Expansion of aquaculture parks and the increasing risk of non‐native species invasions in Brazil

Abstract

Aquaculture is the main vector for introduction of non‐native species in Brazil and around the world. Despite the potentially serious and irreversible ecological impacts caused by non‐native species, they continue to be in many cases the preferred option in aquaculture farms, of which the recent plans of aquaculture expansion promoted by the Brazilian Government are an emblematic example. In this study, we present a survey of publicly available information on aquaculture parks to be installed across the Brazilian territory, with emphasis on species status as native or non‐native, and discuss the implications for the conservation of aquatic biodiversity. One hundred and thirty‐nine aquaculture parks (APs), with a total of 1556 sites covering 941.38 hectares, have been called for bids. Among these, 122 APs will contain at least one non‐native species, and 68 APs will be based exclusively on their cultivation. A predictable consequence is the enhancement of propagule pressure in surrounding aquatic ecosystems, increasing the risk of non‐native species establishment or persistence, which will likely intensify the environmental impacts already in course in four major river basins and along the Brazilian coast. These impacts will add up to more direct effects of aquaculture farming – for example elevated input of nutrients and organic matter – and include changes in habitat and water quality, spread of diseases, biotic homogenization, loss of population viability resulting from hybridization and outbreeding depression, and the local extirpation of native species.

Update on the ichthyofauna of the Piquiri River basin, Paraná, Brazil: a conservation priority area

“…Around the Piquiri River basin, innumerable fish farms are settled and breeding non-native species that show a high invasion risk (Lima Jr. et al 2012, Pelicice et al 2014, Forneck et al 2016. Several authors have asserted the invading potential arising from fish farms and the negative effects of new introductions (Orsi & Agostinho 1999, Daga et al 2015, Daga et al 2016, Lima et al 2016.…”

Neotropical freshwater fishes imperilled by unsustainable policies

“…R$ 4.1 billion (US$ 1.32 billion) to boost intensive aquaculture with non‐native species and implement aquaculture parks in reservoirs (Figure f). About 150 parks will be installed, covering more than 1,500 sites in main river basins (Lima, Oliveira, Giacomini, & Lima Junior, ). Aquaculture has many impacts on aquatic ecosystems (Figure ), including species introduction (Figure g), trophic cascades, eutrophication, pollution, genetic erosion, diseases, habitat destruction (Figure h) and biotic homogenization (Agostinho, Gomes et al., ; Diana, ; Ortega, Júlio Júnior, Gomes, & Agostinho, ; Pelicice, Vitule, Lima Junior, Orsi, & Agostinho, ).…”

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., ).…”

“…As aquaculture remains underexplored in marine and estuarine habitats (please, see Figure and Frehse, Braga, Nocera, & Vitule, ), more than 140 countries have introduced tilapia in fresh waters at least once, and 55% of all countries in the world have feral populations of tilapia that either escaped from net cages or were intentionally introduced (Deines, Wittmann, Deines, & Lodge, ). Now, there is a plan to fill the Paraná River basin with aquaculture parks, which will be primarily used to cultivate non‐native tilapia (Lima et al., ). A natural tendency for an increase in fish species richness seems unachievable in freshwaters, considering the actual level of escapes from aquaculture that is causing the loss of diversity in previously isolated populations (Bellafronte et al., ; Lui et al., ; Moreira‐Filho & Buckup, ).…”