Fish fauna in low-order streams of the Piquiri River, Upper Paraná River basin, Brazil

Abstract The South America ichthyofauna encompasses the highest diversity of the world, however is highly threatened by anthropogenic actions. The fish fauna of nine low-order streams, tributaries of the Piquiri River and impacted by aquaculture, agriculture and urbanization were sampled in the present study. Samplings were done quarterly from December 2017 to September 2018 at three sites in each stream, using a portable electric fishing device in 50-meter segments. A total of 14,507 individuals were collected, belonging to six orders, 20 families, 46 genera, and 70 species. The highest richness and abundance were found for the orders Characiformes and Siluriformes. In this study, nine species that had not been recorded were found, totaling 163 for the basin. In addition, 14 non-native species were captured. The presented list of species contributes to the existing database of ichthyofauna distribution in Neotropical streams, denoting that it is underestimated in the region, mainly in low-order tributaries. The present study reinforces the importance of inventories and monitoring in environments with high biodiversity and sensitive to anthropogenic actions.

摘要 南美洲鱼类区系（ichthyofauna）是全球物种多样性最为丰富的鱼类区系，却正遭受人为活动的严重威胁。本研究对皮基里河（Piquiri River）支流的9条低级别溪流开展鱼类区系采样，这些溪流均受到水产养殖、农业活动及城市化的干扰。采样工作于2017年12月至2018年9月间按季度开展，每条溪流设置3个采样位点，采用便携式电鱼设备对50米长的河段进行采样。本次研究共采集到鱼类个体14507尾，隶属于6目、20科、46属及70种。物种丰富度与个体丰度最高的类群为脂鲤目（Characiformes）与鲶形目（Siluriformes）。本次研究共发现9种此前未被记录于该流域的鱼类，使该流域已知鱼类物种总数增至163种。此外，本次采样还捕获了14种非本土鱼类。本研究整理的物种名录为新热带区（Neotropical）溪流鱼类区系分布的现有数据库提供了重要补充数据，同时表明该区域（尤其是低级别支流）的鱼类物种多样性仍存在低估情况。本研究进一步强调了在生物多样性丰富且对人为活动敏感的生境中开展鱼类区系调查与长期监测的必要性。