Variação Espaço-Temporal na Abundância de Ordens e Famílias de Macroinvertebrados Bentônicos Registrados em Área de Nascente, Campo Verde-Mt

The benthic macroinvertebrates are among the main organisms used in the evaluation of environmental and biological monitoring in aquatic ecosystems. The distribution of these organisms is mainly determined by the type and diversity of habitats available to the community. This paper aims to contribute to the knowledge of the distribution of macroinvertebrates in the state of Mato Grosso, analyzing the macroinvertebrates orders and families occurring in a spring dammed in an agricultural land in the municipality of Campo Verde-MT, evaluating the structure of the community in rainy and dry periods The study area is located in the headwaters of São Lourenço River - TM, where soybeans, millet and cotton (latitude S 15 ° 37 '18.8 "W and longitude 55 º 10 '24.8") are cultivated. In its vicinity (ca. 30 m) one of its sources was dammed, sampled at its input (P2) in the limnetic zone (P3) and at its output (P4). In addition to these three points, we sampled one of its sources (P1) and a stream below the dam (P6). Each point was sampled six times, three during the rainy season and three during the dry season, with three replicates at each point. The increased occurrence of organisms occurred in the rainy season, with 216 organisms at P2 and P3 points. Diptera was the most abundant in the rainy season, represented by the Chironomidae family.Os macroinvertebrados bentônicos estão entre os principais organismos utilizados na avaliação de impactos ambientais e monitoramento biológico em ecossistemas aquáticos. A distribuição desses organismos é determinada pelo tipo e pela diversidade de habitats disponíveis para a comunidade. O presente estudo teve como objetivo contribuir com o conhecimento da distribuição de macroinvertebrados bentônicos em áreas impactadas do estado de Mato Grosso, inventariando as ordens e famílias com ocorrência em uma nascente represada em área agrícola no Município de Campo Verde-MT, analisando a estrutura da comunidade nos períodos chuvoso e de estiagem, avaliando sua abundância e riqueza. A área de estudo está localizada na nascente do Rio São Lourenço-MT, onde são cultivados soja, milheto e algodão (latitude S 15º 37' 18,8" e longitude W 55º10" 24,8"). Em sua adjacência (ca. de 30m) foi represada uma de suas nascentes, amostrada em sua entrada (P2), na zona limnética (P3) e em sua saída (P4). Além desses três pontos, foram amostrados uma de suas nascentes (P1) e um córrego abaixo da represa (P6). Cada ponto foi amostrado seis vezes, três no período chuvoso e três no período de estiagem, com três réplicas em cada ponto. A maior ocorrência de organismos se deu no período chuvoso, com 216 organismos, nos pontos P2 e o P3. Diptera foi a mais abundante no período chuvoso, representada pela família Chironomidae

Quality of water of a dam located in an agricultural area (Campo Verde, MT, Brazil)

In this study spatial and temporal variations in limnological characteristics of a dam located in one of the headwaters of the São Lourenço River (Campo Verde, MT) were evaluated. The surrounding area is used for soybeans cultivation, corn, cotton, and pasture. We examined biotic (heterotrophic bacteria and chlorophyll a) and abiotic factors (precipitation, air and water temperature, electrical conductivity, dissolved oxygen, pH, turbidity, total phosphorus, nitrite, nitrate, and ammonia nitrogen) at three sampling sites along the longitudinal axis of the water body, and at three depths (at the surface, the Secchi depth, and at the sediment-water interface). Samples were taken bimonthly during 2010. Spearman correlation analysis was used to examine the relationship between biotic and abiotic variables, and then principal components and cluster analyses were used to study the relationship between these factors and the variability observed among the various sampling sites, dam depths, and periods of observation. The analyses showed a strong correlation between factors such as rainfall, heterotrophic bacteria, conductivity, turbidity, and phosphorus, indicating the influence of seasonality in cultivated areas. It was observed that the variations between the sampling sites were more significant (p < 0.01) than in the water column for most of the variables, probably due to the particular characteristics of each sample point and its shallow water column