This study presents results of the inventory of algal flora conducted between August 2007 and May 2008 in 18 lakes of the middle Rio Doce lake system, most of which is in the state of Minas Gerais, Brazil. We recorded 481 taxa, increasing the known total phytoplankton diversity of the region (gamma diversity) by 80%. The following classes were represented: Zygnematophyceae (171 taxa), Cyanobacteria (101), Chlorophyceae (71), Bacillariophyceae (42), Euglenophyceae (43), Trebouxiophyceae (24), Dinophyceae (8), Xanthophyceae (8), Chrysophyceae (6), Cryptophyceae (6) and Oedogoniophyceae (1). We identified 221 taxa that were rare (restricted to one or two lakes), and 101 that were considered representative (present in at least nine lakes). Botryococcus braunii, Elakatothrix genevensis, Planktolyngbya limnetica, Peridinium pusillum, Trachelomonas volvocina, Cosmarium contractum, Staurastrum forficulatum, Staurastrum leptocladum, Staurastrum rotula, and Staurodesmus dejectus were present in all lakes. Richness varied from 95 taxa (in Lake Gambazinho) to 168 taxa (in Lake Palmeirinha). Jaccard indices were low, and the highest similarities between lakes were 53% (Ferrugem/Ferruginha), 47% (Central/Almécega) and 46% (Águas Claras/Palmeirinha), demonstrating high environmental and biotic dissimilarities between lakes. Geographic distance was not significantly associated with floristic similarity, suggesting that local factors are more important than are regional ones in shaping the phytoplankton composition of lakes.
It is well known that both niche requirements and dispersal act together to structure communities; however, it remains unclear how the underlying mechanisms create the observed patterns in nature. In plankton communities, traits related to dispersal ability (e.g. body and propagule sizes) and niche breadth (i.e. habitat generalists and habitat specialists) have recently shown promise in this regard. Here, we hypothesized that body size (a proxy for dispersal ability) and niche breadth act together to determine limnetic plankton metacommunity structure in a tropical system of natural landlocked lakes in Brazil. Our hypotheses were partially supported for zooplankton community. Copepoda showed no relation to environmental variables, and the larger-bodied Calanoida was structured only by space. The Cladocera showed the largest spatial and environmental limitation. Rotifers showed the lowest association with space; however, its pure environmental fraction was higher than expected. The phytoplankton community was largely structured by both environment and space. The spatial limitation of this group was a clear divergence from our expectations. Lastly, we revealed that intragroup variation (when species were evaluated individually) was equal or larger than between group variation, indicating that group-specific traits may play a more important role in determining metacommunity structure.
O estudo avalia como a Educação Ambiental é abordada em uma escola pública de Contagem (MG), com foco na distância entre teoria e prática e nos desafios que gestor e professores enfrentam no que se refere a sua essência interdisciplinar. A pesquisa foi baseada em três etapas: i) análise documental dos currículos e do Plano Político e Pedagógico da escola; ii) aplicação de questionários; iii) avaliação visual da utilização dos espaços físicos escolares para tratar as questões ambientais. Os resultados apontam que a Educação Ambiental é abordada de forma superficial. A falta de capacitação do corpo docente e do gestor para desenvolver trabalhos relacionados a este tema, como determina a legislação, destaca-se como fator complicador.
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