Nile tilapia (Oreochromis niloticus) invasions disrupt the functional patterns of fish community in a large subtropical river in China

Abstract

Although non‐native species can modify ecosystem function, their effects in southern China have not been investigated, despite their ecological importance. This study assessed how Nile tilapia Oreochromis niloticus (L.) invasions impact the functional patterns of fish communities in the large subtropical Pearl River by analysing the relationships between invasion and body size over a 9‐year period. The relative abundance of Nile tilapia increased significantly over time. In particular, the established Nile tilapia significantly undermined the relative densities and the body size of the native fishes. Importantly, this study provided empirical evidence that functional indices (such as body size) are more sensitive when evaluating the effects of non‐native species on a community than richness. Understanding processes such as those should be the basis of controlling alien fish species and fisheries management in the Pearl River.

Invasion Risk and Potential Impact of Alien Freshwater Fishes on Native Counterparts in Klang Valley, Malaysia

“…Moreover, the sight of breeding nests belonging to this species in the Klang River confirms that this species had established a breeding population in this river. In line with the findings of this study, Shuai et al [ 64 ] reported an increase in the relative abundance of O. niloticus , which is a non-native species, in a large subtropical river in China. Therefore, the ability of this alien species to successfully breed and multiply over time is confirmed, and this further explains the result of this study.…”

“…Similar to some other high-risk alien ornamental fish species recorded from pet stores in the Klang Valley, Malaysia, which had been earlier screened using the FISK v2 software [ 4 ], O. niloticus was labeled as invasive. Similarly, the high invasion risk of O. niloticus had been established in other regions too, including the Iberian Peninsula [ 65 ], South Africa [ 66 ], and China [ 64 ], where they have negatively impacted the native fish species and the environment. Consequently, the negative impacts that stem from the establishment of invasive species, such as O. niloticus, are also predicted for the water bodies that were the subject of this study.…”

Tilapia Invasion Impacts Trophic Position And Resource Use Of Commercially Harvested Piscivorous Fish In The Large Subtropical Pearl River

“…In the current study, which spanned 9 years in the Pearl River, native sh densities decreased with increasing tilapia density. In particular, a progressive decrease in body size, such as sh plumpness, body length, and body weight, of native shes coincided with the increasing prevalence of Nile tilapia (Shuai et al 2019), and increased competition from Nile tilapia with local native species for food resources. We found that invasive tilapia forced other shes to increasingly rely on zooplankton and aquatic insect resources in the tropical river.…”

“…The sampling data showed that the relative densities of native prey sh decreased signi cantly over time in the invaded Dongjiang River. There has been a great deal of evidence to show that the increase of tilapia in rivers affects the CPUE of the sh community and native sh species (Gu et al 2015), including the most abundant native species mud carp (Cirrhinus molitorella), black amur bream (Megalobrama terminalis), barbel chub (Squaliobarbus curriculus) and common sawbelly (Hemiculter leucisculus) (Shuai et al 2019). The larvae of these sh are an important food source for top predators.…”

“…To restore and maintain shery stocks, shing moratoria, such as shing bans during the spawning season, were introduced in 2010, and since 2018 shing has not been allowed in the Pearl River Basin from March to June annually. One of the most serious ecological problems in the Pearl River is the invasion of tilapia in some tributaries (Gu et al 2015;Shuai et al 2019).…”