Composition and distribution of fishes from the Perequê-Açu river basin, Paraty, Rio de Janeiro, Southeastern Brazil

Abstract The large number of less-known coastal drainages in the Atlantic Forest still represents an important gap in the knowledge of ichthyofauna. It is evaluated the taxonomic diversity, frequency and constancy of occurrence, and the distribution of species in the various segments of the Perequê-Açu river basin, state of Rio de Janeiro, Brazil. Twelve sampling campaigns resulted in 13,423 individuals, belonging to seven orders, 10 families, 21 genera, and 23 native species. Cyprinodontiformes and Siluriformes represented about 87.2% of the total abundance, mainly due to the contribution of Phalloceros anisophallos and Schizolecis guntheri, which account for 63.2% of the total sampled individuals. The analysis of constancy of occurrence reveals that 78.3% of the drainage species are residents, with approximately 93% of the residents of the Carrasquinho River sub-basin. The Sertões River sub-basin had the largest number of species in total: 18. The rarefaction curve did not reach an asymptote, although Chao 2 and bootstrap estimate the richness of 23.9 species and 23.7 species, respectively. The results of PERMANOVA, PCoA, and SIMPER indicate that the fish composition along the catchment is not homogeneous. The conservation status of species is also discussed, regionally, nationally, and globally.

摘要：大西洋森林（Atlantic Forest）区域内大量鲜为人知的沿海排水流域，仍是鱼类区系（ichthyofauna）研究领域的重要空白。本研究针对巴西里约热内卢州Perequê-Açu河流域各河段的物种分类多样性、出现频率与发生恒定性，以及物种分布格局开展评估。共计完成12次采样调查，累计采集到13423尾个体，隶属于7目、10科、21属及23种本土鱼类。鳉形目（Cyprinodontiformes）与鲇形目（Siluriformes）的个体数约占总丰度的87.2%，这主要得益于Phalloceros anisophallos与Schizolecis guntheri的贡献，二者合计占总采样个体数的63.2%。发生恒定性分析结果显示，该流域78.3%的鱼类为定居种，其中约93%的定居种分布于Carrasquinho河子流域。Sertões河子流域的物种总数最多，共计18种。稀疏曲线未达到渐近线，尽管Chao2指数与Bootstrap法分别估计的物种丰富度为23.9种与23.7种。置换多元方差分析（PERMANOVA）、主坐标分析（PCoA）及相似性百分比分析（SIMPER）的结果均表明，该集水区内的鱼类群落组成并不均一。本研究还从区域、国家及全球层面探讨了各鱼类物种的保护现状。