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Annemariè Avenant-Oldewage
Department of Zoology, University of Johannesburg, Johannesburg, South Africa

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Article
Published: 28 August 2021 in Biological Trace Element Research
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Anthropogenic activities influence the natural equilibrium of freshwater ecosystems resulting in negative ecological impacts. Differences in the infection variables of Lamproglena clariae in relation to variable water quality influenced by metal pollution were studied at six sites along the Vaal River, South Africa (March 2017 and October 2018). From each sampling site, in situ water quality parameters, water and sediment samples, and a minimum of 10 Clarias gariepinus were collected. Lamproglena clariae specimens collected from the gills of C. gariepinus were used to calculate the prevalence, mean intensity, and mean abundance of the parasite. Metal concentrations in water and sediment were analysed with inductively coupled plasma–optical emission spectrometry and inductively coupled plasma–mass spectrometry. Parasite intensity correlated negatively with some water quality parameters (conductivity, salinity, pH, total dissolved solids, and dissolved oxygen). Negative correlations were found between L. clariae (intensity and prevalence) and metal concentrations (Cu, Cr, Zn, Cd) in water. Parasite infections were influenced negatively at sites with high metal concentrations recorded in sediment and water and high levels of organic pollution. Sites that were found to be more polluted had lower mean intensity and mean abundance of L. clariae, indicating pollution affects the survival of this ectoparasite.

ACS Style

Marilie Pretorius; Annemariè Avenant-Oldewage. Parasites as Biological Indicators: the Impact of Environmental Quality on the Infections of Lamproglena clariae (Crustacea) on Clarias gariepinus Along the Vaal River, South Africa. Biological Trace Element Research 2021, 1 -11.

AMA Style

Marilie Pretorius, Annemariè Avenant-Oldewage. Parasites as Biological Indicators: the Impact of Environmental Quality on the Infections of Lamproglena clariae (Crustacea) on Clarias gariepinus Along the Vaal River, South Africa. Biological Trace Element Research. 2021; ():1-11.

Chicago/Turabian Style

Marilie Pretorius; Annemariè Avenant-Oldewage. 2021. "Parasites as Biological Indicators: the Impact of Environmental Quality on the Infections of Lamproglena clariae (Crustacea) on Clarias gariepinus Along the Vaal River, South Africa." Biological Trace Element Research , no. : 1-11.

Review
Published: 03 August 2021 in Ecological Indicators
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Monogenea is a Class of ecologically and economically significant platyhelminth parasites of freshwater and marine hosts. Contamination of the environment has been shown to variably affect parasites resulting in alterations at the population and organismal levels. The aim of this study was to perform a meta-analysis of published data to assess similarities among responses of monogeneans to pollution and estimate effect sizes of contaminant exposure on these parasites. Effect size was calculated according to Cohen’s d based on reported mean abundance for monogeneans from individual studies. A total of 57 studies were used in the present study. Each Monogenea–contaminant record represented a single data point in the meta-analysis, and this accounted for a total of 217 useable records. Most studies were concerned with species belong to Gyrodactylidae, Diplozoidae, Ancyrocephalidae and Dactylogyridae. Assessment of the effects of specific pollutants on monogeneans have mostly been restricted to exposure to eutrophication, pulp-mill effluent and metals. Comparison of effect sizes showed strong negative effects for metals and strong positive effects for eutrophication on monogeneans. Other contaminant types had weak effect sizes on monogeneans. Comparison of effect sizes among monogenean families showed that none of the effect sizes calculated were significant but metals and disturbance contaminants showed strong negative and positive effects respectively for Gyrodactylidae. The current comparisons were based on changes in the population structure and infections of monogeneans, however, organ level effects associated with exposure to poor water quality have also been noted. In this instance, exposure has been suggested to result in asymmetry of the attachment organs of some monogeneans. Despite numerous records of impacts of pollution exposure at the population level, understanding of the physiological effects and mechanisms employed by Monogenea to survive and adapt to changes in the environment are yet to be explored. Study of these aspects would enable better understanding of the variation in the trends observed at a population level for monogeneans in relation to the quality of the macroenvironment.

ACS Style

Beric M. Gilbert; Annemariè Avenant-Oldewage. Monogeneans as bioindicators: A meta-analysis of effect size of contaminant exposure toward Monogenea (Platyhelminthes). Ecological Indicators 2021, 130, 108062 .

AMA Style

Beric M. Gilbert, Annemariè Avenant-Oldewage. Monogeneans as bioindicators: A meta-analysis of effect size of contaminant exposure toward Monogenea (Platyhelminthes). Ecological Indicators. 2021; 130 ():108062.

Chicago/Turabian Style

Beric M. Gilbert; Annemariè Avenant-Oldewage. 2021. "Monogeneans as bioindicators: A meta-analysis of effect size of contaminant exposure toward Monogenea (Platyhelminthes)." Ecological Indicators 130, no. : 108062.

Review
Published: 30 October 2020 in Parasites & Vectors
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The use of molecular tools in the study of parasite taxonomy and systematics have become a substantial and crucial component of parasitology. Having genetic characterisation at the disposal of researchers has produced mostly useful, and arguably more objective conclusions. However, there are several groups for which limited genetic information is available and, coupled with the lack of standardised protocols, renders molecular study of these groups challenging. The Diplozoidae are fascinating and unique monogeneans parasitizing mainly freshwater cyprinid fishes in Europe, Asia and Africa. This group was studied from a molecular aspect since the turn of the century and as such, limitations and variability concerning the use of these techniques have not been clearly defined. In this review, all literature and molecular information, primarily from online databases such as GenBank, were compiled and scrupulously analysed for the Diplozoidae. This was done to review the information, detect possible pitfalls, and provide a “checkpoint” for future molecular studies of the family. Hindrances detected are the availability of sequence data for only a limited number of species, frequently limited to a single sequence per species, and the heavy reliance on one non-coding ribosomal marker (ITS2 rDNA) which is difficult to align objectively and displays massive divergences between taxa. Challenging species identification and limited understanding of diplozoid species diversity and plasticity are also likely restricting factors, all of which hamper the accurate taxonomic and phylogenetic study of this group. Thus, a more integrated taxonomic approach through the inclusion of additional markers, application of more rigorous morphological assessment, more structured barcoding techniques, alongside thorough capturing of species descriptions including genetypes, genophore vouchers and reference collections in open sources are encouraged. The pitfalls highlighted are not singular to the Diplozoidae, and the study of other groups may benefit from the points raised here as well.

ACS Style

Quinton Marco Dos Santos; Annemariè Avenant-Oldewage. Review on the molecular study of the Diplozoidae: analyses of currently available genetic data, what it tells us, and where to go from here. Parasites & Vectors 2020, 13, 1 -18.

AMA Style

Quinton Marco Dos Santos, Annemariè Avenant-Oldewage. Review on the molecular study of the Diplozoidae: analyses of currently available genetic data, what it tells us, and where to go from here. Parasites & Vectors. 2020; 13 (1):1-18.

Chicago/Turabian Style

Quinton Marco Dos Santos; Annemariè Avenant-Oldewage. 2020. "Review on the molecular study of the Diplozoidae: analyses of currently available genetic data, what it tells us, and where to go from here." Parasites & Vectors 13, no. 1: 1-18.

Journal article
Published: 22 September 2020 in African Journal of Aquatic Science
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Increasing awareness of deteriorating health of aquatic ecosystems, as a result of human activities, has led to the suggestion that fish host-parasite relationships are possible bioindicators of environmental pollution. This study examined the impact of water quality and trace elements on the seasonal occurrence of Cichlidogyrus philander Douëllou, 1993. In situ water quality variables were recorded, and sediment and water samples collected, for analysis of trace elements and metals. Collections were performed monthly from February 2016 to January 2017, during which 164 Pseudocrenilabrus philander (Weber, 1897) hosts were collected and their C. philander loads were counted. Monogeneans occurred throughout the year, with prevalence, mean intensity and abundance reaching maximum values of 90.74%, 29.9 and 29.4, respectively, in summer. Trace element and metal levels were highest in sediment and lowest in water. No significant correlation was found between water quality and trace elements on infection variables. Trace elements did not have an effect on the occurrence of the parasite, therefore it was concluded that the changes observed during the study were not brought on by changes in water quality as a result of pollution, but rather that these changes relate to seasonal variation in infection biology of C. philander.

ACS Style

Patience C Igeh; Beric M Gilbert; Annemariè Avenant-Oldewage. Seasonal variance in water quality, trace metals and infection variables of Cichlidogyrus philander Douëllou, 1993 (Monogenea, Ancyrocephalidae) infecting the gills of Pseudocrenilabrus philander (Weber, 1897) in the Padda Dam, South Africa. African Journal of Aquatic Science 2020, 46, 88 -99.

AMA Style

Patience C Igeh, Beric M Gilbert, Annemariè Avenant-Oldewage. Seasonal variance in water quality, trace metals and infection variables of Cichlidogyrus philander Douëllou, 1993 (Monogenea, Ancyrocephalidae) infecting the gills of Pseudocrenilabrus philander (Weber, 1897) in the Padda Dam, South Africa. African Journal of Aquatic Science. 2020; 46 (1):88-99.

Chicago/Turabian Style

Patience C Igeh; Beric M Gilbert; Annemariè Avenant-Oldewage. 2020. "Seasonal variance in water quality, trace metals and infection variables of Cichlidogyrus philander Douëllou, 1993 (Monogenea, Ancyrocephalidae) infecting the gills of Pseudocrenilabrus philander (Weber, 1897) in the Padda Dam, South Africa." African Journal of Aquatic Science 46, no. 1: 88-99.

Short communication
Published: 31 August 2020 in Journal of the South African Veterinary Association
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The Journal of the South African Veterinary Association (JSAVA), is a contemporary multi-disciplinary scientific mouthpiece for Veterinary Science in South African and abroad. It provides veterinarians in South Africa and elsewhere in the world with current scientific information across the full spectrum of veterinary science, diseases or other conditions that are endemic in, or particularly relevant to sub-Saharan Africa.

ACS Style

Rosina C. Krecek; Annemarie Avenant-Oldewage; Maggie Fisher; Barend L. Penzhorn; Isaac K. Phiri; Roger Prichard; Derek Sumption; Stephen R. Werre. Model of Success: World Association for the Advancement of Veterinary Parasitology African Foundation (1997–2019). Journal of the South African Veterinary Association 2020, 91, 6 .

AMA Style

Rosina C. Krecek, Annemarie Avenant-Oldewage, Maggie Fisher, Barend L. Penzhorn, Isaac K. Phiri, Roger Prichard, Derek Sumption, Stephen R. Werre. Model of Success: World Association for the Advancement of Veterinary Parasitology African Foundation (1997–2019). Journal of the South African Veterinary Association. 2020; 91 ():6.

Chicago/Turabian Style

Rosina C. Krecek; Annemarie Avenant-Oldewage; Maggie Fisher; Barend L. Penzhorn; Isaac K. Phiri; Roger Prichard; Derek Sumption; Stephen R. Werre. 2020. "Model of Success: World Association for the Advancement of Veterinary Parasitology African Foundation (1997–2019)." Journal of the South African Veterinary Association 91, no. : 6.

Journal article
Published: 13 July 2020 in International Journal for Parasitology: Parasites and Wildlife
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Parasites and environmental features could synergistically act as stressors to the health of their hosts. The objectives of this study were to evaluate the effect of: (i) water quality, host sex, size and body condition on adult digenean parasite infections; (ii) digenean infections and host sex and size on the oxidative stress biomarkers and body condition of hosts; and (iii) water quality on the oxidative stress biomarkers and body condition in Clarias gariepinus. Water quality variables were measured and C. gariepinus were collected each month for a year for examination of two intestinal digeneans, Masenia nkomatiensis and Glossidium pedatum, and determination of body condition and measurement of biomarkers in the host. The results indicated that the intensity of M. nkomatiensis was positively correlated with electrical conductivity and total dissolved solids. Prevalence of G. pedatum was negatively correlated with electrical conductivity, salinity and total dissolved solids. High summer water temperature was strongly associated with high digenean infections. There was no host body condition, sex or size bias for any of the parasite infection variables. Differences in the biomarker levels and body condition between uninfected fish and those infected with M. nkomatiensis or G. pedatum were insignificant indicating a low effect of the digenean parasites on oxidative stress biomarkers and body condition in the fish. However, total protein levels were positively associated with host size, and lipid peroxidation was negatively related to host body condition; total protein levels were also positively correlated with temperature and negatively correlated with dissolved oxygen. Host body condition was only negatively correlated with dissolved oxygen. Overall the trends observed in the data showed that the parasites have a negligible effect on oxidative stress in host fish and the trends observed for all variables (water quality, stress biomarkers, body condition and parasite infections) showed a strong seasonal pattern.

ACS Style

José Chissiua Dumbo; Beric Michael Gilbert; Annemariè Avenant-Oldewage. Oxidative stress biomarkers in the African sharptooth catfish, Clarias gariepinus, associated with infections by adult digeneans and water quality. International Journal for Parasitology: Parasites and Wildlife 2020, 12, 232 -241.

AMA Style

José Chissiua Dumbo, Beric Michael Gilbert, Annemariè Avenant-Oldewage. Oxidative stress biomarkers in the African sharptooth catfish, Clarias gariepinus, associated with infections by adult digeneans and water quality. International Journal for Parasitology: Parasites and Wildlife. 2020; 12 ():232-241.

Chicago/Turabian Style

José Chissiua Dumbo; Beric Michael Gilbert; Annemariè Avenant-Oldewage. 2020. "Oxidative stress biomarkers in the African sharptooth catfish, Clarias gariepinus, associated with infections by adult digeneans and water quality." International Journal for Parasitology: Parasites and Wildlife 12, no. : 232-241.

Journal article
Published: 07 July 2020 in African Journal of Aquatic Science
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The parasite Chonopeltis australis Boxshall, 1976 has been recorded from tributaries of the Orange-Vaal River System. It is host-specific, preferring the cyprinids Labeo capensis (Smith, 1841) and Labeo umbratus (Smith, 1841). Sampling was conducted between spring 2016 and autumn 2019 at various sites on the main stream of the Vaal River. The current study considers current ecological data and compares these to historic data. The species produces a single cohort, with overwintering eggs and adults. The infection of L. capensis peaks in autumn. Parasites aggregate on larger hosts that occur in riverine habitats, but can succeed in shallow impoundments with suitable hard surfaces for egg deposition. This parasite exploits changes in ecological conditions and host biology in order to survive, but will only choose between these two host species where they aggregate on larger hosts. The increased pollution in the Vaal River Barrage and downstream has had an impact on the occurrence of C. australis and it is possibly extirpated in polluted parts of the river.

ACS Style

Lam Neethling; A Avenant-Oldewage. Host selection and notes on the distribution of Chonopeltis australis Boxshall, 1976 in southern Africa. African Journal of Aquatic Science 2020, 45, 500 -508.

AMA Style

Lam Neethling, A Avenant-Oldewage. Host selection and notes on the distribution of Chonopeltis australis Boxshall, 1976 in southern Africa. African Journal of Aquatic Science. 2020; 45 (4):500-508.

Chicago/Turabian Style

Lam Neethling; A Avenant-Oldewage. 2020. "Host selection and notes on the distribution of Chonopeltis australis Boxshall, 1976 in southern Africa." African Journal of Aquatic Science 45, no. 4: 500-508.

Journal article
Published: 02 July 2020 in African Journal of Aquatic Science
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The Vaal River is of considerable economic and environmental importance. It flows through five provinces within South Africa and it is subject to numerous recreational and industrial activities, which often prove detrimental to the health of the system. To determine the extent of the impact that these anthropogenic stressors have on the river system, physiological effects in Clarias gariepinus were assessed during a 2016/2017 sample survey using a suite of biomarkers (exposure and effect). Inhibition of acetylcholinesterase and increased metallothionein concentrations were recorded in response to the increase in organic pollutants and metals. Oxidative stress biomarkers, such as superoxide dismutase, showed significant increases in response to possible recent pesticide exposures, whereas lipid peroxidation and protein damage were evident with increased malondialdehyde and protein carbonyl concentrations respectively. The data provide a novel account of the use of biomarkers to assess negative anthropogenic effects observed along the entire length of the Vaal River system.

ACS Style

Lj Connell; Gr Jansen Van Rensburg; A Avenant-Oldewage; R Greenfield. Biomarker responses in African sharptooth catfish, Clarias gariepinus (Burchell, 1822), as indicators of potential metal and organic pollution along the Vaal River system, South Africa. African Journal of Aquatic Science 2020, 45, 317 -328.

AMA Style

Lj Connell, Gr Jansen Van Rensburg, A Avenant-Oldewage, R Greenfield. Biomarker responses in African sharptooth catfish, Clarias gariepinus (Burchell, 1822), as indicators of potential metal and organic pollution along the Vaal River system, South Africa. African Journal of Aquatic Science. 2020; 45 (3):317-328.

Chicago/Turabian Style

Lj Connell; Gr Jansen Van Rensburg; A Avenant-Oldewage; R Greenfield. 2020. "Biomarker responses in African sharptooth catfish, Clarias gariepinus (Burchell, 1822), as indicators of potential metal and organic pollution along the Vaal River system, South Africa." African Journal of Aquatic Science 45, no. 3: 317-328.

Journal article
Published: 28 May 2020 in International Journal for Parasitology: Parasites and Wildlife
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Stable isotope analysis offers a unique tool for comparing trophic interactions and food web architecture in ecosystems based on analysis of stable isotope ratios of carbon (13C/12C) and nitrogen (15N/14N) in organisms. Clarias gariepinus were collected from six sites along the Vaal River, South Africa and were assessed for ectoparasites and endoparasites. Lamproglena clariae (Copepoda), Tetracampos ciliotheca and Proteocephalus glanduligerus (Cestoda), and larval Contracaecum sp. (Nematoda) were collected from the gills, intestine and mesenteries, respectively. Signatures of δ13C and δ15N were analysed in host muscle tissue and parasites using bulk stable isotope analysis. Variable stable isotope enrichment between parasites and host were observed; L. clariae and the host shared similar δ15N signatures and endoparasites being depleted in δ13C and δ15N relative to the host. Differences in stable isotope enrichment between parasites could be related to the feeding strategy of each parasite species collected. Geographic and spatial differences in enrichment of stable isotopes observed in hosts were mirrored by parasites. As parasites rely on a single host for meeting their nutritional demands, stable isotope variability in parasites relates to the dietary differences of host organisms and therefore variations in baseline stable isotope signatures of food items consumed by hosts.

ACS Style

Beric M. Gilbert; Milen Nachev; Maik A. Jochmann; Torsten C. Schmidt; Daniel Köster; Bernd Sures; Annemariè Avenant-Oldewage. Stable isotope analysis spills the beans about spatial variance in trophic structure in a fish host – parasite system from the Vaal River System, South Africa. International Journal for Parasitology: Parasites and Wildlife 2020, 12, 134 -141.

AMA Style

Beric M. Gilbert, Milen Nachev, Maik A. Jochmann, Torsten C. Schmidt, Daniel Köster, Bernd Sures, Annemariè Avenant-Oldewage. Stable isotope analysis spills the beans about spatial variance in trophic structure in a fish host – parasite system from the Vaal River System, South Africa. International Journal for Parasitology: Parasites and Wildlife. 2020; 12 ():134-141.

Chicago/Turabian Style

Beric M. Gilbert; Milen Nachev; Maik A. Jochmann; Torsten C. Schmidt; Daniel Köster; Bernd Sures; Annemariè Avenant-Oldewage. 2020. "Stable isotope analysis spills the beans about spatial variance in trophic structure in a fish host – parasite system from the Vaal River System, South Africa." International Journal for Parasitology: Parasites and Wildlife 12, no. : 134-141.

Fish parasitology short communication
Published: 06 February 2020 in Parasitology Research
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Parasitism is commonly recognised as a consumer strategy, although, the interaction of parasites in communities and ecosystems are generally poorly understood. As parasites are integral parts of food webs, analysis of the trophic interactions between parasites and hosts was assessed through comparison of stable isotope ratios of carbon (13C/12C) and nitrogen (15N/14N). Largemouth yellowfish (Labeobarbus kimberleyensis) infected with the Asian tapeworm (Schyzocotyle acheilognathi) were collected from the Vaal Dam. Signatures of δ13C and δ15N were assessed in host muscle and liver tissue, and cestodes using an elemental analyser coupled with an isotope ratio-mass spectrometer (EA-IRMS). Hosts were enriched by 4.1‰ in the heavy nitrogen isotope with respect to the S. acheilognathi and therefore occupy a higher trophic position than the parasite. Comparison of δ13C indicates that dietary sources of carbon in cestodes are derived from the host liver. Comparison of stable isotope signatures between Paradiplozoon ichthyoxanthon (another common parasite of the Largemouth yellowfish in the Vaal River) and S. acheilognathi showed that the monogenean was enriched by 5.3‰ in 15N which accounts for a difference of almost two trophic positions. Isotope differences in the host–parasite system considered indicate that differences can be related to the mode of nutrient acquisition employed by host and parasites. Cestodes, being depleted in both 13C and 15N relative to the host and monogenean (P. ichthyoxanthon), indicate that S. acheilognathi assimilates nutrients derived from the host metabolism which are released from the liver.

ACS Style

Beric Gilbert; Milen Nachev; Maik A. Jochmann; Torsten C. Schmidt; Daniel Köster; Bernd Sures; Annemariè Avenant-Oldewage. You are how you eat: differences in trophic position of two parasite species infecting a single host according to stable isotopes. Parasitology Research 2020, 119, 1393 -1400.

AMA Style

Beric Gilbert, Milen Nachev, Maik A. Jochmann, Torsten C. Schmidt, Daniel Köster, Bernd Sures, Annemariè Avenant-Oldewage. You are how you eat: differences in trophic position of two parasite species infecting a single host according to stable isotopes. Parasitology Research. 2020; 119 (4):1393-1400.

Chicago/Turabian Style

Beric Gilbert; Milen Nachev; Maik A. Jochmann; Torsten C. Schmidt; Daniel Köster; Bernd Sures; Annemariè Avenant-Oldewage. 2020. "You are how you eat: differences in trophic position of two parasite species infecting a single host according to stable isotopes." Parasitology Research 119, no. 4: 1393-1400.

Journal article
Published: 20 December 2019 in Parasite
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A new species of Gyrodactylus von Nordmann, 1832 is described from the gills of Alcolapia grahami, a tilapian fish endemic to Lake Magadi. This alkaline soda lake in the Rift Valley in Kenya is an extreme environment with pH as high as 11, temperatures up to 42 °C, and diurnal fluctuation between hyperoxia and virtual anoxia. Nevertheless, gyrodactylid monogeneans able to survive these hostile conditions were detected from the gills the Magadi tilapia. The worms were studied using light microscopy, isolated sclerites observed using scanning electron microscopy, and molecular techniques used to genetically characterize the specimens. The gyrodactylid was described as Gyrodactylus magadiensis n. sp. and could be distinguished from other Gyrodactylus species infecting African cichlid fish based on the comparatively long and narrow hamuli, a ventral bar with small rounded anterolateral processes and a tongue-shaped posterior membrane, and marginal hooks with slender sickles which are angled forward, a trapezoid to square toe, rounded heel, a long bridge prior to reaching marginal sickle shaft, and a long lateral edge of the toe. The species is also distinct from all other Gyrodactylus taxa based on the ITS region of rDNA (ITS1–5.8s–ITS2), strongly supporting the designation of a new species. These findings represent the second record of Gyrodactylus from Kenya, with the description of G. magadiensis bringing the total number of Gyrodactylus species described from African cichlids to 18.

ACS Style

Quinton Marco Dos Santos; John Ndegwa Maina; Annemariè Avenant-Oldewage. Gyrodactylus magadiensis n. sp. (Monogenea, Gyrodactylidae) parasitising the gills of Alcolapia grahami (Perciformes, Cichlidae), a fish inhabiting the extreme environment of Lake Magadi, Kenya. Parasite 2019, 26, 76 .

AMA Style

Quinton Marco Dos Santos, John Ndegwa Maina, Annemariè Avenant-Oldewage. Gyrodactylus magadiensis n. sp. (Monogenea, Gyrodactylidae) parasitising the gills of Alcolapia grahami (Perciformes, Cichlidae), a fish inhabiting the extreme environment of Lake Magadi, Kenya. Parasite. 2019; 26 ():76.

Chicago/Turabian Style

Quinton Marco Dos Santos; John Ndegwa Maina; Annemariè Avenant-Oldewage. 2019. "Gyrodactylus magadiensis n. sp. (Monogenea, Gyrodactylidae) parasitising the gills of Alcolapia grahami (Perciformes, Cichlidae), a fish inhabiting the extreme environment of Lake Magadi, Kenya." Parasite 26, no. : 76.

Preprint content
Published: 17 December 2019
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BackgroundStable isotope analysis offers a unique tool for comparing trophic interactions and food web architecture in ecosystems. This approach is based on analysis of the stable isotope ratios of carbon (13 C/ 12 C) and nitrogen (15 N/ 14 N) in organisms. Studies comparing stable isotope enrichment in hosts and parasites have shown that parasites are variably enriched in stable isotopes relative to the host.MethodsSharptooth catfish (Clarias gariepinus) were collected from six sites along the Vaal River, South Africa and were assessed for ectoparasites and endoparasites. Lamproglena clariae (Copepoda), Tetracampus ciliotheca and Proteocephalus glanduligerus (Cestoda), and larval Contracaecum sp. (Nematoda) were collected from the gills, intestine and mesenteries, respectively. Signatures of δ 13 C and δ 15 N were analysed in host muscle tissue and parasites using bulk stable isotope analysis.ResultsStable isotope enrichment was variable between parasites and the host fish, with L. clariae and the host sharing similar δ 15 N signatures and the endoparasites being depleted in both δ 13 C and δ 15 N relative to the host. Spatial differences in enrichment of stable isotopes were also identified. Fish and parasites collected from below the Vaal River Barrage were more enriched in the 15 N isotope than hosts and parasites collected from other sites. The opposite was identified for 13 C isotope fractionation.ConclusionDifferences in stable isotope enrichment in parasites infecting C. gariepinus could be related to the feeding strategy of each parasite species collected. Enrichment of δ 15 N in L. clariae would relate to the micropredatory nature of this parasite, which feeds on whole blood of the host fish. Depleted isotope levels in endoparasites could relate to their absorptive feeding strategy on metabolic by-products of the host. Spatial differences in both host and parasite tissues identified likely resulted from differences in the diet of the host and related with availability of prey items for the host fish.

ACS Style

Beric M. Gilbert; Milen Nachev; Maik A. Jochmann; Torsten C. Schmidt; Daniel Köster; Bernd Sures; Annemarie Avenant-Oldewage. Stable isotope analysis spills the beans about spatial variance in trophic structure in a fish host – parasite system from the Vaal River System, South Africa. 2019, 1 .

AMA Style

Beric M. Gilbert, Milen Nachev, Maik A. Jochmann, Torsten C. Schmidt, Daniel Köster, Bernd Sures, Annemarie Avenant-Oldewage. Stable isotope analysis spills the beans about spatial variance in trophic structure in a fish host – parasite system from the Vaal River System, South Africa. . 2019; ():1.

Chicago/Turabian Style

Beric M. Gilbert; Milen Nachev; Maik A. Jochmann; Torsten C. Schmidt; Daniel Köster; Bernd Sures; Annemarie Avenant-Oldewage. 2019. "Stable isotope analysis spills the beans about spatial variance in trophic structure in a fish host – parasite system from the Vaal River System, South Africa." , no. : 1.

Original article
Published: 26 November 2019 in Journal of Fish Diseases
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Histopathological changes of Cichlidogyrus philander Douëllou, 1993 on the gills of Pseudocrenilabrus philander (Weber, 1897) were studied using light and scanning electron microscopy. Observations revealed that C. philander attaches to its host by alternating the prohaptor (for temporary attachment or feeding) or haptor (using haptoral parts for firm and secured attachment). The sharp terminal ends of the anchors are inserted basally into the gill lamella, between two adjacent secondary gill lamellae and the marginal hooklets assist by superficially penetrating, holding and lifting epithelial tissue in the proximal region of the secondary gill lamella. The attachment of C. philander resulted in compression, rupturing of the interlamellar epithelium, change in the organization of epithelial cells in both primary and secondary gill lamella, displacement of the extracellular cartilaginous matrix, occasional rupturing of blood vessels and erythrocytes and some cells becoming ill‐defined. At the site of attachment, the host response comprises of hyperplasia, increase in the number of mucous cells and infiltration with neutrophils. It was concluded that the effect of C. philander is mild in natural conditions.

ACS Style

Patience Chwe Igeh; Annemariè Avenant‐Oldewage. Pathological effects of Cichlidogyrus philander Douëllou, 1993 (Monogenea, Ancyrocephalidae) on the gills of Pseudocrenilabrus philander (Weber, 1897) (Cichlidae). Journal of Fish Diseases 2019, 43, 177 -184.

AMA Style

Patience Chwe Igeh, Annemariè Avenant‐Oldewage. Pathological effects of Cichlidogyrus philander Douëllou, 1993 (Monogenea, Ancyrocephalidae) on the gills of Pseudocrenilabrus philander (Weber, 1897) (Cichlidae). Journal of Fish Diseases. 2019; 43 (2):177-184.

Chicago/Turabian Style

Patience Chwe Igeh; Annemariè Avenant‐Oldewage. 2019. "Pathological effects of Cichlidogyrus philander Douëllou, 1993 (Monogenea, Ancyrocephalidae) on the gills of Pseudocrenilabrus philander (Weber, 1897) (Cichlidae)." Journal of Fish Diseases 43, no. 2: 177-184.

Journal article
Published: 15 July 2019 in Journal of Fish Diseases
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The intestines of 154 Clarias gariepinus were examined of which 29 were naturally infected with Masenia nkomatiensis, and of these, seven (intensity ranging from 8 to 231) were examined for pathology. Destruction of the epithelium covering the villi, detachment of epithelial cells and parts of villi were observed. Excessive mucus secretion occurred in the vicinity of the worm and catarrh was observed, indicative of an inflammatory response. The number of mucous and mast cells was higher at the attachment site than at an area 5,000 µm away and in uninfected individuals, suggesting that the parasite triggered a localized innate immune response. The number of neutrophils, basophils and lymphocytes in infected tissue was not significantly different from uninfected tissue confirming that no acquired immune response was produced against the maseniid. The caecae in the anterior part of the parasites' intestine consisted of convoluted epithelium forming invaginations or "crypts." Contraction of the thick layer of circular muscle fibres of the caeca facilitates the movement of digested material. Observation of digested host cells and cell debris within the caecae provides further evidence that M. nkomatiensis is consuming host cells.

ACS Style

José Chissiua Dumbo; Annemariè Avenant‐Oldewage. Histopathological changes induced by the digenean intestinal parasite Masenia nkomatiensis Dumbo, Dos Santos, & Avenant-Oldewage, 2019 of the catfish Clarias gariepinus (Burchell) from Incomati Basin, Mozambique. Journal of Fish Diseases 2019, 42, 1341 -1350.

AMA Style

José Chissiua Dumbo, Annemariè Avenant‐Oldewage. Histopathological changes induced by the digenean intestinal parasite Masenia nkomatiensis Dumbo, Dos Santos, & Avenant-Oldewage, 2019 of the catfish Clarias gariepinus (Burchell) from Incomati Basin, Mozambique. Journal of Fish Diseases. 2019; 42 (10):1341-1350.

Chicago/Turabian Style

José Chissiua Dumbo; Annemariè Avenant‐Oldewage. 2019. "Histopathological changes induced by the digenean intestinal parasite Masenia nkomatiensis Dumbo, Dos Santos, & Avenant-Oldewage, 2019 of the catfish Clarias gariepinus (Burchell) from Incomati Basin, Mozambique." Journal of Fish Diseases 42, no. 10: 1341-1350.

Articles
Published: 30 April 2019 in African Zoology
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The superfamily Plagiorchioidea has a considerable number of genera and species with great uncertainty of their phylogenetic position. The objectives of the current study were to specifically describe the morphology and determine for the first time the phylogenetic position of Glossidium pedatum and Orientocreadium batrachoides. Examination of G. pedatum using conventional light and scanning microscopy techniques revealed undescribed features related to the digestive system, the presence of papillae-like lateral lappets, and terminal lobes covered with backwardly directed spines. Orientocreadium batrachoides revealed a pharynx that is four lobed anteriorly. Both the large (28S) and small (18S) subunits of the ribosomal genome, analysed through Bayesian inference and maximum likelihood, were used to genetically characterise these species. Phylogenies indicate that G. pedatum does not fit well into any known family within the Plagiorchioidea, as currently indicated in various systematic structures based on morphology. However, G. pedatum was closely related to Haematoloechidae according to analyses of 18S and 28S rDNA. Based on 28S rDNA, O. batrachoides formed a well-supported clade with Orientocreadium pseudobagri within the family Orientocreadiidae. In turn, Orientocreadiidae is closely related to Leptophallidae. The current study provides essential information that could be helpful to assign the family for Glossidium in future studies. Characterisation of life-cycle stages may be necessary to fully elucidate the systematic position of G. pedatum.

ACS Style

José Chissiua Dumbo; Quinton Marco Dos Santos; Annemariè Avenant-Oldewage. Morphological and molecular characterization of Glossidium pedatum Looss, 1899 and Orientocreadium batrachoides Tubangui, 1931 from sharptooth catfish, Clarias gariepinus (Burchell, 1822). African Zoology 2019, 54, 43 -61.

AMA Style

José Chissiua Dumbo, Quinton Marco Dos Santos, Annemariè Avenant-Oldewage. Morphological and molecular characterization of Glossidium pedatum Looss, 1899 and Orientocreadium batrachoides Tubangui, 1931 from sharptooth catfish, Clarias gariepinus (Burchell, 1822). African Zoology. 2019; 54 (1):43-61.

Chicago/Turabian Style

José Chissiua Dumbo; Quinton Marco Dos Santos; Annemariè Avenant-Oldewage. 2019. "Morphological and molecular characterization of Glossidium pedatum Looss, 1899 and Orientocreadium batrachoides Tubangui, 1931 from sharptooth catfish, Clarias gariepinus (Burchell, 1822)." African Zoology 54, no. 1: 43-61.

Article
Published: 22 March 2019 in Systematic Parasitology
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A new species of Masenia Chatterji, 1933 is described based on material from the intestine of Clarias gariepinus (Burchell) in the Incomati River, Mozambique. The combination of morphological characteristics and analysis of 18S and 28S rDNA sequences delineated the specimens found in the present study as a distinct species. The new form is distinguished from other Masenia spp. in having a large reniform seminal receptacle, a cirrus-sac ending anterior to the ventral sucker, intestinal caeca extending into the hindbody to the level of the posterior testis, and the vitelline fields extending anteriorly to the ventral sucker and posteriorly to the middle of the ovary. Notably, the new form is the only record of African species having a sac-shaped excretory vesicle. Analysis of 28S rDNA sequence data supported its placement in the Cephalogonimidae Looss, 1899. 18S analyses also supported its placement in this family but showed it was not closely related to Masenia bangweulensis (Beverley-Burton, 1962), the sole other African species for which genetic data is currently accessible. The total pairwise differences for 18S and 28S sequences showed the new form differing from other cephalogonimids. Thus, both morphological and genetic characteristics indicate that the present form represents a distinct species, here described as Masenia nkomatiensis n. sp. An updated key to African Masenia spp., now five, is provided.

ACS Style

José Chissiua Dumbo; Quinton Marco Dos Santos; Annemariè Avenant-Oldewage. Masenia nkomatiensis n. sp. (Digenea: Cephalogonimidae) from Clarias gariepinus (Burchell) (Clariidae) in Incomati Basin, Mozambique. Systematic Parasitology 2019, 96, 311 -326.

AMA Style

José Chissiua Dumbo, Quinton Marco Dos Santos, Annemariè Avenant-Oldewage. Masenia nkomatiensis n. sp. (Digenea: Cephalogonimidae) from Clarias gariepinus (Burchell) (Clariidae) in Incomati Basin, Mozambique. Systematic Parasitology. 2019; 96 (3):311-326.

Chicago/Turabian Style

José Chissiua Dumbo; Quinton Marco Dos Santos; Annemariè Avenant-Oldewage. 2019. "Masenia nkomatiensis n. sp. (Digenea: Cephalogonimidae) from Clarias gariepinus (Burchell) (Clariidae) in Incomati Basin, Mozambique." Systematic Parasitology 96, no. 3: 311-326.

Comparative study
Published: 25 February 2019 in PLOS ONE
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Diplozoidae infects the gills of cyprinid fishes in Africa, Europe, and Asia. Traditionally the hardened internal structures, crucial for identification of diplozoid species, are studied using light microscopy. Recently, the sclerotised haptoral structures of an African diplozoid, Paradiplozoon vaalense, were successfully isolated and visualised using scanning electron microscopy (SEM). In this paper, the haptoral sclerites of three diplozoid species are compared using SEM for the first time. Paradiplozoon ichthyoxanthon and Paradiplozoon vaalense occur on Labeobarbus and Labeo species, respectively, in the Vaal River system, South Africa, while Diplozoon paradoxum is widely-distributed in Europe and Asia, infecting several host species. Diplozoon paradoxum is a well-studied species, as well as being the type species of the family and ideal for inclusion in an exploratory study for comparative purposes. SEM study of D. paradoxum and P. ichthyoxanthon provided valuable information regarding surface morphology of the attachment structures hitherto not observed. Elaborate morphometric study of the haptoral hooks were incorporated, adding 12 point-to-point measurements to current morphometric characteristics. The results were analysed statistically, and significant differences support absolute separation (100.00%) of the three species following discriminant analysis. These point-to-point measurements could also be used for light microscopical study in the future and aid species delimitation within the Diplozoidae.

ACS Style

Quinton Marco Dos Santos; Ewa Dzika; Annemariè Avenant-Oldewage. Using scanning electron microscopy (SEM) to study morphology and morphometry of the isolated haptoral sclerites of three distinct diplozoid species. PLOS ONE 2019, 14, e0211794 .

AMA Style

Quinton Marco Dos Santos, Ewa Dzika, Annemariè Avenant-Oldewage. Using scanning electron microscopy (SEM) to study morphology and morphometry of the isolated haptoral sclerites of three distinct diplozoid species. PLOS ONE. 2019; 14 (2):e0211794.

Chicago/Turabian Style

Quinton Marco Dos Santos; Ewa Dzika; Annemariè Avenant-Oldewage. 2019. "Using scanning electron microscopy (SEM) to study morphology and morphometry of the isolated haptoral sclerites of three distinct diplozoid species." PLOS ONE 14, no. 2: e0211794.

Journal article
Published: 30 January 2019 in Onderstepoort Journal of Veterinary Research
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Lake Kariba is a tropical lake with slight variations in seasonal temperature. Temperature is an important physical variable in the biology of both fish and their parasites. Currently, there is no information on the seasonal occurrence of fish parasites in Lake Kariba. The objective of this study was to investigate the seasonal occurrence of metazoan parasites in Hydrocynus vittatus in Lake Kariba, Zimbabwe. Twenty fish specimens were collected by seine netting per season between October 2014 and July 2015 in the Sanyati Basin, Lake Kariba, and examined for metazoan parasites. Mean water temperatures ranged from 24.1 °C to 31.2 °C with slight variations between the seasons. Metazoan parasites consisting of Monogenea (Annulotrema pikei, Annulotrema pseudonili, Annulotrema bracteatum), Nematoda (Contracaecum larvae), Copepoda (Lamproglena hemprichii), Cestoda (larval cestodes, Ichthybothrium sp.) and Pentastomida (pentastomid larvae) were recorded. Larval cestodes were recorded in autumn and spring, while pentastome larvae were recorded in summer and spring. The Ichthybothrium sp. was recorded once in winter. Annulotrema pikei and A. pseudonili were observed on the gills and A. bracteatum on both the gills and the skin. Contracaecum larvae, L. hemprichii and A. bracteatum (from the skin) were recorded in all the seasons, with slight variations in prevalence, mean abundance and mean intensity. However, these variations were not statistically significant (analysis of variance or ANOVA, p > 0.05). The slight variations in occurrence of the parasites were probably because of the thermal stability of the lake where variation in temperature was small between seasons. Both A. bracteatum and Contracaecum larvae were aggregated on the fish host, whereas L. hemprichii exhibited a random distribution. Parasite diversity was at its highest during winter.

ACS Style

Nyasha Mabika; Maxwell Barson; Cobus Van Dyk; Annemariè Avenant-Oldewage. Seasonal occurrence of metazoan parasites in Tigerfish, Hydrocynus vittatus Castelnau, 1861 (Characiformes: Alestidae) from Sanyati Basin, Lake Kariba, Zimbabwe. Onderstepoort Journal of Veterinary Research 2019, 86, e1 -e6.

AMA Style

Nyasha Mabika, Maxwell Barson, Cobus Van Dyk, Annemariè Avenant-Oldewage. Seasonal occurrence of metazoan parasites in Tigerfish, Hydrocynus vittatus Castelnau, 1861 (Characiformes: Alestidae) from Sanyati Basin, Lake Kariba, Zimbabwe. Onderstepoort Journal of Veterinary Research. 2019; 86 (1):e1-e6.

Chicago/Turabian Style

Nyasha Mabika; Maxwell Barson; Cobus Van Dyk; Annemariè Avenant-Oldewage. 2019. "Seasonal occurrence of metazoan parasites in Tigerfish, Hydrocynus vittatus Castelnau, 1861 (Characiformes: Alestidae) from Sanyati Basin, Lake Kariba, Zimbabwe." Onderstepoort Journal of Veterinary Research 86, no. 1: e1-e6.

Journal article
Published: 29 December 2018 in Science of The Total Environment
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The levels of Cr, Cu, Zn, Se, Ag, Cd, Hg, and Pb were determined in muscle and liver samples from 30 specimens of fish belonging to the species Labeobarbus aeneus, Labeobarbus kimberleyensis, and Labeo umbratus from the Vaal Dam. Health risks for human fish consumers were estimated using the target hazard quotient (THQ), the Se:Hg-ratio, and Se health benefit value (Se HBV). This is the first comprehensive report on Hg levels in fish from this lake. Mean concentrations ranging from 0.247–0.481 mg/kg dw in muscle and from 0.170–0.363 mg/kg dw in liver clearly show a contamination with this element. Although levels in muscle did not exceed maximum allowances for human consumption, a calculated THQ of 0.12 and 0.14 for the two Labeobarbus species, respectively, showed a potential risk due to additive effects. All Se:Hg-ratios as well as Se HBVs clearly suggested positive effects for fish consumers. Levels of Cu were remarkably high in the liver of L. umbratus, calling for further investigation on this species. Cadmium levels were above the maximum allowances for fish consumption in the liver of all three species (means between 0.190 and 0.460 mg/kg dw), but below the LOD in all muscle and intestine samples. This is also the first report of Ag in fish from South Africa. Levels were below the LOD in muscle, but well detectable in liver; they varied significantly between the two Labeobarbus species (0.054 ± 0.030 and 0.037 ± 0.016 mg/kg dw) compared to L. umbratus (1.92 ± 0.83 mg/kg dw) and showed a positive correlation with Cu levels (63.7 ± 17.0; 70.3 ± 9.0 and 1300 ± 823 mg/kg dw), possibly due to similar chemical affinities to metallothioneins. The detected Ag levels can serve as a basis to monitor the development of this new pollutant in aquatic environments in South Africa and worldwide.

ACS Style

Christof Plessl; Beric Gilbert; Martin F. Sigmund; Sarah Theiner; Annemarie Avenant-Oldewage; Bernhard Keppler; Franz Jirsa. Mercury, silver, selenium and other trace elements in three cyprinid fish species from the Vaal Dam, South Africa, including implications for fish consumers. Science of The Total Environment 2018, 659, 1158 -1167.

AMA Style

Christof Plessl, Beric Gilbert, Martin F. Sigmund, Sarah Theiner, Annemarie Avenant-Oldewage, Bernhard Keppler, Franz Jirsa. Mercury, silver, selenium and other trace elements in three cyprinid fish species from the Vaal Dam, South Africa, including implications for fish consumers. Science of The Total Environment. 2018; 659 ():1158-1167.

Chicago/Turabian Style

Christof Plessl; Beric Gilbert; Martin F. Sigmund; Sarah Theiner; Annemarie Avenant-Oldewage; Bernhard Keppler; Franz Jirsa. 2018. "Mercury, silver, selenium and other trace elements in three cyprinid fish species from the Vaal Dam, South Africa, including implications for fish consumers." Science of The Total Environment 659, no. : 1158-1167.

Research article
Published: 13 June 2018 in PLOS ONE
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Parasites of fishes have been shown to be effective bioindicators of the aquatic environment. Few investigations have been conducted on ectoparasite models and therefore little is known about the fate of trace elements and metals which they accumulate. In this study trace element sequestration was observed in the carapace of the fish louse, Argulus japonicus and found to relate to the sex of the parasite, as well as, the degree of sclerotization of the carapace. Adults of A. japonicus were collected from cyprinid hosts in the Vaal Dam, South Africa. Parasites were removed and flash frozen in liquid nitrogen before being sectioned with a cryomicrotome. Sections and whole mounts of parasites were prepared and treated with Phen–Green TM FL cell–permeant diacetate. Cryosections were assessed for trace elements and metals using a scanning electron microscope equipped with energy dispersive spectroscopy. Results indicated that in both male and female parasites, trace elements become bound to the carapace and produce more intense fluorescence than in soft tissues. Sexual dimorphic differences were further observed between male and female parasites. The intensity of the fluorescence signals was greater in the carapace of male parasites than in females, particularly when comparing the carapace of the ventral side of the thorax. In females, an amorphous layer of material surrounding the eggs was observed and produced an intense fluorescent signal. Levels of trace elements and metals detected were not significantly different between male and female parasites. Results observed serve as a demonstration for the first time of trace element sequestration in a freshwater crustacean parasite and possible mechanisms employed to reduce body burdens of trace elements and metals.

ACS Style

Beric Gilbert; Annemarie Avenant-Oldewage. Trace element biomineralisation in the carapace in male and female Argulus japonicus. PLOS ONE 2018, 13, e0197804 .

AMA Style

Beric Gilbert, Annemarie Avenant-Oldewage. Trace element biomineralisation in the carapace in male and female Argulus japonicus. PLOS ONE. 2018; 13 (6):e0197804.

Chicago/Turabian Style

Beric Gilbert; Annemarie Avenant-Oldewage. 2018. "Trace element biomineralisation in the carapace in male and female Argulus japonicus." PLOS ONE 13, no. 6: e0197804.