Gyrhaiss Kapepula Kasembele

Parasite infections in farmed fish may remain unrecognised when fish-health assessment relies mainly on visible signs. We investigated metazoan parasite occurrence, parasite diversity and community composition, associations between gill-parasite burden and histological alterations, and stakeholder recognition of fish-health problems in Nile tilapia (Oreochromis niloticus) aquaculture in central Kenya. We examined 157 fish from 20 farms, assessed gill histology in 137 fish, measured water quality once per farm, and collected questionnaire and interview data from 48 stakeholders. Five metazoan parasite groups were recorded, with monopisthocotylans the most prevalent (36.3%). Higher monopisthocotylan burden was associated with a greater cumulative number of gill lesion types (odds ratio 1.86, 95% CI 1.43-2.42, p < 0.001), whereas copepod burden was not. Parasite diversity was higher in the larger operational pond category across all three Hill-number orders (p = 0.006-0.008), and parasite-community composition differed between categories (PERMANOVA, p = 0.034), although these comparisons were exploratory because only four farms were in the larger category and farm category overlapped with county. Single-time-point water-quality measurements showed no clear associations with parasite burden, diversity or community composition after multiple-testing correction. Farmers and fisheries or extension officers recognised signs of poor fish health but rarely identified parasites as a specific cause, and routine diagnostic confirmation was uncommon. The findings reveal a gap between laboratory detection of parasite-associated gill alterations and farm-level recognition and diagnosis.

This study examined the effects of pollution from the Shituru hydrometallurgic complex on the Upper Lufira Basin, Democratic Republic of the Congo, between September 2015 and September 2017. Physico-chemical water variables and trace metal elements in water and sediment, as well as diversity and infection parameters of monopisthocotylan parasites infesting Clarias ngamensis, were assessed at three sites: the Lufira River, Panda River, and Lake Tshangalele. We hypothesised that low pollution would correlate with greater ectoparasite species richness and higher infection parameters. Results indicated severe ecological degradation in the highly polluted Panda River (with high concentrations of TMEs; e.g., 510.830 ± 0.86; 82.470 ± 0.200 µg/L for Co²⁺ and Cu²⁺ in water; 15,771 ± 7068 and 1585 ± 1450 µg/g for Cu²⁺ and Zn²⁺ in the sediment), where neither fish nor parasites were present. Across the other sites, eight parasite species were identified. Seven species occurred on fish from the slightly polluted Lufira River (mean intensity (MI) of 31.28 ± 28.95 parasites per infested fish), while five were found in Lake Tshangalele (MI: 3.23 ± 2.89 parasites per infested fish), confirming the hypothesis. Three species, Quadriacanthus halajiani, Q. domatanai, and Macrogyrodactylus clarii, demonstrated potential as sensitive bioindicators of aquatic pollution in the region.

In the Upper Congo Basin, there are few records of monopisthocotylan parasites from clariids. More surveys of clariid fishes can lead to the discovery of multiple monopisthocotylan species that are new to the region or new to science. We aimed to investigate the monopisthocotylan parasite fauna belonging to Quadriacanthus of five clariid fishes in the Upper Congo Basin by (i) inventorying the species composition and providing the description of new species when necessary, and (ii) analysing their infection parameters. Clarias ngamensis, C. stappersii, C. buthupogon, C. gariepinus and C. theodorae were purchased from fishermen in the Lufira, Lubumbashi and Kafubu rivers in the Upper Congo Basin. Monopisthocotylans were mounted on glass slides with ammonium picrate-glycerin for identification based on morphological analysis of genital and haptoral sclerotised parts. Eight species, namely Q. aegypticus, Q. allobychowskiella, Q. amakaliae, Q. domatanai, Q. halajiani, Q. kalomboi n. sp., Q. bassocki n. sp. and Q. shigoleyae n. sp. are reported. The most prevalent parasite species was Q. amakaliae on C. stappersii (prevalence 60%) with a mean infection intensity of 9.8 ± 7.7. We report C. stappersii and C. buthupogon as new hosts for species of Quadriacanthus as well as three new parasite species for science and new localities for the first five parasite species mentioned above. The new records and the description of Q. kalomboi n. sp., Q. bassocki n. sp. and Q. shigoleyae n. sp. increase the knowledge of the diversity of monopisthocotylans in this region.

Purpose Studies on monogeneans parasitizing representatives of Siluriformes in Africa remain scarce and fragmentary. In order to contribute to fill this gap, we screened Heterobranchus longifilis from the Lindi River in the Democratic Republic of the Congo. Methods Heterobranchus longifilis was purchased from fishermen in DR Congo, province of Tshopo, in Kisangani town, the Lindi River. The monogeneans were individually isolated from the gill and transferred directly onto a slide in a drop of Hoyer’s medium. Results Quadriacanthus lindiensis n. sp. is morphologically similar to Quadriacanthus longifilisi. However, it is distinguished from the latter by its non-sclerotized vagina, its dorsal cunei shape and the size of its bars. Conclusion Only Q. lindiensis n. sp. was found on the gills of the single individual of H. longifilis screened. In the future, a representative sampling should enable us to verify if Q. lindiensis n. sp. co-occurs with other species known to parasitize H. longifilis.

Monogenean parasites belonging to Quadriacanthus have never been reported from Clarias ngamensis, but are commonly found on congeners. In view of the specificity of monogeneans, the genetic proximity and the co-occurrence of C. ngamensis and C. gariepinus in Africa, it is hypothesised that a parasitological survey of C. ngamensis will yield several species of Quadriacanthus as its congeneric host C. gariepinus harbours these parasites. The present study aims to explore the monogenean parasites from the gills of C. ngamensis in the Upper Congo Basin by (i) inventorying their diversity and providing their morphological characterisation, and (ii) analysing their infection parameters. Monogeneans were isolated from the gills, and identified based on morphological analysis of genital and haptoral sclerotized parts. Seven parasite species belonging to Quadriacanthus were found. Among them, two species, Q. aegypticus and Q. allobychowskiella, are both newly reported in the Upper Congo Basin and newly recorded on C. ngamensis. Quadriacanthus amakaliae sp. nov., Q. halajiani sp. nov., Q. domatanai sp. nov., Q. lubandaensis sp. nov., and Q. curvicirrus sp. nov. are new to science and described herein. The most prevalent parasite species was Q. curvicirrus sp. nov. in the Luapula River (prevalence = 66.7%) with mean infection intensity of 6.3 ± 5.8. Quadriacanthus allobychowskiella and Q. aegypticus are known parasites from C. gariepinus and their presence on C. ngamensis is probably the result of lateral transfers. The discovery of five new species from C. ngamensis highlights the parasite diversity still to be explored in the region.

Background: Monogenean parasites have never been formally reported on fishes from the Lufira River Basin. In this context, we decided to record the monogenean parasite fauna of three cichlid species found in the Upper Lufira River Basin for the first time by inventorizing their diversity (species composition) and analysing their infection parameters (prevalence, mean intensity and abundance). Methods: The African cichlid fishes Oreochromis mweruensis, Coptodon rendalli and Serranochromis macrocephalus were selected for the study, given their economic value and their abundance in the Upper Lufira River Basin. Monogeneans were isolated from the gills and stomach, mounted on glass slides with either Hoyer’s medium or ammonium picrate-glycerin for identification under a stereomicroscope, based on morphological analysis of genital and haptoral hard parts. Indices of diversity and infections parameters were calculated. Results: A total of 13 gill monogenean parasite species (Cichlidogyrus dossoui, C. halli, C. karibae, C. mbirizei, C. papernastrema, C. quaestio, C. sclerosus, C. tiberianus, C. tilapiae, C. zambezensis, Scutogyrus gravivaginus, S. cf. bailloni and Gyrodactylus nyanzae) and one stomach monogenean (Enterogyrus malmbergi) were identified. A species richness (S) of 10 for O. mweruensis, S = 6 for C. rendalli and S = 2 for S. macrocephalus was recorded. Five parasite species were reported to be common amongst O. mweruensis and C. rendalli. According to cichlid species, the most prevalent parasite species was C. halli (prevalence [P] = 80.9%) on O. mweruensis, C. dossoui (P = 92.9%) on C. rendalli and C. karibae and C. zambezensis (both P = 9.1%) on S. macrocephalus. The parasite species with the highest mean intensity (MI) were G. nyanzae (MI = 8.7) on O. mweruensis, C. papernastrema (MI = 17.1) on C. rendalli and C. karibae (MI = 15) on S. macrocephalus. The findings indicate new host ranges for five parasites species (C. quaestio, S. cf. bailloni, E. malmbergi on O. mweruensis, C. halli on C. rendalli and C. karibae on S. macrocephalus) as well as new geographical records for all of them as they are recorded for the first time in the Lufira River Basin. Conclusions: This study highlighted the richness of monogenean communities in the Upper Lufira River Basin and is a starting point for future helminthological studies, such as on the use of fish parasites as indicators of anthropogenic impacts. Graphical

Background: Monogenean parasites have never been formally reported on fish from the Lufira basin. Then it is hypothesised that multiple monogenean species are to be recorded that are new to the region. This study aimed to record the gill monogenean parasite fauna of three cichlid fish species in the Upper Lufira basin by inventorying their diversity (species composition) and analysing their infection parameters (prevalence, mean intensity and abundance). Methods: Oreochromis mweruensis, Coptodon rendalli , and Serranochromis macrocephalus were selected for the study, given their economic value and their abundance in the Upper Lufira basin. Monogeneans were isolated from the gills and stomach, mounted on glass slides with either Hoyer’s medium or ammonium picrate-glycerin for further identification under a stereomicroscope, based on morphological analysis of genital and haptoral hard parts. Indices of diversity and infections parameters were calculated. Results: A total of thirteen gill monogenean parasite species ( Cichlidogyrus dossoui, C. halli, C. karibae, C. mbirizei, C. papernastrema, C. quaestio, C. sclerosus, C. tiberianus, C. tilapiae, C. zambezensis, Scutogyrus gravivaginus, S . cf. bailloni and Gyrodactylus nyanzae ) and one stomach monogenean ( Enterogyrus malmbergi ) were reported. A species richness of S= 10 for O. mweruensis , S= 6 for C. rendalli and S= 2 for S. macrocephalus were recorded. Five parasite species were reported to be common amongst O. mweruensis and C. rendalli . The most prevalent parasite species were C. halli (P= 80.9%) on O. mweruensis, C. dossoui (P= 92.9%) on C. rendalli and C. karibae and C. zambezensis (both of which P = 9.1%) on S. macrocephalus with a respective mean infection intensity of 7.9 on O. mweruensis , 9.8 on C. rendalli and 5 and 15, respectively, on S. macrocephalus . Results of this study reported new host ranges for five parasites species ( C. quaestio, S . cf. bailloni, E. malmbergi on O. mweruensis, C. halli on C. rendalli and C. karibae on S. macrocephalus ) as well as new geographical records for three of them ( S . cf. bailloni, E. malmbergi, C. karibae ). Conclusions: This study highlights the richness of monogenean communities in the Upper Lufira basin and is a starting point for future helminthological studies, e.g. on the use of fish parasites as indicators of anthropogenic impacts.