Benthic macroinvertebrates in a protected area within the Brazilian savannah: environmental factors negatively affect diversity

In the Neotropics, especially in southeastern Brazil, due to sugarcane and eucalypt monocultures, and the expansion of industries and the largely unplanned urban centers entire aquatic ecosystems are threatened. Nonetheless, benthic macroinvertebrates are important biomonitoring tools to assess the biotic and abiotic condition of endangered freshwater environments. In this study we address how benthic macroinvertebrate diversity respond to the combined effect of local environmental factors. We also aimed to evaluate how benthic macroinvertebrates diversity respond according to the habitat integrity. We expected to find higher diversity in the sampling sites with higher habitat integrity (i.e., low potential of hydrogen, electrical conductivity and water temperature, and high canopy coverage and concentration of dissolved oxygen). By using a multivariate approach (i.e., PCA) and a regression analysis (i.e., Linear Mixed-Effect Model) we were able to address the combined effect of local environmental variables on the benthic macroinvertebrate community. Our results show a negative effect of the environmental factors on the benthic macroinvertebrate diversity. As expected, sites with higher integrity and water quality values according to, respectively, the Habitat Integrity Index (i.e., HII) and the Biological Monitoring Working Party (i.e., BMWP’) tended to have higher benthic macroinvertebrates diversity. This is the first report that provides knowledge of the benthic macroinvertebrate community in the Paulicéia river, within the Cerrado Pé-de-Gigante, a conservation unity of full protection of a State Park in the Neotropics.新热带区（Neotropics）内，尤以巴西东南部为甚，受甘蔗与桉树单一栽培、工业扩张以及大量无序扩张的城镇中心影响，整片水生生态系统均受到严重威胁。尽管如此，底栖大型无脊椎动物（benthic macroinvertebrates）仍是评估濒危淡水生境生物与非生物状态的重要生物监测工具。本研究旨在探究底栖大型无脊椎动物多样性对各类局域环境因子联合作用的响应规律，同时评估其多样性随生境完整性的变化特征。研究假设：生境完整性更高的采样点位（即氢离子指数（pH）、电导率与水温更低，冠层覆盖率与溶解氧浓度更高的区域），其底栖大型无脊椎动物多样性也更高。本研究采用多元分析方法（主成分分析（Principal Component Analysis, PCA））与回归分析方法（线性混合效应模型（Linear Mixed-Effect Model）），解析局域环境变量对底栖大型无脊椎动物群落的联合影响。研究结果显示，局域环境因子对底栖大型无脊椎动物多样性存在显著负向影响。如研究假设所言，分别依据生境完整性指数（Habitat Integrity Index, HII）与生物监测工作组指数（Biological Monitoring Working Party, BMWP）判定的生境完整性与水质更佳的采样点位，其底栖大型无脊椎动物多样性普遍更高。本研究是首次针对新热带区某州立全面保护公园——塞拉多佩德吉甘特（Cerrado Pé-de-Gigante）境内的保利塞亚河（Paulicéia river）底栖大型无脊椎动物群落开展的相关研究，为该区域的相关科研工作填补了空白。