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 Eschweilera tetrapetala é uma árvore endêmica das Florestas Sazonais Submontanas (SSF) da Chapada Diamantina, remanescentes de floresta Atlântica, Brasil. Os efeitos das mudanças climáticas no padrão de distribuição espacial dessa espécie foram investigados para identificar áreas prioritárias de conservação. Os padrões de distribuição e as densidades populacionais foram obtidos por amostragem de indivíduos em dez transectos de 200 x 10 m e trinta parcelas adicionais de 10 x 10 m situadas em borda e interior de uma área da SSF. Esses dados de ocorrência foram submetidos à Modelagem de Nicho Ecológico usando os algoritmos Bioclim, Maxent e Support Vector Machine. O modelo previsto para sua distribuição atual, usando os algoritmos Bioclim, Maxent e Support Vector Machine (SVM), evidenciou áreas de forte adequabilidade ambiental a leste da Serra do Sincorá. Os modelos determinaram expansão da área de adequabilidade ambiental durante o Holoceno Médio, retração no presente e maiores reduções previstas em cenários futuros. O número de indivíduos nas parcelas variou de zero a 14, indicando distribuição agregada. O índice de Morisita indicou distribuição aleatória ao longo da borda da floresta, mas agregada no interior da floresta. Eschweilera tetrapetala é sensível às mudanças climáticas e pressão antropogênica, em escalas regional e local.

Abstract Eschweilera tetrapetala is a tree endemic to Submontane Seasonal Forests in inland Atlantic forest areas of the Chapada Diamantina Mountains, Northeastern Brazil. The effects of climate change on the spatial distribution pattern of that species were investigated to identify priority areas for its conservation. Distribution patterns and population densities were obtained by sampling individuals in ten 200 x 10 m transects, and in thirty additional 10 x 10 m border and interior forest plots. The occurrence data were subjected to Ecological Niche Modelling using Bioclim, Maxent, and Support Vector Machine algorithms. The predicted model for the current distribution of E. tetrapetala, using the Bioclim, Maxent, and Support Vector Machine algorithms, evidenced stable areas of strong environmental suitability in the east of the Chapada Diamantina. The models also show an expansion of areas with environmental suitability during the Mid-Holocene, with retraction in the present and greater reductions predicted in future global warming scenarios. The number of individuals in the plots varied from zero to 14, indicating an aggregated distribution. Morisita’s index indicated a random distribution along a forest edge but aggregated in the forest interior. Eschweilera tetrapetala is sensitive to climatic change and anthropogenic pressure, at both regional and local scales.

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.

A Floresta Atlântica apresenta padrões de heterogeneidade ainda pouco conhecidos, em especial aqueles associados à altitude, raramente investigados no eixo setentrional brasileiro. O objetivo do presente trabalho foi verificar a ocorrência de variações na composição florística, diversidade e estrutura da vegetação num remanescente de floresta Montana no sul da Bahia, através da análise de dois trechos de vegetação em diferentes altitudes. Foram amostrados no total 0,5 ha através de cinco plots separados entre si e alocados numa floresta úmida na RPPN Serra Bonita, Bahia, Brasil. Registraram-se 354 espécies de 68 famílias, sendo Myrtaceae, Fabaceae, Rubiaceae e Lauraceae as mais ricas. Os dois trechos apresentaram diferenças em densidade, área basal e estrutura, percebendo-se que com o aumento da altitude, ocorre uma diminuição no porte da floresta, refletindo maior densidade no sub-bosque, além de redução na riqueza específica. A Serra Bonita apresentou alta diversidade, similar a outras áreas na Bahia, porém maior que na Floresta Atlântica no sudeste do Brasil. Os trechos amostrados apresentaram bom estado de conservação, com abundância de lianas lenhosas, elevada área basal e baixa evidência de extração madeireira. As variações detectadas entre os trechos inventariados sugerem modificações estruturais abruptas, influenciadas possivelmente por precipitação, temperatura e barreiras locais determinadas por uma topografia acidentada, mas não por fatores edáficos.

The Atlantic Forest has a heterogeneity that is still largely unappreciated, especially that associated with altitudinal factors; this has rarely been examined in the northern extension of this biome. The study investigated the occurrence of variation in floristic composition, diversity, and vegetation structure at two altitudes in a remnant area of forest in southern Bahia state. A total of 0.5 ha of vegetation was sampled in five separate plots established in a wet forest in the RPPN Serra Bonita, Bahia, Brazil. A total of 354 species belonging to 68 families were found, with Myrtaceae, Fabaceae, Rubiaceae and Lauraceae being the richest taxa. The two altitudinal sites showed significant differences in density, basal area and structure. There were notable changes in forest structure with increasing altitude, reflected in higher densities of the understory and a reduction in species richness. Serra Bonita had high species diversity that was similar to other areas in Bahia, but higher than found in the Atlantic Forests of southeastern Brazil. The forest sections sampled were well preserved, as indicated by the abundance of woody vines, elevated basal area, and lack of evidence of significant logging activities. The variation detected between the areas suggests the existence of abrupt structural modifications influenced not by edaphic factors but by rainfall differences, temperature variations, and by local barriers determined by the steep topography.