Search

The red swamp crayfish, Procambarus clarkii (Girard, 1852), is a paradox in China because it has developed as a popular aquaculture species while becoming a notorious invasive species. We investigated the population genetic diversity and population dynamics of wild Chinese populations of P. clarkii based on proPO fragments and the morphological traits across these populations. The results showed that the populations of P. clarkii exhibit high genetic diversity and significant population structure, inferring that the crayfish was artificially transferred rapidly among different locations for different reasons. Results also revealed distinct phenotypic differentiation, with individuals of some populations having a shorter pleon and wider carapace width, whereas other populations have a small length to width ratio. This study provided comprehensive insights into the population dynamics and morphological variations of P. clarkii, which contribute to understanding the rapid evolution of phenotypic traits after its successful invasion. Results should help establish efficient management strategies for the control of the invasion and at the same time using the genetic information in crayfish aquaculture.

Co-culture modes of rice and aquatic animals as rice-crayfish, rice-fish and rice-turtle have expanded rapidly in paddy rice cultivation regions, due to its ecological efficiency, contributions to food security, food productivity and economic benefits. However, different co-culture strategies have great influences on rice or aquatic animal growth and related ecological benefits. In this study, we investigated the effect of turtle stocking density on the dynamics of paddy soil fertility and microbial community characteristics in a rice-turtle co-culture ecosystem. The Chinese soft-shell turtles (Pelodiscus sinensis) were allocated to experimental paddy fields at four gradient stocking densities ranging from 360 to 540 kg· ha−1. In comparison with conventional rice cultivation with a higher input rate of chemical fertilizer, rice yields were higher in the rice-turtle paddies. In addition, soil pH and organic matter were relatively stable in the rice-turtle mode, whereas both parameters decreased over time in conventional paddies. Stocking density significantly benefited soil fertility, with soil organic matter increasing in response to higher stocking density. Total soil nitrogen concentration was lower in the conventional rice cultivation and low stocking density co-culture groups, compared with the high stocking density groups. Furthermore, the soil microbial communities were also affected by turtle stocking density. Redundancy analysis showed that soil pH, organic matter and available potassium concentration were the major factors influencing the abundance of the dominant microbes. The findings revealed the responses of paddy soil fertility and microbial community characteristics in rice-turtle co-culture modes, which could help optimize the co-culture mode and provide a basis for soil nutrient management in such ecosystems.

Grass carp (Ctenopharyngodon idellus) is one of the most important freshwater cultural species in China. However, obesity, fatty liver and digestive tract inflammation commonly exist in commercial grass carp, which may be due to excessive food and energy intake in daily feeding. Therefore, the feeding strategy should adapt to fish appetite, nutrition requirements and welfare in intensive aquaculture. To investigate the effects of feeding frequency on growth, physiology and metabolism-related fgf21 expression to provide a reference for the selection of feeding strategy, healthy and homogeneous juvenile grass carp (45.2 ± 2.5 g) were randomly divided and adapted to four feeding frequencies of 1, 2, 3 or 4 times/day following satiated feeding for 8 weeks. The growth rate increased with increasing feeding frequency. The hepatosomatic and abdominal fat-somatic indexes were higher in the higher feeding frequency groups, while the gut-somatic index was higher in the low feeding frequency groups (P

The Ultra Performance Liquid Chromatography-Triple-Time of Flight Mass Spectrometer (UPLC-Triple-TOF-MS/MS) based platform was developed to investigate the serum metabolic profile associated with the growth performance in Chinese softshell turtle fed with the diet added with Traditional Chinese Medicines (TCMs) feeding additive. 0.0%, 1.0%, 2.0%, 3.0%, 4.0% of TCMs were added to the base ration of the control group (CG), TCMs treatment group1 (TG1), TCMs treatment group2 (TG2), TCMs treatment group3 (TG3) and TCMs treatment group4 (TG4), respectively. Compared with control group (CG), the weight gain and special growth ratio firstly increased and lately decreased with increased dietary TCMs levels. The highest weight gain (5.824 ± 1.205) and specific growth rate (3.887 ± 0.367) were found in the TCMs treatment group 2 (TG2) (P < 0.05), and the lowest feed conversion ratio (1.785±0.015) also appeared in the TG2 group (P < 0.05). In the metabolomics assay, a total of 795 (VIP> 1) out of 3089 variable metabolites were significantly different between the TG2 and CG. 43 potential biomarkers between TG2 and CG groups were finally screened out on the basis of VIP > 1 and P < 0.05. The potential networks and pathways for the model were explored using MetaboAnalyst. A total of 43 potential biomarkers were confirmed involving thirteen different metabolic pathways. Following the diet added with 2% TCMs feeding additive, five metabolic pathways were affected, these included the following: phenylalanine, tyrosine and tryptophan biosynthesis, tyrosine metabolism, cysteine and methionine metabolism and arginine biosynthesis. This study indicated that the dietary supplementation TCMs as feed additives could influence the growth performance of the healthy juvenile turtles, and the optimal dose of supplementing TCMs to juvenile turtleswas 20 g/kg in diet.