Invasive peacock basses (Cichla spp.) and decreased abundance of small native fish in Brazilian reservoirs

Abstract

1. Peacock basses (Cichla spp.) have been introduced in impoundments for decades, and their negative impacts on the native fish fauna have been documented.However, previous studies largely focused on the overall responses of fish assemblages, often neglecting specific predator-prey interactions and the underlying effects of environmental characteristics.2. Here, the effects of peacock bass introduction on the size structure (<120, 120-180 and >180 mm in total length) of fish assemblages in reservoirs of the Paraíba do Sul river basin were assessed. The abundance and time since the introduction of peacock basses were used as predictors, together with reservoir features, limnological variables and habitat composition as potential influencing factors.3. Descriptors of the overall community (richness, abundance and species composition) were only marginally associated with the occurrence of peacock basses. However, small and (to a lesser extent) medium-sized fish were adversely affected by the abundance and introduction time of peacock basses. Two pelagic native characidsnamely Astyanax cf. bimaculatus and Oligosarcus hepsetuswere the most affected.4. Redundancy analysis showed that reservoir age and macrophyte cover were the best predictors of fish assemblage composition. Older reservoirs and reservoirs with a higher cover of macrophytes showed a greater abundance of catfish and characids, respectively. 5. Peacock basses appear to affect fish assemblages through predation on small fish.Therefore, analyses of assemblages by size are recommended, as the use of overall assemblage descriptors may not be sufficient to capture the adverse effects of peacock basses. Moreover, these findings underscore the importance of conserving and restoring habitats in littoral zones, which function as refuges for native fish species in reservoirs. Further educational and management measures are warranted to prevent the spread of peacock basses to other reservoirs in Brazil.

Cannibalism facilitates and sustains the invasion of top‐predator fish (Cichlidae: Cichla) in human‐modified ecosystems

“…probably in response to a long-term impact exerted by the nonnative peacock basses through predation, which corroborates H1. These findings also corroborate many other studies describing the impacts of peacock basses (Franco, Petry, García-Berthou, et al, 2022;Leal et al, 2021;Pelicice & Agostinho, 2009;Pelicice et al, 2015;Sharpe et al, 2017), but adding further evidence based on a long-term perspective. The degree of impact of predation directed at certain taxa is related to the behaviour and morphology of the predator.…”

“…Globally, at least 551 species of non-native freshwater fish have been reported as established in 3120 basins, with the common carp (Cyprinus carpio Linnaeus, 1758), rainbow trout (Oncorhynchus mykiss Walbaum, 1792) and brown trout (Salmo trutta Linnaeus, 1758) being the most introduced species (Bernery et al, 2022). A common and well-documented trail of ecological impacts follows the IAS, including the decline and extirpation of native populations (Franco, Petry, García-Berthou, et al, 2022;Pelicice & Agostinho, 2009;Sharpe et al, 2017), food-web disruption (Bezerra et al, 2018), biotic homogenisation (Bezerra, Ribeiro, et al, 2019;Villéger et al, 2011), changes in the composition of functional traits (Le Hen et al, 2023) and disease emergence (Zaret & Paine, 1973). These impacts affect ecosystem services and functions (e.g., water supply, food, productivity, fishing) and generate billion-dollar economic losses (Haubrock et al, 2022;Leal et al, 2021).…”

Relatório temático sobre espécies exóticas invasoras, biodiversidade e serviços ecossistêmicos

“…sul, e da truta-arco-íris (Oncorhynchus mykiss) em rios de cabeceiras do sudeste e sul brasileiro (Agostinho et al 2007, Franco et al 2022b). Tais introduções visam aumentar o interesse turístico de ambientes que sofrem impacto antropogênico de outros estressores (por exemplo, represamentos) ou que previamente não apresentavam tais espécies (por exemplo, riachos sem peixes) (Agostinho et al 2007, Franco et al 2022b.…”

“…Esse grupo é composto por nove espécies nativas da região Amazônica, Orinoco, Essequibo e Tocantins-Araguaia (Winemiller et al 2021). Por conta de seu apelo para a pesca esportiva, foram introduzidos em diversas bacias brasileiras e do mundo (Franco et al 2022a), onde vêm reduzindo a diversidade de espécies nativas, em especial peixes de pequeno porte, além da interromper serviços ecossistêmicos e causarem o surgimento de doenças (Zaret & Paine 1973, Menezes et al 2012, Pelicice et al 2015, Franco et al 2022b. Mesmo com os inúmeros registros de impactos causados pelos tucunarés (Franco et al 2022c), eles continuam sendo introduzidos no Brasil e protegidos por legislações que, equivocadamente, visam manter essas populações não-nativas para fomento de pesca esportiva (Franco et al 2022d).…”

Impactos de espécies exóticas invasoras sobre as Contribuições da Natureza para as Pessoas (CNP), o Desenvolvimento Sustentável e a boa qualidade de vida.

“…al. 2022a), onde vêm reduzindo a diversidade de espécies nativas, em especial peixes de pequeno porte, além da interromper serviços ecossistêmicos e causarem o surgimento de doenças(Zaret & Paine 1973, Menezes et al 2012, Pelicice et al 2015, Franco et al 2022b). Mesmo com os inúmeros registros de impactos causados pelos tucunarés(Franco et al 2022c), eles continuam sendo introduzidos no Brasil e protegidos por legislações que, equivocadamente, visam manter essas populações não-nativas para fomento de pesca esportiva(Franco et al 2022d).Tucunaré (crédito: Ekenitr [CC BY-NC 2.0]).…”