On the karyosystematics of cyprinid fishes and a summary of fish chromosome studies in China

To date, the chromosomes of 210 species of fresh-water fishes have been studied in China. They are principally cyprinids. Based upon the karyotypic data so far obtained mainly by the authors' laboratory, a report is here submitted on the karyosystematics of Chinese cyprinid fishes.The primitive karyotype of cyprinid fishes may be inferred as being 2n=50. During phyletic evolution the cyprinid fishes probably have been differentiated into two large branches, one of which with the Leuciscinae as a basic group and another branch with the Barbinae as a basic group. As to the modes of their chromosome evolution, Robertsonian translocation seems to be prominent in the first branch, whereas polyploidization appears to be prominent in the second branch. Based on the chromosome studies in cyprinid fishes, some tentative ideas about the classification of the subfamilies in Cyprinidae are presented.A table containing the karyotypes of Chinese fresh-water fishes is attached.This work was partially supported by the Science Fund of the Chinese Academy of Science.     

Can host body size explain the parasite species richness in tropical freshwater fishes?

Summary The variability of monogenean gill ectoparasite species richness in 19 West African cyprinid species was analyzed using the following seven predictor variables: host size, number of drainage basins, number of sympatric cyprinid species, host diversity, association with mainland forest, host ecology, and monogenean biological labelling. The size of the host species accounted for 77% of the variation in the number of parasite species per host, and host ecology an additional 8%. Together the effects of host size and host ecology accounted for 85% of the variation in monogenean species richness. This study shows that the deciding factors for explaining monogenean species richness in West African cyprinid fishes are host species size and host ecology. These results were compared with main factors responsible for parasite species richness in fish communities. Other possible explanations of monogenean community structure in west African cyprinids are discussed.     

Genome size variation in North American minnows (Cyprinidae). II. Variation among 20 species

Genome sizes (nuclear DNA contents) from 200 individuals representing 20 species of North American cyprinid fishes (minnows) were examined spectrophotometrically. The distributions of DNA values of individuals within populations of the 20 species were essentially continuous and normal; the distribution of DNA values among species was continuous and overlapping. These observations suggest that changes in DNA quantity in cyprinids are small in amount, involve both gains and losses of DNA, and are cumulative and independent in effect. Significant heterogeneity in mean genome size occurs both between individuals within populations of species and among species. The former averages maximally around 6% of the cyprinid genome and is nearly the same as the amount of DNA theoretically needed for the entire cyprinid structural gene component. The majority of the DNA content variation among the 20 species is distributed above the level of individuals within populations. Comparisons of average genome size difference or distance between individuals drawn from different levels of taxonomic organization indicate that considerably greater divergence in genome size has occurred in the extremely speciose cyprinid genus Notropis as compared with other North American cyprinid genera. This may suggest that genome size change is concentrated in speciation episodes. Finally, no associations were found between interspecific variation in genome size and five life-history characters. This suggests that much of the variation in genome size within and among the 20 species may be phenotypically inconsequential.     

Melanophores of Zacco temmincki (Teleostei) are light sensitive

The responses of melanophores of a cyprinid fish Zacco temmincki to changes in illumination were examined in isolated scale preparations of the adult fishes. Melanosomes in the melanophores aggregated in darkness and dispersed in light. These responses were invariably induced, even in denervated melanophores. These light responses, the dark-induced aggregation and the light-induced dispersion, were not affected by a number of alpha and beta adrenergic blocking agents. It was concluded that the melanophores of Zacco temmincki were themselves light sensitive and responded directly to light by melanosome translocations. The light responses were quantitatively assessed in relation to the intensity of illumination.     

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.     

On the populations of roach (Rutilus rutilus), rudd (Scardinius erythrophthalmus), and their hybriin Esthwaite Water, with notes on the distinctions between them

Samples of cyprinid fishes from Esthwaite Water, Westmorland, have been examined and identified as roach ( Rutilus rutilus ), rudd ( Scardinius erythrophthalmus ), with a high degree (37%) of hybridization between these species. The distinguishing features of roach and rudd are discussed in the light of the difficulty of distinguishing the roach x rudd hybrid from the roach. It is concluded that the only reliable characters are the number and external morphology of the pharyngeal teeth.     

Lower sensitivity of cyprinid fishes to three acetylcholinesterase inhibitor pesticides: an evaluation based on no-effect concentrations

Researchers have suggested that cyprinid fishes are less sensitive to chemical stress than comparable fish families, yet few empirically based evaluations of this hypothesis have been conducted. In this study, we developed a generalized linear mixed model in which the no-effect concentrations (NECs; threshold concentration below which no effect on survival is predicted during prolonged exposure) of 29 fish species from 13 families exposed to an acetylcholinesterase inhibitor pesticide (carbaryl, chlorpyrifos, or malathion) were used as the response variable. The corresponding specific somatic maintenance (SSM) rates, as a size-independent proxy for fish metabolism and a categorical variable regarding whether the species is a cyprinid, were used as the predictor variables. We included SSM rates in the analysis because previous work demonstrated that they are negatively correlated with NECs. Our results indicate that the NECs for cyprinid fishes were significantly higher than those for other fishes, suggesting that cyprinids are indeed less sensitive to the three studied pesticides. Although the SSM rates were negatively related with the NECs, the actual relationship between the two was not clear, implying that the importance of SSM rates may depend on the taxonomic group tested.     

Do constructional constraints influence cyprinid (Cyprinidae: Leuciscinae) craniofacial coevolution?

Constraints on form may determine how organisms diversify. As a result of competition for the limited space within the body, investment in adjacent structures could represent an evolutionary compromise. For example, evolutionary trade‐offs resulting from limited space in the head could have influenced how the sizes of the jaw muscle, as well as the eyes, evolved in North American cyprinid fishes. To test the evolutionary independence of the size of these structures, we measured the mass of the three major adductor mandibulae muscles and determined the eye volume in 36 cyprinid species. Using a novel phylogeny, we tested the hypotheses that the sizes of these four structures were negatively correlated with each other during cyprinid evolution. We found that evolutionary change in the adductor mandibulae muscles was generally positively and/or not correlated, suggesting that competition for space among cyprinid jaw muscles has not influenced their evolution. However, there was a negative relationship between mass of adductor mandibulae 1 and eye volume, indicating that change in these physically adjacent structures is consistent with an evolutionary constructional constraint. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 103 , 136–146.     

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.     

Species of Proteocephalus Weinland, 1858 (Cestoda: Proteocephalidae) from cyprinid fishes in North America

A taxonomic study of Proteocephalus species parasitizing cyprinid fishes in North America, namely Proteocephalus ptychocheilus Faust, 1920 and Proteocephalus cobraeformis Haderlie, 1953, has demonstrated their conspecificity with Proteocephalus torulosus (Batsch, 1786), a common parasite of cypriniform fishes (Cyprinidae and Cobitidae) in the Palaearctic Region. Proteocephalus ptychocheilus and P. cobraeformis are considered junior synonyms of P. torulosus.     

Distribution of metacercariae of Centrocestus formosanus (Trematoda: Heterophyidae) on the gills of Aplocheilus panchax

The metacercariae of Centrocestus formosanus (Nishigori 1924) occur on the gills of freshwater fishes in association with blood vessels. The microecology of the metacercariae on the gills of the cyprinid fish Aplocheilus panchax (Ham. & Buch.) was investigated. The cysts showed a preference for anterior gills and for the dorsal section of each gill. Variations in the density of infection, season and size of the fish do not affect the spatial distribution of metacercariae. It is presumed that ventilation water currents spread the cercariae onto the anterior gills and then the cercariae actively select the preferred habitat.     

Piscivorous fishes diet dominated by the Asian cyprinid invader,topmouth gudgeon (<Emphasis Type="Italic">Pseudorasbora parva</Emphasis>)

Predation on the non-native cyprinid, Pseudorasbora parva, was reported during an annual study in a small connecting canal about 40 km south of Brno, Czech Republic. Two cyprinid fish species (Pseudorasbora parva, Rutilus rutilus) were identified in the diet of 23 piscivores belonging to three native fishes (Perca fluviatilis, Sander lucioperca, Esox lucius). The relative abundance of prey fishes changed seasonally and was dominated by the topmouth gudgeon in spring. Thereafter roach incidence continuously increased. In contrast, topmouth gudgeon was found to be a more sized-available prey and was the most dominant prey species in the diet of all piscivorous fishes during the whole season. Strong piscivory towards this alien might be beneficial for its eradication or control to support ecological integrity in natural and modified seminatural habitats.     

Identification of keratins and analysis of their expression in carp and goldfish: comparison with the zebrafish and trout keratin catalog

With more than 50 genes in human, keratins make up a large gene family, but the evolutionary pressure leading to their diversity remains largely unclear. Nevertheless, this diversity offers a means to examine the evolutionary relationships among organisms that express keratins. Here, we report the analysis of keratins expressed in two cyprinid fishes, goldfish and carp, by two-dimensional polyacrylamide gel electrophoresis, complementary keratin blot binding assay, and immunoblotting. We further explore the expression of keratins by immunofluorescence microscopy. Comparison is made with the keratin expression and catalogs of zebrafish and rainbow trout. The keratins among these fishes exhibit a similar range of molecular weights and isoelectric points, with a similar overall pattern on two-dimensional gels. In addition, immunofluorescence microscopy studies of goldfish and carp tissues have revealed the expression of keratins in both epithelial and mesenchymally derived tissues, as reported previously for zebrafish and trout. We conclude that keratin expression is qualitatively similar among these fishes, with goldfish and carp patterns being more similar to each other than to zebrafish, and the cyprinid fishes being more similar to each other than to the salmonid trout. Because of the detected similarity of keratin expression among the cyprinid fishes, we propose that, for certain experiments, they are interchangeable. Although the zebrafish distinguishes itself as being a developmental and genetic/genomic model organism, we have found that the goldfish, in particular, is a more suitable model for both biochemical and histological studies of the cytoskeleton, especially since goldfish cytoskeletal preparations seem to be more resistant to degradation than those from carp or zebrafish. This work was supported by grants to J.M. from the Stiftung Rheinland Pfalz für Innovation (836-386261/138) and the Deutsche Forschungsgemeinschaft (Ma 843/5-1) and a grant to D.G. from the National Science Foundation (INT-0078261).     

Chromosomal heterochromatin differentiation of cyprinid fishes

The chromosomes of 10 species of Chinese cyprinid fishes were analyzed by means of C-banding technique. It has been found that there is extensive variation in the constitutive heterochromatin among these fishes. Some of these species possess considerable quantities of heterochromatin, and some possess little heterochromatin. These results seem to show that constitutive heterochromatin has played an important part in the chromosomal evolution of cyprinids.     

Microhabitat use by 0+ and older fishes in a small English chalk stream

The microhabitat use of two size/age classes of fish (0 +, ≥1+) in the River Lee, based on measurements of 14 environmental variables, was studied using point abundance sampling by electrofishing over the summer and autumn of 1995. Microhabitat use by all cyprinid species (barbel Barbus barbus, minnow Phoxinus phoxinus , chub Leuciscus cephalus and gudgeon Gobio gobio ) differed between 0+ and older (≥1+) with lentic, shallow, littoral environments being important for 0+ fishes, whereas deeper, faster areas in mid-channel were important for ≥ 1 + fishes. There was more overlap in microhabitat use by 0+ juvenile cyprinids in the River Lee than in larger systems such as the River Danube (Slovakia/Hungary) and River Great Ouse (U.K.).     

Effects of Eutrophication on Young-of-the-year Freshwater Fish Communities in Coastal Areas of the Baltic

Abundance, growth, habitat and food choice of young-of-the-year (Y-O-Y) freshwater fishes were investigated in a gradient of eutrophication in a Baltic inlet. Secchi-disc depth decreased from 3 to 0.5m along the gradient with an accompanying reduction in submerged vegetation coverage. There were positive trends in Y-O-Y abundance with increasing turbidity for cyprinids, pikeperch, ruffe and smelt, and a negative trend for perch, leading to a shift from a perch dominated community in the reference area to a cyprinid dominated in the eutrophic area. The species composition of adult fishes resembled the Y-O-Y species community, indicating that community structure was determined already during early juvenile interval. Perch and cyprinid Y-O-Y preferred areas with submerged macrophytes while pikeperch and smelt were found more frequently in open waters. Perch Y-O-Y growth was reduced in eutrophic areas compared to references, especially in the size range where they change from foraging on zooplankton to benthic organisms. The deterioration of visual conditions caused by high turbidity is suggested to be negative for feeding of perch especially in deeper water. There was no evident growth reduction for pikeperch, which may be explained by a visual physiology well adapted to turbid conditions. The combined effects of turbidity and competition for food resources on growth and survival in eutrophic waters are discussed.     

鲤科七种鱼的银染核型研究

对鲤科七种鱼的银染核型进行了比较研究。这七种鱼均有4个NORs。其中鲴亚科五种鱼的Ag-NORs彼此特征相似;鮈亚科的似刺鳊鮈sm_3染色体上的NORs与次缢痕的位置、形态一致;雅罗鱼亚科的鳡鱼sm_6同源染色体上的一对NORs显示相对大小异形。结合以前的工作,本文以NORs为指标,讨论了有关雅罗鱼亚科几种鱼的亲缘关系及亚科鱼类染色体进行保守等问题。     

On some species of Chonopeltis (Crustacea: Branchiura) from the rivers of the extreme South West Cape region of Africa

Two new species of Chonopeltis (Crustacea: Branchiura), parasitic on cyprinid fishes, are described from rivers in the extreme S.W. Cape region of Africa. These emphasize the remarkable nature of the fauna of these rivers, which includes several endemic fishes. Like their hosts these closely related parasites came from the north and have close affinity with a species from the Orange River system. Their probable evolutionary history is discussed. Keys to both sexes of all described species of Chonopeltis are given.