How do substrate composition and environmental variables influence the richness and abundance of molluscs in an urban river from the Brazilian semiarid region?

This study investigates the influence of substrate composition and environmental variables on the richness and abundance of freshwater molluscs in the urban stretch of the Guaribas River, located in the semi-arid region of Piauí, Brazil. Bimonthly collections were conducted between October 2021 and August 2022 across five sampling points, where molluscs were gathered from sediment and macrophyte substrates. Environmental parameters, including pH, water temperature, and water column depth, were also recorded. A total of 2479 individuals were identified, predominantly gastropods, with higher species richness and abundance observed in macrophyte substrates compared to sediment. Statistical analysis revealed a positive correlation between mollusc abundance and macrophyte presence and a significant interaction between pH and temperature on mollusc distribution. The results highlight the crucial role of macrophytes in enhancing habitat complexity and supporting mollusc diversity while demonstrating the negative impact of sediment pollutants in urban river systems. These findings provide insights into the ecological dynamics of molluscs in semi-arid environments, contributing to conservation and management strategies in these regions.

本研究针对巴西皮奥伊州半干旱区域内的瓜里巴斯河城市河段，探讨基底组成与环境变量对淡水软体动物(freshwater molluscs)物种丰富度及个体丰度的影响。研究于2021年10月至2022年8月期间开展每两月一次的采样工作，共设置5个采样点位，分别从沉积物与大型水生植物(macrophyte)基底中采集软体动物样本；同时记录了pH值、水温、水深等环境参数。本次采样共鉴定出2479个个体，绝大多数为腹足类(gastropods)；相较于沉积物基底，大型水生植物基底中的物种丰富度与个体丰度均更高。统计学分析结果显示，软体动物丰度与大型水生植物存在量呈显著正相关，且pH值与水温对软体动物分布存在显著交互作用。本研究结果凸显了大型水生植物在提升栖息地复杂度、维持软体动物多样性方面的关键作用，同时证实了城市河流系统中沉积物污染物的负面影响。上述发现揭示了半干旱环境中软体动物的生态动态特征，可为该区域的软体动物保护与管理策略制定提供科学参考。