Explorando a biodiversidade do rio Xingu: apresentação e validação de um novo equipamento de amostragem de DNA ambiental

Abstract

Knowledge and monitoring of biodiversity are key elements for defining actions and initiatives focused on nature conservation and restoration. However, monitoring techniques are generally expensive and time-consuming, which complicates efforts to identify and manage biological diversity. In this sense, it is essential to investigate new fast, non-invasive and low-cost methods that can provide reliable and robust results and information, highlighting, in this context, approaches based on the use of environmental DNA (eDNA). eDNA is a complex mixture of genetic material originating from entire organisms or parts of them, present in environmental matrices, which can be, for example, soil, water or sediment. This project presents a prototype of a simple and low-cost equipment to obtain eDNA sampling, aiming to explore the richness and composition of the ichthyofauna in the Fish Transposition System of the Belo Monte Hydroelectric Power Plant (HPP), located in the middle course of the Xingu River, a hyperdiverse river located in the Amazon Brazilian. To this end, a new and affordable piece of equipment was manufactured for passive collection of genetic material (eDNA) using a metal structure and two PVC tubes. A flow meter was attached to one of the tubes and two rolls of gauze were firmly attached to the other tube. From the samples, which were collected every two hours over a 24-hour period, a species inventory was generated using a combination of fish-specific molecular markers (Tele02 12S). To validate the equipment and the proposed methodology, the temporal variation in the richness and composition of the fish fauna detected with eDNA were compared with those recorded during monitoring using the Video-Image System located at the exit of the STP. The results indicate that the method was efficient and sampled 100% of the ichthyofauna orders that were recorded in monitoring with SVI, but the similarity between the two methods reduced as taxonomic specificity increased. This result can be explained by the low representation of Xingu species in existing genomic libraries. In this sense, eDNA is a promising approach with great potential to become a valuable tool for studying and monitoring the composition of fish in highly diverse tropical freshwater rivers with affordable costs and minimal impacts on organisms and habitats, but which, in this At the moment, more basic research is needed so that it can replace and/or complement traditional sampling methods.