Xinbin Duan

Changes in abundance of larvae of the four domestic Chinese carps in the middle reach of the Yangtze River, China, before and after closing of the Three Gorges Dam

The four domestic Chinese carps, i.e. grass carp (Ctenopharyngodon idella), black carp (Mylopharyngodon piceus), silver carp (Hypophthalmichthys molitrix) and bighead carp (Hypophthalmichthys nobilis), cast their drifting eggs in the running water of the Yangtze River. In 1997 ~ 2005, a systematic study on the dynamics of the abundance the larvae of the four domestic Chinese carps was performed in the middle reach of the Yangtze River, close to Sanzhou city. It was calculated that in breeding seasons from early May to late June every year the abundance of fry drifting through the section of Sanzhou was 3.59 billion in 1997, 2.75 billion in 1998, 2.15 billion in 1999, 2.85 billion in 2000, 1.90 billion in 2001, 1.90 billion in 2002, 406 million in 2003, 339 million in 2004 and 105 million in 2005 respectively. Several environmental parameters related to the dynamics of larval abundance were also examined simultaneously. The construction of the Three Gorges Dam near Yichang between the upper and middle reaches of the Yangtze River has apparently had a drastic influence on the abundance of fish larvae.

Relationship between meteorological conditions and natural reproduction behavior of the four famous Chinese carps

Known as the four famous carps in China, black carp (Mylopharyngodon piceus), grass carp (Ctenopharyngodon idella), silver carp (Hypophthalmichthys molitrix) and bighead carp (Hypophthalmichthys nobilis) are commercially important fish species with a high production in China. To reveal the relationships between meteorological conditions and the natural spawning behavior of these fishes, we considered six meteorological factors (including wind, rainfall, temperature, air pressure, sunshine hours and humidity) and the weather conditions in 80 spawning events. The results showed that the spawning activities were more likely to be activated in consecutive rainy days or days when weather changed drastically, while the spawning activities showed no tendency for the weather type except consecutive rainy days. Our analyses also showed that the average rainfall in the initial spawning days is higher than that in the spawning time windows (the time from the earliest spawning activity to the latest spawning activity), while other meteorological elements remained at more or less the same values in both time periods; spawning activity tended to happen in days when the average air pressure was going down or the average temperature going up, while the other meteorological elements showed no consistent tendency.

Threatened fishes of the world: Gymnocypris przewalskii (Kessler, 1876) (Cyprinidae: Schizothoracinae)

Common name: Qinghai Lake naked carp. Local name: Huang Yu (Chinese); Scaleless carp. Conservation status: Endangered, China Species Red List (Wang and Xie 2004). Identification: Fin rays: D(IV) 6–9, A(III)5, P(I)16–20, V(I)8–10; pharyngeal teeth: 3.4–4.3; gill rakers of the first gill arch: 30(13–51), 46 (23–72); body elongate and compressed, mouth terminal or sub-inferior and horseshoe-shaped; no barbels; body naked except 14–41 anal scales and 3–4 rows of scales in the shoulder girdle; lateral line scales degenerated to skinfold; last unbranched ray of dorsal fin hard with posterior serrations (Wu and Wu 1992). Illustration from Chen and Cao (2000). Distribution: Narrowly distributed in Qinghai Lake Basin located on the Qinghai-Tibet plateau in western China, with a record in Keluke Lake, Qinghai province (Wu and Wu 1992). Abundance: Up to 20×10 tons in 1960 (Shi et al. 2000), but has sharply decreased since 1970s to less than 0.5×10 tons now (Chen et al. 2009), and has not been collected in Keluke Lake since 1997 (Zhao 2006). Habitat and ecology: Predominantly distributed the layer about 2 m under the surface (Chen et al. 2009), mainly feeds on crustacean zooplankton, aquatic insects and Bacillariophyceae (Wang et al. 1975), slow growth. Reproduction: Sexual maturity over 7 years, relative fecundity 28.75 eggs per gram, seasonally migrates to inflowing rivers to spawn over the sandy, gravel beds, at 6–17.5°C water temperature from April to July (Hu et al. 1975). Threats: Illegal fishing, reduction of spawning habitat by construction of weirs, irrigation diversions and inflowing rives running dry, and ecological deterioration, especially decreasing water lever and increasing salinity (Walker et al. 1996). Conservation actions: Closed fishing for four times since 1982: 1982–1984, 1986–1989, 1994–2000, 2001–2010. Rescue Center of Gymnocypris przewalskii was established in 2003. Conservation recommendations: Effective spawning habitat protection and restoration is critical. Artificial enhancement and release, forbidding fishing, Longtime monitoring and increased public awareness are necessary. Environ Biol Fish (2010) 87:351–352 DOI 10.1007/s10641-010-9609-x

Complete mitochodrial genome of the redlip loach Leptobotia rubrilaris (Teleostei, Cypriniformes: Cobitidae)

Abstract In this study, the complete mitochondrial genome sequence of the Leptobotia rubrilaris has been obtained. The genome includes 13 protein-coding genes, 22 tRNA genes, 2 rRNA genes and a non-coding control region with the total length of 16,585 bp. The gene arrangement and composition were identical to other vertebrate. Most of the genes are encoded on heavy strand, except for eight tRNA and ND6 genes. The complete mitochondrial genome sequence of L. rubrilaris would contribute to better understand population genetics and protect its genetic diversity.

Identification and characterization of eighteen polymorphic microsatellite loci for a threatened freshwater fish, Botia superciliaris

Botia superciliaris, an endemic fish (Cobitidae) of China, is mainly distributed in the middle and upper reaches of the Yangtze river. It is an important freshwater species with potential commercial value. It lives in the bottom of the river with swift currents and spawns pelagic eggs (Yang and Ding 2010; Li et al. 2011). Relatively long rivers with continuous flow of water are necessary for its embryonic development and larval growth. However, with the construction of cascade hydropower stations within its distribution, B. superciliaris is suffering from severe threats to its survival (Yang and Ding 2010). In addition, due to overfishing and water pollution, natural resources of B. superciliaris have drastically decreased in recent years. Conservation and recovery of the genetic resources of this species should therefore be paid urgent attention (Heiner et al. 2011). For better planning of conservation efforts, it is necessary to understand its population genetic structure and genetic diversity. Unfortunately, very little is known about the population genetics of B. superciliaris, and the genetics studies thus far have focussed on mitochondrial markers (Liu et al. 2009). Microsatellite markers are useful for answering population genetics and conservation genetics questions because of codominance and high allelic polymorphism (Lawson and Zhang 2006). Nevertheless, there are no microsatellite markers available for B. superciliaris. The development of microsatellites for this species and their application is therefore very important. So, here, to enhance the conservation and recovery of genetic resources of B. superciliaris, we report the development and characterization of 18 polymorphic microsatellite loci in this species.

The mitogenome of Leptobotia microphthalma (Teleostei, Cypriniformes: Cobitidae)

Abstract The Leptobotia microphthalma belongs to family Cobitidae, which is endemic to the upper reaches of the Yangtze River in China. In this studying, the complete mitochondrial genome sequence of L. microphthalma has been obtained with PCR, which contains 13 protein-coding genes, 22 tRNA genes, 2 rRNA genes and a non-coding control region with the total length of 16,512 bp. The gene arrangement and composition are similar to that of other vertebrates. Most of the genes are encoded on heavy strand, except for eight tRNA and ND6 genes. The complete mitochondrial genome sequence of L. microphthalma would contribute to better understand population genetics and protect its genetic diversity.

The mitochondrial genome of Gnathopogon imberbis (Cypriniformes, Cyprinidae)

Abstract In the present study, the complete mitogenome sequence of Gnathopogon imberbis is determined using PCR amplification and DNA sequencing, which contains 13 protein-coding genes, 22 tRNA genes, 2 rRNA genes and a non-coding control region with the total length of 16,598 bp. Except for eight tRNA and ND6 genes, all other mitochondrial genes are encoded on the H-strand. The codon usage followed the typical vertebrate mitochondrial pattern (ATG or GTG for start codon and TAA or TAG for stop codon). The overall nucleotide composition was 30.0% A, 27.0% T, 25.8% C and 17.2% G, with an A + T bias of 57.0%. The complete mitochondrial genome sequence will be useful for phylogenetic analysis and studies of population genetics of G. imberbis.

Isolation and characterization of twelve microsatellite loci of Leiocassis albomargintus (Rendhal) in the Yangtze River

Leiocassis albomargintus (Rendhal) is endemic to the Yangtze River basin in China. By using the fast isolation by amplified fragment length polymorphism of sequences containing repeats protocol, we identified twelve microsatellite loci in a wild population. The number of alleles per locus ranged from 4 to 13. The observed and expected heterozygosity ranged from 0.4887 to 1.000 and from 0.5025 to 0.9180, respectively. Cross-amplification was tested in related species L. tenuifurcatus and L. crassilabris.

Species diversity of drifting fish eggs in the Yangtze River using molecular identification

The dam constructions greatly changed the hydrologic conditions in the Yangtze River, and then significantly affected the spawning activities of indigenous river fish. Monitoring the species composition of drifting eggs during spawning season is important for protection issues. In this study, we have sampled drifting fish eggs in nine locations from 2014 to 2016. Eggs were identified using the mitochondrial cyt b gene sequence. A total of 7,933 fish eggs were sequenced successfully and blasted into the NCBI database. Thirty-nine fish species were identified, and were assigned to four families and two orders. Approximately 64% of the species identified, and 67% of the eggs, were classified in the Family Cyprinidae. Abundance and Shannon–Wiener diversity index of species were higher in the main river than in tributaries of the river. However, tributaries may be important spawning grounds for some fish species. The Jaccard’s similarity index and river-way distances among sampled stations were negatively correlated suggesting the environment shapes species composition in the sampled spawning grounds. These results showed that mitochondrial DNA sequence is a powerful and effective tool for fish egg identification in Yangtze River and these data are useful for conservation efforts.

Using environmental DNA to detect Hypophthalmichthys molitrix during the spawning period in the Yangtze River

The silver carp, Hypophthalmichthys molitrix, is one of four carps farmed in China, and its natural resources have been critically declining in the middle and upper reaches of the Yangtze River. Here, we applied the environmental DNA (eDNA) methodology to detect silver carp during the spawning period in the Yangtze River to supplement traditional survey techniques for determining spawning grounds and the scale of breeding. The results showed that the variations in the concentration of silver carp eDNA were detected by quantitative PCR assay, and also suggested that its genetic diversity could be rapidly monitored using the eDNA method.