On the occurrence of three non-native cichlid species including the first record of a feral population ofPelmatolapia(Tilapia)mariae(Boulenger, 1899) in Europe

Abstract

Thermally influenced freshwater systems provide suitable conditions for non-native species of tropical and subtropical origin to survive and form proliferating populations beyond their native ranges. In Germany, non-native convict cichlids (Amatitlania nigrofasciata) and tilapia (Oreochromis sp.) have established populations in the Gillbach, a small stream that receives warm water discharge from a local power plant. Here, we report on the discovery of spotted tilapia (Pelmatolapia mariae) in the Gillbach, the first record of a reproducing population of this species in Europe. It has been hypothesized that Oreochromis sp. in the Gillbach are descendants of aquaculture escapees and our mtDNA analysis found both O. mossambicus and O. niloticus maternal lineages, which are commonly used for hybrids in aquaculture. Convict cichlids and spotted tilapia were most probably introduced into the Gillbach by aquarium hobbyists. Despite their high invasiveness worldwide, we argue that all three cichlid species are unlikely to spread and persist permanently beyond the thermally influenced range of the Gillbach river system. However, convict cichlids from the Gillbach are known to host both native and non-native fish parasites and thus, non-native cichlids may constitute threats to the native fish fauna. We therefore strongly recommend continuous monitoring of the Gillbach and similar systems.

Consistent Behavioral Syndrome Across Seasons in an Invasive Freshwater Fish

“…(site 1, Figure 1A) will have dispersed from the source at some point. The population's maximum spatial range is estimated to be < 2 km downstream, as no guppies have been found beyond this point during multiple samplings over multiple years (see Supplementary Tables 1, 2, Höfer and Staas, 1998;Jourdan et al, 2014;Lukas et al, 2017a).…”

“…In Germany, tropical fishes have established populations in several artificially heated stream systems (Lukas et al, 2017b), the most investigated being the Gillbach near Cologne (see Figure 1A, Jourdan et al, 2014;Lukas et al, 2017a;Kempkes et al, 2018). To estimate seasonal fluctuations in temperatureassociated abiotic and biotic conditions within the sampled range of the stream, we continuously recorded water temperatures with submerged data-loggers.…”

A global analysis of the susceptibility of river basins to invasion of a freshwater zooplankton (Daphnia lumholtzi)

“…Despite the relatively low incidence of tilapia species in river basins in Europe and the strict legislation to control the species in public waters (Patoka et al., 2018), escapes from breeding grounds and aquarium releases are inevitable. The occurrence of established tilapia populations in stream in the River Rhine catchment receiving thermal pollution drainage water in Germany (Lukas et al., 2017) and under similar conditions in the River Bacchiglione in Italy (Bianco & Turin, 2009) are examples of this. Thus, it is possible that D. lumholtzi propagules continuously arriving with tilapias could also generate established populations, if favourable climatic–environmental conditions become a reality.…”

Notes on the Distribution of the Genus Oreochromis in the East Mediterranean Region of Turkey

“…They are tropical freshwater species and their native habitats are mainly located tropical and subtropical regions of America and Africa, as well as Madagascar, India, and Sri Lanka (Salzburger & Meyer, 2004;Maan & Sefc, 2013). However, they can also be found as non-native species such as Florida in America (Schofield et al, 2014), in North, South and Central America (Cassemiro et al, 2018), in Thailand (Nico et al, 2007), in Germany (Lukas et al, 2017), in Portugal (Carecho et al, 2018), and in Russia (Zworykin & Pashkov, 2010). The family is represented by 250 genera, including Tilapia (Froese & Pauly, 2019).…”