RESUMO
Eutrophication is a global problem causing the reduction of water quality and the loss of ecosystem goods and services. The lakes of the "Lagunas de Montebello" National Park (LMNP), Chiapas, Mexico, not only represent unique and beautiful natural scenic sites in southern Mexico but are also a national protected area and RAMSAR site. Unfortunately, some of these lakes started showing eutrophication signs since 2003. Anthropogenic activities (e.g., land-use change from forested to agricultural and urban development) are leading to water quality and trophic state alterations of the lakes of the LMNP. This study shows the results of a coupled limnological characterization and high-throughput sequencing of the V4 hypervariable region of the 16S rRNA gene to analyze the microbial composition of the water column in a set of oligotrophic and eutrophic lakes. Chlorophyll a (Chl-a) was the main environmental parameter correlated with the trophic conditions of the lakes. Although the microbial diversity was similar, the microbial composition changed significantly from oligo to eutrophic lakes. Proteobacteria, Firmicutes, and Cyanobacteria were the main components of oligotrophic lakes, and Cyanobacteria, Proteobacteria, and Bacteroidetes of eutrophic lakes. While Acinetobacter (Proteobacteria) and Cyanobium (a unicellular cyanobacterium) dominated in oligotrophic lakes, the filamentous, bloom-forming, and toxin-producing cyanobacteria Planktothrix was the dominant genus in eutrophic lakes. High-throughput sequencing allowed the detection of changes in the composition of the microbial component in oligotrophic lakes, suggesting a shift towards eutrophication, highlighting the relevance of sensitive monitoring protocols of these ecosystems to implement remediation programs for eutrophicated lakes and conservation strategies for those yet pristine.
Assuntos
Cianobactérias , Lagos , Lagos/análise , Ecossistema , Clorofila A , México , RNA Ribossômico 16S/genética , Parques Recreativos , Cianobactérias/genéticaRESUMO
Abstract: Cyanobacteria and microalgae make up a very diverse group and exhibit diverse morphological, biochemical and physiological differences. The knowledge of these organisms that inhabit epicontinental waters in Brazil is extremely heterogeneous in relation to the geographic region and the taxonomic group. Taxonomically there is much more knowledge about the algae of the South and Southeast regions of the country than there is about the algae of the North and Central-West regions. Therefore, this research presents a revised and updated knowledge of the algae that occur in the National Park of the Chapada dos Guimarães (PNCG) and surrounding areas. Our area of study is located in the state of Mato Grosso, in the center-west region of Brazil. The database was obtained from published literature related to taxonomic and ecological inventories, as well as new collections carried out in the area. The collection methods were quite diverse to cover all types of organisms, in plankton, periphyton, filamentous masses, sludge and water accumulated in bromeliads, the new collections are samples collected exclusively in the plankton. They were listed 182 taxa, distributed in 83 genera, 45 families, 11 classes and seven taxonomic divisions. In total, 89 taxa were found in the new samplings, of which nine taxa were already registered in the existing literature, so 80 taxa are new records for the region. A large number of taxa previously mentioned in the literature were not recorded in the sampled environments, most of them composed of Bacillariophyceae, Conjugatophyceae and Euglenophyceae. As well as three species of cyanobacteria of great sanitary importance were registered. Therefore, CGNP has great importance in the maintenance of aquatic biodiversity and to know this community becomes increasingly important to support management measures.
Resumo: As cianobactérias e as microalgas compõem um grupo bastante diversificado e exibem diversas diferenças morfológicas, bioquímicas e fisiológicas. O conhecimento desses organismos que habitam as águas epicontinentais no Brasil é extremamente heterogêneo em relação à região geográfica e ao grupo taxonômico. Taxonomicamente, há muito mais conhecimento sobre as algas das regiões Sul e Sudeste do país do que sobre as algas das regiões Norte e Centro-Oeste. Portanto, esta pesquisa apresenta um conhecimento revisado e atualizado das algas que ocorrem no Parque Nacional da Chapada dos Guimarães (PNCG) e arredores. Nossa área de estudo está localizada no estado de Mato Grosso, na região centro-oeste do Brasil. O banco de dados foi obtido a partir de literatura publicada relacionada a inventários taxonômicos e ecológicos, assim como novas coletas realizadas na área. Os métodos de coletas foram bastante diversos de modo que abrangesse todo tipo de organismos, no plâncton, perifíton, massas filamentosas, lodo e água acumulada em bromélias, as novas coletas são amostras coletadas exclusivamente no plâncton. Foram listados 182 táxons, distribuídos em 83 gêneros, 45 famílias, 11 classes e sete divisões taxonômicas. No total, 89 táxons foram encontrados nas novas amostragens realizadas, destes, nove táxons, já haviam sido registrados na literatura existente, portanto 80 táxons são novos registros para a região. Um grande número de táxons citados anteriormente na literatura, não foram registrados nos ambientes amostrados, na sua grande maioria constituído por Bacillariophyceae, Conjugatophyceae e Euglenophyceae. Como também foram registradas três espécies de cianobactérias de grande importância sanitária. Sendo assim o PNCG possui grande importância na manutenção da biodiversidade aquática e conhecer essa comunidade torna-se cada vez mais importante para embasar medidas de manejo.
RESUMO
The Amazon Rainforest holds great tropical biodiversity, mainly because of its favourable climatic conditions. The high temperatures, luminosity and humidity coupled with the nutritional simplicity of cyanobacteria allow undiscovered diversity to flourish within this group of microorganisms. Some efforts to reveal this diversity have been attempted; however, most were focused on the microscopic observation of environmental samples without any genetic information. Very few studies focusing on morphological, ecological and molecular criteria have been conducted, and none have been devoted to homocytous cyanobacteria forms in Amazonia region. Therefore, the genetic relationships amongst strains retrieved from this ecosystem with regard to other environments from Brazil and the world have not been tested and, consequently, the Amazonian strains would naturally be assumed as novel to science. To examine these relationships, cultured homocytous cyanobacteria isolated from two Amazonian rivers (Amazonas and Solimões) were evaluated using a phylogenetic perspective, considering the 16S rRNA gene sequence. A total of eleven homocytous cyanobacterial strains were isolated. Morphologically, they were identified as Pseudanabaena, Leptolyngbya, Planktothrix and Phormidium, but genetically they were included in the typical clusters of Planktothrix, Pseudanabaena, Cephalothrix, Pantanalinema and Alkalinema. These three latter genera have been detected in other Brazilian ecosystems only (Pantanal, Atlantic Rainforest and Pampa), while those remaining have been extensively found in many parts of the world. The data provided here indicate that Amazonian rivers support a homocytous cyanobacterial diversity previously reported from other geographical and ecological environments.
Assuntos
Biodiversidade , Cianobactérias/classificação , Filogenia , Rios/microbiologia , Sequência de Bases , Brasil , Cianobactérias/genética , Cianobactérias/crescimento & desenvolvimento , Cianobactérias/isolamento & purificação , DNA Bacteriano/genética , DNA Espaçador Ribossômico/genética , Geografia , Concentração de Íons de Hidrogênio , Funções Verossimilhança , Conformação de Ácido Nucleico , RNA Ribossômico 16S/genéticaRESUMO
Feeding behavior of the invasive bivalve Limnoperna fortunei in the presence of single-celled, colonial, and filamentous cyanobacteria was tested in laboratory experiments to evaluate the effects of size and shape on mussel feeding. The first hypothesis holds that golden mussel filters more efficiently smaller particles, such as single cells of Microcystis, which could be more easily assimilated by its filtering apparatus. The second hypothesis sustains that L. fortunei filters more efficiently rounded colonies, such as Microcystis, which would be more easily ingested than lengthy filamentous, such as Planktothrix. Filtration rates of golden mussel in the presence of single-celled, colonial and filamentous cyanobacteria were similar. Nevertheless, there was a great difference in the ingestion and pseudofeces production rates. Single cells were widely accepted as food, while filamentous and colonial cyanobacteria were massively expelled as pseudofeces. The results confirmed the first hypothesis that golden mussel prefers to ingest smaller particles. The second hypothesis was rejected since filamentous were preferentially ingested than colonial cyanobacteria. Golden mussel has the potential to remove toxic cells (Microcystis), however this potential would be reduced in cyanobacteria blooms, where colonial forms which are preferentially rejected by L. fortunei, are predominant. In this case, the presence of this invasive bivalve could also enhance the occurrence of blooms by rejecting colonial and filamentous cyanobacteria in pseudofeces.
O comportamento alimentar do bivalve invasor Limnoperna fortunei na presença de cianobactérias solitárias, coloniais e filamentosas foi testado em experimentos laboratoriais, para avaliar os efeitos do tamanho e da forma na alimentação dos mexilhões. A primeira hipótese sustenta que o mexilhão dourado filtra as partículas menores com maior eficiência, como as células solitárias de Microcystis, as quais seriam assimiladas mais facilmente. A segunda hipótese sustenta que L. fortunei filtra com mais eficiência as colônias arredondadas, como Microcystis, que seriam mais facilmente ingeridas do que os filamentos longos, como Planktothrix. As taxas de filtração do mexilhão dourado na presença das cianobactérias solitárias, coloniais e filamentosas foram semelhantes. No entanto, houve uma grande diferença nas taxas de ingestão e produção de pseudofezes. As células solitárias foram amplamente aceitas como alimento, enquanto as cianobactérias filamentosas e coloniais foram massivamente expulsas sob a forma de pseudofezes. Os resultados confirmaram a primeira hipótese, a de que o mexilhão dourado prefere ingerir partículas menores. A segunda hipótese foi rejeitada, pois os filamentosos de Planktothrix foram preferencialmente ingeridos em relação às colônias de Microcystis. O mexilhão dourado apresenta potencial para remover células tóxicas de cianobactérias (Microcystis); entretanto, esse potencial ficaria reduzido em eventos de floração, em que as formas coloniais, preferencialmente rejeitadas por L. fortunei, são predominantes. Nesse caso, a presença do bivalve no ambiente poderia ainda potencializar a ocorrência da floração via rejeição das cianobactérias coloniais e filamentosas nas pseudofezes.
Assuntos
Animais , Bivalves/fisiologia , Cianobactérias , Comportamento Alimentar/fisiologia , Microcystis , Tamanho da Partícula , Análise de Célula ÚnicaRESUMO
Feeding behavior of the invasive bivalve Limnoperna fortunei in the presence of single-celled, colonial, and filamentous cyanobacteria was tested in laboratory experiments to evaluate the effects of size and shape on mussel feeding. The first hypothesis holds that golden mussel filters more efficiently smaller particles, such as single cells of Microcystis, which could be more easily assimilated by its filtering apparatus. The second hypothesis sustains that L. fortunei filters more efficiently rounded colonies, such as Microcystis, which would be more easily ingested than lengthy filamentous, such as Planktothrix. Filtration rates of golden mussel in the presence of single-celled, colonial and filamentous cyanobacteria were similar. Nevertheless, there was a great difference in the ingestion and pseudofeces production rates. Single cells were widely accepted as food, while filamentous and colonial cyanobacteria were massively expelled as pseudofeces. The results confirmed the first hypothesis that golden mussel prefers to ingest smaller particles. The second hypothesis was rejected since filamentous were preferentially ingested than colonial cyanobacteria. Golden mussel has the potential to remove toxic cells (Microcystis), however this potential would be reduced in cyanobacteria blooms, where colonial forms which are preferentially rejected by L. fortunei, are predominant. In this case, the presence of this invasive bivalve could also enhance the occurrence of blooms by rejecting colonial and filamentous cyanobacteria in pseudofeces.
O comportamento alimentar do bivalve invasor Limnoperna fortunei na presença de cianobactérias solitárias, coloniais e filamentosas foi testado em experimentos laboratoriais, para avaliar os efeitos do tamanho e da forma na alimentação dos mexilhões. A primeira hipótese sustenta que o mexilhão dourado filtra as partículas menores com maior eficiência, como as células solitárias de Microcystis, as quais seriam assimiladas mais facilmente. A segunda hipótese sustenta que L. fortunei filtra com mais eficiência as colônias arredondadas, como Microcystis, que seriam mais facilmente ingeridas do que os filamentos longos, como Planktothrix. As taxas de filtração do mexilhão dourado na presença das cianobactérias solitárias, coloniais e filamentosas foram semelhantes. No entanto, houve uma grande diferença nas taxas de ingestão e produção de pseudofezes. As células solitárias foram amplamente aceitas como alimento, enquanto as cianobactérias filamentosas e coloniais foram massivamente expulsas sob a forma de pseudofezes. Os resultados confirmaram a primeira hipótese, a de que o mexilhão dourado prefere ingerir partículas menores. A segunda hipótese foi rejeitada, pois os filamentosos de Planktothrix foram preferencialmente ingeridos em relação às colônias de Microcystis. O mexilhão dourado apresenta potencial para remover células tóxicas de cianobactérias (Microcystis); entretanto, esse potencial ficaria reduzido em eventos de floração, em que as formas coloniais, preferencialmente rejeitadas por L. fortunei, são predominantes. Nesse caso, a presença do bivalve no ambiente poderia ainda potencializar a ocorrência da floração via rejeição das cianobactérias coloniais e filamentosas nas pseudofezes.