Composição da ictiofauna de uma unidade de conservação urbana da bacia do alto rio Paraná

Abstract

The Paragem Natural Municipal Park (PNMP) is an urban Conservation Unit from Dourados municipality, Mato Grosso do Sul, Brazil, that includes a stretch of the Paragem stream and a few headwaters channels that flows into it. The local is deteriorated by the reception of street’s pluvial run-off, non-treated effluent discharge, and solid waste disposal. Since its creation in 2007, there wasn’t any studies about the Park’s fish fauna. The aim of the research was to conceive an inventory of the fish fauna from the PNMP, in order to contribute for the species’ conservation. Five sampling sites were chosen, and the fish samples were conducted between March and April 2022. At each sampling site, the physical characterization of the stream channel was executed, and water physicochemical parameters were collected. The fish sampling was performed using trawls, a dip net, and a fishing bait trap. The captured individuals were anesthetized with eugenol solution, fixed with 10% formalin, and stored in 70% alcohol. The specimens were identified by using specialized literature. Rarefaction and extrapolation curves of species richness were generated using the R software. Eighteen species were found in the study, eight of them being nonnative from the Upper Paraná River basin. The sampling site which presented the greatest richness was the site 4. Sites 1 and 5 presented the lowest number of species. The site 3’s richness might have been underestimated, and its number of species could raise if a higher sampling effort was applied. The species with major occurrence were Astyanax lacustris and Poecilia reticulata. Most of the ichthyofauna belonged to Characiformes and Siluriformes orders, what was expected for Neotropical streams. Coptodon rendalli and P. reticulata are the exotic species found in the study, and both are known for their role as bioindicators of altered and low environmental complexity water bodies, when they’re found outside their original habitat. The superior species richness in the small streams inside the Park area suggests that they possess a better environmental quality than Paragem stream and could possibly provide habitat and resources to various populations. The knowledge about extant species in urban parks contributes for local environmental sensibilization, and protection of natural resources and biodiversity. It’s of relevant need for the PNMP’s fish fauna that ecologic processes once lost are reestablished by the research, management, and control of invasive species, besides efforts that aim to mitigate the effects of the pollution on the region and recover the riparian forest.