Human impacts and the loss of Neotropical freshwater fish diversity

Abstract

Neotropical Ichthyology promotes the Special Issue (SI) “Human impacts and the loss of Neotropical freshwater fish diversity” with the purpose of publishing relevant scientific articles on the current biodiversity crisis and the loss of Neotropical freshwater fishes in the Anthropocene. The SI is composed of 22 publications, being two review articles and 20 original articles. A total of 107 researchers contributed to these papers, involving 44 institutions based in Brazil and six other countries. Published articles investigated main anthropic activities and their impacts on fish diversity, with special focus on river regulation, mining, land use changes, aquaculture, and fisheries. Studies provided evidence about the loss of fish diversity in the Neotropics, including fish kill events, demographic changes, contamination, changes in assemblage structure, loss of taxonomic and functional diversity, besides the degradation of ecosystem functions and services, and the lack of effective protection and conservation. Studies were conducted in rivers, streams, lakes, and reservoirs from different Neotropical systems. The studies published in this SI represent a relevant sample of the current worrisome situation of freshwater fishes in the Neotropical region and call for urgent revision in environmental policies, management and conservation initiatives, and socioeconomic priorities.

Recruitment of migratory fish in free‐flowing rivers with limited floodplain development

“…The consistent decline of migratory fish in areas degraded by dams (Agostinho et al, 2016) is robust evidence that human development has caused conflict with fish conservation. There is no easy solution, as indicated by recent studies (Reis et al, 2016;Pelicice et al, 2017Pelicice et al, , 2021. Dams cause multiple impacts that act synergistically to limit or prevent fish recruitment, including restrictions on upstream and downstream migration of adults and young (Pelicice, Pompeu & Agostinho, 2015), genetic isolation (Rosso et al, 2017;Baggio et al, 2018), the loss of critical habitats (Du et al, 2013), changes in environmental triggers and conditions (Dugan et al, 2010;Tamario et al, 2019), and anomalous behaviour in reservoirs and fishways (Hahn et al, 2020;Lopes et al, 2021;Silva et al, 2021).…”

Chromosomal rearrangements and the first indication of an ♀X1X1X2X2/♂X1X2Y sex chromosome system in Rineloricaria fishes (Teleostei: Siluriformes)

“…Indeed, previously overlooked taxonomic entities such as cryptic species and species complexes are being continuously revealed, especially with the help of cytogenetic and molecular approaches (Cioffi et al ., 2018; Milan et al ., 2020; Pereira et al ., 2013; Ramirez et al ., 2017). Besides representing suitable model groups for studying diversification and speciation, a proper understanding of Neotropical ichthyofauna is necessary also owing to the urgent need for improved conservation strategies (Pelicice et al ., 2021; Torres & Artoni, 2019).…”

Impacts of river fragmentation on limiting individual dietary specialization of Amazonian predatory fish

“…Habitat fragmentation by hydroelectric dams causes multiple impacts on the structure, dynamics, history, and functioning of freshwater ecosystems ( Pelicice et al, 2021 ). For example, the fragmentation of the Madeira River has modified the food spectrum of piscivores mainly changes in piscivorous abundance, diet composition, niche breadth, and resource partitioning among piscivorous fish ( Lonardoni et al, 2021 ).…”