Academic literature on the topic 'Fish Parasitology'

I was delighted to be able to join with so many friends and colleagues, in writing this short paper to mark the retirement of Donald Lee. There are many outstanding milestones in Donald's career. However, I thought that I could perhaps draw special attention to his long and distinguished association with the British Society for Parasitology (BSP), and the journal, Parasitology. He was President of the BSP between 1978 and 1980 and, in recognition of his service to the Society and contributions to the discipline of parasitology, was elected an Honorary Member in 1980. Donald has also had a long association with Parasitology, as a member of the Editorial Board and as a frequent contributor. His first paper in the journal was published in 1958; it described the occurrence of Syngamus sp. in a fieldfare (Turdus pilaris) that had been accidentally killed. At the time of writing, his most recent publication, but I suspect not his last, was a biochemical study on proteins produced by Nippostrongylus brasiliensis, Nematodims battus and Ascaridia galli (Foster & Lee, 1996). Of course, Donald has published in many other journals and authored several books. However, if one considers only those papers published in Parasitology, they provide a record of intellectual vigour and curiosity that has remained undiminished throughout his career.

Abstract The investigation of fish parasites in Bosnia and Herzegovina in recent years became significant, and therefore new records of parasitic trematodes and their hosts are important for better understanding of fish parasitology and pathology. In this study 41 parasitic specimens were collected and the basic taxonomical characters were measured (body length and width, diameter of oral and ventral sucker, length and width of pharynx, ovary length and width, testes length and width and eggs length and width). After the sampling of the parasites, they were collected and conserved in 70% ethanol. After that procedure the aforementioned characters were measured using Digimizer Image Analyzer Version 4.1. After all measurements, the trematode parasite Azygia robusta was confirmed for the first time on brown trout Salmo trutta. This first record was found in the Vrbas River near Banja Luka, Bosnia and Herzegovina (Sava River Basin). Former records of this parasite in Europe were observed on other salmonid fish species, as huchen Hucho hucho. This new record should be very important part of data of fish parasitology in Bosnia and Herzegovina.

The objective of this study was to identify parasites that infect mackerel fish (Euthynnus affinis) at fish auction in Lhoknga, Aceh Besar. Fifteen mackerel fish collected from fish auction in Lhoknga were examined at Parasitology Laboratory, Faculty of Veterinary Medicine Syiah Kuala University Banda Aceh to observe the presence of ectoparasites and endoparasites. The ectoparasite examination was conducted by observation of the external body part and then examined under microscope, while endoparasite examination conducted by observation of inner surface of digestive tract. The data showed that two types parasites infested the mackerel fish at fish auction in Lhoknga were Anisakis simplex and Neobenedia melleni. A total of 87% mackerel fish was infested with A. simplex and 7% was infested with N. melleni.

Virulence (parasite- induced host fitness reduction) is thought to correlate positively with pathogen reproduction rates, but its relationship with pathogen transmission is likely to be determined by a trade- off between the costs and benefits of harming hosts. This project aims to investigate factors which affect host-parasite interactions and particularly those which may play a role in virulence evolution. In doing so, it describes experiments carried out using a monogenean ectoparasitic flatworm (Gyrodactylus arcuatus) and its three-spined stickleback (Gasterosteus aculeatus) host. Populations of this fish species experience a range of both environmental and ecological conditions. Such environmental heterogeneity has been found to drive changes in fish phenotypic traits such as morphology, behaviour, life history and physiology which may consequently affect parasite fitness. I demonstrate that under these conditions, parasite strains from different host populations evolve variation in virulence levels. I also reveal that coevolution in this host parasite system is likely to lead to local adaptation of G. arcuatus at the host population level. I show that competition between parasite species sharing a single host leads to increased parasite reproduction rates, but it shortens the infection time which may be due to earlier stimulation of host immune responses. I show that virulence is neither influenced by the population density, immunity (epidermal mucus), social behaviour of fish hosts nor the natural parasite life expectancy. Lastly, I find that virulence in this system is negatively influenced by the density of stickleback predators and positively associated with loch water pH. Taken together, these results suggest that in this host parasite system, both ecological and environmental factors which drive phenotypic changes in fish hosts may evolutionarily feedback to affect parasite virulence.

Mesopelagic (open ocean, 200-1000 m depth) fishes are important consumers of zooplankton and are prey of oceanic predators. Some mesopelagic fishes (e.g., myctophids and stomiids) undertake a diel vertical migration where they ascend to the near-surface waters during the night to feed and descend into the depths during the day to avoid predators. Other mesopelagic fishes (e.g., Sternoptyx spp.) do not vertically migrate and remain at deep depths throughout the day. While in the epipelagic zone (surface – 200 m depth), vertically migrating fishes become prey to upper-trophic level predators, such as: tunas and billfishes. Benthic fishes (e.g., macrourids) often vertically migrate as well, ascending into the pelagic zone to feed on pelagic organisms. Fishes of different depths and vertical migration habits likely have a different ecological role in food webs. The relationship between parasites and gut contents provides insights into ecological processes occurring within assemblages, as prey items are often vectors for parasites. This study examined the differences between the prey items present in the gastrointestinal cavity and parasites of 26 mesopelagic fish species in the Gulf of Mexico. Results showed that based on the proportionally dominant prey items per species, six different feeding guilds existed within this assemblage, five based on planktivory: copepodivores, predators of copepods and other zooplankton, predators of copepods and euphausiids, gelatinivores, generalists, crustacean decapodivores, and upper-trophic level predators. Larger fishes preyed on larger prey items and harbored more parasites. Sigmops elongatus exhibited an ontogenetic diet shift at 75 mm standard length, progressing from eating primarily copepods at small sizes to eating primarily euphausiids at large sizes. Compared to similar studies, this study revealed a higher parasitic infestation by trematodes, an endoparasite (parasite within the host) class often restricted to nearshore hosts, in Gulf of Mexico fishes. Helicometrina nimia, the dominant parasite of the gempylid Nealotus tripes, has not previously been recorded in hosts below 200 m depth, suggesting a foodweb pathway that transitions from nearshore to offshore. These data can be used to develop and refine models aimed at understanding ecosystem structure and connectivity.

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This research aimed to study the taxonomy of dactylogyrids species associated with three host species: Pimelodus maculatus Lacep?de, 1803, Pimelodus heraldoi Azpelicueta, 2001 and Iheringichthys labrosus (L?tken, 1874) from Cachoeira de Emas, Mogi Gua?u River, Pirassununga, S?o Paulo, Brazil. The fishes were collected using nets and cast nets in the Cachoeira de Emas and transported to the laboratory of do Centro Nacional de Pesquisa da Conserva??o de Peixes Continentais, Instituto Chico Mendes para Conserva??o da Biodiversidade CEPTA/ICMBio, where they were examined. The parasites were fixed in 4% formalin and processed for identification in the Laboratory of Fish Parasitology of UFRRJ. Fourteen new locality records were included, 12 of them are new hosts records. Among these, five new species were proposed. Ameloblastella sp. n 1 collected from P. maculatus differs from its congeners by having a MCO (Male copulatory organ) with 2 rings, ventral and dorsal anchors with curved shaft and curved point toward to the base and a vagina with a ligule-like structure at the vestibule roof and a duct that leads into the distal portion of the vaginal vestibule. Ameloblastella sp. n. 2 is distinguished from the other species of the genus by a MCO with 2 rings, accessory piece distally divided into two subunits, and anchors with long points surpassing the tip of the superficial root. Seven Demidospermus species were recorded and commented based mainly on morphological and morphometric variations. Pavanelliella sp. n. 1, collected from nasal cavities of P. maculatus differs from its congeners by having a MCO with 2?4 rings and anteriorly directed vagina containing five irregular rings around the vestibule. Pavanelliella sp. n. 2 collected from P. heraldoi, was distinguished from all its congeners by having a robust MCO with 2-3 rings, an accessory piece with an irregular distal portion resembling flames, vaginal canal sinuous with 2-3 loops and vaginal vestibule not differentiated. Pavanelliella sp. n. 3 collected from P. heraldoi is separated from the other species of the genus by having a MCO with 4 rings (2 anterior and 2 posterior to accessory piece), accessory piece with bifurcated distal end, with one end hook-like, vaginal canal with 3 loops and vaginal vestibule not differentiated. Pavanelliella sp. n. 1 showed the highest values of prevalence, mean intensity and mean abundance infestation. Besides the three new Pavanelliella species proposed, some details about the morphology of P. pavanellii were added. Additionally a proposal to amend the diagnosis of the genus Demidospermus and a key to diagnosis of the Dactylogyrinea genera whose haptor presents no bar and no anchors and for Pavanelliella species are included herein.
Visando contribuir para o conhecimento da biodiversidade da regi?o Neotropical, a presente pesquisa teve como objetivos realizar o estudo taxon?mico das esp?cies de dactylogyr?deos associadas a tr?s esp?cies de hospedeiros: Pimelodus maculatus Lacep?de, 1803, Pimelodus heraldoi Azpelicueta, 2001 e Iheringichthys labrosus (L?tken, 1874) de Cachoeira de Emas, rio Mogi Gua?u, Pirassununga, S?o Paulo. Os peixes foram coletados utilizando redes e tarrafas na localidade de cachoeira de Emas e tranportados at? o laborat?rio do Centro Nacional de Pesquisa da Conserva??o de Peixes Continentais, Instituto Chico Mendes para Conserva??o da Biodiversidade CEPTA/ICMBio, onde foram examinados. Os parasitos coletados foram fixados em formol a 4% e processados para identifica??o no laborat?rio de Parasitologia de Peixes da UFRRJ. Cinco esp?cies foram propostas como novas e quatorze novos registros de localidade foram apresentados, dos quais 12 representam novos registros para hospedeiros. Ameloblastella paranaensis, encontrada nas br?nquias das tr?s esp?cies de hospedeiros examinadas, ? registrada e comentada em detalhes. Ameloblastella sp. n. 1 coletada em P. maculatus difere de seus cong?neres por apresentar um OCM (?rg?o copulat?rio masculino) com 2 an?is, ?ncoras ventral e dorsal com l?mina curva e ponta recurvada no sentido da base e uma vagina com uma estrutura epivestibular em forma de l?gula e um ducto que desemboca na por??o distal do vest?bulo vaginal. Ameloblastella sp. n. 2 coletada em P. heraldoi se distingue das demais esp?cies do g?nero por apresentar um OCM com 2 an?is, pe?a acess?ria distalmente dividida em duas subunidades, e ?ncoras com pontas longas ultrapassando a extremidade da raiz superficial. Sete esp?cies de Demidospermus foram registradas e comentadas em detalhes. Pavanelliella sp. n. 1, coletada das cavidades nasais de P. maculatus se diferencia de seus cong?neres por possuir um OCM com 2?4 an?is e a vagina anteriormente direcionada contendo aproximadamente cinco an?is irregulares ao redor do vest?bulo vaginal. Pavanelliella sp. n. 2 coletada em P. heraldoi, se distingui de todos seus cong?neres por apresentar um OCM robusto com 2?3 an?is, uma pe?a acess?ria de extremidade distal irregular em forma de flamas, um canal vaginal sinuoso com 2?3 voltas na por??o distal e vest?bulo vaginal n?o diferenciado. Pavanelliella sp. n. 3 coletada em P. heraldoi se diferencia das demais esp?cies do g?nero por ter um OCM com 4 an?is (2 anteriores e 2 posteriores a pe?a acess?ria), uma pe?a acess?ria com uma extremidade distal bifurcada com uma das pontas em forma de gancho, canal vaginal sinuoso com 3 voltas na sua por??o distal e vest?bulo vaginal n?o diferenciado. Pavanelliella sp. n. 1 foi a que apresentou os maiores valores de preval?ncia, intensidade m?dia e abund?ncia m?dia de infesta??o. Al?m das tr?s novas esp?cies de Pavanelliella propostas, alguns caracteres morfol?gicos s?o adicionados a P. pavanellii. Adicionalmente apresenta-se uma proposta de emenda da diagnose do g?nero Demidospermus e uma chave para diagn?stico dos g?neros de Dactylogyrinea cujo haptor n?o apresenta barras e nem ?ncoras e para as esp?cies de Pavanelliella. O presente estudo revela a riqueza parasit?ria para uma localidade na qual nada se sabia a respeito desses dactylogyr?deos.

Le foisonnement filamenteux est un problème récurant dans de nombreuses stations d'épuration à boues activées. L'objectif de ces travaux est d'améliorer la compréhension des mécanismes physiologiques et moléculaires impliqués dans la filamentation des microorganismes, afin de pouvoir orienter de futures stratégies de lutte contre le phénomène de bulking. Sphaerotilus natans, qui peut croître réversiblement sous forme monocellulaire ou filamenteuse, a été utilisée comme bactérie modèle pour cette étude. Différents types de cultures, ainsi que des suivis par cytométrie en flux et marquage au cFDA/SE, ont montré que les diverses souches de S. natans adoptent des morphologies différentes et que les filaments croissent par divisions cellulaires successives et non par un chaînage des bactéries. Une analyse par RT-QPCR a mis en évidence que l'expression du gène sthA augmente fortement après induction de la filamentation et reste ensuite à un niveau élevé. Une comparaison de l'expression protéique des formes monocellulaire et filamenteuse, par LC-MS-MS, a permis d'identifier des protéines impliquées dans la filamentation, et notamment dans la synthèse de la gaine. La concentration intracellulaire en ARNr, mesurée par RT-QPCR, varie durant la croissance de S. natans et d'autres microorganismes, entraînant une diminution importante de l'intensité du marquage FISH, mesurée par cytométrie en flux. L'utilisation de la technique FISH pour quantifier des microorganismes est donc remise en question, d'autant plus dans des matrices aussi complexes que les boues activées. Ces observations mettent également en doute l'hypothèse, émise en utilisant ce mode de quantification, d'une déstructuration des filaments consécutive à un retour à des conditions de culture plus favorables.

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Between December 2004 to November 2005, were collected 50 specimens of Geophagus brasiliensis (Quoy e Gaimard, 1824) and 35 specimens of Astronotus ocellatus (Cope, 1872) from the River Guandu, near to the Station of Treatment of water (ETA) (22?48'32"S, 43?37'35"W), State of Rio de Janeiro, for the study of their communities of metazoan parasites. In G. brasiliensis, nine species of metazoan parasites were collected: 3 digeneans, 1 nematode, 2 hirudineans, 2 acantocephalans and 1 gloquidian. Most of parasite specimens collected were digeneans (95.9 %), being Posthodiplostomum macrocotyle Dubois, 1937 (metacercariae) founded in the eyes the more prevalent species (88.0%) and with highest mean intensity value (12.4), followed for the metacercariae of Austrodiplostomum compactum (Lutz, 1928) (metacercariae) and the hirudinean of family Glossiphoniidae showed prevalence of 14.0% and 10.0% respectively. In A. ocellatus, six species of metazoan parasites were collected: 1 monogenean, 1 nematode, 1 hirudinean, 1 acantocephalan, 1 crustacean, and 1 gloquidian. Most of parasite specimens collected were monogenetic (91.9 %), being Gussevia sp. founded in the gills the more prevalent species (71.4%) and with highest mean intensity value (17.6), followed for the acanthochepalan Polymorphus sp. showed prevalence of 17.1%. The parasite species of G. brasiliensis and A. ocellatus showed the typical aggregated pattern of distribution.
Entre os meses de dezembro de 2004 ? novembro de 2005 foram coletados 50 esp?cimes de Geophagus brasiliensis (Quoy e Gaimard, 1824) e 35 esp?cimes de Astronotus ocellatus (Cope, 1872) provenientes do Rio Guandu, pr?ximo ? barragem da Esta??o de tratamento de ?gua (ETA) (22?48 32 S, 43?37 35 O), Estado do Rio de Janeiro, para o estudo de suas comunidades de metazo?rios parasitos. Em G. brasiliensis foram encontradas nove esp?cies de metazo?rios parasitos: 3 digen?ticos, 1 nemat?ide, 2 hirud?neos, 2 acantoc?falos e 1 larva gloqu?dia. A maioria dos esp?cimes de parasitos coletados foram digen?ticos (95,9%), sendo Posthodiplostomum macrocotyle Dubois, 1937 (metacerc?ria) a esp?cie mais prevalente (88,0%) e com a maior intensidade m?dia (12,4) sendo a maioria dos esp?cimes encontrados parasitando os olhos, seguido pelo digen?tico Austrodiplostomum compactum (Lutz, 1928) (metacerc?ria) e pelo hirud?neo da fam?lia Glossiphoniidae, que apresentaram preval?ncias de 14,0% e 10,0% respectivamente. Em A. ocellatus foram encontradas seis esp?cies de metazo?rios parasitos: 1 monogen?tico, 1 nemat?ide, 1 hirud?neo, 1 acantoc?falo, 1 crust?ceo e 1 larva gloqu?dia. A maioria dos esp?cimes de parasitos coletados foram monogen?ticos (91.9%), sendo Gussevia sp. a esp?cie mais prevalente (71,4%) e com a maior intensidade m?dia (17,6) sendo todos os esp?cimes encontrados parasitando as br?nquias, seguido pelo acantoc?falo Polymorphus sp. que apresentou uma preval?ncia de 17,1%. Os parasitos encontrados em G. brasiliensis e A. ocellatus apresentaram o t?pico padr?o de distribui??o agregado.

Les genres Anisakis, Pseudoterranova, Hysterothylacium et Contracaecum, membres de la famille des Anisakidae, sont des nématodes dont les larves sont présentes chez de nombreuses espèces de poissons et céphalopodes. Ces larves peuvent induire des pathologies digestives et/ou allergiques chez l’Homme. En France, la consommation des produits de la pêche, surtout crus ou peu cuits est en augmentation. Ce travail de thèse s’intègre dans le programme ANR Fish-Parasites, financé par l’ANR (ANR-10-ALIA-004). Il a pour but d’évaluer les risques liés à la consommation des produits de la pêche et pour objectif principal d’étudier la répartition des Anisakidae dans les produits de la pêche. _x000D_Le plan d’échantillonnage a été établi suite à une analyse de type risk-ranking utilisant les données de consommation, l’origine géographique, des données de prévalence déjà existantes sur les Anisakidae. Au total, 1768 poissons appartenant à 18 espèces ont été collectés. L’ensemble des organes a été disséqué pour isoler les parasites. Ceux-ci ont été identifiés selon 2 méthodes : i) analyse individuelle par séquençage Sanger pour les organes ayant moins de 11 nématodes ii) analyse en pool par séquençage à haut débit (HTS) pour le reste. Le développement de plusieurs outils (création d’une base de séquences de référence, conception des amorces, mise au point de la préparation de matrice de séquençage et développement d’un pipeline d’analyse automatisé) a été nécessaire pour la mise en place de la méthode HTS. A partir des résultats obtenus, une acquisition et une structuration des données de prévalence des parasites potentiellement pathogènes pour l’Homme et présents dans les produits de la pêche couramment consommés a pu être réalisée.Sur 1 768 poissons échantillonnés, deux espèces n’étaient pas du tout parasitées : plies (Pleuronectes platessa) et saumon Atlantique (Salmo salar) d’élevage. 43,30 % des poissons n’étaient pas infectés par des Anisakidae. Sur la totalité des poissons, 28,62 % étaient infectés au niveau des viscères ; 22,96% dans les viscères et les filets et 5,49 % n’étaient infectés par des Anisakidae que dans les filets.Les cinq espèces de poisson dont la prévalence dans les filets était la plus élevée étaient : la lingue bleue (100 %), la cardine franche (70 %), le lieu noir (63 %), la baudroie (61 %) et le merlu (60 %).Les Anisakidae les plus identifiés étaient : Anisakis simplex, Anisakis pegreffii, Hysterothylacium aduncum, Pseudoterranova krabbeii.Anisakis a été retrouvé dans toutes les localisations et généralement de façon plus importante, Contracaecum a été retrouvé principalement dans le foie, Hysterothylacium dans la cavité corporelle et Pseudoterranova dans les filets et la cavité corporelle.Anisakis simplex était présent dans toutes les zones de pêches sauf dans le golfe du Lion. La zone des eaux féringiennes était la zone dans laquelle la diversité des Anisakidae était la plus importante sur une seule espèce de poisson échantillonnée (lingue bleue).L’étude statistique logistique multivariée a montré que la variable espèce et la variable taille du poisson influencent la prévalence d’Anisakis et Pseudoterranova dans les filets.Le HTS sur le PGM™ Ion Torrent s’est révélé être un outil puissant et innovant permettant l’analyse d’un grand nombre d‘échantillons d’Anisakidés à moindre coût, en peu de temps et avec un résultat équivalent à la méthode individuelle par séquençage Sanger
Anisakis, Pseudoterranova, Hysterothylacium and Contracaecum genera, members of the Anisakids family, are nematodes which larvae are recovered from numerous fish and cephalopods species. These larvae may induce digestive and/or allergic pathologies in human being. In France, the consumption of fishery products, mostly raw or undercooked is increasing. This PhD work is part of the research program Fish-Parasites funded by the ANR (ANR-10-ALIA-004). It aimed to assess risks related to fishery products consumption and its main goal was to study the distribution of Anisakids in fishery products.The sampling plan was based on a risk-ranking analysis using data on fishery products consumption, fishing areas and prevalence data from previous work on Anisakids. A total of 1 768 fish from 18 species were collected. All the organs were dissected for parasites isolation. Parasites were identified using two approaches : i) single analysis by Sanger sequencing for organs containing less than 11 nematodes ii) pooled analysis by high throughput sequencing (HTS) for the remaining. The development of numerous tools (database creation with reference sequences, primers design, set up of the sequencing template preparation and development of an automatic analytical pipeline) was necessary for the HTS method set up. From the sequencing results, acquisition and structuring of the prevalence data has been carried out on parasites potentially pathogenic for human being and recovered from commonly consumed fishery products.On 1 768 sampled fish, two species were not parasitized at all: plaice (Pleuronectes platessa) and aquacultured Atlantic salmon (Salmo salar). 43.30 % of the fish were not infected by Anisakids. Concerning infected fish, 28.62% were contaminated in the visceral organs; 22.96% in both visceral organs and fillets and, finally, 5.49% of the fish were infected by Anisakids only in fillets.The five fish species with an elevated prevalence in their fillets were by decreasing values: blue ling (100 %), megrim (70 %), saithe (63 %), monkfish (61 %) and hake (60 %). The most identified Anisakids were: Anisakis simplex, Anisakis pegreffii, Hysterothylacium aduncum, Pseudoterranova krabbeii.Anisakis has been recovered in all the localisations and generally in higher quantities, Contracaecum has mainly been recovered from the liver, Hysterothylacium from the corporal cavity and Pseudoterranova from both fillets and corporal cavity. Anisakis simplex was isolated from all the fishing areas except for the Lion Gulf and it was the genus with the most important number of individuals. The zone of Feroan waters was the region with the most important diversity of Anisakids into a single sampled fish species (blue ling).The multivariate logistic statistical study showed that the fish species and size affect the prevalence of Anisakis and Pseudoterranova in fish fillets.HTS with the PGM™ Ion Torrent proved to be a powerful and innovative tool for the analysis of large numbers of Anisakids samples with low cost, in a shorter time and with a result equivalent to the individual method of Sanger sequencing

The conservation of biodiversity and endemism in South Africa’s freshwater aquatic ecosystems is a high priority, particularly in the Cape Floristic Region. However, the perception that South Africa lacks suitable fish species for recreational angling, aquaculture and biological control, led to the widespread introduction and use of alien fish species. As a result, formal stocking programs have seen the introduction of five of the world’s top 100 invasive species into South Africa (Dudgeon et al. 2006). According to Dudgeon et al. (2006) freshwater ecosystems are the most endangered ecosystem in the world. The threats to freshwater biodiversity, according to Dudgeon et al. (2006), can be grouped into five categories that interact with one another: overexploitation, water pollution, flow modifications, destruction of habitat and invasion by exotic species. This PhD study took place in the Amatola region of the Eastern Cape Province, South Africa. The Amatola region is a rural area with no large-scale mining or industrial developments, only localised settlements. These developments are mainly situated around impoundments, because of the resources such as water and food that they provide. Thus the dams within the Amatola region should theoretically have no major industrial stressors on them. The three impoundments studied were Binfield Park, Sandile and Wriggleswade Dams. Binfield Park Dam is a 260ha impoundment. It impounds the Tyume River and is used by both subsistence anglers from the local communities and occasionally by recreational bass anglers. Sandile Dam is a 146ha impoundment and is the smallest of the three dams in this study. It impounds the Wolf and Keiskamma Rivers. Wriggleswade Dam is a 1000ha impoundment used extensively by recreational bass and carp anglers, and impounds the Kubusi River. There is a paucity of information regarding the health of the indigenous and alien fish species from the study region, as well as on the parasite diversity of these various fish species. In order to fill the gaps in the information the following hypothesis was proposed. That the necropsy based and histology based fish health assessment can be successfully implemented as tools to assess the effects of heavy metal pollution and alien fish parasites in freshwater fish from selected impoundments in the Amatola region, Eastern Cape Province, South Africa. In order to achieve this hypothesis the main aim of this study will be to use the necropsy- and histology- based fish health assessment to determine the health status of the fish species in these impoundments as well as to understand the potential threat of water pollution and fish parasites. Fish were sampled with the aid of gill nets, fyke nets and by angling from each of the three impoundments over three surveys in July 2011, and March and August 2012. Following capture fish were transported to a field laboratory in aerated containers. At the field laboratory the fish were examined and dissected using the methods recommended by Adams et al. (1993) for a necropsy-based fish health assessment. Gills, livers, kidneys and gonads samples were also collected for histological analysis. Macroscopic and histology-based fish health assessment index was used, as well the analysis of muscle tissue of Micropterus salmoides and surface water and sediment from Binfield Park, Sandile and Wriggleswade Dams. It was shown that, according to the macroscopic fish health assessment index, M. salmoides in Wriggleswade Dam had a higher FHAI score compared to those in Binfield Park and Sandile Dam, there were no significant differences between the FHAI scores. However, the cause of the higher FHAI in the Wriggleswade Dam was because of the external skin damage caused by the presence of the alien parasite Lernaea cyprinacea. The histology-based fish health assessment index, however, showed that M. salmoides from Binfield Park had significantly higher histology Fish Index (IFISH) scores compared to those in Sandile and Wriggleswade Dams. The main contributors to the high IFISH score of Binfield Park were the significantly high Liver Index (IL) and Kidney Index (IK). The increased severity of the alterations observed in the liver and kidney tissue of the Binfield Park M. salmoides samples may have been as a result of the high concentration of mercury found in the muscle tissue of M. salmoides. The water quality and metals detected in the water of Binfield Park, Sandile and Wriggleswade Dams were all below the target water quality guideline values, as well as below those of previous research into the nutrients and presence of metals in these impoundments. The sediment metal analysis showed that the levels of Co, Mn and Ni were above the target guideline levels for Binfield Park, Sandile and Wriggleswade Dams, Cu was above target guidelines levels for Sandile Dam, and uranium was above the target guideline concentrations for Wriggleswade Dam. Binfield Park Dam had significantly high levels of mercury in the muscle tissue of M. salmoides, while Sandile Dam had significantly high levels of zinc in the muscle tissue of M. salmoides. It was shown that M. salmoides from each of the three impoundments are in a healthy state according to the parameters assessed. However, the presence of heavy metals, particularly mercury, uranium and zinc, do indicate the presence of human activities. The indigenous parasites of Anguilla mossambica have been well documented including the gastrointestinal nematode Paraquimperia africana, and the stomach nematode Heliconema africanum. Indigenous parasites such as the swimbladder nematode Anguillicola papernai had no effect on the condition factor of infected and uninfected eels. However, the damage caused by the alien parasites were evident, including the first documented effects of the alien gill monogenean Pseudodactylogyrus anguillae on indigenous wild populations of the longin fin eel A. mossambica from the Eastern Cape, South Africa. Histological observations indicated that an alien gill monogenean caused hyperplasia, increase in mucous cells, rupture of pillar cells as well as telangiectasia. This alien parasite has invaded the Keiskamma and Kei River systems in the Eastern Cape, South Africa. According to the macroscopic fish health assessment index, A. mossambica from Binfield Park, Sandile and Wriggleswade Dams are in a healthy state. However, the histology-based health assessment highlighted that the effects on P. anguillae have a severe negative impact on the health of A. mossambica. Using the macroscopic and histology-based fish health assessment, a comprehensive investigation into the fish health status of Mugil cephalus and Myxus capensis from Binfield Park Dam revealed that human effects and parasites are not the only threats to freshwater fish. Nephrocalcinosis is a non-infectious kidney disease which is characterised by abnormal calcium deposition in the kidneys of humans and some fish species. According to the macroscopic and histology-based fish health assessment, the M. cephalus and M. capensis are not in a healthy condition. The macroscopic and histology-based fish assessment indices are not stressor-specific, and therefore the cause of the poor health state of these two fish species could not be determined. A possible suggestion for the poor health of these two species is the age of the species. Because the two mullet species were stocked into Binfield Park Dam, Ellender et al. (2012) could successfully age them accurately to ten years of age, which is the upper limit of the life span for these species. Macroscopic and histology-based fish heath assessments were conducted on Labeo umbratus from Sandile Dam in order to determine the health of this species. Macroscopic and histology-based fish health assessment indicated that its L. umbratus are in a healthy state. The March 2012 survey specimens had a significantly higher macroscopic FHAI score than those from the July 2011 survey. The increased FHAI score was because of parasite infections, as well as discoloured livers and increased total blood plasma protein levels, which are indicators of nutritional state. However, the presence of the anchor worm parasite Lernaea barnimiana in low numbers had no significant impact on the health of L. umbratus. The effect of the alien anchor worm parasite Lernaea cyprinacea was shown on the transloacted small mouth yellowfish Labeobarbus aeneus. It was also shown that L. aeneus are, according the macroscopic FHAI and the histology-based fish health assessment index, in a healthy state. However, the high scores observed in the macroscopic fish health assessment index were primarily as a result of the presence of the alien parasite L. cyprinacea and its associated affects on the fish host. Because of the significant impact of this alien parasite species on the translocated host species, it can be assumed that this alien parasite species will have a negative effect on the health of indigenous fish species in the Great Kei River. It is clear from the results presented in this study that the necropsy based and histology based fish health assessment can be successfully implemented as tools to assess the effects of heavy metal pollution and alien fish parasites in freshwater fish from selected impoundments in the Amatola region, Eastern Cape Province, South Africa, thus the original hypothesis of this thesis is accepted. Based on work done in this research the gaps in research have been identified. Due to the high levels of mercury indentified in the muscle tissue of M. salmoides from Binfield Park Dam. A human health assessment and edibility should be conducted in order to determine if the fish from Binfield Park Dam is safe for human consumption. In order to conserve South Africa’s Freshwater fish biodiversity, country wide surveys of indigenous fish species must be undertaken so that the health and the parasite diversity can be evaluated.
PhD (Zoology), North-West University, Potchefstroom Campus, 2015