Jianbo Chang

Feeding habits and habitats preferences affecting mercury bioaccumulation in 37 subtropical fish species from Wujiang River, China.

The present study is the first to report the total mercury concentration of 37 fish species collected from Wujiang River, which is the largest branch on the southern bank of Yangtze River, China and proposed for hydropower development. Total mercury concentrations varied among the 37 subtropical species examined. We found higher mercury concentrations in carnivorous species demonstrating greater mercury bioaccumulation in species with more predatory feeding habits. There is no significant difference between fish grouped by habitat preference and feeding habit. However, carnivorous species preferring benthic positions had higher total mercury concentrations than others suggesting that mercury accumulation is related to the interaction of feeding habit and habitat preference. In our study, fish that are bottom living and feed on other fish or aquatic animals are more likely at high risk of mercury exposure. Additional mercury contamination and future impoundment may raise mercury concentration in fish in the Wujiang causing concern for human health and ecological impacts.

Effects of damming on population sustainability of Chinese sturgeon, Acipenser sinensis : evaluation of optimal conservation measures

The numbers of spawning sites for Chinese sturgeon have been drastically reduced since the construction of the Gezhouba Dam across the Yangtze River. This dam has blocked migration of Chinese sturgeon to their historic spawning ground causing a significant decline of the Chinese sturgeon population. We conducted a VORTEX population viability analysis to estimate the sustainability of the population and to quantify the efficiency of current and alternative conservation procedures. The model predicted the observed decline of Chinese sturgeon, resulting from the effect of the Gezhouba Dam. These simulations demonstrated the potential interest of two conservation measures: increasing spawning area and reducing predation on sturgeon eggs. The simulations also demonstrated that the actual restocking program is not sufficient to sustain sturgeon population as the artificial reproduction program induce the loss of more wild mature adults that the recruitment expected by the artificial reproduction.

Acute Toxicity, Respiratory Reaction, and Sensitivity of Three Cyprinid Fish Species Caused by Exposure to Four Heavy Metals

Using 3 cyprinid fish species zebra fish, rare minnow, and juvenile grass carp, we conducted assays of lethal reaction and ventilatory response to analyze sensitivity of the fish to 4 heavy metals. Our results showed that the 96 h LC50 of Hg2+ to zebra fish, juvenile grass carp, and rare minnow were 0.14 mg L−1, 0.23 mg L−1, and 0.10 mg L−1, respectively; of Cu2+0.17 mg L−1, 0.09 mg L−1, and 0.12 mg L−1 respectively; of Cd2+6.5 mg L−1, 18.47 mg L−1, 5.36 mg L−1, respectively; and of Zn2+44.48 mg L−1, 31.37 mg L−1, and 12.74 mg L−1, respectively. Under a 1-h exposure, the ventilatory response to the different heavy metals varied. Ventilatory frequency (Vf) and amplitude (Va) increased in zebra fish, juvenile grass carp, and rare minnows exposed to Hg2+ and Cu2+ (P<0.05), and the Vf and Va of the 3 species rose initially and then declined when exposed to Cd2+. Zn2+ had markedly different toxic effects than the other heavy metals, whose Vf and Va gradually decreased with increasing exposure concentration (P<0.05). The rare minnow was the most highly susceptible of the 3 fish species to the heavy metals, with threshold effect concentrations (TEC) of 0.019 mg L−1, 0.046 mg L−1, 2.142 mg L−1, and 0.633 mg L−1 for Hg2+, Cu2+, Cd2+, and Zn2+, respectively. Therefore, it is feasible to use ventilatory parameters as a biomarker for evaluating the pollution toxicity of metals and to recognize early warning signs by using rare minnows as a sensor.

Spatiotemporal patterns of the fish assemblages downstream of the Gezhouba Dam on the Yangtze River

An explicit demonstration of the changes in fish assemblages is required to reveal the influence of damming on fish species. However, information from which to draw general conclusions regarding changes in fish assemblages is insufficient because of the limitations of available approaches. We used a combination of acoustic surveys, gillnet sampling, and geostatistical simulations to document the spatiotemporal variations in the fish assemblages downstream of the Gezhouba Dam, before and after the third impoundment of Three Gorges Reservoir (TGR). To conduct a hydroacoustic identification of individual species, we matched the size distributions of the fishes captured by gillnet with those of the acoustic surveys. An optimum threshold of target strength of −50 dB re 1 m2 was defined, and acoustic surveys were purposefully extended to the selected fish assemblages (i.e., endemic Coreius species) that was acquired by the size and species selectivity of the gillnet sampling. The relative proportion of fish species in acoustic surveys was allocated based on the composition (%) of the harvest in the gillnet surveys. Geostatistical simulations were likewise used to generate spatial patterns of fish distribution, and to determine the absolute abundance of the selected fish assemblages. We observed both the species composition and the spatial distribution of the selected fish assemblages changed significantly after implementation of new flow regulation in the TGR, wherein an immediate sharp population decline in the Coreius occurred. Our results strongly suggested that the new flow regulation in the TGR impoundment adversely affected downstream fish species, particularly the endemic Coreius species. To determine the factors responsible for the decline, we associated the variation in the fish assemblage patterns with changes in the environment and determined that substrate erosion resulting from trapping practices in the TGR likely played a key role.

The complete mitochondrial genome of Chinese sturgeon (Acipenser sinensis)

Abstract The complete mitochondrial genome of Chinese sturgeon (Acipenser sinensis) was determined by direct sequencing of PCR products. The Chinese sturgeon mitochondrial DNA is a circular molecule (16,688 bp in length) with the typical gene arrangement of vertebrate mtDNA, containing 13 protein-coding genes, two ribosomal RNA and 22 transfer RNA genes, and a non-coding control region. Its control region contains 4.5 copies of unit with 82 bp long at 5′ end, which has been reported before for this species. Phylogenetic tree based on 13 protein-coding genes confirmed that the complete mtDNA sequence of Chinese sturgeon was reported here for the first time.

Isolation and characterization of 15 microsatellite loci in an endemic Chinese cyprinid fish, Pseudogyrincheilus prochilus , and their cross-species amplification in two related species

Fifteen polymorphic microsatellite loci were developed for an endemic Chinese cyprinid fish, Pseudogyrincheilus prochilus. The number of observed alleles per locus ranged from 2 to 17. The observed and expected heterozygosities ranged from 0.067 to 1.000 and from 0.066 to 0.932, respectively. No significant linkage disequilibrium was detected among the loci. Two loci showed significant deviation from Hardy–Weinberg equilibrium, and one of them had evidence for null alleles. Fourteen primer pairs cross-amplified in Garra pingi pingi, and 13 primer pairs cross-amplified in Onychostoma sima. These microsatellite loci should prove highly informative for future studies of genetic diversity conservation.

The complete mitochondrial genome of the spotted longbarbel catfish, Hemibagrus guttatus (Siluriformes, Bagridae)

Abstract Spotted longbarbel catfish, Hemibagrus guttatus (Siluriformes, Bagridae), is regarded as one of the “four famous fish” in the Pearl River system in China. So far, very few genomic resources from this species were available. In the present study, the complete mitochondrial genome of H. guttatus was determined to be 16,528 bp long circular molecule with a typical gene arrangement of vertebrate mitochondrial DNA. It includes 22 transfer RNA genes, 2 ribosomal RNA genes, 13 protein-coding genes, and a non-coding control region (D-loop). The complete mtDNA genome sequence obtained in this study would be useful for studying genetic diversity and phylogenetics in H. guttatus and related taxa in future.

Microsatellites development for rock carp ( Procypris rabaudi ) and cross-species testing in Onychostoma sima and Spinibarbus sinensis

A total of thirty-six microsatellite loci were isolated and characterized in the endemic and endangered fish species rock carp (Procypris rabaudi) from China. Each locus was screened in a population of natural and artificial breeding individuals. The number of alleles observed per locus ranged from 2 to 13. The observed and expected heterozygosities ranged from 0.267 to 1.000 and 0.378 to 0.910. No significant linkage disequilibrium was detected among the loci. Significant deviations from Hardy–Weinberg equilibrium were found in fifteen loci, of which seven loci had evidence of null alleles. Twenty-five primer pairs cross-amplified in Onychostoma sima while thirty-two primer pairs cross-amplified in Spinibarbus sinensis. These microsatellite loci will be useful for future investigation on genetic population structure of P. rabaudi as well as other related species.

A Review on Conservation Issue in Chinese Paddlefish, Psephurus Glasius

Chinese paddlefish, Psephurus gladius, is an extremely rare species native to the Yangtze River. Its main spawning grounds are located in the upper reaches of the Yangtze River whereas young sturgeons have been known to drift from the upper reaches down to the river’s estuary. Due to the impact of Gezhouba hydraulic project construction, the paddlefish population has been divided into two population groups — one in the middle and lower reaches and the other in the upper reaches of the river, under the pressure of overfishing and environmental pollution, both of which are declining steadily. At present, the population in the middle and lower reaches is critically endangered, and the population in the upper reaches has not been successfully sighted in recent years. Since the 1980s, many protection measures have been implemented to protect the paddlefish, such as fishing restrictions, artificial breeding and habitat protection. However, with the deterioration of the overall ecological environment in the Yangtze River basin, it has proven difficult to reverse the decline in paddlefish population. Based on over 20 years of experience in paddlefish conservation, it is pointed out that more attention should be paid to the characteristics of the species as well as environmental protection in the whole basin. It is recommended that planning on the ecological rectification and restoration of the river basin that is centered on the conservation of fish species and their habitats be conducted.