ABSTRACT

Plankton in rivers are good indicators of water quality and their study along the longitudinal axis allows for understanding the interactions between natural and anthropogenic variations and diversity at different spatial scales. We compared the taxonomic biodiversity of planktonic microcrustaceans in two sections of the Frades River Basin, Brazil. Water and microcrustaceans were sampled in August 2018, April 2019, July 2019, and October 2019 in the basin. We recorded 43 taxa as the regional diversity of microcrustaceans. Alpha diversity was statistically higher in the upper section of the basin. The analysis of indicator species showed that nine species were characteristic of the studied sections. The upper section was represented by Nicsmirnovius paggii, Acroperus tupinamba, Alonella dadayi, Alona guttata, and Microcyclops finitimus and characterized by higher dissolved oxygen, higher values of pH of water and lower nitrate and total coliforms concentrations. Diaphanosoma birgei, Alona sp., Grimaldina brazzai, and Ilyocryptus spinifer were characteristic of the lower sections of the basin, with the highest concentrations of nitrate and total coliforms. The microcrustaceans in the lower sections were limited by the gradient of environmental conditions, making local communities simpler (low species richness) and with few species probably adjusted to narrow ranges of environmental conditions.

摘要

河流中的浮游生物是水质的良好指标，它们沿纵轴的研究有助于了解不同空间尺度的自然和人为变化和多样性之间的相互作用。我们比较了巴西弗拉德河流域两个河段浮游微甲壳动物的分类生物多样性。2018年8月、2019年4月、2019年7月和2019年10月在该盆地采集了水和微型甲壳类动物样本。我们记录了 43 个类群作为微甲壳动物的区域多样性。统计上，盆地上部的阿尔法多样性较高。对指示物种的分析表明，9 个物种是研究部分的特征物种。上半部分以Nicsmirnovius paggii、Acroperus tupinamba、Alonella dadayi、Alona guttata为代表和Microcyclops finitimus，其特征是较高的溶解氧、较高的水 pH 值以及较低的硝酸盐和总大肠菌群浓度。Diaphanosoma birgei、Alona sp.、Grimaldina brazzai和Ilyocryptus spinifer是盆地下部的特征，硝酸盐和总大肠菌浓度最高。下部地区的微甲壳类动物受到环境条件梯度的限制，使得当地群落更加简单（物种丰富度低），并且很少有物种可能适应狭窄的环境条件范围。