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

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.

受热影响的淡水生境可为热带及亚热带起源的外来物种提供适宜生存条件，使其能在原生分布范围之外形成大规模增殖种群。在德国，外来九间慈鲷（Amatitlania nigrofasciata）以及罗非鱼（Oreochromis sp.）已在吉尔巴赫河（Gillbach）建立了定居种群，该小型溪流接收本地发电厂排放的温排水。本研究首次在吉尔巴赫河中发现斑点罗非鱼（Pelmatolapia mariae），这也是该物种在欧洲可繁殖种群的首个记录。已有假说提出，吉尔巴赫河中Oreochromis属未定种的种群为水产养殖逃逸个体的后裔；本研究的线粒体DNA（mtDNA）分析显示，其同时存在莫桑比克罗非鱼（Oreochromis mossambicus）和尼罗罗非鱼（Oreochromis niloticus）的母系谱系，这两个物种均为水产养殖杂交育种的常用亲本。九间慈鲷与斑点罗非鱼极有可能是由水族爱好者引入吉尔巴赫河的。尽管这三个物种在全球范围内均具有较强的入侵性，但本研究认为，这三种慈鲷均不太可能扩散并永久定居在吉尔巴赫河水域受热影响范围之外。然而，已有研究表明，吉尔巴赫河中的九间慈鲷可携带本土与外来鱼类寄生虫，因此外来慈鲷可能对本土鱼类区系构成威胁。因此，本研究强烈建议对吉尔巴赫河及同类受热影响的淡水生境开展持续监测。