Effects of urbanization on the fauna of Odonata on the coast of southern Brazil

Abstract: Urbanization significantly increases the rates of environmental disturbance, being one of the main causes of habitat loss and biodiversity. The growing trend of converting the natural landscape into areas for real estate speculation in the coastal region of the southernmost part of Brazil is a current concern, as the region is home to unique ecosystems, such as dunes, wetlands and large brackish lagoons. As they are organisms sensitive to environmental changes, variations in the structure of Odonata communities are used as indicators of habitat quality reflecting the human impact on the environment. Here we assessed how the Odonata community is affected by the growing urbanization around natural ponds on the coast of the state of Rio Grande do Sul, testing the hypothesis that the increase in the percentage of urbanization negatively influences the Odonata community, following the same pattern found for other groups of invertebrates. The collections took place in 28 coastal ponds, which were classified as urbanized and non-urbanized based on the surrounding ground cover. Anisoptera’s richness, abundance and composition were influenced by urbanization, but the same was not found for Zygoptera. The analysis of indicator species specifies three species associated with non-urbanized areas: Erythrodiplax sp.1, Erythemis credula and Telebasis corallina. Our study highlights the importance of Odonata as organisms that indicate environmental integrity and reinforces the need for urban planning strategies that favor the conservation and maintenance of the environments affected by urbanization.

摘要：城市化显著加剧了环境干扰强度，是生境丧失与生物多样性丧失的主要诱因之一。当前，巴西南部沿海地区正出现将自然景观改造为房地产开发用地的日益增长的趋势，这一现状引发了广泛担忧——该区域拥有沙丘、湿地与大型咸淡水泻湖等独特生态系统。由于蜻蛉目（Odonata）生物对环境变化极为敏感，其群落结构的变化常被用作生境质量的指示指标，以反映人类活动对环境造成的影响。本研究以巴西南大河州沿海的自然池塘为研究对象，探究其周边日益加剧的城市化对蜻蛉目群落的影响，并验证如下假说：城市化占比的提升会对蜻蛉目群落产生负面影响，这一规律与其他无脊椎动物类群的研究结果一致。研究共选取28处沿海池塘作为样地，依据周边地表覆盖类型将其划分为城市化样地与非城市化样地两类。结果显示，城市化对差翅亚目（Anisoptera）的物种丰富度、个体数量及群落组成均产生了显著影响，但该效应并未在束翅亚目（Zygoptera）中体现。指示物种分析结果表明，有3个物种与非城市化样地显著相关：Erythrodiplax sp.1、Erythemis credula与Telebasis corallina。本研究凸显了蜻蛉目作为环境完整性指示生物的重要价值，同时强调了制定有利于受城市化影响区域的生态保护与环境维持的城市规划策略的必要性。