Protosalanx Hyalocranius Research Articles

Ontogenetic diet shifts and temporal separations in gonad development of two icefish species in Hongze Lake, China

Abstract Resource partitioning through temporal, spatial and/or trophic dimensions is suggested as a mechanism for long‐term coexistence among sympatric species. However, how the combined effects of the different dimensions contribute to the partitioning during the ontogenetic process is unclear. We sampled two sympatric icefish species [Protosalanx hyalocranius (Abbott, 1901) and Neosalanx taihuensis (Chen, 1956)] monthly from July 2015 to June 2016 in Hongze Lake, China. We evaluated the hypothesis that combined effects of separation in gonad development dynamics and ontogenetic diet shifts facilitate resource partitioning in temporal and trophic dimensions during the entire life cycle process of the two icefish species. Increased gonadosomatic index (GSI) of female P. hyalocranius occurred during October 2015 to January 2016, and that of female N. taihuensis occurred during January to March 2016. Thus, energy and nutrition investments in gonad development separated seasonally between the two species. Consequently, temporal separations in gonad development between P. hyalocranius (GSI peaked in January) and N. taihuensis (GSI peaked in March) indicated potential segregations in spawning time and consequent larval abundance peaks, suggesting reduced overlap of prey consumption during the early life stages. The dominant diet of P. hyalocranius shifted from cladocerans to copepods, and then shrimp, and finally to fish during its ontogeny, whereas the dominant diet of N. taihuensis changed gradually from cladocerans to copepods during its ontogeny. The diet overlap in cladocerans during May was high between the two species. Our findings support the hypothesis of an associative strategy, combining temporal (separations in gonad development and subsequently spawning time) and trophic (ontogenetic diet shifts) dimensions, for the resource partitioning between P. hyalocranius and N. taihuensis, which may be an important mechanism for long‐term coexistence among sympatric short‐lived fishes.

Using a topological approach to identify keystone species of fish in eutrophic lake ecosystems: A case of Zhushan Bay, Taihu Lake

AbstractEutrophication is a global aquatic environmental problem. Traditional biomanipulation targeting keystone species has been effective for restoring eutrophic lakes. In this study, we conducted monthly fishery assessments and identified keystone species in Zhushan Bay of Taihu Lake, the most representative lake in the middle and lower reaches of the Yangtze River. We built the topological structure of Zhushan Bay's food web based on feeding relationships and calculated network indices of fish groups in the food web using network analysis, combined with Key Player Problem operation. Culter mongolicus, Culter alburnus, Protosalanx hyalocranius and Salangichthys tangkahkeii were the keystone species in Zhushan Bay's food web. Culter mongolicus and Culter alburnus had the greatest impact on the food web after removal. Protosalanx hyalocranius had the fastest speed of transmitting information. Salangichthys tangkahkeii was the key baitfish with the strongest ability to determine structure of species in higher trophic levels. Our study provided a reference for scientific management of shallow lake ecosystems and biological solutions for restoration of eutrophic lakes.

Anthropogenic influences on genetic diversity and differentiation of the clearhead icefish (Protosalanx hyalocranius), as revealed by mitochondrial and microsatellite DNA markers

The clearhead icefish, Protosalanx hyalocranius, is an economically important fishery species in China. For the past few decades, the wild resources of P. hyalocranius have markedly decreased due to human activities such as overfishing, hydro-projects and water pollution. Meanwhile, P. hyalocranius has been widely introduced into lakes and reservoirs of northern China and some have become established, invasive populations, leading to detrimental effects on ecosystems. Using mitochondrial control region sequences and nine microsatellite DNA markers, the aim of this study was to assess to what extent human activities could impact the genetic diversity and population structure of P. hyalocranius, and explore the sources of the invasive Heilong River population based on genetic characterization. Based on mitochondrial DNA, the average haplotype diversity and nucleotide diversity among six populations were 0.737 and 0.0029 respectively. Based on microsatellite markers, the observed (HO) and expected (HE) heterozygosities in each population ranged from 0.481 to 0.565 and 0.478 to 0.565, respectively. Both mitochondrial and microsatellite markers indicated the genetic diversity in Chaohu Lake was the lowest. HO and HE of the two anadromous populations (Liao River Estuary and Yalu River Estuary) were close to Chaohu Lake and relatively low among all populations. The pairwise Dest values showed high and significant genetic differentiation between Taihu Lake and other populations. There was no evidence of genetic differentiation between Chaohu Lake and the two anadromous populations. No significant reduction of genetic diversity was observed in the Heilong River population. Bottleneck analysis showed that the two anadromous populations may have experienced a recent genetic bottleneck. DIYABC analysis suggested that the sources of the invasive Heilong River population were Taihu and Hongze lakes, with a greater genetic contribution from Hongze Lake. Therefore, the anadromous populations of P. hyalocranius may have suffered more impacts from human activities than the strictly freshwater populations. Among freshwater populations, Chaohu Lake should also be paid more attention in fisheries management. In addition, our study demonstrated that multiple introductions can give rise to high genetic diversity in an invasive population.

Phylogenetic Analysis of Core Melanin Synthesis Genes Provides Novel Insights Into the Molecular Basis of Albinism in Fish.

Melanin is the most prevalent pigment in animals. Its synthesis involves a series of functional genes. Particularly, teleosts have more copies of these genes related to the melanin synthesis than tetrapods. Despite the increasing number of available vertebrate genomes, a few systematically genomic studies were reported to identify and compare these core genes for the melanin synthesis. Here, we performed a comparative genomic analysis on several core genes, including tyrosinase genes (tyr, tyrp1, and tyrp2), premelanosome protein (pmel), microphthalmia-associated transcription factor (mitf), and solute carrier family 24 member 5 (slc24a5), based on 90 representative vertebrate genomes. Gene number and mutation identification suggest that loss-of-function mutations in these core genes may interact to generate an albinism phenotype. We found nonsense mutations in tyrp1a and pmelb of an albino golden-line barbel fish, in pmelb of an albino deep-sea snailfish (Pseudoliparis swirei), in slc24a5 of cave-restricted Mexican tetra (Astyanax mexicanus, cavefish population), and in mitf of a transparent icefish (Protosalanx hyalocranius). Convergent evolution may explain this phenomenon since nonsense mutations in these core genes for melanin synthesis have been identified across diverse albino fishes. These newly identified nonsense mutations and gene loss will provide molecular guidance for ornamental fish breeding, further enhancing our in-depth understanding of human skin coloration.

Female-specific genomic regions and molecular sex identification of the clearhead icefish (Protosalanx hyalocranius)

BackgroundThe clearhead icefish, Protosalanx hyalocranius, is an economically important fishery species in China. Since 1980s, P. hyalocranius was widely introduced into lakes and reservoirs of northern China for aquaculture. However, the lack of a rapid and cost-effective sex identification method based on sex specific genetic markers has hindered study on sex determination mechanisms and breeding applications.ResultsFemale-specific genomic regions were discovered by comparing whole genome re-sequencing data of both males and females. Two female-specific genomic regions larger than 50 bp were identified, and one (598 bp) contained a putative FOXI gene, which was paralogous to another FOXI gene with sex-associated SNPs. The two FOXI sequences displayed significant length difference with nine deletions of total length of 230 bp. This deletion-type structural variation could be easily and efficiently detected by traditional PCR and agarose gel electrophoresis with one 569 bp band for males and two bands (569 and 339 bp) for females, which were validated in 50 females and 40 males with known phenotypic sexes.ConclusionsThe results provided structural genomic evidence for the ZZ/ZW sex determination system in P. hyalocranius discovered in our previous study with association analysis of SNPs. Moreover, the female-specific markers and rapid and cost-effective PCR-based genetic sex identification method should have applications in further studies of sex determination mechanism for this species.

Fshr: a fish sex-determining locus shows variable incomplete penetrance across flathead grey mullet populations.

SummaryWhole-genome sequencing data were produced from a single flathead grey mullet female and assembled into a draft genome sequence, whereas publicly available sequence data were used to obtain a male draft sequence. Two pools, each consisting of 60 unrelated individuals, respectively, of male and female fish were analyzed using Pool-Sequencing. Mapping and analysis of Pool-Seq data against the draft genome(s) revealed >30 loci potentially associated with sex, the most promising locus of which, encoding the follicle-stimulating hormone receptor (fshr) and harboring two missense variants, was genotyped on 245 fish from four Mediterranean populations. Genotype data showed that fshr represents a previously unknown sex-determining locus, although the incomplete association pattern between fshr genotype and sex-phenotype, the variability of such pattern across different populations, and the presence of other candidate loci reveal that a greater complexity underlies sex determination in the flathead grey mullet.

Genome‐wide association analyses based on whole‐genome sequencing of Protosalanx hyalocranius provide insights into sex determination of Salangid fishes

Identification of sex determination system and sex-determining genes have important implications in conservation, ecology and evolution. However, much remains to be discovered about the evolution of different sexual determination systems in teleost fishes, of which the mechanisms of sex determination are remarkably variable. In the present study, the whole genomes of 20 males and 20 females of a Salangid fish, Protosalanx hyalocranius, were sequenced and genome wide association analyses were conducted to uncover its sex determination system and putative sex-determining genes. A total of 150 SNPs were significantly associated with sex, which showed high differentiation between sexes (FST ranged from 0.245 to 0.556). Of the 150 sex-associated SNPs, 76 SNPs displayed sex specificity with even coverage of depth and were female heterogametic, which suggested a ZZ/ZW sex determination system. Interestingly, one scaffold containing sex-specific SNPs displayed synteny to the sex chromosome of medaka. Annotations of sex-associated loci suggested that both transcriptional regulators (e.g., FOX genes) and secreted hormones and their receptors might be involved in the sex determination/differentiation of P.hyalocranius. More strikingly, we found a nonsense mutation in one copy of GALNT homology gene of all females, which suggested that "Z dosage" effect might play a vital role in the processes of sex determination/differentiation. These sex-specific loci could be a valuable resource for further research on sex determination of Salangid fishes and the results could contribute to the understanding of sex determination mechanisms and the evolution of sex chromosome in teleost fishes.

Long-term monitoring revealed fish assemblage zonation in the Three Gorges Reservoir

Reservoirs are important artificial ecosystems that modify the hydrological and ecological characteristics of a river. Knowledge of the basic characteristics of fish assemblages in reservoirs is a first step toward the development of effective conservation policies. We used the information collected over a 10-year period (2006-2015) to assess the structure of the fish assemblages in the Three Gorge Reservoir (TGR) in a river-dam gradient. Three fish zones were detected in TGR. Species richness was the highest in the upper zone and lowest in the lower zone. The riverine zones were dominated by rheophilic species Coreius guichenoti and Pelteobagrus vachelli. The transitional zones were dominated by Coreius heterodon and Rhinogobio cylindricus. The lacustrine zones were dominated by eurytopic species Hypophthalmichthys molitrix, Aristichthys nobilis, Hemiculter bleekeri and Cvprinus carpio. For the functional characteristics, fish assemblages in riverine and transitional zones were dominated by insectivorous species, equilibrium strategists and rheophilic species (e.g., Coreius heterodon and Coreius guichenoti). In lacustrine zones, the fish assemblage was dominated by habitat generalists common to lakes and reservoirs (e.g., Hemiculter bleekeri, Hypophthalmichthys molitrix, Aristichthys nobilis). Moreover, 18 exotic species (e.g., Protosalanx hyalocranius, Ictalurus punctatus, Megalobrama amblycephala, Tilapia) were collected in TGR, most of which only existed in the lacustrine zone. The results highlight the importance of freely flowing riverine reaches for conserving native fish in the upper Changjiang River and adaptive management strategies for fisheries in TGR.

Complete mitochondrial genome of the Salangid icefish Neosalanx taihuensis (Actinopterygii: Osmeriformes: Salangidae)

The complete mitochondrial DNA genome of the Salangid icefish (Neosalanx taihuensis) was sequenced by the primer walking sequence method. The entire mitochondrial genome of this species is 17,035 bp in length, making it the longest among the reported mitochondrial genomes of Osmeriformes. It contains 13 protein-coding genes, 2 ribosomal RNA (rRNA) genes, 22 transfer RNA (tRNA) genes, and one control region (CR). The gene arrangement, nucleotide composition, and codon usage pattern of the mitochondrial genome are similar to those of other teleosts except for two long tandem repeats in the CR. A 486 bp tandem repeat fragment was identified that comprises 2 copies of 243 bp motif and accounts approximately 35.5% of the CR. The 243 bp tandem repeat motif can be folded into a stem-loop secondary structure. Phylogenetic analysis based on 12 concatenated protein-coding genes of the heavy strand shows the genus Neosalanx diverged most recently and clustered with Protosalanx hyalocranius as a clade.

Whole genome sequencing of Chinese clearhead icefish, Protosalanx hyalocranius.

Background: Chinese clearhead icefish, Protosalanx hyalocranius, is a representative icefish species with economic importance and special appearance. Due to its great economic value in China, the fish was introduced into Lake Dianchi and several other lakes from the Lake Taihu half a century ago. Similar to the Sinocyclocheilus cavefish, the clearhead icefish has certain cavefish-like traits, such as transparent body and nearly scaleless skin. Here, we provide the whole genome sequence of this surface-dwelling fish and generated a draft genome assembly, aiming at exploring molecular mechanisms for the biological interests. Findings: A total of 252.1 Gb of raw reads were sequenced. Subsequently, a novel draft genome assembly was generated, with the scaffold N50 reaching 1.163 Mb. The genome completeness was estimated to be 98.39 % by using the CEGMA evaluation. Finally, we annotated 19 884 protein-coding genes and observed that repeat sequences account for 24.43 % of the genome assembly. Conclusion: We report the first draft genome of the Chinese clearhead icefish. The genome assembly will provide a solid foundation for further molecular breeding and germplasm resource protection in Chinese clearhead icefish, as well as other icefishes. It is also a valuable genetic resource for revealing the molecular mechanisms for the cavefish-like characters.

Effects of 17β-estradiol and 17α-ethinylestradiol on the embryonic development of the clearhead icefish (Protosalanx hyalocranius)

Estrogenic effects of 17β-estradiol (E2) and 17α-ethinylestradiol (EE2) on animals have been widely reported. The high sensitivity of fish in the early-life stages to xenobiotics can be exploited to evaluate the developmental effects of environmentally relevant levels of E2 and EE2. In this work, clearhead icefish (Protosalanx hyalocranius) embryos (blastula stage) were exposed to E2 or EE2 at concentrations between 0.05 ng/L and 1 mg/L. The toxicity endpoints of mortality, teratogenesis, and hatching retardation were evaluated. The results showed that continuous exposure of the fish embryos/larvae to higher concentrations of E2 and EE2 dramatically increased mortality after 17 days, when the hatching period started. An E2 concentration of 8 μg/L (day 16) and an EE2 concentration of at 0.2 mg/L (day 18) induced maximum teratogenesis rates of 30% and 35%, respectively. Embryos exposed to 0.2 mg E2 or EE2/L had a significantly retarded hatching time compared to the control. Thus, although environmentally relevant concentrations E2 and EE2 are not lethal for P. hyalocranius embryos or larvae, their ability to induce teratogenesis and hatching retardation merits concern.

黄海中部近岸春夏季鱼卵、仔稚鱼群落结构特征

PDF HTML阅读 XML下载 导出引用 引用提醒 黄海中部近岸春夏季鱼卵、仔稚鱼群落结构特征 DOI: 10.5846/stxb201410091983 作者: 作者单位: 中国海洋大学水产学院,中国海洋大学水产学院,中国海洋大学水产学院,中国海洋大学水产学院,中国海洋大学水产学院,中国科学院海洋研究所海洋生态与环境科学重点实验室 作者简介: 通讯作者: 中图分类号: 基金项目: 高等学校博士学科点专项科研基金项目(20120132130001);中央高校基本科研业务费专项资金项目(201262004);国家自然科学基金委-山东省联合基金项目(U1406403);海洋公益性行业科研专项经费项目(201305030) The community structure of ichthyoplankton in the central Yellow Sea in spring and summer Author: Affiliation: College of Fisheries,Ocean University of China,Qingdao-,College of Fisheries,Ocean University of China,Qingdao-,College of Fisheries,Ocean University of China,Qingdao-,College of Fisheries,Ocean University of China,Qingdao-,College of Fisheries,Ocean University of China,Qingdao-,Key Laboratory of Marine Ecology and Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences. Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:2013年4月下旬至7月上旬,采用浅水I型网垂直拖网的调查方式对黄海中部20m以浅海域(34°30'-35°30'N,119°20'-120°20'E)的鱼卵、仔稚鱼种类组成与数量分布进行了6个航次的综合调查。春夏季共采集鱼卵21种(未定种3种),共计2247粒,隶属于9科15属。仔稚鱼22种(未定种1种),共计286尾,隶属于13科17属。鱼卵优势种为日本鳀Engraulis japonicus、赤鼻棱鳀Thryssa kammalensis、江口小公鱼Stolephorus commersonnii、皮氏叫姑鱼Johnius belengerii和属Callionymus spp.。仔稚鱼优势种为大银鱼Protosalanx chinensis、白姑鱼Argyrosomus argentatus、日本鳀、赤鼻棱鳀和皮氏叫姑鱼。鱼卵丰度和分布与经度呈负相关、与SST呈正相关,但与其他环境因子如纬度、表层盐度(SSS)和水深等无显著相关性。仔稚鱼丰度和分布与上述环境因子均未表现出显著相关性。基于Bray-Curtis指数的聚类分析表明,鱼卵优势种包括集中分布于研究水域34°48'N以南海域(江口小公鱼、皮氏叫姑鱼和青鳞小沙丁Sardinella zunasi)、10m等深线以内(赤鼻棱鳀),以及北部水域(日本鳀和属)3种主要聚集类型;仔稚鱼优势种包括集中分布于34°48'N-35°12'N海域(赤鼻棱鳀和日本鳀)、连云港外海浅水区(白姑鱼、皮氏叫姑鱼和梭鱼Liza haematocheilus,以及南部水域(褐菖鲉Sebastiscus marmoratus和鲬Platycephalus indicus)3种主要聚集类型。研究结果揭示了黄海中部近岸海域鱼卵、仔稚鱼群落的时空分布格局动态,为科学认识环境变动下该海区渔业种群数量动态和资源变化提供了科学依据。 Abstract:Knowledge of the ecology of ichthyoplankton (eggs, larvae, and fry) is important for understanding the spawning ecology and the population dynamics of fishery species. In this study, a total of six fishery research cruises were conducted to investigate the community structure and ecology of ichthyoplankton in the central Yellow Sea (34°30'-35°30' N, 119°20'-120°20' E), one of the most concentrated spawning areas for fishery species in Chinese coastal waters, from late April to early July 2013. To collect ichthyoplankton, zooplankton nets (mouth diameter=50 cm, length=145 cm, and mesh size=0.505 mm) were vertically trawled in waters below the 20 m isobath line. The species composition, abundance, and distribution of the ichthyoplankton, and their relationships with environmental factors, were studied. A total of 2247 eggs and 286 larvae were collected during the research cruises. The eggs were identified as belonging to 18 species in 15 genera in 9 families; 3 species could not be identified. The eggs were dominated by Engraulis japonicus, Thryssa kammalensis, Stolephorus commersonii, Johnius belengerii, and Callionymus spp. The larvae were identified as belonging to 21 species in 17 genera in 13 families; only one species could not be identified. The dominant larval species included Protosalanx hyalocranius, Argyrosomus argentatus, E. japonicus, T. kammalensis, and J. belengerii. The abundance of the eggs was positively correlated with the sea surface temperature (SST) but was negatively correlated with the longitude (P < 0.05). In contrast, the abundance of the larvae did not show a significant correlation with any of the investigated environmental factors, such as longitude, latitude, SST, sea surface salinity (SSS), or water depth. Cluster analysis based on the Bray-Curtis similarity index identified three assemblages of eggs and larvae at the 35% and 12% similarity levels, respectively. The eggs were grouped into assemblages dominating the southern waters from 34°48'N (S. commersonii, J. belengerii, and Sardinella zunasi), the < 10 m isobath waters (T. kammalensis), and the northern waters (E. japonicas and Callionymus spp.). The larvae were grouped into assemblages that were mainly distributed in the 34°48'N-35°12'N waters (T. kammalensis and E. japonicus), the shallow waters off Lianyungang (A. argentatus, J. belengerii, and Liza haematocheilus), and the southern part of the study area (Sebastiscus marmoratus and Platycephalus indicus). The findings of this study clarified the spatial and temporal distribution patterns as well as the structure of the ichthyoplankton community in the central Yellow Sea, which may help to improve our understanding of the population dynamics of fishery species in these waters. 参考文献 相似文献 引证文献

Aquatic biota as potential biological indicators of the contamination, bioaccumulation and health risks caused by organochlorine pesticides in a large, shallow Chinese lake (Lake Chaohu)

Aquatic biota have long been recognized as bioindicators of the contamination caused by hydrophobic organic contaminants (HOCs) in aquatic environments. The primary purpose of the present study is to identify which species of aquatic biota are the most sensitive to organochlorine pesticides (OCPs) in Lake Chaohu and can therefore serve as indicators of the lake's health and assist in the assessment of OCPs risks to human health. OCP levels in eight species of aquatic biota were measured using GC–MS, and the relationships between the biota and OCP levels in the water and suspended solids were studied. DDTs pose potential human health risks and were the predominant OCP components found in the aquatic biota. DDT had the highest mean bioaccumulation factor (BAF) and biota suspended solids accumulation factor (BSSAF) of all of the studied OCP components. The food web magnification factors (FWMF) for p, p′-DDT were greater than 1, implying that biomagnification occurred. This finding indicates that DDTs still pose a serious threat to the ecosystem and human health in Lake Chaohu, even though the agricultural application of DDT powder has been officially banned since 1983. There were significant positive relationships between OCPs levels in Culter erythropterus and those in both water and suspended solids, as well as between OCPs levels in Protosalanx hyalocranius and those in suspended solids. This finding suggests that C. erythropterus and P. hyalocranius are the most sensitive aquatic biota to OCPs and may serve as the most effective bioindicators for monitoring OCP contamination in the water and suspended solids of Lake Chaohu. Megalobrama amblycephala, which contained the highest wet weight mean OCP concentration, is the most sensitive OCP indicator and can be used to assess the human carcinogenic risk of OCPs in Lake Chaohu.

松嫩湖群鱼类群落相似性

松嫩湖群鱼类群落相似性

Clearhead icefish, (Protosalanx hyalocraniusAbbott, 1901) (Salmoniformes, Salangidae), a new non-native species has established a population in the Amur River, China

Clearhead icefish, (<i>Protosalanx hyalocranius</i>Abbott, 1901) (Salmoniformes, Salangidae), a new non-native species has established a population in the Amur River, China

Complete mitochondrial genome of clearhead icefish Protosalanx hyalocranius (Salmoniformes: Salangidae)

In this study, we sequenced and determined the complete mitochondrial genome of clearhead icefish (Protosalanx hyalocranius). The circular mitochondrial genome (16,693 bp) contained 13 protein-coding genes, 22 transfer RNA genes, 2 ribosomal RNA genes, and 1 control region. All genes were encoded on the heavy strand with the exception of ND6 and eight tRNA genes.

Diet composition and transition of clearhead icefish(Protosalanx hyalocranius)in Lake Xingkai

Diet compositions of alien clearhead icefish(Protosalanx hyalocranius)in Lake Xingkai were investigated monthly from June 2010 through January 2011. Protosalanx hyalocranius preyed mainly on cladoceran, copepoda, shrimp, and larvae or juvenile fish. In June, P. Hyalocranius were smaller than 60 mm standard length(SL), and their diets were composed of zooplankton only. In July, fish began to appear infrequently in the diet of P. Hyalocranius larger than 60 mm SL, and by August fish was occurring in the diets of P. hyalocranius larger than 80 mm, 100 mm in September, and 120 mm in October and thereafter, respectively. The increase in the minimum SL of P. hyalocranius preying on fish within a given season reflects changes in resource availability, largely attributed to the corresponding increase in prey fish size as seasons progress. Protosalanx hyalocranius and Hemiculter sp. were the dominant prey fish in the diets of P. hyalocranius.

Metal accumulation in fish from different zones of a large, shallow freshwater lake

Metal (Cd, Pb, Cr, Ni, Mn, Cu, and Zn) concentrations in different fish species sampled from two distinct (phytoplankton- and macrophyte-dominated) lake zones of a large, shallow freshwater lake, Taihu Lake, were investigated. Concentrations of most metals in muscle of the small-sized fish (Protosalanx hyalocranius, Pseudorasbora parva, and Rhodeus ocellatus) were always significantly higher than those of the large-sized (Carassius auratus, Cyprinus carpio, and Aristichthys nobilis) and carnivorous fish (Pelteobagrus fulvidraco, Cultrichthys erythropterus, and Erythroculter ilishaeformis). Metal accumulation in the small-sized fish from the phytoplankton-dominated lake zone was always greater than those from the macrophyte-dominated lake zone in summer. However, no significant differences were observed between the two lake zones for most metals in the small-sized fish collected in winter. Metal accumulation in gills, liver, and intestine of the large-sized fish from the phytoplankton-dominated lake zone was generally greater than those from the macrophyte-dominated lake zone in summer. The presence of distinct ecological regions in the lake might affect the metal distribution in the small-sized or large-sized fish. For the carnivorous fish, however, metal concentrations in fish tissues from the two different lake zones were not significantly different, suggesting that metal accumulation in carnivorous fish might be less influenced by the ecological status of the lake.

Growth, length-weight relationship and biological information on the clearhead icefish (Protosalanx hyalocraniusAbbott, 1901) in Lake Khanka (Xingkai)

This paper reports the growth pattern and length-weight relationship and summarizes biological data for the clearhead icefish (Protosalanx hyalocranius) in Lake Khanka (Xingkai), on the border between China and Russia. The von Bertalanffy growth was estimated as SL = 20.3(1 - e-2.93 (t - 0.21)). The length-weight relationship was W = 0.00448 SL2.99 for juveniles, and W = 0.000896 SL3.59 for adults. P. hyalocranius mature in December and spawn in January, when the lake is still covered with ice, then die after spawning. The larvae hatch in March. Juveniles feed mainly on zooplankton whereas adults also feed on other fishes.

Genetic diversity of &lt;i&gt;Neosalanx taihuensis&lt;/i&gt; based on mitochondrial COI sequences

利用线粒体细胞色素C氧化酶I(COI)分子标记分析长江中下游太湖新银鱼(Neosalanx taihuensis)8个地理种群132个样本的遗传多样性.该基因630 bp片段的碱基序列共检出8个核苷酸变异位点(变异率1.27%),其中局域性单倍型居多(75%),群体单倍型多样性较高(h=0.576±0.036),而核苷酸多样性较低(π=0.00112±0.00204).不同地理种群遗传多样性差异显著:有人工移植历史种群遗传多样性较高、隔离度较高的种群遗传多样性较低,但大部分的遗传变异来自于种群内(54.83%),反映出地理隔离和人为干扰对太湖新银鱼遗传格局影响显著.研究表明COI基因适于银鱼科鱼类物种鉴别和系统发育研究,同时可为同种种群间遗传关系分析提供一定的信息.;Neosalanx taihuensis is an annual fish with commercial importance. This species is endemic to China, occurring in inland waters affiliated to the eastern-flowing rivers southern to the Yellow River, e. g. the rivers of Yellow, Huaihe, Yangtze, Ou and Pearl etc. Among these river basins, the Yangtze River tests to be the most important region for this species with the highest fishery stocks and the most populations, and thus to be the core area for its conservation and sustainable exploitation. In the near decades, however, N. taihuensis decreased severely with most of the natural populations extinguished economically or even ecologically. The local population extinction infers that the species' genetic diversity must have suffered bad influence and some genetic types must have lost as result. To test this presumption, we conducted an icefish-specific investigation in the mid-lower reaches of Yangtze River during August, 2006. Totally eight populations were sampled and used in the followed experiment on their genetic diversity. Based on the gene diversity of mitochondrial cytochrome oxidase subunit I(COI), we mainly focus on two points:1) to find out the genetic diversity in single population and among populations for understanding the genetic status of wild N. taihuensis in the river basin, 2) to check the suitability of COI gene for DNA barcoding study in the family of Salangidae. We selected 132 specimens, representing eight different geographic populations in the mid-lower Yangtze River basin, and analyzed their base sequences of COI gene. Among the 630 bp nucleotide sequence of COI gene, eight(1.27%) was variation sites, contributing to eight gene haplotypes. Although the number of gene haplotype and the nucleotide diversity index(π=0.00112 ± 0.00204) were not high, haplotype diversity(h) was fairly rich(h=0.576 ± 0.036) in the populations at river basin scale. Taking spatial distribution pattern into account, most gene haplotypes distributed in spatially narrow region with quite low occurrence incidences of 12.5% or 25.0%, occurred in one or two lakes respectively. Haplotype richness in each population varied significantly from each other, with a high fixation index. The least haplotypes occurred in the two highly isolated lakes of Dongting and Liangzi, and the highest haplotype richness occurred in the two lakes with icefish introduction histories. This result indicates that a high inter-population variation existed in the studied region. So we concluded that wild populations of N. taihuensis have suffered great ecological isolation, although they are geographically near to each other. Comparing with several other salangid fishes, e. g. Protosalanx hyalocranius, Hemisalanx brachyrostralis and N. oligodontis, the inter-specific genetic distance was 4.443%, amounting to some 35 times of that in N. taihuensis populations(0.125%). Compared with other fish taxa, such as Coilia, Culter, Oncorhynchus and Salmo, the intra-specific genetic distance was much smaller within N. taihuensis populations(< 1%). In conclusion, the COI gene is good and suitable to DNA barcode study in species identifying and systematic study, and can be useful in the assessment, monitoring and conservation management of icefish genetic diversity.