Fisheries targets in Lake Tanganyika under the magnifying glass: a look at their monogeneans.
|Year of publication||2017|
|MU Faculty or unit|
|Description||Lake Tanganyika (LT) is one of the African biodiversity hotspots and its fishes are an important food source for local people. While most previous studies have focused on the lake’s spectacular largely endemic cichlid fauna, knowledge about the economically most important species is still poor. The fisheries effort is concentrated mainly on the lake’s pelagic zone, with two clupeids (Limnothrissa miodon, Stolothrissa tanganicae) and four latid species (Lates angustifrons, L. mariae, L. microlepis, L. stappersii) as dominant targets. We examined the abovementioned hosts for the presence of monogeneans to explore 1) which monogeneans infect clupeids and latids in LT, 2) freshwater parasite versus marine host origin and 3) seasonal, environmental and geographical gradients in intraspecific morphological variation and infection parameters. Samples originated from 25 localities in LT including all three historical subbasins. Monogenean species identification and delineation was based on the sclerotised structures, combined with molecular characterisation using nuclear and mitochondrial markers. The effect of host species, environmental, geographic and fixative on monogenean morphological intraspecific variability was tested. In total, 800 fish specimens were examined and infection of three different monogenean species was detected. While clupeids were infected by typically freshwater monogeneans assigned to the new genus called Kapentagyrus, three of the four latid species were parasitized by a representative of the marine genus Diplectanum. Phenomenon of lower monogenean host-specificity in pelagic zone of LT compared to littoral habitat was therefore enhanced by two monogenean genera from non-cichlid fishes. Seasonality in parasite prevalence on clupeids related to host species was observed. Moreover, morphological analyses of K. tanganicae indicated that phenotypic variation depended on host species. No shared infection trends of collected monogenean species in last 80 were detected. The parasite population structure inferred from part of the COI gene shows no north-south gradient. For future studies, the phylogeography of these parasites can reflect historical events that are too recent to be inferred from host genetics.|