Co-introduction success of monogeneans infecting the fisheries target Limnothrissa miodon differs between two non-native areas: the potential of parasites as a tag for introduction pathway

Abstract

Fish have been widely translocated into non-native areas, commonly as fishery targets. Since fish figure as hosts of various parasite taxa, their introduction may pose often-underestimated threats to ecosystems. However, parasites can also serve to track host species’ introduction routes when these would otherwise be unknown. To verify the potential of parasites in reconstructing invasion routes, we investigated two of the best-documented introductions: those of Limnothrissa miodon into lakes Kivu and Kariba. As a proof of concept, we investigate the possibility of using parasites to evaluate the effect of host size in the introduction pathway and to track the host origins of L. miodon. Combining historical collections and recent field samples, specimens of L. miodon from Lake Kivu and Lake Kariba were examined for monogenean flatworms. Intraspecific variation was investigated using morphometrics of the parasite’s sclerotised structures. Three markers from the ribosomal DNA region were used for genetic parasite identification. In Lake Tanganyika, L. miodon is infected by two species of monogeneans, Kapentagyrus limnotrissae and K. tanganicanus. One of these species, K. limnotrissae, was found on L. miodon from Lake Kariba. In contrast, not a single monogenean individual was found in specimens from Lake Kivu. Morphometric results suggested that the origin of K. limnotrissae introduced into Lake Kariba may be the southern part of Lake Tanganyika, which corresponds to historical reports. Moreover, differences in the size of introduced fish, fry versus juveniles, were proposed as one of the factors influencing parasite occurrence in non-native areas. This supports the potential use of monogeneans as markers for host origin.