Ictiofauna em igarapés da Região Metropolitana de Santarém - Pará

Abstract

Igarapés are small and dynamic water bodies that host a great diversity of Amazonian ichthyofauna responsible for the trophic support of the aquatic biota. The objective of this study was to analyze the spatiotemporal composition of ichthyofauna in peri-urban streams in the municipality of Santarém, Pará. Collections were conducted in October 2016 (dry season) and April 2017 (wet season). Five streams belonging to four watersheds were sampled. Each igarapé was sampled in four stretches with segments of 50 meters in length, blocked upstream and downstream with 5 mm mesh nets. Two collectors conducted two hours of active sampling using "rapichés" and a manual trawl net 1.2 meters in height, 7 meters long, and 5 mm mesh. Each sampling point, pH, electrical conductivity, dissolved oxygen, and water temperature were measured. Statistical analyzes were performed using the software PAST. A total of 9,193 individuals belonging to 62 species, 17 families, and 6 orders were collected. Fifty species were recorded in both periods, of which 12 occurred exclusively in the wet season and 12 in the dry season. The most abundant species were Hyphessobrycon cantoi, Iguanodectes variatus and Copella callolepis. PERMANOVA showed a significant difference in species composition between drainages (p=0.0001), with indicator species correlated with the environmental variables of conductivity and pH. Recognizing the composition of ichthyofauna in streams and their changes due to abiotic factors under anthropogenic influence is a fundamental and necessary step for establishing strategies and measures to protect and conserve the biodiversity of aquatic biota.