindo com as menores concentrações de nutrientes inorgânicos dissolvidos. A densidade celular variou entre 20 células L-1 (janeiro de 2019) e 1,8 × 106 células L-1 (março de 2018); neste último, ocorreu uma floração em condições de baixa salinidade (5,7) e a maior concentração de nutrientes inorgânicos dissolvidos registrada para o estudo. A densidade celular (1,7 × 105 L-1) aumentou novamente em novembro de 2018. Nenhum dos eventos teve efeitos prejudiciais no sistema estuarino. Este estudo permitiu-nos compreender melhor os padrões de distribuição de S. cf. acuminata considerando as características ambientais que podem favorecer seu desenvolvimento.

Abstract Scrippsiella acuminata is a species complex that can cause anoxic conditions in the water column during blooms. This study aimed to analyze the occurrence and distribution of Scrippsiella cf. acuminata along the estuarine gradient of Paraguaçu River, from bimonthly sampling (March 2018 to March 2019) performed at 12 sampling points. Environmental variables were measured in situ, and water samples were collected for analysis of dissolved inorganic nutrients and phytoplankton cell density. At each point, samples were collected for analysis of species composition and preserved with formaldehyde at a final concentration of 4%. S. cf. acuminata occurred throughout the estuarine gradient (salinity 0.1–38.9), except in July, coinciding with the lowest concentrations of dissolved inorganic nutrients. Cell density varied between 20 cel L-1 (January 2019) and 1.8 × 106 cell L-1 (March 2018); in the latter, the species bloomed under conditions of low salinity (5.7) and the highest dissolved inorganic nutrient concentration recorded in the study. Cell density (1.7 × 105 L-1) increased in November 2018. Neither event had any detrimental effects on the estuarine system. This study allowed us to better understand the distribution patterns of S. cf. acuminata considering the environmental characteristics that can favor its development.

Abstract The objective of this study was to evaluate variations in the composition and abundance of the phytoplankton community after an exceptional harmful bloom of Akashiwo sanguinea that occurred in Todos os Santos Bay (BTS) in early March, 2007. Samples were collected every ten days, between April, 2007 and March, 2008, from the estuarine gradient of the Paraguaçu River to BTS. The physical and chemical variables were measured in situ using a multiparameter sensor. Water samples were collected for analysis of the dissolved inorganic nutrient concentrations and for the study of composition and abundance of the microphytoplankton. Overall, 135 taxa were identified, with a higher richness of diatoms. The total cell density ranged from 2.92 × 103 to 1.16 × 107 (5.47 × 105 ± 1.69 × 106) cells L−1, with higher values in the freshwater zone than in the marine area. Five species showed peaks of abundance throughout the study, forming small blooms. Four of these blooms occurred in the rainy season, formed by the species Guinardia striata (April, 2007), Scrippsiella cf. acuminata (August, 2007), Euglena gracilis (August, 2007), and Skeletonema cf. costatum (September, 2007), while a new bloom of the species Akashiwo sanguinea occurred during the dry season (December, 2007). The environment was typically oligotrophic, with low spatiotemporal variation in the concentrations of dissolved nutrients. Even so, we observed short-term variations in the structure and composition of the phytoplankton community, demonstrated by rapid bloom events, followed by an increase in the total abundance of microphytoplankton, especially during the rainy season. The blooms did not cause any notable changes in the water column and did not present any harmful effects on the system.

ABSTRACT Hypnea pseudomusciformis was recently described from South America, and has three morphological variants: “musciformis”, “nigrescens”, and “valentiae”. Information on the biology of these variants may help to explain this species’ wide morphological variation despite the absence of genetic divergence among variants. More morphological and ecological data has accumulated on the “musciformis” variant occurring on the Brazilian coast than for the others. In this study, we described the reproductive morphology of a tropical “nigrescens” population and investigated its phenology to provide crucial biological information about this taxon, and perhaps also assist in answering questions about the systematics of H. pseudomusciformis variants. The population analyzed showed no significant fluctuations in its total biomass throughout the year. All reproductive stages were frequently recorded during this study, which contributes greatly to our knowledge of the reproductive morphology of the “nigrescens” variant. Phenological variations were correlated with environment variables, such as air and sea-surface temperatures, insolation, precipitation, and humidity. Male gametophytes were frequently present, which has never been reported for the “musciformis” variant. We showed that, despite being members of the same genetic species, the “nigrescens” and “musciformis” morphological variants exhibit remarkable differences in their ecology and biology.

Resumo A comunidade fitoplanctônica representa o primeiro elo na cadeia trófica aquática e o conhecimento de sua composição é uma ferramenta importante para a caracterização ecológica de um sistema. Inclusive como indicador potencial de impactos antrópicos na água. O litoral sul da Bahia é um dos segmentos da costa brasileira em melhor estado de preservação ambiental, ainda conhecendo-se muito pouco à respeito da sua biodiversidade, especialmente a ficoflora marinha. Com o objetivo de caracterizar a composição do microfitoplâncton (> 20 µm) nesta região, foram coletadas amostras, em arrastos horizontais de subsuperfície, utilizando-se rede de plâncton (20 µm de malha) para estudar a composição da comunidade. Amostras de água foram coletadas com garrafa de Van Dorn, para analisar a densidade celular do microfitoplâncton. Foram identificados um total de 149 taxa, distribuídos nos filos: Bacillariophyta, Miozoa, Cianobacteria, Euglenophyta, Haptophyta e Ochrophyta. As diatomáceas (63%) e os dinoflagelados (26%) foram os grupos mais representativos na composição específica e 43 novas occorrências taxonômicas foram registradas para a costa da Bahia, litoral do Nordeste e litoral do Brasil.

Abstract The phytoplankton community is the first link in the aquatic trophic chain and knowledge of its composition is an important tool for ecological characterization; including as potential indicator of anthropic impacts. The southern coast of Bahia is one of the best preserved parts of the Brazilian coast, however, little is known about its biodiversity, especially on marine phycoflora. With the objective of characterizing the composition of microphytoplankton (> 20 µm) in this region, samples were collected by a horizontal dredger using a plankton net (20 µm mesh size) to study the community composition. Water samples were taken from the subsurface using a Van Dorn bottle in order to analyze phytoplanktonic cell concentration. A total of 149 taxa were identified, distributed in the following phyla: Bacillariophyta, Miozoa, Cyanobacteria, Euglenophyta, Haptophyta, and Ochrophyta. Diatoms (63%) and dinoflagellates (26%) were the most representative groups in the specific composition. 43 new taxonomic occurrences were recorded for the coasts of Bahia, Northeastern Brazilian coast, and Brazilian coast.

Em geral, o acúmulo de exopolissacarídeos (EPS) produzidos pelos microrganismos ocorre na presença de excesso de substrato e condições limitantes de elementos essenciais ao crescimento, como nitrogênio, fósforo, enxofre, ou magnésio. A presença de EPS associada com células bacterianas é reconhecida em meio sólido para a formação de colônias mucoides e no meio líquido pelo aumento da viscosidade. Este trabalho propõe um método alternativo para realizar triagem de bactérias láticas produtoras de EPS utilizando meio sólido contendo discos de papel de filtro impregnado pela cultura. A seleção foi realizada em diferentes condições de cultivo, variando o tipo de açúcar, pH e temperatura. A produção de EPS foi visualizada pela presença da colônia mucoide sobre os discos, que foram confirmadas pelo precipitado, quando parte desta colônia foi misturada com álcool absoluto. As condições de cultivo em que houve maior produção de EPS foram: sacarose 10%, pH 7,5 a 28 ºC. Este método provou ser eficaz e econômico, uma vez que várias cepas podem ser testadas na mesma placa, sendo possível realizar uma prévia confirmação da produção do EPS.

The accumulation of exopolysaccharides (EPS) produced by microorganisms occurs in the presence of excess substrate and limiting conditions of elements that are essential to growth, such as nitrogen, phosphorus, sulfur, and magnesium. The presence of EPS produced by bacterial cells contributes to slime colonies formation in solid medium and increased viscosity in liquid medium. This paper proposes an alternative method for screening EPS-producing lactic acid bacteria using solid medium-containing discs of filter paper that are saturated with active cultures. The screening was carried out under different culture conditions varying the type of sugar, pH, and temperature. EPS production was visualized by the presence of mucoid colonies on the discs, which was confirmed by the formation of a precipitate when part of this colony was mixed with absolute alcohol. The established conditions for obtaining a high number of isolates producing EPS were 10% sucrose, pH 7.5 and 28 ºC. This method proved to be effective and economical because several strains could be tested on the same plate, with immediate confirmation.