Transmission of parasites from introduced tilapias: a new threat to endemic Malagasy ichthyofauna

Abstract

Invasive species are a major threat to biodiversity. In Madagascar, one quarter of freshwater fish fauna consist of introduced species. The introduction of non-native species affects native biota by means of direct interactions but also through indirect interactions including those mediated by parasites, as parasites are usually co-introduced with their hosts. Almost nothing is known about the parasites co-introduced with their fish hosts into Madagascar and their potential impact on native endemic fish fauna. We studied the metazoan parasites of native and introduced cichlid fishes (and some non-cichlids) in the northern part of Madagascar.Using parasite data we evaluated the effect of fish introduced from mainland Africa on native Malagasy cichlid fauna.We documented the co-introduction into Madagascar of parasite species from mainland Africa and also probably from Eurasia. Malagasy cichlids and some other species living in sympatry with non-native cichlids acted as competent hosts for generalist parasites and also for host-specific parasites of African mainland cichlids. However, African mainland cichlids were not susceptible to infection by parasites specific to Malagasy cichlids. The different compositions of parasite communities and infection parameters in endemic and non-native cichlids in the regions investigated may be potentially explained by the different sources and timings of fish introductions. In addition, native endemic parasite fauna even seem to be outcompeted by introduced parasites, which cross the barriers of host specificity. The transmission of non-native parasites associated with the introduction of non-native freshwater fishes may represent a serious risk to endemic freshwater fish and parasite fauna in Madagascar.

Somewhere I belong: phylogeny and morphological evolution in a species-rich lineage of ectoparasitic flatworms infecting cichlid fishes

“…Furthermore, a small yet increasing number of natural and invasion-induced host switches are reported in the literature from cichlids to non-cichlids, e.g. in the Hemi+ clade (Birgi and Euzet, 1983;Birgi and Lambert, 1986), and from African cichlids to cichlids and non-cichlids in the Americas, the Levant, and Madagascar (C. arthracanthus, C. sclerosus, C. tiberianus, C. tilapiae, C. thurstonae, and Scutogyrus longicornis) (Paperna, 1960;Jiménez-Garcia et al, 2001;Šimková et al, 2019). While the literature suggests that most African fish families have their own monogenean lineages (Carvalho Schaeffner, 2018) and the number of similar host switches might, hence, be limited, more host switches might be discovered in the future if more (non-cichlid) host species are studied.…”

Historical museum collections help detect parasite species jumps after tilapia introductions in the Congo Basin

“…Reports of spillover and spillback of parasites from these genera exist from other continents and Madagascar, where tilapias are non-native (Cone et al 1995, Jiménez-García et al 2001, Mendoza-Franco et al 2006, Roche et al 2010, Šimková et al 2019. In general, sub-Saharan Africa is underrepresented in the literature on invasion biology (Pyšek et al 2008) and its helminthological diversity is also very much understudied (Poulin et al 2019).…”

Six new species of Cichlidogyrus Paperna, 1960 (Platyhelminthes: Monogenea) from the gills of cichlids (Teleostei: Cichliformes) from the Lomami River Basin (DRC: Middle Congo)

“…Several genera of the Monogenea, such as Cichlidogyrus Paperna, 1960, Dactylogyrus Diesing, 1850 and Gyrodactylus von Nordmann, 1832, are reported to include potential fish pathogens, especially in aquaculture stocks [3][4][5]. There is a possibility that they switch from introduced to native fish, where they can cause high mortality (see [5][6][7] and references herein). Additionally, spillback phenomena from native to introduced fish have been observed [8].…”