Patterns in composition and occurrence of the fish fauna in shallow areas of the São Francisco River mouth

Authors

  • Renato Luiz Bot Neto Universidade Federal do Paraná, Programa de Pós-graduação em Ecologia e Conservação, Laboratório de Ecologia de Peixes
  • André Pereira Cattani Universidade Federal do Paraná, Centro de Estudos do Mar, Laboratório de Ecologia de Peixes https://orcid.org/0000-0002-9692-4122
  • Henry Louis Spach Universidade Federal do Paraná, Centro de Estudos do Mar, Laboratório de Ecologia de Peixes
  • Riguel Feltrin Contente Universidade Federal do Paraná, Centro de Estudos do Mar, Programa de Pós-graduação em Sistemas Costeiros e Oceânicos
  • Olímpio Rafael Cardoso Universidade Federal do Paraná, Centro de Estudos do Mar, Laboratório de Ecologia de Peixes https://orcid.org/0000-0003-3392-9687
  • Camila Marion Instituto Federal de Educação, Ciência e Tecnologia do Pará
  • Roberto Schwarz Júnior Universidade Federal de Sergipe, Departamento de Engenharia de Pesca e Aquicultura, Laboratório de Ictiologia Estuarina e Marinha https://orcid.org/0000-0002-1852-043X

Abstract

Abstract The construction of dams causes changes in river variables, as a result of direct changes in their hydrological and biogeochemical cycles. One of the most notable changes is the flow regulation, which reduces seasonal events and the hydrostatic pressure exerted by freshwater, increasing the saltwater wedge intrusion into the system. Changing the salinity regime causes modifications in downstream ecosystems as well as in the distribution and composition of the fish fauna. In Brazil, the São Francisco River stands out, which has a system of cascading dams, built between the 70’s and 90’s. Because of these changes caused in the natural course of the river, this study aimed to analyze the patterns of composition and occurrence of the ichthyofauna at the mouth of the São Francisco River and relate them to the physical and chemical variables of the region. In order to evaluate the patterns of composition and occurrence of the fish fauna at the mouth of the São Francisco River, monthly trawls were conducted along the bank and physical and chemical variables were analyzed in the river channel over a period of one year. The relationship between abundance and species richness with environmental variables was verified using Generalized Linear Models. A total of 101,958 fish belonging to 87 taxa were caught, with emphasis on marine fish, both in number of individuals (99.92%) and in biomass (99.31%). A spatial gradient was detected, in which sites 1 and 2 were under marine influence, sites 3 and 4 represented the transition between the environments and site 5 was under the influence of brackish and freshwater. In general, the effect of the São Francisco River dams on the fish fauna was observed, with a predominance of fauna with more estuarine and less freshwater characteristics.

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Published

2023-01-01

How to Cite

Bot Neto, R. L., Cattani, A. P., Spach, H. L., Contente, R. F., Cardoso, O. R., Marion, C., & Schwarz Júnior, R. (2023). Patterns in composition and occurrence of the fish fauna in shallow areas of the São Francisco River mouth. Biota Neotropica, 23(2). Retrieved from //www.biotaneotropica.org.br/BN/article/view/1996

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