First insights into the parasite diversity of economically important fish in Lake Tanganyika.
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| Year of publication | 2016 |
| Type | Conference abstract |
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| Description | Lake Tanganyika is a unique freshwater ecosystem famous for its remarkable evolutionary history not merely of cichlids but also other families of vertebrates and invertebrates. Surprisingly, parasites have been overlooked for many decades, despite increasing interest in the last few years, mostly focused on the diverse littoral zone. Contrary to the littoral, the pelagic zone is relatively species poor in fishes and it is dominated by two endemic clupeids (Limnothrissa miodon and Stolothrissa tanganicae) and four endemic latid predators (Lates angustifrons, L. mariae, L. microlepis, L. stappersii). Both families originate from marine environment and their existence in a truly freshwater pelagic system is rare. Although they figure as an important component of the food web and form the main part of local fisheries, almost nothing is known about their parasite fauna. In our project, we focused on providing of first insights into the parasite diversity of abovementioned clupeid and latid species in Lake Tanganyika to answer the question: are those hosts infected by typical freshwater parasites or do they have kept marine parasite genera? Fish specimens originated from several localities in Lake Tanganyika and were deposited in the collection of the Royal Museum for Central Africa in Tervuren (Belgium) in several decades of the 20th century. Samples needed for molecular analyses come from a field expedition of Walter Salzburger and colleagues in 2014. A total number of 180 fish specimens were examined to date. Phylogenetic analyses were conducted using selected nuclear genes (28S, 18S and ITS 1). Preliminary results indicate clupeid species are infected by different monogenean parasites belonging to Ancyrocephalus: A. limnothrissae and another species new for science. A monogenean species morphologically similar to Diplectanum lacustris (originally described from Lates niloticus) was reported from three out of four latid predators. This result supports the observed pattern of lower host specificity in the pelagic and bathypelagic zone, suggested in previous studies in Lake Tanganyika as well as in marine environments. Phylogenetic analyses situated the collected species of Ancyrocephalus inside the family Dactylogyridae and showed the unresolved situation and most likely polyphyly of Diplectanum. Moreover, while Ancyrocephalus is mainly reported from European freshwater fishes, Diplectanum is a parasite typical for marine and brackish perciform fish. Therefore, different mechanisms may have given rise to the monogenean fauna infecting clupeids and latids in Lake Tanganyika. However, other investigations are needed, especially DNA samples of parasites from other closely related host species, to reveal the evolutionary history and possible geographical or host related variability of the observed species. |
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