Trichodinids (Ciliophora: Peritrichia) from a calanoid copepod and catfish from South Africa with notes on host specificity

A case study is presented in which a trichodinid infestation was found on Clarias gariepinus (Burchell, 1822) larvae in a hatchery. Upon examination of copepods in the water system, it was found that they too hosted this trichodinid species. After following the infestation for some time it was found that the trichodinids on the catfish disappeared, whilst the infestation on the calanoid copepods persisted. It was concluded that the trichodinid originated from the copepods and could not establish a viable infestation on the catfish larvae. Specimens of catfish fry from the same farm, however, hosted a different trichodinid which is described as a new species. After analysis of published information, it was concluded that the trichodinid from these calanoid copepods belongs to the same species as described by different authors from various localities from Eurasia. In order to provide a specific identification of this trichodinid, a literature review is presented. In a discussion of host specificity, it is concluded that the trichodinid involved is specific to planktonic copepods and cannot establish an infestation on fish.     

大亚湾养殖鱼类寄生车轮虫的种类组成与季节动态

2017年8月至2018年7月对大亚湾8种养殖鱼类的车轮虫感染情况进行了调查, 采用Lom倡导的“统一特定方法”及Van As & Basson提出的“齿体定位描述法”对采获的车轮虫标本进行了形态鉴定与描述。结果在卵形鲳鲹(Trachinotus ovatus)、星点笛鲷(Lutjanus stellatus)、鞍带石斑鱼(Epinephelus lanceolatus)、眼斑拟石首鱼(Sciaenops ocellatus)和虎龙杂交斑[E. fuscoguttatus (♀) × E. lanceolatus (♂)]等5种鱼上共检获5种车轮虫: 亚卓车轮虫(Trichodina jadranica)、莱普斯车轮虫(T. lepsii)、长须鳠车轮虫(T. guliae)、劳牧小车轮虫(Trichodinella lomi)和斜拟车轮虫(Paratrichodina oblique); 其中卵形鲳鲹5种虫均有寄生, 虎龙杂交斑感染了4种虫, 星点笛鲷、眼斑拟石首鱼和鞍带石斑鱼分别感染了3种、2种和1种虫。周年感染数据表明: 5种虫的感染率均以卵形鲳鲹最高, 眼斑拟石首鱼上2种虫的感染率最低; 莱普斯车轮虫平均感染强度最高的宿主是虎龙杂交斑, 其他4种虫的均是卵形鲳鲹。寄生车轮虫的季节动态表明: 冬季的感染率和平均感染强度较低; 不同虫种感染高峰出现的季节不一, 其中斜拟车轮虫的感染高峰出现在秋季, 其春夏秋季的平均感染强度均大于其他4种虫。研究填补了大亚湾海区鱼类寄生车轮虫研究的空缺, 为该海区车轮虫病的诊断与防控提供了参考。     

The salinity tolerance of trichodinids (Protozoa) parasitic on the Three-spined stickleback Gasterosteus aculeatus

Sticklebacks from a variety of habitats have been examined for trichodinids. Two species of trichodinid were found on fish at every site. They were identified as Trichodina domerguei subsp. domerguei and T. tenuidens , and these identifications are discussed in relation to previous observations by other workers. The tolerance to change in salinity has been examined for both species and the activity of the contractile vacuole of T. domerguei has been examined in detail.     

Differential diagnosis of the genera in the family Trichodinidae (Ciliophora: Peritrichida) with the description of a new genus ectoparasitic on freshwater fish from southern Africa

A trichodinid ectoparasite was collected from mormyrid fish in the Olifants River System, South Africa. A new genus, Hemitrichodina, is described to accomodate these trichodinid ciliophorans of which the blades are reduced and with an adoral spiral of more than 360°, but less than two full turns. A differential diagnosis of the genera within the family Trichodinidae is presented.     

Parasite fauna of seabass (Lates calcarifer) under mariculture conditions in Lampung Bay, Indonesia

Fish parasites have been repeatedly reported to be a major threat to the developing industry of finfish mariculture in Indonesia, due to severe parasite and disease outbreaks. The aim of this study was to identify the metazoan parasite fauna and trichodinid ciliates that infect Lates calcarifer in a representative mariculture farm in Indonesia. Examined were 105 L. calcarifer (seabass) for the metazoan parasite fauna and trichodinid ciliates. Thirty‐five specimens each from the net cages of the National Sea Farming Development Centre (Balai Budidaya Laut, BBL) in Lampung Bay, South Sumatra, Indonesia were investigated in three consecutive seasons (two dry and one rainy season from 2002 to 2003). Nineteen parasite species were identified; all fish specimens were infected with two to 10 parasite species, demonstrating a species‐rich parasite fauna. Protozoans (1 species), myxozoans (1), digeneans (3), monogeneans (5), cestodes (3), nematodes (5) and acanthocephalans (1) were found, including 11 new host records in cultured L. calcarifer from Indonesia. Larval and adult parasite stages were isolated, demonstrating that this fish species, although kept inside the net cages, still functions as an intermediate and final host for marine fish parasites. During all seasons, the six detected monoxenous (single host life cycle) parasite species showed a higher prevalence than the 13 heteroxenous (multiple hosts) species. Most abundant were the fish pathogenic monogeneans Pseudorhabdosynochus epinepheli, Pseudorhabdosynochus lantauensis, Benedenia epinepheli and Neobenedenia melleni with a high prevalence. Most heteroxenous parasites (Digenea, Cestoda, Nematoda and Acanthocephala) occurred with a low prevalence below 26%, caused by the specific culture conditions. Diversity of the heteroxenous parasites was higher in the dry seasons than in the rainy season. Though some seasonality could be observed for the fish pathogenic monogeneans, severe disease outbreaks of these ectoparasites cannot be excluded in either the dry or rainy season.     

Trichodinid ectoparasites (Ciliophora: Peritrichida) of some River Nile fish, Egypt

Four species of trichodinid ectoparasites (Ciliophora: Peritrichida) were collected from the gills of the following River Nile fish in Egypt: Hydrocynus forskalii, Mormyrus kannume, Schilbe mystus. These species are: Trichodina heterodentata Duncan, 1977, Trichodina fahaka sp. n., Trichodinella epizootica Raabe, 1950, Tripartiella dactylodentata sp. n. Photomicrographs and morphometric data are presented for each species.     

Occurrence of Trichodina heterodentata (Ciliophora: Trichodinidae) infesting tadpoles of Rhinella pombali (Anura: Bufonidae) in the Neotropical area

Data on trichodinid ciliophorans in Brazil are scarce and generally do not use the modern silver-impregnation technique, which is essential to the taxonomy of the group. The present study reports not only on the first occurrence of Trichodina heterodentata in Brazil but also on the first record of this trichodinid infesting tadpoles of the species Rhinella pombali. This study also constitutes a second report on T. heterodentata from tadpoles. In September 2007, tadpoles were collected from a stream in a small farm in the agricultural area of the city of Juiz de Fora, southeastern Brazil. The ciliophorans found on the tadpoles' bodies and tails were submitted to techniques such as silver impregnation and scanning electron microscopy. Our biometric data of T. heterodentata population infesting Rhinella pombali were compared to five other South-African populations of T. heterodentata infesting tadpoles of Xenopus laevis laevis. Results were discussed in terms of low host specificity as well as the wide geographical distribution of this trichodinid.     

矩形车轮虫的再描述

目的：我们对泸州市鲇类寄生车轮虫进行调查,对于已经发现,但由于原来的技术水限制需要重新描述的,或缺少资料的车轮虫,给予重新描述或补充新的资料。方法：用国际间统一的千银法染色以显示车轮虫的附着盘结构和口围绕度,用Lom（1958）倡导的”统一的特定方法”（Uniform specific characteristic system）进行测量,用Van＆Bassion（1989）提供的方法描述车轮虫的齿体。结果：对寄生在泸州地区养殖鱼类斑点叉尾鲴（Ietalums punetaus）的鳃上的车轮虫进行了描述,该车轮虫是矩形车轮虫（ Trichodina rectangli）。结论：矩形车轮虫是陈启鎏和谢杏人1964年在青鱼、草鱼等鱼身体上发现的,但是没有显微照片。国际上有许多它的同种异名的车轮虫的描述,这些文献也只有附着盘的显微照片。斑点叉尾鲡是矩形车轮虫的新寄主记录。本研究用国际统一的方法对矩形车轮虫进行描述,并绘出了矩形车轮虫的齿体定位图,提供了完整的统计数据,以及完整的显微照片,即附着盘、口围绕度和细胞核显微照片。     

Parasite fauna of bream Abramis brama and roach Rutilus rutilus from a man-made waterway and a freshwater habitat in northern Germany

Fifty specimens each of bream Abramis brama and roach Rutilus rutilus were examined for metazoan parasite fauna and trichodinid ciliates; 25 specimens of each species were collected from the Kiel Canal, a man-made waterway, and a nearby freshwater lake, the Dieksee. This is the first detailed parasitological examination of A. brama and R. rutilus at these locations: 30 parasite species were found, comprising 4 protozoans, 4 myxozoans, 5 digeneans, 3 monogeneans, 2 cestodes, 6 nematodes, 2 acanthocephalans, 3 crustaceans and 1 hirudinean. The crustacean Caligus lacustris occurred in both habitats while 2 other crustacean species, 2 acanthocephalans and 1 hirudinean were recorded exclusively for the lake habitat. Larval as well as adult stages of the different parasite species were found, indicating that both fish species act as intermediate and final hosts in both habitats. The Kiel Canal (total of 17 parasite species) showed a lower parasite species richness for A. brama and R. rutilus (14 and 10 parasite species, respectively) than the lake (25 parasite species). A. brama had a higher parasite richness (22 species) than R. rutilus (16 species) in the lake habitat. Most parasites collected were of freshwater origin. Consequently, the observed infection pattern of both fish species in the waterway is mainly influenced by the limited salinity tolerance of freshwater parasites, which are negatively affected even by a salinity of 2.3 to 4.5. In the central Kiel Canal, neither fish species was infected with marine parasites of low host specifity. These parasites are either limited by the low salinity at this sampling site (<4.5 to 6.0) or they cannot enter the canal due to the environmental conditions prevailing in this artificial brackish water habitat. Thus, the canal may comprise a natural barrier preventing the distribution of North Sea parasites into the Baltic Sea. However, the brackish water Baltic Sea nematodes Paracuaria adunca and Cosmocephalus obvelatus were found in R. rutilus from the canal, demonstrating the ability of some parasite species to invade and extend their range of distribution through this man-made shipping route from the Baltic to the North Sea.     

Hyperparasitism of trichodinid ciliates on monogenean gill flukes of two marine fish

Two unusual cases of hyperparasitism of trichodinid ciliates on monogenean gill flukes are described from southern Israel (Red Sea). The first case occurred in cultured European sea bass Dicentrarchus labrax infected by Diplectanum aequans, while the second was observed in a feral devil firefish Pterois miles infected by Haliotrema sp. In both cases, the trichodinids heavily co-infested the host fish gills. The flukes were completely coated by the ciliates, which gave them a cobblestone appearance, but no damage to their tegument was apparent. Both cases are most likely a result of accidental hyperparasitism, brought about by perturbed environmental conditions.     

Trichodinid (Ciliophora; Peritricha) gill parasites of freshwater fish in South Africa

Summary Trichodinella epizootica (Raabe, 1950) and seven new species of trichodinid ectoparasites (Ciliophora: Peritricha) were identified from both wild and pond fishes collected during an extensive survey of fish ponds, rivers and lakes in the Transvaal, South Africa. The new species are Tripartiella clavodonta n. sp., T. lechridens n. sp., T. leptospina, n. sp., T. macrosoma n. sp., T. nana n. sp., T. orthodens n. sp. and Trichodinella crennulata n. sp.     

Spatial organization and population density of the fish community of the litter banks within a central Amazonian blackwater stream

Results of a study of the fish community of the leaf litter banks in the lower reaches of the Taruma-Mirim, a small central Amazonian stream is presented. The Taruma-Mirim is an acidic, blackwater, forest stream which flows through igapo forest and enters the Rio Negro close to Manaus. The commonly held view that these blackwaters hold an impoverished ichthyofauna is challenged. The studied litter banks hold about 20 species of fish, all of which were found to live within distinct subregions of the habitat. Average fish density was about 100 individuals m⁻². Absolute population sizes were found to be remarkably small; within a 200 m² area the most abundant species had a population size of about 10⁴ and the least abundant <10² individuals. It is argued that high species richness linked to specialized habitat requirements and small population size indicates considerable population stability. The factors leading to the evolution of such species richness are discussed.     

Cytochemical characterisation of the leucocytes and thrombocytes from Murray cod (Maccullochella peelii peelii,Mitchell)

Cytochemistry has proven effective in differentiating specific cell lineages and elucidating their functional properties. This study utilised a range of cytochemical techniques to further investigate the leucocyte populations from Murray cod, an iconic Australian teleost fish species. This analysis provided clear insight into the structure and function of the leucocytes from this fish, which were found to be broadly similar to those of other fish species. However, some important differences were identified in Murray cod, such as the presence of naphthol AS chloroacetate esterase activity in the heterophil population, positive staining for periodic acid Schiff's, alkaline phosphatase and Sudan black B in the lymphocyte population, and a prevalent population of myeloid precursor cells.     

广西鱼类一新纪录:唐鱼(鲤形目:鲤科)

于2008年在广西一山涧小溪发现了国家Ⅱ级保护野生动物唐鱼(Tanichthys albonubes)种群,属、种均为广西新纪录.与广东从化野生唐鱼比较,广西唐鱼背鳍、腹鳍和臀鳍有明显黑色斑纹,尾柄较高,广西唐鱼种群在可量性状主成分分析上与广东从化唐鱼野生种群可以明显区分开来.我们还对唐鱼栖息地生境与环境进行了调查,栖...     

Direct Estimation of Food Consumption of Juvenile Fish in a Shallow Inlet of the Southern Baltic

The species composition and feeding behaviour of fish larvae and juveniles was investigated in a shallow inlet of the Southern Baltic. The aim of the study was to examine if there was a predatory impact of young fish on the observed annual collapse of the copepod population. Dominant fish species were herring (Clupea harengus), perch (Perca fluviatilis) and roach (Rutilus rutilus). Roach larvae preferred shallower areas, whereas young herring and perch were found in open water. Highest consumption values were always observed in the evening. By computing complete evacuation of the digestive tract in approximately 3.5 hours, daily consumption in percent of fish fresh weight was 1.3, 4.7 and 5.5% for young herring, roach and perch, respectively. The impact of young fish on the dynamics of the population of the copepod species Eurytemora affinis is negligible.     

Formation and development of the Black Sea-Caspian kilka Clupeonella cultriventris (Clupeidae) in the Rybinsk reservoir

We studied the state and development of the population of the Black Sea-Caspian kilka Clupeonella cultriventris in the Rybinsk reservoir from 1994 to 2010. The population dynamics, the rate of growth of the kilka, as well as its food relationships with other fish species of the pelagial community, were analyzed. It was found that the period of exponential increase in the numbers was replaced by the period of interannual fluctuations. With the development of the population, tendencies for a decrease in the rate of growth of the kilka and aggravation of its food relationships with other species are revealed, which is determined by changes in the structure of pelagic aggregations of fish. One of the most significant environmental factors determining dynamics of the numbers and state of the kilka population in the northernmost part of its modern range is water temperature.     

Historical and recent reductions in genetic variation of the <Emphasis Type="Italic">Sarotherodon galilaeus</Emphasis> population in the Sea of Galilee

The Sea of Galilee has great significance as a natural habitat and a freshwater source for Israel. Anthropogenic impacts have been placing significant pressure on the species inhabiting this lake, among which is Sarotherodon galilaeus, an omnivorous fish with a relatively large population and significance for commercial fishing. An alarming decline in annual catch towards 2008 suggested that this unique population might be at risk. With that in mind, we characterized the current genetic variation of this species in Israel with reference to fish from Ghana, based on D-loop and microsatellite markers. Genetic variation and differentiation were found mostly among fish from Ghanaian localities and between fish from Israel and Ghana, whereas fish from all Israeli localities had uniform and limited variation, a signature compatible with historical founder effect followed by local adaptations. Such historical processes could leave a population vulnerable as reflected in the sudden and recent population decline. Comparing genetic variation between archived 30 year-old scales and modern lake fish revealed further reduction in genetic variation coincident with the recent population decline. Thus, a recently occurring genetic bottleneck had placed this unique and isolated population at an even higher risk. We carefully discuss the events leading to the current risk status for S. galilaeus in Israel and highlight the need for vigilant monitoring and active management to support a more sustainable future for this and other fish communities in this important habitat.     

A lymphosarcoma in an Atlantic salmon (Salmo salar)

A lymphosarcoma that appeared to be of thymic origin and of lymphoblastic type was found in a 3.5-yr-old Atlantic salmon (Salmo salar). The fish was from a population of 60 broodfish maintained at a research fish laboratory. A large tumor mass was found under the left operculum. Small tumor nodules were found on the swim bladder and in the abdominal adipose tissue. The location of this neoplasm differed from those of previously described tumors in this fish species.