Efeitos do grau trófico e distância espacial entre sub-bacias alteram a distribuição de rotíferos em um grande rio?
Carregando...
Data
2021-08-31
Autores
Martins, Bárbara Araújo [UNESP]
Título da Revista
ISSN da Revista
Título de Volume
Editor
Universidade Estadual Paulista (Unesp)
Resumo
Foram estudados os rotíferos coletados na Bacia do Rio da Prata, a segunda maior da América do Sul, em janeiro (verão) e julho (inverno) de 2010, em 43 pontos, em trechos lóticos e reservatórios (zona de montante e próximo às barragens). As amostras foram realizadas por meio de arrasto vertical na coluna d’água com rede planctônica de malha de 50 μm. Os resultados foram divididos em três capítulos: 1. Composição e riqueza de rotíferos da Bacia do rio da Prata, 2. Influência do gradiente de nitrogênio, fósforo e clorofila-a na estrutura da comunidade de rotíferos em reservatórios da bacia do rio da Prata e 3. Determinantes da diversidade beta em rotíferos da Bacia do Rio da Prata. No capítulo 1 é apresentada a lista de espécies e a riqueza nas sub-bacias amostradas, assim como a diferença na riqueza entre os períodos amostrados. Neste capítulo foram registradas 106 espécies, e novas ocorrências foram encontradas no Brasil (Estado de São Paulo) e na Argentina. A sub bacia com maior riqueza foi do Baixo rio Paraná. No capítulo 2 foram utilizados apenas os pontos em 15 reservatórios da Bacia do Rio da Prata. Foi utilizada a análise TITAN com o objetivo de: i) avaliar qual é o limiar de concentração de variáveis relacionadas à eutrofização que alteram a estrutura da comunidade para rotíferos, ii) compreender quais espécies de Rotifera estão relacionadas positiva ou negativamente ao aumento dessas variáveis tendo sido encontradas 71 espécies e dessas 06 foram consideradas bioindicadoras, reforçando que rotíferos respondem às variáveis ambientais relacionadas diretamente com o nível trófico de ambientes aquáticos, especialmente em reservatórios. E no capítulo 3 a heterogeneidade, a diversidade beta e a influência de variáveis ambientais de rotíferos foi estudada em rios e reservatórios. Foram utilizadas as análises db-RDA, PERMANOVA, o coeficiente de dissimilaridade de Sorensen, ANOVA e a diversidade beta foi separada nos componentes substituição e diferenças na riqueza/abundância. Testamos as hipóteses: (i) os principais determinantes da diversidade beta dos rotíferos são variáveis ambientais relacionadas à eutrofização; (ii) devido à sua ampla distribuição geográfica em geral, o fator espacial não será importante; (iii) devido a heterogeneidade ambiental entre as sub-bacias, a substituição de espécies será mais importante do que a perda/ganho de espécies. Os resultados indicaram que a substituição de espécies explicou a maior porcentagem da dissimilaridade entre as sub-bacias, sendo as variáveis ambientais o principal fator determinante.
Were studied the rotifers collected from La Plata River Basin, the second largest of South America, in January (Summer) and July (Winter) of 2010, in 43 sites, in lotic and reservoirs (upstream and dam stretches). Sampling were performed through vertical hauls of plankton net of 50 μm. The results were divided in three chapters: 1. Composition and richness of rotifers from La Plata River Basin; 2. Rotifers community structure controlled by nitrogen, phosphorus and chlorophyll-a in reservoirs from La Plata River Basin, and 3. Drivers of beta diversity of rotifers from La Plata River Basin. In the chapter 1 is presented the list of species and the richness in the sub basins sampled, as the difference in the richness among the periods sampled. In this chapter were registered 106 species, and new occurrences were found in Brazil (São Paulo State) and Argentina. The sub basin with the greatest richness was Lower Paraná Rivers. In the chapter 2 were used only the points of the 15 reservoirs of La Plata River Basin. The TITAN analysis were used with the objective: i) i) evaluate what is the concentration threshold of variables related to eutrophication that change the community structure of rotifers, ii) understand which Rotifera species are positively or negatively related to the increase in these variables. 71 species were found, and of these 06 were considered bioindicators, reinforcing that rotifers respond to environmental variables directly related to the trophic level of aquatic environments, especially in reservoirs. And in chapter 3 the heterogeneity, beta diversity and the influence of environmental variables of rotifers was studied in rivers and reservoirs. Were used the analysis db-RDA, PERMANOVA, Sorensen dissimilarity coefficient and ANOVA, and the beta diversity were divided in the components replacement and richness/abundance differences. We tested the hypothesis: i) the main determinants of the beta diversity of rotifers are environmental variables related to eutrophication; ii) due to its wide geographic distribution in general, the spatial factor will not be important; iii) due to environmental heterogeneity among sub-basins, species replacement will be more important than species loss/gain. The results indicated that species replacement explained the highest percentage of dissimilarity among the sub-basins, with environmental variables being the main determining factor.
Were studied the rotifers collected from La Plata River Basin, the second largest of South America, in January (Summer) and July (Winter) of 2010, in 43 sites, in lotic and reservoirs (upstream and dam stretches). Sampling were performed through vertical hauls of plankton net of 50 μm. The results were divided in three chapters: 1. Composition and richness of rotifers from La Plata River Basin; 2. Rotifers community structure controlled by nitrogen, phosphorus and chlorophyll-a in reservoirs from La Plata River Basin, and 3. Drivers of beta diversity of rotifers from La Plata River Basin. In the chapter 1 is presented the list of species and the richness in the sub basins sampled, as the difference in the richness among the periods sampled. In this chapter were registered 106 species, and new occurrences were found in Brazil (São Paulo State) and Argentina. The sub basin with the greatest richness was Lower Paraná Rivers. In the chapter 2 were used only the points of the 15 reservoirs of La Plata River Basin. The TITAN analysis were used with the objective: i) i) evaluate what is the concentration threshold of variables related to eutrophication that change the community structure of rotifers, ii) understand which Rotifera species are positively or negatively related to the increase in these variables. 71 species were found, and of these 06 were considered bioindicators, reinforcing that rotifers respond to environmental variables directly related to the trophic level of aquatic environments, especially in reservoirs. And in chapter 3 the heterogeneity, beta diversity and the influence of environmental variables of rotifers was studied in rivers and reservoirs. Were used the analysis db-RDA, PERMANOVA, Sorensen dissimilarity coefficient and ANOVA, and the beta diversity were divided in the components replacement and richness/abundance differences. We tested the hypothesis: i) the main determinants of the beta diversity of rotifers are environmental variables related to eutrophication; ii) due to its wide geographic distribution in general, the spatial factor will not be important; iii) due to environmental heterogeneity among sub-basins, species replacement will be more important than species loss/gain. The results indicated that species replacement explained the highest percentage of dissimilarity among the sub-basins, with environmental variables being the main determining factor.
Descrição
Palavras-chave
Ecologia, Indicadores biológicos, Diversidade beta, Rotifera, Bioindicator, Ecology, Beta diversity