16 research outputs found
Planktonic production and respiration in a subtropical lake dominated by Cyanobacteria
Planktonic primary production and respiration rates were estimated in a subtropical coastal lake dominated by Cyanobacteria in order to investigate the temporal and vertical variation in this lake and to evaluate its relationships with limnological variables and phytoplankton. Light and dark bottles were incubated at four different depths in the central part of the lake and were performed bimonthly from June/2009 to December/2010. No significant difference was evident among depths in relation to phytoplankton, limnological variables and metabolic rates. However, the highest production rates were recorded at the surface, and decreased towards the bottom, coupled with phytoplanktonic photosynthetic capacity. Wind induced mixing in Peri Lake played an important role in nutrient and phytoplankton redistribution, characterizing this lake as polymictic. According to density and biovolume, the phytoplankton community was dominated by filamentous Cyanobacteria, especially Cylindrospermopsis raciborskii (Woloszynska) Seenayya and Subba-Raju. This study has shown that both water temperature and nutrient availability drive phytoplankton growth and consequently the temporal variation in metabolic rates, where respiration is higher than primary production
First record of Ceratium furcoides (Dinophyta), an invasive species, in a temporary high-altitude lake in the Iron Quadrangle (MG, Southeast Brazil)
Dinoflagellates of the genus Ceratium are generally marine organisms, but rare occurrences in freshwater have been observed in Brazil. In this paper we are recording for the first time the presence of Ceratium furcoides, an invasive species, in a shallow, natural intermittent pool formed at a high-altitude at the southern end of the Iron Quadrangle, an iron-mining district of Minas Gerais State (Southeast Brazil). Samples were collected in October and November of 2010 (rainy period). The population density of this organism observed in Lagoa Seca (“Dry Pool”) was very low, at most 4 ind L–1. Mountain lakes are extremely vulnerable to atmospheric deposition of organisms, making them valuable witnesses both of the many forms of impact arising from human activities and of the extended global connections that facilitate the dispersion and introduction of new species over great distances. Studies on the population dynamics of C. furcoides in natural tropical systems are still rare and very recent to the brazilian scenario and hence the monitoring of its dynamics and the potential impact on aquatic communities of its becoming established are essential to an understanding of the process of bioinvasion by this species
Primeiro registro de Ceratium furcoides (Dinophyta), uma espĂ©cie invasora, em um lago temporário de alta altitude no Quadrilátero FerrĂfero (MG, Sudeste do Brasil).
Dinoflagelados do gĂŞnero Ceratium sĂŁo principalmente marinhos, porĂ©m existem raras ocorrĂŞncias em água doce no Brasil. Neste estudo registramos pela primeira vez a ocorrĂŞncia de Ceratium furcoides, uma espĂ©cie invasora em um lago altitudinal natural raso localizado na porção sul do Quadrilátero FerrĂfero, uma área de extração mineral no estado de Minas Gerais. As coletas foram realizadas nos meses de outubro e novembro de 2010 (perĂodo chuvoso). As densidades observadas para C. furcoides na Lagoa Seca foram muito baixas, com máximo de 4 ind L–1. Lagos de altitude sĂŁo altamente vulneráveis Ă deposição atmosfĂ©rica, o que os torna importantes testemunhos nĂŁo sĂł dos mĂşltiplos impactos derivados de atividades humanas, mas tambĂ©m das extensas conexões globais, que acabam por facilitar a dispersĂŁo e introdução de espĂ©cies. Estudos sobre a dinâmica de C. furcoides em sistemas tropicais naturais ainda sĂŁo escassos e por isso, o monitoramento de sua dinâmica e dos impactos potenciais em comunidades aquáticas a partir do seu estabelecimento, torna-se fundamental para o entendimento dos processos relacionados Ă bioinvasĂŁo desta espĂ©cie.Dinoflagellates of the genus Ceratium are generally marine organisms, but rare occurrences in freshwater have been observed in Brazil. In this paper we are recording for the first time the presence of Ceratium furcoides, an invasive species, in a shallow, natural intermittent pool formed at a high-altitude at the southern end of the Iron Quadrangle, an iron-mining district of Minas Gerais State (Southeast Brazil). Samples were collected in October and November of 2010 (rainy period). The population density of this organism observed in Lagoa Seca (“Dry Pool”) was very low, at most 4 ind L–1. Mountain lakes are extremely vulnerable to atmospheric deposition of organisms, making them valuable witnesses both of the many forms of impact arising from human activities and of the extended global connections that facilitate the dispersion and introduction of new species over great distances. Studies on the population dynamics of C. furcoides in natural tropical systems are still rare and very recent to the brazilian scenario and hence the monitoring of its dynamics and the potential impact on aquatic communities of its becoming established are essential to an understanding of the process of bioinvasion by this species
First record of Ceratium furcoides (Dinophyta), an invasive species, in a temporary high-altitude lake in the Iron Quadrangle (MG, Southeast Brazil)
Dinoflagellates of the genus Ceratium are generally marine organisms, but rare occurrences in freshwater have been observed in Brazil. In this paper we are recording for the first time the presence of Ceratium furcoides, an invasive species, in a shallow, natural intermittent pool formed at a high-altitude at the southern end of the Iron Quadrangle, an iron-mining district of Minas Gerais State (Southeast Brazil). Samples were collected in October and November of 2010 (rainy period). The population density of this organism observed in Lagoa Seca (“Dry Pool”) was very low, at most 4 ind L–1. Mountain lakes are extremely vulnerable to atmospheric deposition of organisms, making them valuable witnesses both of the many forms of impact arising from human activities and of the extended global connections that facilitate the dispersion and introduction of new species over great distances. Studies on the population dynamics of C. furcoides in natural tropical systems are still rare and very recent to the brazilian scenario and hence the monitoring of its dynamics and the potential impact on aquatic communities of its becoming established are essential to an understanding of the process of bioinvasion by this species
Novos registros de Eunotia Ehrenberg (Eunotiaceae-Bacillariophyta) para o Estado do Rio Grande do Sul e Brasil
O trabalho tem como objetivo apresentar as caracterĂsticas morfolĂłgicas, e/ou estruturais e mĂ©tricas de 12 espĂ©cies de Eunotia (E. batavica A. Berg, E. deficiens Metz., Lange-Bert & GarcĂa-Rodr., E. genuflexa Nörpel-Sch., E. hepaticola Lang-Bert. & Wydrz., E. herzogii Krasske, E. mucophila (Lange-Bert., Nörpel-Sch. & Alles) Lange-Bert., E. pileus Ehr., E. pirla Carter & Flower, E. schwabei Krasske, E. subarcuatoides Alles, Nörpel-Sch. & Lange-Bert., E. transfuga Metz. & Lange-Bert. e E. yanomami Metz. & Lange-Bert.) encontradas nas áreas da Lagoa do Casamento e dos Butiazais de Tapes, entre as coordenadas 30Âş10'-30Âş40'S e 50Âş30'-51Âş30'W, na PlanĂcie Costeira do Rio Grande do Sul. SĂŁo incluĂdos comentários sobre a distribuição e os ambientes onde os táxons foram encontrados.<br>This paper presents the morphological and/or structural and mensurable characteristics of 12 Eunotia species (E. batavica A. Berg, E. deficiens Metz., Lange-Bert. & GarcĂa-Rodr., E. genuflexa Nörpel-Sch., E. hepaticola Lang-Bert. & Wydrz., E. herzogii Krasske, E. mucophila (Lange-Bert., Nörpel-Sch. & Alles) Lange-Bert., E. pileus Ehr., E. pirla Carter & Flower, E. schwabei Krasske, E. subarcuatoides Alles, Nörpel-Sch. & Lange-Bert., E. transfuga Metz. & Lange-Bert. and E. yanomami Metz. & Lange-Bert.) found in the Lagoa do Casamento and Butiazais de Tapes areas, between 30Âş10'-30Âş40'S and 50Âş30'-51Âş30'W, on the Rio Grande do Sul State Coastal Plain. Comments on distribution and habitats where the taxons are found are included