RESUMEN

The Qilu Lake is an eutrophic shallow lake located in Yunnan Province, China. An ecological fishery project was initiated in the lake from 2011 to 2021 to introduce filter-feeding fish species that feed on algae, with the aim of improving water quality. In January 2022, when the ecological fishery project expired, all fisheries-related activities (including fish stocking and fishing activities) ceased in the lake. To comprehensively evaluate the initial alterations in fish community structure and diversity resulting from the fishing cessation in the Qilu Lake, the present study conducted field surveys within the one year before the fishing cessation (referred to as BFC) and the one year after the fishing cessation (referred to as AFC). A total of twenty-one fish species were collected, including four native species. Four species were recorded in the lake for the first time, including Pelteobagrus fulvidraco, Pelteobagrus vachelli, Paramisgurnus dabryanus, and Hyporhamphus intermedius. The number of fish species decreased from 21 to 13 following the fishing cessation. The fishes collected in both BFC and AFC are mainly omnivorous-feeding and of bottom-dwelling habits. The mean size of the fishes in the AFC sample shows a significant decrease compared to those in BFC. After the fishing cessation, the Shannon-Wiener diversity index and Margalef richness index of the fish slightly declined. The fish community structure of the Qilu Lake exhibits a high degree of similarity to adjacent lakes in central Yunnan. Our study demonstrates a significant shift in the fish community of the Qilu Lake following the fishing cessation, one which may adversely impact the stability of the lake ecosystem. To enhance fish species diversity in the Qilu Lake, it is recommended that policies be implemented to promote the ecological fishery project and improve habitat restoration for native fish species, while also regulating fish community structure.

RESUMEN

The post-release performance of cultured fish is crucial for understanding the viability of cultured fish and assessing the effects of stock enhancement programs. This study aimed to investigate the initial post-release performance of cultured Cyprinus chilia juveniles by examining their movement, spatial distribution, gut fullness, and gut microbiota in nature. In July 2022, a total of 20,000 C. chilia juveniles, tagged with visible implant fluorescence (VIE), were released into Qilu Lake, a shallow lake in southwestern China. Subsequently, continuous recapture was conducted at fixed recapture sites using trap nets during the first 7 days, one month and three months after release. Out of the released fish, 512 were recaptured, resulting in a recapture rate of 2.56%. The recaptured fish had a 100% tag retention rate. The majority (98.05%) of the recaptured fish were found in the recapture sites located on the eastern or western lakeshore, while only 10 fish were recaptured from the recapture sites in the northern lake area. The water depth range where the recaptured fish were found ranged from 190 to 350 cm, with most fish preferring depths less than 300 cm. The majority of the released fish migrated towards the eastern and western lakeshore, with long-distance movement (greater than 100 m) primarily occurring within the first four days after release. The level of gut fullness in the released fish initially decreased and then increased over time following release. Regarding gut microbiota, the dominant phyla observed in most samples were Firmicutes, Proteobacteria, Cyanobacteria, and Fusobacteria. Furthermore, significant variations in the dominant genera were observed across different samples. Principal coordinates analysis (PCoA) revealed clear separation between the microbial communities of pre-release and post-release C. chilia juveniles. This study demonstrated that VIE tagging was a suitable method for short-term marking of C. chilia juveniles. Lakeshores with water depths less than 300 cm were identified as preferred habitats for C. chilia juveniles. The primary adaptation period for cultured C. chilia juveniles released into the natural environment was found to be approximately 4-5 days. These findings contribute to our understanding of the post-release performance of cultured fish and may provide guidance for the management and evaluation of relevant stock enhancement programs.

RESUMEN

This study was conducted to determine the optimal temperature for Juvenile Coreius guichenoti, which is critically endangered in China. Test fish with an initial body weight range of 17.60-18.78 g were reared in 5 independent recirculating aquaculture systems (RAS) with three tanks (50 fish/tank) for 8 weeks. The water temperature of the RAS was set at 14 °C, 18 °C, 22 °C, 26 °C, and 30 °C, respectively. At conclusion of the feeding trial, the effects of water temperature on C. guichenoti were analyzed based on survival, growth performance, digestive enzymes activities, and antioxidant capacity. The results showed that the fish survived in all temperature groups. The fish in the groups (26 °C and 30 °C) had higher values of body length, body weight, specific growth rate, weight gain rate, and daily gain than those in the group (22 °C). The lowest values of growth performance were observed in the groups (14 °C and 18 °C) among the 5 groups. The lowest values of feed conversion ratio (FCR) were observed in the group (26 °C). Regression analysis identified the minimum FCR at 26.55 °C. The feeding rates (FR) were increased gradually with the increase of temperature. Regression analysis identified the maximum FR at 28.33 °C. The activities of protease and lipase in the gut were higher than those in the liver, while amylase activity was lower in the gut than that in the liver. There were no significant differences in activities of protease and lipase among different parts of the intestinal tract at the temperatures range from 18 to 26 °C. When the temperature was out the optimal range, C. guichenoti would be under chronic stress, resulting in decreased lysozyme activity and cortisol concentration. Inconclusion, the optimal temperature for juvenile C. guichenoti is 26.55-28.33 °C based on the maximal growth performance and feed utilization.

Asunto(s)

RESUMEN

The study compare the diversity patterns and processes of microbial community assembly in the water and sediment of Lake Wuchang (China) using high-throughput sequencing of 16S rRNA gene amplicons. A higher microbial α-diversity in the sediment was revealed (P < 0.01), and the most common bacterial phyla in water column were Proteobacteria, Cyanobacteria and Actinobacteria, while Proteobacteria, Acidobacteria, Chloroflexi and Nitrospirae were dominant in sediment. Functions related to phototrophy and nitrogen metabolism primarily occurred in the water column and sediment, respectively. The microbial communities in water column from different seasons were divided into three groups, while no such dispersion in sediment based on PCoA and ANOSIM. According to Pearson correlation analysis, water temperature, dissolved oxygen, water depth, total nitrogen, ammonium, and nitrite were key factors in determining microbial community structure in water column, while TN in sediment, conductivity, and organic matter were key factors in sediment. However, the stochastic processes (|ßNTI| < 2) dominated community assembly in both the water column and sediment of Lake Wuchang. These data will provide a foundation for microbial development and utilization in lake water column and sediment under the circumstances of increasing tendency of lake ecological fishery in China.

Asunto(s)

RESUMEN

Numerous studies have shown that thermal tolerance and intestinal heat resistance are strongly associated with temperature acclimation. However, few reports have successfully conducted similar research on fishes from the Qinghai-Tibetan Plateau, an area that is facing the threat of climate warming. Therefore, the present study determined the growth, thermal tolerance, and intestinal heat stress (exposure to 30°C) responses in juveniles of a Tibetan fish, Oxygymnocypris stewarti, acclimated to three temperature levels (10°C, 15°C, and 20°C, named as T10, T15, and T20, respectively) for 30 days. The fastest growth was recorded in the T15 group. At 1°C/30 min heating rate, the critical thermal maximum (CTMax ) ranged from 31.3°C to 32.3°C, and the lethal thermal maximum (LTMax ) ranged from 31.8°C to 32.6°C among the three acclimation temperatures. According to the results of thermal tolerance tests, the heat stress temperature was set to 30°C. When the water temperature reached 30°C, the expression of the intestinal heat shock protein 70 (HSP70) gene as well as the intestinal microbiome and histology of experimental fish were monitored at 0, 2, 6, and 12 h. The expression of HSP70 reached the highest level at 2 h in all three temperature treatments. The histological analysis showed damage to intestinal cells, including diffuse infiltration of lymphocytes, villi epithelial cell swelling, decrease of intestinal villi length, and cytoplasmic light staining at 2 h in all three temperature treatments. In terms of the intestinal microbiome, phyla Proteobacteria and Firmicutes dominated the treatments at each monitored time in the T10 and T15 groups and at 0 h in T20 group, while phyla Fusobacteria, Proteobacteria, and Cyanobacteria were dominant in treatments at 2, 6, and 12 h in the T20 group. The overall results indicated that acclimation temperature could affect the growth, thermal tolerance, and intestinal heat stress response of O. stewarti juveniles. As the first report on intestinal heat stress response associated with temperature acclimation in a Tibetan fish, this study will help to understand the potential effects of climate change on highland fishes.

RESUMEN

In this study, the eutrophication levels and nitrogen and phosphorus carrying capacities of Lake Changhu in Jingzhou, Hubei Province, China, were measured using the trophic level index (TLI) and Dillon model for the first time. The measurements were taken before (2013 and 2015) and after (2017 and 2018) the removal of pen aquaculture from the lake. The lake was divided into three districts: Lake Haizihu, Mahongtai Channel, and Lake Dahu. The results showed total nitrogen (TN), chemical oxygen demand (COD), chlorophyll a (Chl-a), and total suspended solid values were significantly higher in 2017 than in the other years. The Lake Haizihu district was predicted to be more seriously polluted than the other districts. In the sediment, the organic matter, STN (TN in sediment) and STP (TP in sediment) contents increased from 2013 to 2018. The mean TLI values ranged from 62.99 to 78.93 in the studied years, and the eutrophication level was highest in 2017. According to the Dillon model, when the target water quality was level III (GB 3838-2002, Ministry of Environmental Protection of China, 2002), the remaining TN and TP loading capacities were -1470.72 t/a and -182.74 t/a, respectively, in 2015, and 320.03 t/a and -111.14 t/a, respectively, in 2018. Our results provide valuable and integrated information about the water conditions of Lake Changhu, thus laying a foundation for the theoretical study of water eutrophication process in lakes and paving the way for informed decision-making for managing water environments to ensure the safety of ecology.

Asunto(s)

RESUMEN

To elucidate the role of dmrt1 in sex differentiation of a teleost fish Schizothorax kozlovi, the full-length sequences of its cDNA and promoter were cloned by rapid amplification of cDNA ends (RACE) and genome walking. The relative mRNA expression levels were determined by quantitative real-time PCR (RT-PCR). The 1095-bp dmrt1 cDNA was predicted to encode a protein of 264 amino acids. It was expressed only in the gonads, and the expression was 17-times higher in the testis than in the ovary. The 1215-bp promoter sequence of dmrt1 was cloned and analyzed to detect sex-related differences in its methylation levels. A significant negative relationship between the dmrt1 expression and CpG methylation of its promoter were found in the testes and ovaries of S. kozlovi. Significant differences in dmrt1 expression levels were also found between the larval and juvenile stages. No significant differences in expression were found during the entire larval stage, and in the individuals among three different temperature groups (10°C, 14°C, and 18°C). Considering that the sex of sampled larval fish cannot be distinguished, correlations between dmrt1 expression and effects of temperature on sex differentiation in S. kozlovi need further study.

Asunto(s)

RESUMEN

Pseudecheneis immaculatus is an endemic fish species in the Lantsang River. In this study, the complete mitochondrial genome sequence of P. immaculatus was determined and analyzed. The 16,432 bp long circular molecule consisted of 13 protein-coding genes, 2 rRNA genes, 22 tRNA genes, and a control region, and all genes show the typical gene arrangement conforming to the vertebrate consensus. The phylogenetic tree showed that P. immaculatus is closely related to P. sulcata. The present study can provide population genetics information for further exploration of the taxonomic status of P. immaculatus.

RESUMEN

Glyptothorax deqinensis is a small endangered Sisoridae fish mainly distributed in the southwest of China. In the present study, the complete mitochondrial genome of G. deqinensis was firstly sequenced. The total length of the G. deqinensis mitogenome is 16,542 bp, including 13 protein-coding genes, two ribosomal RNA genes, 22 transfer RNA genes, and a control region. Among these genes, 28 are encoded by the H-strand and 9 by the L-strand. The information mitogenome obtained herein will provide useful tools for future studies on population genetic and phylogenetic analyses of this fish.

RESUMEN

Bighead carps (Aristichthys nobilis) were divided into four groups with different feeding strategies: group A, nature live food only (fertiliser only, 200 g urea + 160 g ethylamine phosphate + 250 g Huangjintai bio-fertiliser); group B, nature live food + 1/2 formulated feed; group C, nature live food + formulated feed; and group D, formulated feed only. The intestinal microbiomes of the different groups were compared through the Illumina MiSeq sequencing of the bacterial 16S rRNA gene. The specific growth rate (SGR), survival and blood biochemical factors of the fish were also investigated. Results showed that feeding treatment influenced the intestinal communities in the fish. In specific, more bacterial phyla dominated in groups A and B (phyla Bacteroidetes, Fusobacteria, Firmicutes and Proteobacteria in group A, phyla Proteobacteria and Fusobacteria in group B) than in groups C and D (phylum Proteobacteria). The diversity was also lower in groups C and D than in groups A and B. Unweighted pair-group method analysis revealed a clear difference in intestinal microbiota among the different feeding treatments. No difference in survival rate was found among the treatment groups, but the SGR was significantly higher (P < 0.01) in groups B, C and D than in group A. Functional analysis showed that the intestinal bacteria correlated with fish glucose metabolism in group A but with lipid metabolic activity in groups B, C and D. In summary, the intestinal microbiomes and their potential functions vary in bighead carp under different feeding treatments. This study provides new insights into the gut microbiomes of filter-feeding and formulated diet-fed fish.

RESUMEN

To elucidate the role of amh and foxl2 in sex differentiation of the teleost fish Schizothorax kozlovi, the full-length cDNAs were cloned from the mature testis and ovary by rapid amplification of cDNA ends (RACE), and their relative mRNA expression levels were determined by quantitative real-time polymerase chain reaction among tissues and temperature groups. The complete amh and foxl2 cDNAs of S. kozlovi were 2060 bp and 1750 bp, which encoded 568 and 306 amino acids, respectively. The amh were expressed only in gonads, while foxl2 was expressed in the gills, brain and gonads, both exhibiting relatively high tissue specificity. The amh exhibited sex-specific expression pattern in the gonads. No sex differences in the foxl2 expression were observed in the brain and gonads, but significant sex differences were found in the gills. No significant differences were found in the foxl2 expression, from the larval to the juvenile stage, and also between different temperature groups. However, significant differences were found in the expression levels of amh from the larval (12-63 days posthatching (dph)) to the juvenile stage (190 dph), and also among the 18°C and 10°C groups at 31 dph. This result suggested that amh plays an important role in male sex differentiation of S. kozlovi during the early developmental stage, but no similar effect was observed in foxl2.

Asunto(s)

RESUMEN

BACKGROUND: Largemouth bronze gudgeon (Coreius guichenoti) is of economic importance in China, distributed in upstream regions of the Yangtze River in China. But it has recently dramatically declined and is close to elimination. However, there is little knowing about the character of its intestinal microbiota. This study was conducted to elucidate the intestinal microbiota of wild largemouth bronze gudgeon with different body weight and gender. RESULTS: Thirty wild largemouth bronze gudgeon were measured for body length and body weight, and identified for male and female according to gonadal development, and thereafter the intestinal microbiota's were assessed by MiSeq sequencing of 16S rRNA genes. The results revealed that phyla Proteobacteria and Tenericutes were dominant in wild largemouth bronze gudgeon intestine independent of the body weight. Shannon's and Inverse Simpson's diversity indexes were significant (P < 0.05) different between male and female fish. The phylum profile in the intestine of male fish revealed that phylum Proteobacteria was dominant, in contrast to female fish where five phyla Tenericutes, Proteobacteria, Firmicutes, Fusobacteria and Spirochaetes were dominant. The genus profile revealed that genera Shewanella and Unclassified bacteria were dominant in male fish, while genus Mycoplasma was dominant in female fish. CONCLUSIONS: Our results revealed that the intestinal microbial community of wild largemouth bronze gudgeon was dominated by the phyla Proteobacteria and Tenericutes regardless of the different body weight, but the communities are significant different between male and female fish. These results provide a theoretical basis to understand the biological mechanisms relevant to the protection of the endangered fish species.

Asunto(s)

RESUMEN

Effect of rearing temperature on growth and thermal tolerance of Schizothorax (Racoma) kozlovi Nikolsky larvae and juveniles was investigated. The fish (start at 12d post hatch) were reared for nearly 6 months at five constant temperatures of 10, 14, 18, 22 and 26°C. Then juvenile fish being acclimated at three temperatures of 14, 18 and 22°C were chosen to determine their critical thermal maximum (CTMax) and lethal thermal maximum (LTMax) by using the dynamic method. Growth rate of S. kozlovi larvae and juveniles was significantly influenced by temperature and fish size, exhibiting an increase with increased rearing temperature, but a decline with increased fish size. A significant ontogenetic variation in the optimal temperatures for maximum growth were estimated to be 24.7°C and 20.6°C for larvae and juveniles of S. kozlovi, respectively. The results also demonstrated that acclimation temperature had marked effects on their CTMax and LTMax, which ranged from 32.86°C to 34.54°C and from 33.79°C to 34.80°C, respectively. It is suggested that rearing temperature must never rise above 32°C for its successful aquaculture. Significant temperature effects on the growth rate and thermal tolerance both exhibit a plasticity pattern. Determination of critical heat tolerance and optima temperature for maximum growth of S. kozlovi is of ecological significance in the conservation and aquaculture of this species.

Asunto(s)

RESUMEN

Under the conditions of simulated micro-habitat in laboratory, and by using experimental ecological methods, this paper evaluated the suitability index (HSI) of young Procypris rabaudi for habitat factors (substrate, light intensity and water depth). The habitat suitability models of the young P. rabaudi were established, and the minimum habitat area of the young P. rabaudi was estimated. The young P. rabaudi preferred the habitats with the gravel diameter from 10 to 15 cm, light intensity from 0.2 to 1.8 lx, and water depth from 0 to 15 cm (distance from the bottom of the tank). The three suitability index models of the substrate, light intensity and water depth for the young P. rabaudi were SI(s) = 1.7338e(-0.997x)(SI(S) is the suitability index of substrate, and x is the gravel diameter; R2 = 0.89, P < 0.01), SI(L) = 3.0121e(-1.339x)(SI(L) is the suitability index of light intensity, and x is the light intensity; R2 = 0.93, P < 0.01), and SI(W) = 2.4055e(-1.245x)(SI(W) is the suitability index of water depth, and x is the water depth; R2 = 0.97, P < 0.01), respectively. Arithmetic mean model HSI = (SI(S)+SI(L)+SI(W))/3 was most available for the estimation of the habitat suitability of young P. rabaudi. A total of seven groups of young P. rabaudi which established and maintained a relatively stable habitat area range were found. This habitat area ranged from 628 to 2015 cm2, with an average of 1114 cm2.

Asunto(s)

RESUMEN

A total of 36 females and 21 males of Chinese sturgeon Acipenser sinensis were caught in 1998-2004 excluding 2002 to study the characteristics of their reproductive biology and the effect of their artificial propagation. The results showed that the body length (BL), body mass (BM) and age of the females were 240-320 cm, 140-432 kg, and 15-30 years, and those of the males were 153-284 cm, 70-244 kg and 12-26 years, respectively. The inducing rate was 93.1% for females and 100% for males, and the ova had 7 different colors. The absolute fecundity was 200,000-590,000 eggs, with an average of 358,000 eggs, and the relative fecundity to BM was 820-3,020 eggs per kg, with an average of 1,590 eggs per kg. The sperm had 4 different colors. The absolute sperm quantity obtained from one male was 1,000-5,952 ml, with an average of 2,597.8 ml, and the relative sperm quantity to BM was 1.25-31.24 ml . kg(-1), with an average of 13.3 ml . kg(-1). During the study period, the average fertilization rate in artificial propagation was 63.7%, and the hatching rate was 48.1%, with 4,762,000 fry obtained. Compared with the data in 1976, the natural reproductive capacity of the Chinese sturgeon broodstocks declined greatly.

Asunto(s)