Interactions Between the Invasive Fish Rotan and Native Freshwater Hydrobionts

The fish rotan Perccottus glenii (Odontobutidae) is one of the most widespread invasive fish in Eurasia. Interactions between this fish and native hydrobionts were studied both in field and experimental conditions. Rotan is able to effectively use trophic resources ranging from ciliates to vertebrates. This fish negatively impacts native freshwater communities by depressing macroinvertebrate, fish, and amphibian diversity through competition, predation or behavioural change. There are many examples of extirpation of native fish species from small waterbodies by rotan. Reproductive success of some native dragonflies and beetles as well as many amphibian species is absent in such waterbodies however some amphibians have noxious substances which protect them from consumption by rotan. In larger water bodies, rotan is sometimes prey for predatory fish species, amphibians (rarely), reptiles (southern regions), birds, and mammals. There is also evidence that rotan may be involved in indirect interactions with native fish and reptiles through transmission of parasites. Finally, by entirely or partly eliminating aquatic larvae of terrestrial animals (insects and amphibians), rotan reduces the export of organic nitrogen from aquatic ecosystem. Thus, theoretically, eutrophication of small waterbodies may be accelerated following the introduction of rotan.