The invasion of tilapia in South China freshwater systems: A review

Abstract

Tilapia invasion has become a significant concern to ecologists and conservationists, posing severe threat to freshwater biodiversity. Many tilapia species have been introduced to China since 1957, with some having invaded freshwater ecosystems in South China. Accordingly, the present review examined the driving factors for successful tilapia invasion and their ecological impacts, information essential for practical management purposes. This review identified aquaculture as the main pathway spreading tilapias into the wild freshwater systems through their escape and release. Their biological and life history traits, including flexible habitat requirements, environmental tolerance, and generalist feeding are essential factors facilitating their ability to inhabit varying habitats. Biodiversity loss and habitat degradation further promote tilapia invasions by creating exploitable habitats for them, noting their considerable tolerance to degraded ecosystems. Regarding ecological effects, tilapias stimulate phytoplankton growth by increasing nutrient concentrations in the water column through excretion and bioturbation. Tilapias also depress benthic algal growth by promoting sediment resuspension, deteriorating water quality, and enhancing eutrophication. Moreover, tilapias cause the decline of native fish species biomass through competition and may threaten fish biodiversity. The findings in the present review suggest direct removal of tilapias can be a useful practice for controlling them. Furthermore, imposing regulations on tilapias introductions, efficient aquaculture management, and biodiversity conservation should also be considered in controlling and preventing the invasion and spread of tilapias.