Infection Characteristics of Clonorchis sinensis Metacercariae in Fish from Republic of Korea

The infection nature of Clonorchis sinensis metacercariae (CsMc) in freshwater fish hosts is closely related to the transmission of human clonorchiasis. This article reviewed the infection characteristics of CsMc in freshwater fish in the Republic of Korea (Korea). The status of CsMc infection was examined in a total of 17,792 cyprinid fish of 49 species in 9 water systems, which included Hantan-/Imjin-gang, Han-gang, Geum-gang, Mangyeong-gang, Yeongsan-gang, Tamjin-gang, Seomjin-gang, Nakdong-gang, and streams in the east coastal areas from 2010 to 2020. The infection status of CsMc was examined according to cyprinid fish species and water systems, after which analyzed by endemicity and susceptibility index. The high endemicity was shown in the cyprinid fish from 3 regions (6.1%) in the upper reaches of Nakdong-gang, such as Banbyeon-cheon (stream), Yongjeon-cheon, and Wi-cheon. The moderate levels were observed in fishes from 8 regions (16.3%), and low endemicity was shown in fishes from 20 regions (40.8%). No CsMc were detected in fish from 18 regions (36.7%). The susceptibility of CsMc in index fish, Puntungia herzi, was found to be a reliable index without examination of other fish species. CsMc infection rates were closely related to subfamily groups in the cyprinid fish hosts in a highly endemic area. In Korea, a total of 58 fish species in 10 families has been listed as the second intermediate hosts for C. sinensis. This review provides several novel features of CsMc infection and clarifies the species of second intermediate freshwater fish host in Korea.     

Variation in abundance and survival of fish larvae in shallow eutrophic lake Tjeukemeer

Synopsis Variations in abundance and survival of larvae of the major fish species, bream, roach, pikeperch, perch and smelt were studied in shallow eutrophic lake Tjeukemeer (1986–1988). Except for smelt, the size of the spawning stock and the abundance of larvae were not related. Both the timing of appearance of larvae and their growth rate were determined by water temperature as was shown by a growth model developed earlier for Tjeukemeer fishes. In cyprinids and percids the survival of the larvae was hypothesized to be negatively related to the duration of the earliest stages. Except in cyprinids, the abundance of 0+ juvenile fish could be explained by the number of larvae. In cyprinids 0+ juvenile abundance at the end of the year was not related to the number of larvae in May and June. The cyprinid juvenile survival rates are hypothesized to be related to the size of the main cyprinid predator, 0+ pikeperch.     

S7核糖体蛋白基因序列变异与(鱼丹)亚科鱼类的单系性研究

使用分子生物学的方法对Dan亚科鱼类的单系性进行了探讨。通过PCR方法,获得了13种鲤科鱼类S7核糖体蛋白基因第1内含子序列,其中包括6种Dan亚科鱼类。使用MEGA软件中的Neighbor-Joining法和Most-Parsimony法分别构建分支系统图。研究结果显示目前所确认的Dan亚科鱼类实际上没有形成单系类群。其中Dan属、波鱼属和低线Lie属位于系统树基部,显示出原始性,而由细鲫属、马口鱼属和Lie属构成的类群相对于Dan亚科中的原始种类起源较晚,可能和较晚起源的东亚鲤科类群之间有更为密切的关系。     

Interannual variability in seasonal dynamics and species composition of drifting young-of-the-year fishes in two European lowland rivers

st young-of-the-year (YOY) fishes in two lowland rivers in the Czech Republic (Danube Basin) drifted from mid-May to mid-July and almost exclusively at night. The peak of drift density lasted c . 3 weeks and depended on water temperature (by its effect on fish spawning), but not on discharge. Peak drift densities varied between years and rivers from 80 to 1354 fish 1000 m⁻³. More than 98% of drifting fish were cyprinids. Rutilus rutilus, Rhodeus sericeus, Gobio spp., Alburnus alburnus and Abramis brama were dominate in the 22 species encountered in the River Morava. Carassius auratus gibelio and R. sericeus were the most common of 17 species in the River Kyjovka. Species composition of drifting fishes was similar among years in the Morava but varied in the Kyjovka. The species composition of drifting fishes did not differ from those of the YOY fish assemblage in nursery areas during the drift season. Relative abundances in nursery areas decreased after the drift season in species that dominated in the drift, but increased in those that avoided drift. It is suggested that drift is a regular part of the life history of many cyprinid fishes and interannual variability in density and species composition of drifting YOY fish can be explained by variable spawning success among years. Differences in the relative abundances of the YOY fish assemblage in nurseries during and after the drift season suggests that drift may cause significant mortality.     

Spatially variable response of native fish assemblages to discharge,predators and habitat characteristics in an arid‐land river

1. Fish assemblages and habitats were sampled annually at fixed sites in three tributaries of the Gila River catchment over a 21‐year span that included prolonged low‐ and high‐flow periods. Model selection was used to evaluate responses of seven native fishes with variable ecological traits (four small‐bodied cyprinids, one large‐bodied cyprinid, and two large‐bodied catostomids) to mean annual discharge and predacious non‐native fishes across the three sites. We also compared habitat use and overlap of native and non‐native fishes to identify potential for negative interactions among species. 2. Assemblage structure (species abundance and richness) and recruitment of native species was strongly and primarily affected by mean annual discharge and secondarily by location and densities of non‐native predators (mainly the centrarchid Micropterus dolomieui). 3. Densities of age‐0 catostomids and small‐bodied cyprinids were positively associated with discharge, and this pattern was strongest in the tributary with the lowest densities of non‐native predators. Absence or extreme low abundance of natives during low‐flow years was most pronounced at the sites where non‐native predators were comparatively common. Densities of adults of large‐bodied native species also varied by site, but often were positively associated with densities of non‐native predators. 4. Spatially variable responses of native fish assemblages indicated that the persistence of native fishes could be jeopardized if key habitats were lost or flow regimes unnaturally altered, particularly during low‐flow conditions when recruitment of native fishes is low and predation by non‐natives is high. Large‐bodied species may be less vulnerable to multiple years of poor conditions because adults are able to avoid predation by non‐natives and thus can rely on occasional high discharge years for successful recruitment. 5. As in other arid‐land streams, native fish assemblages of the Gila River Basin continue to decline. Our results indicate that conservation requires specific knowledge and consideration of physical influences as well as life‐history attributes of native and non‐native fishes.     

Importance of live coral habitat for reef fishes

Live corals are the key habitat forming organisms on coral reefs, contributing to both biological and physical structure. Understanding the importance of corals for reef fishes is, however, restricted to a few key families of fishes, whereas it is likely that a vast number of fish species will be adversely affected by the loss of live corals. This study used data from published literature together with independent field based surveys to quantify the range of reef fish species that use live coral habitats. A total of 320 species from 39 families use live coral habitats, accounting for approximately 8 % of all reef fishes. Many of the fishes reported to use live corals are from the families Pomacentridae (68 spp.) and Gobiidae (44 spp.) and most (66 %) are either planktivores or omnivores. 126 species of fish associate with corals as juveniles, although many of these fishes have no apparent affiliation with coral as adults, suggesting an ontogenetic shift in coral reliance. Collectively, reef fishes have been reported to use at least 93 species of coral, mainly from the genus Acropora and Porities and associate predominantly with branching growth forms. Some fish associate with a single coral species, whilst others can be found on more than 20 different species of coral indicating there is considerable variation in habitat specialisation among coral associated fish species. The large number of fishes that rely on coral highlights that habitat degradation and coral loss will have significant consequences for biodiversity and productivity of reef fish assemblages.     

Trophic consequences for riverine cyprinid fishes of angler subsidies based on marine‐derived nutrients

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A multivariate comparison of the stress response in three salmonid and three cyprinid species: evidence for inter‐family differences

The response of six species of freshwater fishes, from the families Cyprinidae (common carp Cyprinus carpio, roach Rutilus rutilus and chub Leuciscus cephalus) and Salmonidae (rainbow trout Oncorhynchus mykiss, brown trout Salmo trutta and Arctic charr Salvelinus alpinus), to a standardized stressor was evaluated. A 6 h period of confinement resulted in changes to plasma cortisol, glucose, amino acid and lactate levels compared with unconfined controls. There were significant differences in the response profiles both within and between families. The cyprinid species exhibited higher and more sustained stress‐induced increases in plasma cortisol and glucose than the salmonid species. In cyprinids, plasma lactate and plasma amino acid concentration showed less disturbance following stress than in salmonids. The results of the study, together with an evaluation of previously published data for eight salmonid species and six cyprinid species, support the hypothesis that differences in core elements of the stress response exist between species of fishes, and that this variation may have a systematic basis.     

Toothless predators: feeding performance and techniques among the piscivores within Lake Tana's endemic barbus species flock (Pisces:Cyprinidae)

With more than 2000 fish species the Cyprinidae is the largest family of vertebrates. Lake Tana, a large lake (3050 km²) situated in the NW‐ highlands of Ethiopia, harbours, as far as we know the only remaining intact species flock of large (max. 100 cm FL) cyprinid fishes (15 Barbus spp.). One of the most intriguing aspects of this endemic Barbus species flock is the large number of piscivores (8). Cyprinid fishes seem not well designed for piscivory, they lack teeth in the oral jaw, have a small slit‐shaped pharyngeal cavity and all lack a stomach with low pH for digesting large prey. Many barbs are benthivorous species, like the ancestral barb in Lake Tana's isolated system. Why then is piscivory, which is rare among cyprinids, so common in Lake Tana Barbus? The aim of present study was to compare the performance and techniques of these piscivorous Barbus with known piscivores from other fish families. We studied prey handling times over prey size, prey capture using high‐speed movies, and assessed the effect of prey size on performance and prey selection in the field. Performances were explained by functional morphology of their feeding system. Overall, Lake Tana's piscivorous Barbus perform relatively 'poor', compared to piscivores from other fish families. For example, Lake Tana's piscivores are only able to handle prey fish smaller than 16% of their own body length. However, Lake Tana lacks potential piscivorous competitors, rendering the piscivorous Barbus by far the 'best' and apparently highly successful. They have adapted to all available macro‐habitats (littoral, offshore pelagic and offshore benthic), using different techniques (ambush, pursuit and cruising), a unique scenario for barbs.     

Patterns of Fish Growth along a Residential Development Gradient in North Temperate Lakes

Residential development of lakeshores is expected to change a variety of key lake features that include increased nutrient loading, increased invasion rate of nonnative species, increased exploitation rates of fishes by anglers, and alteration of littoral habitats. All of these factors may alter the capacity of lakes to support productive native fish populations. Fourteen north temperate lakes were surveyed to examine how growth rates of two common fish species (bluegill sunfish, Lepomis macrochirus; largemouth bass, Micropterus salmoides) varied along a residential development gradient. Size-specific growth rates for both species were negatively correlated with the degree of lakeshore residential development, although this trend was not statistically significant for largemouth bass. On average, annual growth rates for bluegill sunfish were 2.6 times lower in heavily developed lakes than in undeveloped lakes. This effect of lakeshore development on fish growth was not size specific for bluegills between 60 and 140 mm in total length. An index of population production rate that accounted for both the size-specific growth rate and the size distribution of fishes showed that bluegill populations were approximately 2.3 times less productive in highly developed lakes than in undeveloped lakes. Our results suggest that extensive residential development of lakeshores may reduce the fish production capacity of aquatic ecosystems. Received 29 April 1999; Accepted 26 October 1999.     

A critical scanning electron microscope study of the scolex of Bothriocephalus acheilognathi Yamaguti, 1934, with a review of the taxonomic history of the genus Bothriocephalus parasitizing cyprinid fishes

Summary Bothriocephalus specimens from one Ctenopharyngodon idella (O+) were fixed using three different techniques and the scolex morphology was examined using scanning electron microscopy. The scolices were compared with figures of the five species of Bothriocephalus and one species of Schyzocotyle previously described from cyprinid fishes. The taxonomic history of the Bothriocephalus species parasitizing cyprinid fish is reviewed. It is concluded that there is only one Bothriocephalus species parasitizing cyprinid fishes, and that continued use should be made of the name B. acheilognathi Yamaguti, 1934. ac]19840326     

Effects of summer drawdown on cyprinid fish larvae in Lake Biwa, Japan

The effects of artificial water-level manipulations in Lake Biwa, initiated in 1992 to prevent flooding, on cyprinid fish larvae were assessed by measuring and estimating the topographic change in the reed zones. The shallow, litter-accumulated water in those zones was inhabited by larvae of two species, Carassius spp. and Cyprinus carpio. More than 70% (by volume) of these shallow areas in Lake Biwa was estimated to be lost when the water level was artificially lowered by 30cm from June to October 1997. During the low water level period, significantly fewer eggs of these cyprinid fishes were collected in a reed zone than in April and May of the same year, a comparison with a previous study suggesting that spawning of the fishes was inhibited during the period of low water level. The artificial reductions in water level probably resulted in a significant decrease in the volume of shallow water in the lake and may be linked to the drastic decline in these cyprinid fishes.     

Comparative study of gill neuroepithelial cells and their innervation in teleosts and Xenopus tadpoles

Peripheral O₂ chemoreceptors initiate adaptive cardiorespiratory responses to hypoxia in vertebrates. Morphological and physiological evidence suggests that, in fish, neuroepithelial cells (NECs) of the gill perform this role. We conducted a comparative examination in three species of teleosts (zebrafish, goldfish and trout) and larvae of the amphibian Xenopus laevis, using whole-mount gill preparations and confocal immunofluorescence, to elucidate the distribution, morphology and innervation of gill NECs. Nerve fibres were immunolabelled with the neuronal marker zn-12 and were associated with serotonin-immunoreactive NECs in the gills of all species tested. With the exception of trout, innervated NECs were present on all gill arches in the filaments and respiratory lamellae in fish and on homologous structures in Xenopus (i.e. gill “tufts”, including respiratory terminal branches). Thus, the distribution and innervation of NECs of the internal gills of amphibians and teleosts are relatively well conserved, suggesting an important role for gill NECs as O₂ chemoreceptors in aquatic vertebrates. Furthermore, the size and density of gill NECs is variable among teleosts and developmental stages of Xenopus larvae and may be dependent on general gill dimensions or environmental conditions. This report constitutes the first comparative study of gill NECs in fish and amphibians and highlights the significance of gill NECs as an evolutionary model for studying O₂ sensing in vertebrates. We acknowledge the Natural Sciences and Engineering Research Council (NSERC) of Canada for funding through an operating grant to C.A.N., and the NSERC and the Ontario Graduate Scholarship (OGS) program for postgraduate scholarships to M.G.J.     

Oocyte morphology of several mesopelagic fishes in connection with their taxonomic status and habitat conditions

The inner structure of oocytes was studied in 9 species of mesopelagic fish from the Myctophidae, Melamphaidae, Bathylagidae and Platytroctidae families. It was revealed that species of the same family (Myctophidae) differed less in oocyte structure than species from different families. Within the limits of subfamilies the myctophid fishes had the maximum similarity in their oocyte structure. It was established, that oocytes of fishes of different families differ by the size of vacuoles and yolk granules, and by their localization in cytoplasm.     

Relationships between fishes and habitat in rainforest streams in Sabah, Malaysia

Distinct fish assemblages were found at the mesohabitat scale in 14 streams in eastern Sabah, Malaysia. Sites were designated a priori as pool, run or riffle on the basis of physical habitat structure and properties. Principal components analysis of physical habitat data confirmed the validity of the a priori designation with a major axis of three correlated variables: water velocity, depth and substratum type. Canonical discriminant analysis on fish abundance and biomass data confirmed the existence of a specialized assemblage of fishes from riffle areas of all streams. Overall, pool and run assemblages were highly variable, dependent on stream size, but also variable between streams of the same size. Multiple regression of species richness, diversity, abundance and biomass data on principal components revealed significant but low correlations with measured habitat variables. Riffle habitats showed lower species richness and diversity but high abundance. The fish assemblage in riffles was dominated by balitorid species, specialized for fast-water conditions. Pool assemblages had the highest species diversity and were dominated by cyprinid species of a number of morphological and ecological guilds. Run assemblages were intermediate in assemblage characteristics between riffle and pool assemblages. Between-stream variation in assemblage composition was less than within-stream variation. Of 38 species collected, seven could be designated as riffle specialists, 18 as pool specialists and 13 as ubiquitous, although most of the latter showed size-specific habitat use with larger size classes found in slower, deeper water.     

The future distribution of river fish: The complex interplay of climate and land use changes,species dispersal and movement barriers

The future distribution of river fishes will be jointly affected by climate and land use changes forcing species to move in space. However, little is known whether fish species will be able to keep pace with predicted climate and land use‐driven habitat shifts, in particular in fragmented river networks. In this study, we coupled species distribution models (stepwise boosted regression trees) of 17 fish species with species‐specific models of their dispersal (fish dispersal model FIDIMO) in the European River Elbe catchment. We quantified (i) the extent and direction (up‐ vs. downstream) of predicted habitat shifts under coupled “moderate” and “severe” climate and land use change scenarios for 2050, and (ii) the dispersal abilities of fishes to track predicted habitat shifts while explicitly considering movement barriers (e.g., weirs, dams). Our results revealed median net losses of suitable habitats of 24 and 94 river kilometers per species for the moderate and severe future scenarios, respectively. Predicted habitat gains and losses and the direction of habitat shifts were highly variable among species. Habitat gains were negatively related to fish body size, i.e., suitable habitats were projected to expand for smaller‐bodied fishes and to contract for larger‐bodied fishes. Moreover, habitats of lowland fish species were predicted to shift downstream, whereas those of headwater species showed upstream shifts. The dispersal model indicated that suitable habitats are likely to shift faster than species might disperse. In particular, smaller‐bodied fish (<200 mm) seem most vulnerable and least able to track future environmental change as their habitat shifted most and they are typically weaker dispersers. Furthermore, fishes and particularly larger‐bodied species might substantially be restricted by movement barriers to respond to predicted climate and land use changes, while smaller‐bodied species are rather restricted by their specific dispersal ability.     

Characterization of a highly conserved microsatellite marker with utility potentials in cyprinid fishes

A microsatellite locus, MFW1, originating from common carp is highly conserved in flanking nucleotides but variable in repeat length in some fishes from different families of the Cypriniformes. This orthologous locus is polymorphic in approximately 58% of the species tested in the order and is inherited by Mendelian law. It proved to be a potentially good marker in population genetics and in the cyprinid species‐breeding programme in which no microsatellite markers were available.     

永兴岛附近海域珊瑚礁鱼类群落结构特征

为更好地保护和管理西沙永兴岛附近海域珊瑚礁鱼类,于2020—2021年对永兴岛上岸渔获物进行了调查研究,分析了鱼类群落结构组成及其变化和演替特征。结果表明:调查共发现永兴岛附近海域珊瑚礁鱼类101种,隶属于5目21科,以鲈形目鱼类最多,占总种类的84.16%,生物量超总渔获物的90%;科级水平鹦嘴鱼科鱼类最多,达21种,生物量超总渔获物的45%。28种珊瑚礁鱼类是永兴岛附近海域主要捕捞对象,占总渔获物的80%以上。永兴岛附近海域珊瑚礁鱼类呈现过度捕捞,一是主要渔获物中的中大型鱼类均重偏小;二是本海域个体体型最大的鱼类出现较多消亡;三是肉食性鱼类大量消亡;四是植食性鱼类生物量占比超过了肉食性鱼类。永兴岛附近海域珊瑚礁鱼类已经演替到以植食性鱼类为主导的生态系统;大量海胆的出现,表明了这一珊瑚礁生态系统在进一步衰退,向以海胆为主导的生态系统演变。保护西沙永兴岛附近海域珊瑚礁鱼类已经刻不容缓,需要严格地控制本海域的捕捞强度。     

Learned or innate production of acoustic signals in fishes: a test using a cyprinid

No information on the inheritance of the ability to produce sounds exists for fishes. In birds, which usually provide extensive post-hatching parental care, acoustic signals are learned in some species but are innate in others. Almost no fishes provide extensive post-hatching parental care and, consequently, the offspring have little opportunity to hear and learn sounds produced by the parents (usually the male in fishes); they may, however, be exposed to acoustic signals of conspecifics in the same habitat. We used a cyprinid, Codoma ornata, to test whether sound production is learned from the parents or whether it is innate. Fertilized eggs of this species were raised in isolation from adults. Upon maturity, these fish were tested for sound production in aggressive and reproductive contexts. Fish which had no contact with adults, and therefore no opportunity to hear the acoustic signals of their species, produced sounds that were similar to those produced by their parents, and they produced these in the same contexts. Significant differences were observed in dominant frequency for one context, with the smaller F₁ fish having signals of higher frequency than parental fish. Since no opportunity for learning existed, this provided evidence that the ability to produce sounds is innate in this minnow species.