Observations on two species of phyllodistomes (Trematoda : Gorgoderidae) from fishes of the Hubei Province, central China, with an erection of Neophyllodistomum gen. n.

Two rare trematode species so far reported in the genus Phyllodistomum Braun, 1899, P. pawlovskii (Zmeev, 1936) and P. serrispatula Chin, 1963, were found in the urinary system the yellow catfish Pelteobagrus fulvidraco (Richardson) of Bao'an Lake (prevalence 8 %) and the swamp eel Monopterus albus (Zouiev) of Liangzi Lake (prevalence 6 9/6), respectively, from the Hubei Province, central China. In contrast to the original description, P. pawlovskii showed a considerable morphological variability particularly in the shape, size and topography of testes. A unique morphological feature of P. serrispatula is the presence of many conspicuous lateral outgrowths on the hindbody and, principally based on this character, a new genus Neophyl-lodistomum is erected (type species N. serrispatula (Chin, 1963) comb. n.)) to accommodate this species. Both trematode species are briefly redescribed. P. pawlovskii and N. serrispatula are reported for the first time from the Hubei Province and the former from the Yangtze River drainage system.

Mitochondrial d-loop sequence variation and phylogeny of gobiobotine fishes

The mitochondrial DNA control region is amplified and sequenced from 8 genera and 10 species of gobiobotine fishes. The phylogenetic tree of Gobiobotinae and some representative species of other Cyprinid subfamilies obtained by the method of neighborhood joining, maximum likelihood and maximum parsimony with Danio rerio as an outgroup indicates that Gobiobotinae fishes are a monophyletic group which is close to Gobioninae subfamily. Gobiobotinae should be included into subfamily Gobioninae in terms of phylogenetic analysis. The research result supports that Gobiobotinae can be divided into genus Xenophysogobio and Gobiobotia. Xenophysogabio is the most primitive genera in the subfamily.

Testing the relationships of Chinese freshwater Unionidae (bivalvia) based on analysis of partial mitochondrial 16s rRNA sequences

This study presents partial mitochondrial 16S rRNA sequences of 13 unionid bivalve species from China and analyses their relationships in combination with known data of 21 American mussels. According to our results, Chinese unionids, formerly regarded as two subfamilies, should be divided into three subfamilies: Ambleminae, Anodontinae and Unioninae. The genera Hyriopsis, Solenaia, Lamprotula and Ptychorhynchus, hitherto placed in Unioninae or Anodontinae, should be moved to the subfamily Ambleminae, demonstrated for the first time from China. The other genera recorded from China are suggested to belong to Anodontinae and Unioninae, which is in agreement with traditional classifications, except for the genus Lepidodesma.

Sequence variations of the S7 ribosomal protein gene in primitive cyprinid fishes: Implication on phylogenetic analysis

Cyprinidae is the largest fish family in the world and contains about 210 genera and 2010 species. Appropriate DNA markers must be selected for the phylogenetic analyses of Cyprinidae. In present study, the 1st intron of the S7 ribosomal protein (r-protein) gene is first used to examine the relationships among cyprinid fishes. The length of the 1st intron obtained by PCR amplification ranges from 655 to 859 by in the 16 cyprinid species investigated, and is 602 by in Myxocyprinus asiaticus. Out of the alignment of 925 nucleotide sites obtained, the parsimony informative sites are 499 and occupy 54% of the total sites. The results indicate that the 1st intron sequences of the S7 r-protein gene in cyprinids are rich in informative sites and vary remarkably in sequence divergence from 2.3% between close species to 66.6% between distant species. The bootstrap values of the interior nodes in the NJ (neighbor-joining) and MP (most-parsimony) trees based on the present S7 r-protein gene data are higher than those based on cytochrome b and the d-loop region respectively. Therefore, the 1st intron sequences of the S7 r-protein gene in cyprinids are sensitive enough for phylogenetic analyses, and the 1st intron is an appropriate genetic marker for the phylogenetic reconstruction of the taxa in different cyprinid subfamilies. However, attempts to discuss whether the present S7 r-protein gene data can be applied to the phylogeny of the taxa at the level of the family or the higher categories in Cypriniformes need further studies.

Ontogenetic behavior and migration of Chinese sturgeon, Acipenser sinensis

The Chinese sturgeon, Acipenser sinensis, is an anadromous protected species that presently only spawns in the Yangtze River. Using laboratory experiments, we examined the behavioral preference of young Chinese sturgeon to physical habitat (water depth, illumination intensity, substrate color, and cover) and monitored their downstream migration. Hatchling free embryos were photopositive, preferred open habitat, and immediately upon hatching, swam far above the bottom using swim-up and drift. Downstream migration peaked on days 0-1, decreased about 50% or more during days 2-7, and ceased by day 8. Days 0-1 migrants were active both day and night, but days 2-7 migrants were most active during the day. After ceasing migration, days 8-11 embryos were photonegative, preferred dark substrate and sought cover. Free embryos developed into larvae and began feeding on day 12, when another shift in behavior occurred-larvae returned to photopositive behavior and preferred white substrate. The selective factor favoring migration of free embryos upon hatching and swimming far above the bottom may be avoidance of benthic predatory fishes. Free embryos, which must rely on yolk energy for activity and growth, only used 19 cumulative temperature degree-days for peak migration compared to 234 degree-days for growth to first feeding larvae, a 1 : 12 ratio of cumulative temperature units. This ratio suggests that sturgeon species with large migratory embryos, like Chinese sturgeon, which require a high level of energy to swim during migration, may migrate only a short time to conserve most yolk energy for growth.

Diving behaviour of freshwater finless porpoises (Neophocaena phocaenoides) in an oxbow of the Yangtze River, China

Dive-depth and swim-speed of a juvenile and an adult free-ranging, Yangtze finless porpoises (Neophocaena phocaenoides) were observed using velocity-time-depth recorders in an oxbow of the Yangtze River. In total, 8222 individual dives were recorded over 59 hours. Two dive types, deep-dive (greater than or equal to 2.7 m) and shallow-dive. were recognized. Horizontal travel distances of two finless pot-poises in a day were 94.4 km and 90.3 km, which were longer than those of oceanic relative species (harbor porpoises, Phocoena phocoena). Although the shallow water limited the maximum dive-depth, dive-duration, and bottom-time of finless porpoises were similar to the harbor porpoises. A sudden drop of swim-speed below 0.25 m s(-1) was frequently observed nearby the maximum dive-depth. This seemed to indicate "turning, around" behaviour, possibly during prey pursuit. (C) 2002 Published by Elsevier science Ltd on behalf of International Council for the Exploration of the Sea.

Molecular variation of Bothriocephalus acheilognathi Yamaguti, 1934 (Cestoda : Pseudophyllidea) in different fish host species based on ITS rDNA sequences

The molecular variation in Bothriocephalus acheilognathi Yamaguti, 1934 from 11 species of freshwater fish collected in Australia, China, the Czech Republic, England and Hawaii was investigated by determining the nucleotide sequences of the internal transcribed spacer region. The length of the first and second internal transcribed spacer sequences of multiple individuals ranged from 553 to 571 bp and 553 to 615 bp, and the G + C content from 53.1 to 53.5%. The percentage sequence divergence varied between 0 and 0.9% in the ITS1 and 0 and 6.6% in the ITS2, respectively, indicating the occurrence of intraspecific variation. It is demonstrated that the fragment length variation resulted primarily from microsatellite polymorphisms present in the ITS region, especially in the ITS2 region. Phylogenetic analyses revealed that B. acheilognathi examined in this study consisted of three closely related genotypes with certain degrees of host-specificity, and the genotype representing isolates from Cyprinus carpio L. was the most common and diverse form within the species B. acheilognathi.

The precocious Chinese mitten crab: Changes of gonad, survival rate, and life span in a freshwater lake

Changes of the gonad. survival rate, and life span of the precocious (i.e., sexually mature in their first October-November, at the age of 5 or 6 months) Chinese mitten crab (Eriocheir sinensis) were studied in a small, shallow, macrophytic, freshwater lake along the middle reaches of the Changjiang River, China. The gonosomatic index (GSI) reached peak during the next March when the female GSI was 12.32 +/- 1.75 SD% and the male GSI A as 4.24 +/- 0.19%. The sexual glands degraded from then on. In the first ten-day period of the following July, there was no complete ovum in the ovary. and the sperm became thin and lost adhesion. The population declined sharply from November to July, and the last one (a female) died in the middle of July, which indicated that the life span of the precocious crab was about 12 months (from larval hatching in June to death in July of next year). The survival curve might be expressed as Y = 1.09exp(-0.018x) (Y survival rate; x: days) for the precocious crabs stocked in experimental cages.

Effects of CO2 enrichment on microstructure and ultrastructure of two species of freshwater green algae

order to investigate the morphological response of freshwater green algae to elevated CO2 concentration, Chlamydomonas reinhardtii Dang and Scenedesmus obliquus Kutz were cultured with enriched CO2, and their microstructure and ultrastructure were examined by microscopy and electron microscopy. The effect of CO2 enrichment to 186 mumol/L, was insignificant on the shape and size of C. reinhardtii, but significant in reducing the volume of S. obliquus. High-CO2 increased the amount of chloroplast. The pyrenoids occurred in low-CO2-grown cells but not in high-CO2-grown ones and more starch granules were observed in the former.

Enhancement of planktonic rotifers by Microcystis aeruginosa blooms: An enclosure experiment in a shallow eutrophic lake

Enclosure experiments with three treatments (sediment addition, sediment + nitrogen enrichment, sediment + phosphorus enrichment) and unfertilized controls were performed in shallow hypereutrophic Lake Donghu during the summer of 2000. Dense Microcystis aeruginosa blooms occurred in all the enclosures during the experimental period but not in the surrounding lake water. Generally, the dominant rotifers were Polyarthra vulgalis, Filinia longiseta, Proales sp. and Asplanchna sp. at the beginning of the experiment, followed by a shift to Brachionus calyciflorus, Trichocerca similis, Cephalodella catellina and Anuraeopsis fissa, and finally to F. longiseta, Proales sp. and Keratella cochleris. M. aeruginosa blooms strongly suppressed the larger Diaphanosoma brachyurum but enhanced the development of the smaller cladocerans and rotifers that probably efficiently utilized organic matter from M. aeruginosa through the detritus food chain. The smaller cladoceran and rotifers coexisted successfully throughout the experimental period.

The uplift of Qinghai-Xizang (Tibet) Plateau and the vicariance speciation of glyptosternoid fishes (Siluriformes : Sisoridae)

Based on the phylogenetic and biogeographical studies of the glyptosternoid fishes in Qinghai-Tibet area, the following hypothesis is proposed: the speciation of this group has a direct relationship with the three uplift intervals of the Qinghai-Tibet Plateau. This process was explained by the theory of vicariance of biogeography. The ancestor of this group was similar to Bagarus and/or Glyptothorax, which still have a wide distribution. At the moment when the Tethys sea closed, the Indian tectonic plate collided with the Eurasian tectonic plate, so the Glyptothorax-like and Bagarus-like ancestors entered Eurasia and gradually became widely distributed. After the Pleistocene, with the enforced colliding, the gradual uplift of the Qinghai-Tibet Plateau brought about the current water environment, and the Glyptosternoids were generated from Glyptothorax-like fish under this environment. The present Glyptosternum, distributed across the Himalayas is the ancestor of Glyptosternoids. In the three uplift intervals of the plateau, the water system of this region was separated gradually and Glyptosternum-like ancestor was isolated in different rivers and evolved into various species. All this resulted in the speciation and formation of the biogeographical pattern of glyptosternoids.

A conserved family of doublesex-related genes from fishes

The sex-determining gene Mab-3 of C. elegans and the doublesex gene of Drosophila each contain a common DM domain and share a similar role. Human doublesex-related gene DMRT1 also encodes a conserved DM-related DNA-binding domain. We present here the amplification of a broad range of DM domain sequences from three fish species using degenerate PCR. Our results reveal unexpected complexity of the DM domain gene family in vertebrates. (C) 2002 Wiley-Liss, Inc.

Small fish communities in two regions of the Liangzi Lake, China, with or without submersed macrophytes

Small fish communities were compared between the vegetated and vegetation-free regions of the Liangzi Lake, a shallow lake along the middle reach of the Yangtze River, China. Fish were sampled using 10 x 10 m(2) block nets and poisoning. Three samples were taken from either the near shore area or lake centre of each region. A total of 19 fish species were collected; all species occurred in the vegetated region but only 12 occurred in the vegetation-free region. The dominant small fish were Carassius auratus auratus in the vegetated region and Ctenogobius giurinus in the vegetation-free region. Diversity, density and biomass of small fishes were significantly higher in the vegetated region than in the vegetation-free region in both near shore and lake centre areas. In the vegetated region, density and biomass of small fishes was significantly higher, while species diversity significantly lower in the near shore area than in the lake centre. In the vegetation-free region, density of small fishes was significantly higher in the near shore area than in the lake centre area, but species diversity or biomass was unaffected by location.

Phylogeny of the specialized schizothoracine fishes (Teleostei : Cypriniformes : Cyprinidae)

Phylogeny of the specialized schizothoracine fishes (Teleostei: Cypriniformes: Cyprinidae). Zoological Studies 40(2). 147-157. To elucidate phylogenetic relationships within the specialized schizothoracine fishes, we used 41 variable osteological and external characters among this groups, three species of Schizothorax, and 1 fossil species. When the 3 species of Schizothorax were designated as an outgroup and all 41 characters were set as unordered with equal weighting, the data matrix yielded a single most-parsimonious tree with a tree length of 71 steps, a consistency index of 0.6761, and a retention index of 0.7416. Meanwhile, a bootstrap test was conducted to verify the reliability of the results. The matrix was also analyzed for different conditions: all characters were ordered and the fossil species was added as an outgroup. The phylogenetic analyses presented herein support the following hypotheses. 1) All species of the specialized schizo-thoracines fishes form a monophyletic group. 2) Monophyly of the genus Ptychobarbus is not supported by the bootstrap test or when these characters are ordered. 3) The genus Gymnodiptychus forms a monophyletic group. 4) All species of Ptychobarbus and Gymnodiptychus form a monophyletic group with Diptychus as its sister group.

Sequences of cytochrome b gene for primitive cyprinid fishes in East Asia and their phylogenetic concerning

1140 bp of cytochrome b gene were amplified and sequenced from 14 species of primitive cyprinid fishes in East Asia. Aligned with other ten cytochrome b gene sequences of cyprinid fish from Europe and North America retrieved from Gene bank, we obtained a matrix of 24 DNA sequences. A cladogram was generated by the method of Maximum likelihood for the primitive cyprinid fishes. The result indicated that subfamily Leuciscinae and Danioninae do not form a monophyletic group. In the subfamily Danioninae, Opsariichthys biden and Zacco platypus are very primitive and form a natural group and located at the root. But the genera in subfamily Danioninae are included in different groups and have not direct relationship. Among them, Aphyocypris chinensis and Yaoshanicus arcus form a monophyletic group. Tanichthys albonubes and Gobiocypris rarus have a close relation to Gobioninae. The genus Danio is far from other genera in Danioninae, In our cladogram, the genera in Leuciscinae were divided into two groups that have no direct relationship. The genera in Leuciscinae distributed in Europe, Sibera and North America, including Leuciscus, Rutilus, Phoxinus, N. crysole, Opsopoeodus emilae, form a monophyletic group. And the Leuciscinae in southern China including Ctenopharyngodon idellus, Mylopharyngodon piceus, Squalibarbus and Ochetobius elongatus have a common origination.