Non‐native fish impacts on Mediterranean freshwater ecosystems: current knowledge and research needs

Abstract

Non‐native fishes are often blamed for exerting adverse ecological impacts on native fishes, but the evidence is circumstantial and the true impacts remain largely unknown. This dilemma is particularly acute for freshwater ecosystems of the Mediterranean Region, where a high level of endemism (a biodiversity hotspot) makes native fish extinctions much more likely because of their small natural ranges. The aim of this paper is to review non‐native fish impacts, from genes to ecosystem level, in the fresh waters of the Mediterranean Region and identify gaps in knowledge that currently hamper effective conservation and management of native species and ecosystems. Most studies reviewed reported potential impacts rather than realised impact mechanisms, and these were conducted predominantly in the European part of the Mediterranean Region. No studies of realised impacts were found for three of the 15 most introduced fishes, which emphasises the need for evidence‐based studies of non‐native species impacts.

Parasites of native Cichlidae populations and invasive Oreochromis niloticus (Linnaeus, 1758) in tributary of Amazonas River (Brazil)

“…In a new habitat, the establishment success of an exotic parasite species depends on the acceptable abiotic conditions and complexity of the parasites' life cycle (GALLI et al, 2005;RIBEIRO;LEUNDA, 2012). The transmission of exotic parasites depends, primarily, on biological factors, host-parasite interaction, congeniality of host species and parasite specificity (JIMÉNEZ-GARCÍA et al, 2001;GALLI et al, 2005;ROCHE et al, 2010;RIBEIRO;LEUNDA, 2012).…”

“…The transmission of exotic parasites depends, primarily, on biological factors, host-parasite interaction, congeniality of host species and parasite specificity (JIMÉNEZ-GARCÍA et al, 2001;GALLI et al, 2005;ROCHE et al, 2010;RIBEIRO;LEUNDA, 2012). Thus, the intensity and type of native parasites (ectoparasites and endoparasites) acquired vary among different invasive exotic hosts (PATERSON et al, 2012).…”

Factors influencing tropical Island freshwater fishes: species, status, threats and conservation in Hainan Island

“…China is currently the most seriously threatened county by invasion of aquatic organisms (Xiong et al, 2015;Wang et al, 2016;Xiong et al, 2017). Although little is known about the negative impacts of these non-native freshwater fishes in Hainan Island, these non-native fish species have caused great negative impacts in other regions of world (Pimentel et al, 2000;Ribeiro and Leunda, 2012). Non-native freshwater fish could lead to declines of native endemic species by hybridization, competition for food and habitat, predation, and habitat and ecosystem alterations (Xiong et al, 2015).…”

Status of the Catalan chubSqualius laietanus(Actinopterygii, Cyprinidae) in France: input from morphological and molecular data

“…Hybridization and introgression following the introduction of a non-native species are one of the major threats to endemic freshwater fishes (e.g. Ribeiro and Leunda, 2012). In France, until further data about its presence in the neighbour basins to the Agly and Tech (Têt and Baillaury drainages), Catalan chub has only been recorded in three small drainages, where it cohabits with a species with which it can probably hybridise.…”