Cage fish farm act as a source of changes in the fish community of a Neotropical reservoir

Abstract

Brazil has shown an increase in cage fish farms activity in reservoirs. However, this activity shows potential to cause several changes in the environment with consequences in the structure of native fish fauna community. Thus, the hypothesis of this work is that three cage fish farms, located in the different areas of Chavantes reservoir, high Paraná basin, have potential to interfere with resident fish communities, modifying their structure. Fish were caught in twelve monthly field samplings around three cage fish farms (FF) (FF1 and FF2-Dec/06-Nov/07; FF3-Mar/08-Feb/09) and their respective reference sites (RF) (RF1, RF2 and RF3), using gillnets with 3 to 14 cm between opposite knots. Our data showed that cage fish farms cause increase in fish abundance and biomass around cages. However, Margalef Richness and Shannon-Wiener diversity decreased in these areas. Spatially, fish community around cage fish farms differed from those observed in the reference sites (Permanova two-way: (F = 12.747; p = 0.001)). However, seasonal differences were not observed (F = 1.3732; p = 0.089). This difference was illustrated by NMDS, that showed the formation of two groups, one composed by fish farms and another by reference sites. These differences were mainly influenced by a small group of fish species (Apareiodon affinis, Steindachnerina insculpta (detritivores) and Pimelodus maculatus (generalist) (Simper analysis)) that are able to consume wastes released. We conclude that the cage fish farm act as a driver of alterations in the fish community, increasing the abundance and biomass of a few species which contributes to decrease Richness and Diversity.

A network meta‐analysis of threats to South American fish biodiversity

“…The relationship between fish diversity and biological invasions can be controversial (Halwart et al., ; Olden et al., ). Beyond the increase in the dominance of a few species and a decrease in biodiversity at the community level (Nobile et al., ), trophic mechanisms associated with invaders include higher nutrient cycling relative to that of the natural community (Attayde & Hansson, ; Lima et al., ; Vanni, ; Verant, Konsti, Zimmer, & Deans, ). Non‐native fish can drive alternate ecosystem states through predation interactions with natives and other non‐natives (Bezerra et al., ).…”

Composition and richness of monogonont rotifers from La Plata River Basin, South America

“…It is possible that its occurrence in the La Plata basin is related to aquaculture activities as has occurred in other regions (Coelho & Henry 2017). In many reservoirs of the La Plata basin, there are aquaculture activities, mainly with non-native fish species (Azevedo-Santos et al 2011, Nobile et al 2018. This rotifer may be introduced from cage aquaculture in upstream rivers (e.g., Grande and Paranapanema Rivers) and reached downstream areas where we captured it.…”

Biology of non-native species (Rhaphiodon vulpinus Agassiz, 1829) (Characiformes, Cynodontidae) in a cage fish farm area, Upper Paraná River Basin, Brazil

“…the structure of the wild ichthyofauna (Uglem et al, 2014;Ramos et al, 2013;Nobile et al, 2018) and increases in parasitic infection rates in wild fish (Ramos et al, 2014). Another important environmental influence caused by fish farms is the introduction of non-native species, with at least 32 registered entries (Ortega et al, 2015).…”