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This study was designed to generate the full-length transcriptome of Coilia nasus using single-molecule long read isoform sequencing (SMRT-seq) technology. RNAs of brains, ovaries, and testes of C. nasus conditioned in both seawater and freshwater except for gut which was only from the fish conditioned in freshwater, were isolated. All the RNAs were pooled together equally for SMRT sequencing. One SMRT cell produced 64.18 Gb clean data, including 765,184 circular consensus (CCS) reads and 616,126 full-length non-chimeric (FLNC) reads. Finally, 93,793 non-redundant transcripts were obtained after clustered and polished. Structural analysis of the 93,793 non-redundant transcripts predicted 8242 alternative splicing events, a total of 229,825 SSR and 72,037 complete CDS. A total of 8437 lncRNA were identified. 84,617 transcripts were annotated in NR, Swissprot, GO, COG, KOG, eggnog, Pfam and KEGG database totally. This is the first full-length transcriptome of Coilia nasus, including transcripts appeared in the case of seawater, which will facilitate exploration of genetic data and life story of Coilia nasus.

Ecological stoichiometry is a scientific discipline that studies the balance of energy and multiple chemical elements in biological systems, and it has been widely applied in fish research. However, there are few studies on fishes with different reproductive modes, such as Coilia, which experience habitat shifts during their life history and serve as important ecological links between marine and freshwater ecosystems. To address this gap, we compared the ecological chemical elements of four Coilia species (C. nasus, C. brachygnathus, C. mystus and C. grayii) to understand their organismal stoichiometry pattern in terms of changes in C, N, and P. The result shows, 1) The C content of Coilia had a wide range and was higher than the general fish, ranging from 40% -70%, while N% and P% were 4%-12% and 0.5%-3%, respectively. 2) Diadromous populations showed wider variations of elemental stoichiometry during migration than non-migration populations, with a higher coefficient of variation of elements and C:N:P than other Coilia species. In particular, the C content of diadromous Coilia nasus was the highest (>60% in the East China Sea) when the fish was ready for spawning migration, while N and P were opposites. Diadromous fish might have evolved a mechanism to store as much lipid as possible in their bodies to meet the energy demand during their long migration journey; 3) There were certain similarities between the biochemical composition and elemental changes. The trends of total fat and C content curves were consistent, with anadromous Coilia nasus storing a large amount of fat before migration to meet their energy needs during long-distance migration. The variation trends of crude protein and N content curve were similar to some degree, with crude protein and total fat having opposite trends, meaning that increased with a decrease in total fat, and vice versa

Current study explored the acute toxicity and oxidative stress of ammonia-N on Macrobrachium rosenbergii. Prawns were exposed to ammonia-N at 3.01, 3.55, 4.18, 4.92, 5.80, 6.82, and 8.04 mg·L−1 for a 96 h acute toxicity test. In the subsequent sublethal toxicity text, they were exposed to ammonia-N at 0.5 or 1.88 mg·L−1 (1/2 96 h LC50) for 3, 8, 12, 24, 48, and 72 h. The total superoxide dismutase (T-SOD) activity, catalase (CAT) activity and malondialdehyde (MDA) content were detected in the muscle, haemolymph, and gill. The gene expression of antioxidases (Cu/ZnSOD, CAT, GPX), heat shock proteins (HSP60, HSP70, HSP90), and apoptosis-related genes (Caspase 3, Bok) in the muscle and hepatopancreas also was evaluated. The LC50 values of non-ionic ammonia at 24, 48, 72, and 96 h were 7.72, 5.44, 4.28, and 3.78 mg·L−1, respectively. Ammonia-N significantly affected the T-SOD and CAT activities in the haemolymph and gill but not in the muscle. After 72 h of ammonia-N exposure, MDA content in the muscle, haemolymph, and gill in 1.88 mg·L−1 group significantly increased. The relative mRNA expression of antioxidant enzymes, heat shock proteins and Caspase 3 were upregulated in the hepatopancreas and muscle after ammonia exposure, especially in 1.88 mg·L−1. This result suggested that 1/2 96 h LC50 ammonia exposure induced severe oxidative stress, eventually even apoptosis of M. rosenbergii through the caspase pathway.Highlights Half of 96 h LC50 ammonia-N caused severe oxidative stress on M. rosenbergii. Ammonia-N induced the antioxidase and HSP to protect cells from oxidative stress. Ammonia-N induced mRNA expression level of Caspase 3 of M. rosenbergii.

Seasonal variation in phytoplankton community structure within Tang-Pu Reservoir (Shaoxing city, Zhejiang province, China) was investigated in relation to variation in physicochemical and hydrological characteristics. Over the three-study seasons (autumn, winter, and spring), phytoplankton abundance and biomass showed a gradual increase with the peak in spring season. During this study period, phytoplankton community comprised of 7 phyla, 80 genera, and 210 species. The dominating phyla were Chlorophyta 80 species, Bacillariophyta 46, and Cyanophyta 44 as well as other phyla of freshwater ecosystems except Xanthophyta. The phytoplankton density and biomass varied in the six sampling sites between a minimum of 257.42 × 10

It is a common practice to improve the water environment of rivers and lakes in China by the enhancement and releasing (EAR) of silver carp (Hypophthalmichthys molitrix) and bighead carp (Hypophthalmichthys nobilis) for biomanipulation. However, the quantity of bighead carp and its effect on water quality and plankton community have been the focus of debate among ecologists. Herein, in order to more accurately simulate the environmental conditions of lakes, we selected earthen ponds with large areas adjacent to Lake Qiandao from May to August in 2016 to study the responses of water quality condition and plankton community to a gradient of bighead carp stocked alone. Experimental groups with different densities of carp stocked were set as follows: 12.1 (LF), 23.5 (MF), and 32.5 g/m

In this paper, the complete mitochondrial DNA (mtDNA) sequence of Thryssa kammalensis was determined. The mitochondrial genome is 16,884 bp in length, including 13 protein-coding genes, 2 ribosomal RNAs (rRNAs), 22 transfer RNAs (tRNAs), and a non-coding control region as those found in other vertebrates, with the gene identical to that of typical vertebrates. The overall base composition of the heavy strand is 31.07% A, 24.82% T, 28.33% C, and 15.78% G, with an AT bias of 55.89%. Phylogeny of T. kammalensis suggested more close relationship with Lycothrissa crocodilus and Setipinna taty. The complete mitogenome of this species can provide a basic data for the studies on population history, molecular systematics, phylogeography, stock evaluation, and conservation genetics.

Traditional monoculture farming of the giant freshwater prawn Macrobrachium rosenbergii causes a deterioration in water quality as a result of effluent discharge, leading to frequent disease outbreaks and environmental pollution. In the present study, the effects of integrated multitrophic aquaculture (IMTA) systems on the growth of M. rosenbergii and water quality were evaluated. Six treatments, with 4 replicates each, were used, including prawn monoculture (MP), prawn with aquatic plants (Lemna minor) (PP), prawn with silver carp Hypophthalmichthys molitrix (PF), prawn with mussels (Anodonta sp.) and H. molitrix (PMF), prawn with Anodonta sp. and L. minor (PMP) and prawn with Anodonta sp., L. minor and H. molitrix (PMPF). Growth rates of M. rosenbergii and physical, chemical and biological parameters were assessed every 10 d and on the last day of the 64 d experiment. Average weight gain in M. rosenbergii was highest in the PMPF group, although this was not statistically significant. There was also no significant difference in survival rate among treatments. Dissolved oxygen concentrations were significantly higher in the PMPF group, whereas total nitrogen and chlorophyll a concentrations were highest in the PF group. Compared to the MP group, stocking with H. molitrix (PF, PMF and PMPF) effectively reduced PO4P. L. minor exhibited effective uptake of both N and P. In contrast to the group stocked only with H. molitrix (PF), stocking with L. minor (PP and PMP groups) reduced phytoplankton biomass. In summary, culturing M. rosenbergii in a multitrophic PMPF system provides the potential for increased economic profits and ecological benefits.

This work evaluates the application potential of a new indigenous aerobic denitrifier, strain Pseudomonas CW-2, isolated from a largemouth bass culture pond. The rate of ammonium-N removal by strain CW-2 was approximately 97% at a DO concentration of 5.2 mg/L. Furthermore, when nitrate and ammonia coexisted, the strain gave priority to assimilating ammonia, and thereafter to denitrification. Under optimal cultivation conditions, citrate and acetate were the carbon resources, C/N was 8, dissolved oxygen was 5.2 mg/L, and pH was 7; the removal rate of ammonium reached nearly 90%. The changing patterns of different bacteria in strain CW-2-treated and the control pond water were also compared. Lower levels of ammonia, nitrite, and phosphates were observed in the treated water as compared with the controls. Meanwhile, phylum-level distributions of the bacterial OTUs revealed that Proteobacteria, Bacteroidetes, Planctomycetes, and Nitrospirae continuously changed their relative abundances in relation to carbon and the addition of strain CW-2; this finding implies that the conventional denitrification process was weakened under the effects of carbon or the presence of strain CW-2. We propose that strain CW-2 is a promising organism for the removal of ammonium in intensive fish culture systems, according to our evaluations of its denitrification performance.

Six experimental groups were established for a land-based enclosure experiment: Macrobrachium rosenbergii Monoculture group; M. rosenbergii and Hyriopsis cumingii polyculture group; M. rosenbergii and silver and bighead carp polyculture group; and M. rosenbergii, H. cumingii, and silver and bighead carp polyculture groups (GSBH1, GSBH2, and GSBH3) in different densities of H. cumingii. Each group had four replicates. Control of cyanobacterial blooms in different polyculture patterns and the effects of these patterns on water quality and microbial community were studied. Results showed that the silver and bighead carp polyculture could control cyanobacterial blooms. The H. cumingii and silver and bighead carp polyculture improved water quality, and the GSBH2 group had the best purifying effect. Moreover, different microbial communities were observed in the different polyculture patterns. The silver and bighead carp polyculture exerted obvious effect on microbial community, whereas H. cumingii only slightly affected microbial community. Water quality parameters that significantly influenced microbial community included Secchi depth transparency, total nitrogen content, total phosphorus content, total dissolved phosphate content, nitrite nitrogen content, chemical oxygen demand, and chlorophyll a content. Thus, microbial community could also serve as an indicator of nutrient levels of water bodies.

Coilia nasus is an important economic fish species in China due to its excellent meat quality and wonderful flavor. The germplasm resources of C. nasus have recently been seriously degraded by human activities. It is urgent to develop the genetic markers of C. nasus in order to apply to conservation of this species. In this study, we used C. nasus transcriptomic data from GENBANK to identify single nucleotide polymorphism (SNP) markers for this species. From 148,156 unigenes with functional annotations, 85,454 putative SNPs were identified. Forty-one of the 61 SNP loci (including 31 loci that were associated with osmoregulation-related genes and 10 loci associated with other functions) were successfully validated and showed bi-allelic polymorphism in three rivers. Nine, six and eleven of these SNP loci deviated significantly from Hardy–Weinberg equilibrium (P

High-throughput sequencing was applied to analyze the effects of toxic Microcystis aeruginosa on the silver carp Hypophthalmichthys molitrix. Silver carps were exposed to two cyanobacteria species (toxic and non-toxic) for RNA-seq and miRNA-seq analysis. RNA-seq revealed that the liver tissue contained 105,379 unigenes. Of these genes, 143 were significantly differentiated, 82 were markedly up-regulated, and 61 were remarkably down-regulated. GO term enrichment analysis indicated that 35 of the 154 enriched GO terms were significantly enriched. KEGG pathway enrichment analysis demonstrated that 17 of the 118 enriched KEGG pathways were significantly enriched. A considerable number of disease/immune-associated GO terms and significantly enriched KEGG pathways were also observed. The sequence length determined by miRNA-seq was mainly distributed in 20–23 bp and composed of 882,620 unique small RNAs, and 53% of these RNAs were annotated to miRNAs. As confirmed, 272 known miRNAs were differentially expressed, 453 novel miRNAs were predicted, 112 miRNAs were well matched with 7,623 target genes, and 203 novel miRNAs were matched with 15,453 target genes. qPCR also indicated that Steap4, Cyp7a1, CABZ01088134.1, and PPP1R3G were significantly differentially expressed and might play major roles in the toxic, detoxifying, and antitoxic mechanisms of microcystin in fish.

Bighead carp (Aristichthys nobilis) is one of the most economically and ecologically important fish species widely stocked in lakes or cultured in ponds throughout China. The natural populations are facing the stringent challenges of germplasm resources reduction because of pollution and culture. Thus, developing sufficient molecular markers for the conservation and molecular-aided selection of bighead carp is urgent. In this study, we used SNaPshot to develop single nucleotide polymorphism (SNP) markers in bighead carp. A total of 38861 putative SNP markers were identified from the RAD sequencing of bighead carp. Among the markers, 28 SNPs were randomly selected and 25 loci exhibited significant polymorphisms in genotyping by SNaPshot. To the best of our knowledge, this is the first report about SNP marker development in bighead carp based on SNaPshot. These SNP markers can provide an effective tool for the resource conservation and genetic improvement of bighead carp.

Two fishing methods including gillnetting and trawling to estimate attributes of fish assemblage were compared in Dianshan Lake from August 2009 to July 2010. Species composition differed significantly between the gears, with four significant contributors in gillnet catches and one in trawl catches. Trawling collected more proportions of benthic species by number and biomass than gillnetting. Size distribution was significantly influenced by fishing technique; gillnetting captured relatively less small-sized fishes and trawling captured less large-sized individuals. Trawling produced species richness closer to the one expected than gillnetting. On the whole, trawl catch was a quadratic polynomial function of gillnet catch and a significantly negative correlation was found between them, both of which varied as different polynomial functions of temperature. However, trawl and gillnet catches were significantly correlated only in one of five month groups. It is concluded that single-gear-based surveys can be misleading in assessments of attributes of fish assemblages, bottom trawling is a more effective gear for assessing fish diversity than benthic gillnetting, and using gillnet catches as an indicator of fish density depends on fishing season in the lake.

Ammonia nitrogen elevated is one of the commonest problem in the aquatic system, which caused a great threat to the survival and growth of prawn. However, little is know about the ammonia metabolism and detoxification strategy of prawn. In this study, the effects of ammonia-N (0, 0.108, 0.216, 0.324, or 0.54 mg L−1) on growth and metabolizing enzymes in hepatopancreas of Macrobrachium rosenbergii, including glutamine synthetase (GS), alanine aminotransferase (ALT), aspartate aminotransferase (AST), and glutamate dehydrogenase (GDH), were investigated. The metabolome of its muscle was also analyzed after exposure to ammonia-N (0, 0.108, 0.324, or 0.54 mg L−1) for 20 days. The survival rate of M. rosenbergii decreased significantly after treatment with 0.54 mg L−1 ammonia-N compared with that in the other groups. However, ammonia-N had no significant effect on the growth of the river prawn after exposure for 20 days. GS activity increased significantly after exposure to 0.108 mg L−1 ammonia-N compared with the control and other ammonia-N-treated groups. Hepatopancreatic GDH activity was lower in the prawns treated with 0.216, 0.324, or 0.54 mg L−1 ammonia-N than in the control by 34.70%, 38.80%, or 41.94%, respectively. Ammonia-N had no significant effect on hepatopancreatic AST or ALT activity. Urea nitrogen was higher in the prawns treated with 0.216 mg L−1 ammonia-N than in the control or those treated with 0.54 mg L−1 ammonia-N. Ammonia-N had significant effects on the lipid, carbohydrate. and protein metabolism of M. rosenbergii, including purine metabolism, amino sugar and nucleotide sugar metabolism, α-linolenic acid metabolism, arginine and proline metabolism, glutathione metabolism, and phosphonate and phosphate metabolism, and on the terpenoid biosynthesis, lysine degradation, and lysine biosynthesis pathways. High concentrations of ammonia-N stress increased the content of glutamate and arginine, which may participate in the urea cycle, which synthesizes glutamine or urea to eliminate ammonia toxicity.

Global warming significantly affects fish, particularly cold-water fish, because increased temperature adversely impacts their abilities to grow or reproduce, and eventually influences their fitness or even causes death. To survive, fish may alter their distribution or behavior to avoid the stress, and perhaps acclimate or evolve resistance to the elevated temperature. Brachymystax lenok tsinlingensis is an endangered cold-water species in China, and it has been found to alter the altitudinal distribution, decrease swimming efficiency and develop resistance under heat exposure, which badly impact the continuing conservation work. To better protect them, it is essential to understand how they respond to thermal stress behaviorally and physiologically. Therefore, the fish were exposed to 24.5 °C and based on the time taken for them to lose equilibrium, they were separately sampled as sensitive and tolerant groups. Both gill and liver tissues were collected from both groups for transcriptome sequencing. Sequencing results demonstrated that control and tolerant groups were similar in transcriptomic patterns and sensitive groups differentially expressed more genes than tolerant ones, suggesting the gene expression of tolerant groups may return to base levels as exposure time increased. Tissue differences were the major factor affecting gene expression, and they also displayed different physiological responses to heat stress. Consistent with other studies, heat shock response, immune response, metabolic adjustment and ion transport were found to be triggered after exposed to elevated temperature. The findings would contribute to a better understanding of responding mechanisms of fish to thermal stress and provide guidance for future conservation programs.

Xenocypris microlepis (Bleeker, 1871) and Xenocypris davidi (Bleeker, 1871) are two closely related xenocyprinid species potentially subject to exploitative competition. They often coexist in many freshwater ecosystems, which offers an opportunity to analyze their relationships. The present study describes the seasonal feeding habits of age‐3 X. microlepis and X. davidi in Xin'anjiang Reservoir, located in Zhejiang, China, as determined by stable isotope analysis. Particulate organic matter (POM; 50%) and periphyton (50%) were the major items observed in the X. microlepis diet, whereas periphyton (>60%) was prevalent in the X. davidi diet. Seasonal variations were observed in the diet compositions of both xenocyprinid species. Whereas X. microlepis tended to ingest more sediment organic matter (SOM) in autumn than in spring and summer, SOM was the secondary food item for X. davidi over the three seasons. The seasonal diet shift observed in this work indicates niche segregation of the sympatric pair. The results of this study contribute to the current knowledge of seasonal trophic interactions in predator–prey systems where sympatric xenocyprinids are present.

Bloom-forming microalgae and hypoxia are considered as the two main co-occurring stressors associated with eutrophication. How these two stressors might alter the sail mussel exposed to toxic cyanobacteria and hypoxia has not been well evaluated histophysiologically. Therefore, the present study was designed to evaluate the combined effects of the harmful cyanobacteria ( Microcystis aeruginosa ) and hypoxia on the histopathological alterations in the gill, digestive gland, and stomach of an ecologically and economically important mussel species inhabiting lakes and reservoirs, the triangle sail mussel ( Hyriopsis cumingii ). To evaluate the histophysiological changes due to the stressors, a 2 × 2 factorial design with four treatments was adopted: two dissolved oxygen levels (hypoxia: 1 mg O 2 l − 1 ; normoxia: 6 mg O 2 l − 1 ) and two treatments, one with 0% and another with 100% (1.8 × 10 7 cell ml − 1 ca. 50 mg l − 1 ) cell biomass of toxic M. aeroginosa . The non-toxic green alga ( Chlorella vulgaris ) was supplemented to maintain the same algal biomass in the four treatments. Samples from the treatments were collected on days 0, 3, 5, 7, 14, and 21. The microcystin content in sail mussels exposed to M. aeruginosa increased over the entire experimental span, under both normoxia and hypoxia, but was significantly lower in mussels under hypoxic conditions. Pathological alterations were observed in the gills, digestive diverticula and stomach of mussels under hypoxia, when fed 100% M. aeruginosa diet, and when intoxicated with M. aeruginosa under hypoxia. Hyperplasia, exfoliation of latero-frontal cilia, filament fusion, and epithelial desquamation of filaments in the gills were observed following 7 days of exposure to M. aeruginosa and hypoxia. After 7 days of exposure, the damage in the gills, digestive gland, and stomach increased. Hypoxia induced more severe effects in the gill structures than the harmful alga, whereas the digestive gland was more affected by exposure to M. aeruginosa . The stomach, however, was equally affected by both stressors. Results of this preliminary study highlight the need for further in depth studies on the combined effect of toxic cyanobacteria and hypoxia on the triangle sail mussel, and the potential implications for the freshwater pearl production in China. Statement of relevance Hyriopsis cumingii has been considered as an aquaculture species for pearl production in China. In recent years, the mussels have been often suffered from hypoxia and toxic algae, but the effects of Microcystis aeruginosa associated with hypoxia on the morphological changes of selected organs such as gill, digestive gland and stomach are unclear. This study just clarified that the selected tissues of H. cumingii were more severely affected by the both stressors, which may clarify how the toxic algae and hypoxia cause some diseases in the mussel H. cumingii .

This paper studied the sources of food and the trophic levels of silver and bighead carps using stable isotopes (δ 13 C and δ 15 N) analysis in Lake Qiandao and Lake Taihu. The δ 13 C values of POM and phytoplankton indicated that Particulate Organic Matter (POM) is of terrestrial origin in LQ and phytoplankton origin in LT. The different signature of δ 15 N of phytoplankton and POM also showed the different extent of anthropogenic impacts on the two lakes, with higher impacts in LT than in LQ. In LQ the trophic levels of silver and bighead carps were significantly different (2.48 ± 0.19 and 2.66 ± 0.19, respectively), while in LT the difference was not significant (2.15 ± 1.54 and 2.36 ± 0.38, respectively). Using a mixing model, we found that silver and bighead carps consumed a major proportion on phytoplankton and/or POM in both lakes with higher contribution of phytoplankton in more eutrophic lake. Silver and bighead carps had clear differentiation in food resources with silver carp more on POM and bighead more on zooplankton in deep and mesotrophic lakes. Contrary to this, both carps fed primarily on phytoplankton (and POM) and may have more niche overlaps in shallow and eutrophic lakes.

In order to explore the effect of different dam structures on the genetic diversity of freshwater fish, the genetic diversity of Sinibrama macrops in Min River was investigated using mitochondrial control region (D-loop) sequences. Populations of S. macrops at Jianyang and Shaowu rivers were separated from the rest of the system by low dams and the population at Gutian was isolated from the rest of the river by a high dam. The haplotype diversity in the samples analyzed varied from 0.577 to 0.933 and nucleotide diversity varied from 0.0031 to 0.00441. The lowest values of haplotype diversity and nucleotide diversity were obtained from Gutian. Indices of genetic differentiation between populations, gene flow, analysis of molecular variance and net genetic distance between populations showed widespread gene exchange among different populations, with the exception of Gutian and Yongtai. These results may be associated with the isolation of Gutian by the high dam. The result of neutrality test and mismatch distributions showed that the evolutionary history of Gutian population was different from others in the river system. Our results imply that high dams have a larger effect on S. macrops , leading to reduction of genetic diversity and genetic differentiation from other populations.

The single and combined effects of toxic cyanobacteria Microcystis aeruginosa and hypoxia on the energy budget of triangle sail mussel Hyriopsis cumingii were determined in terms of scope for growth (SfG). Mussels were exposed to different combinations of toxic M. aeruginosa (0%, 50%, and 100% of total dietary dry weight) and dissolved oxygen concentrations (1, 3, and 6.0mg O2l(-1)) with a 3×3 factorial design for 14 days, followed by a recovery period with normal conditions for 7 days. Microcystin contents in mussel tissues increased with the increase in the exposed M. aeruginosa concentration at each sampling time. Adverse physiological responses of H. cumingii under toxic M. aeruginosa and hypoxic exposure were found in terms of clearance rate, absorption efficiency, respiration rate, excretion rate, and SfG. Results emphasized the importance of combined effects of hypoxia and toxic cyanobacteria on H. cumingii bioenergetic parameters, highlighted the interactive effects of toxic algae and hypoxia, and implied that the two stressors affected H. cumingii during the exposure period and showed carryover effects later. Thus, if H. cumingii is used as a bioremediation tool to eliminate M. aeruginosa, the waters should be oxygenated.

The sustainability of Global Important Agriculture Heritage System (GIAHS) such as the Qingtian rice-fish coculture system relies heavily on the good economic return that ensures the willingness of farmers to adopt, which in turn relies on the effectiveness of the technology. The dynamic conservation concept makes it possible for each GIAHS project to be optimized in technology while overall systems are conserved. To reach this goal, we compared the effects of three rice planting densities (20 cm × 30 cm, 30 cm × 30 cm and 40 cm × 30 cm) on both the fish growth performance and the rice productivities in this study. In one hand, the survival rate (SR), specific growth rate (SGR), amino acid (AA) and fatty acid (FA) of the fish (Cyprinus carpio var. color) in paddy field under three rice planting densities were compared. In the other hand, the rice yield indicators and rice stem characters were also calculated and compared among the different rice planting densities. The results showed that the SGR of fish reached the highest (4.54 ± 0.03) % in the medium rice density group (i.e., the 30 cm × 30 cm group), which was extremely significantly higher than that in the high density (20 cm × 30 cm) (3.62 ± 0.04) % (P = .001). However, the survival rates of fish were not significantly different among treatments (P = .298). The content of essential amino acid (EAA) in fish muscle under the high, medium and low rice cultivation densities were (37.35 ± 1.07) %, (37.35 ± 0.27) %, (32.20 ± 1.29) %, respectively. The first limiting amino acid was Met; the the total essential amino acid (TEAA) and the essential amino acid index (EAAI) in the medium and high density were all slightly higher than those in the low density. There were no significant differences in rice yield indicators among the treatments (P = .687); the number of effective panicles in the low density was significantly higher than that in the high density (P = .000), and panicle setting rate in the low density was significantly higher than that in the medium and high density (P = .038). In summary, the fish can obtain a faster growth rate while ensuring the rice yield in the rice density of 30 cm × 30 cm.

Partial sequences of mitochondrial DNA 16S rDNA and COI genes (395 bp and 498 bp respectively) were sequenced from samples of ten cultured populations of Macrobrachium rosenbergii (Giant Freshwater Prawn – GFP) in Zhejiang, Guangdong and Guangxi Provinces in China and two wild populations of GFP from Mekong River and Dongnai River in Viet Nam. Five haplotypes of 16S rDNA were identified in the 360 samples. The wild populations displayed nucleotide diversity (π) of 0.0008 and 0.0003, and genetic diversity (h) of 0.3030 and 0.1310 in the Mekong River and Dongnai River respectively. The cultured populations displayed no significant genetic diversity. COI sequences identified 17 haplotypes based on 21 polymorphic sites. At this marker, the 12 populations showed a range of h from 0.1290 to 0.6940 and π from 0.0003 to 0.0073. The largest genetic distance (Da) among the 12 populations was 0.0065 (between ZJB and BT/DN populations) and the lowest Da was 0.0003 (between GDD and GDA populations). The wild populations had higher genetic diversity than the cultured populations, but three of cultured populations from Zhejiang (ZJA, ZJB and ZJC) had π higher than wild populations, because they originated from Thailand, Bangladesh and the Mekong River in Viet Nam.

The spatial and seasonal pattern of macrozoobenthic structure and its relationship with environmental factors were studied from July 2006 to April 2008 in Mingzhu Lake, Chongming Island, Shanghai at the Changjiang River mouth. The congruences in water quality bioassessment based on diversity and biotic indices and using different taxonomic categories were also explored to find the best assessment method of water quality for the lake. All major structural characteristics of macrozoobenthic community, including species composition, abundance, biomass and four biomass-based diversity indices (Shannon’s diversity, Simpson’s diversity, Pielou’s evenness and Simpson’s evenness index) fluctuated significantly in season but in space. The above four abundance-based diversity indices plus abundance-based Margalef’s richness index did not display significant spatial variations; and significant seasonal differences were found in three indices only. Water temperature was the key environmental factor responsible for macrozoobenthic spatio-temporal distribution patterns. Water quality assessed by Shannon’s index (Ha′) and biological pollution index (BPI) rather than the other four biotic indices were consistent with those by trophic state index (TSI). Results from chironomids and oligochaetes did not always agree to those from the whole community when Ha′ or Hilsenhoff biotic index was applied to bioassessment. Therefore, combining multiple indices and avoiding a single taxonomic category to assess water quality are strongly recommended and in Mingzhu Lake using a mixture of Ha′ and BPI will ensure the most effective investigation of water quality. Our results also show that the main structural characteristics of macrozoobenthic communities in the small lake may display consistent spatial patterns.

Accurate estimation of phytoplankton chlorophyll-a (chl-a) concentration from remote sensing data is challenging due to the complex optical properties of case II waters. Recently, a novel semi-analytical four-band model was developed to estimate chl-a concentration in turbid productive waters. The objective of this study was to evaluate the performance of the four-band model and extend its application to hyperspectral satellite data for estimating chl-a concentration in Qiandao Lake of China. Based on field spectral measurements and in situ water sampling, the four-band model expressed as [Rrs−1(661.6) – Rrs−1(706.7)] [Rrs−1(714.8) – Rrs−1(682.2)]−1 was calibrated after band tuning, where Rrs−1 represents the reciprocal of the remote sensing reflectance. The spectral-based four-band model accounted for more than 88% of variance in chl-a concentration with a root mean square error (RMSE) of 1.47 μg l−1. To justify the potential of this model with satellite data, comparable wavelengths selected from HJ-1A H...

Coilia nasus is widely distributed along the coast, and rivers and lakes that connect with the ocean in China. It is a diadromous fish but has residential populations in the middle and lower reach of the Yangtze River and its associated lakes such as Lake Taihu. These ecologically differentiated diadromous and residential populations are difficult to identify and separate, even with current molecular screening methods such as applying the mtDNA markers. The objective of the present study was to screen these populations by the means of the whole body elemental fingerprint analysis (EFA). Our results showed that the diadromous population had significantly lower concentrations of Al, B, Ca, Cr, Fe, K, Mg, Mn, P, S, and Zn, and significantly higher As than the residential populations. The spawners had lower concentrations of B, Cr, P, and S before laying eggs than after laying eggs. Advanced statistical models detected distinct spatial patterns between the diadromous and residential populations, and between groups before and after spawning. The current study showed that the whole body EFA can clearly distinguish C. nasus populations in the Yangtze River Basin and thus proved to be useful and may substitute the elemental fingerprint of fish otolith in future fish ecological studies that need to identify different populations. (C) 2015 Elsevier Ltd. All rights reserved.

The Giant freshwater prawn (GFP), Macrobrachium rosenbergii, is one of the most important crustacean species cultured in China, but information on the genetic diversity of GFP in China is still limited. In this study we analyzed the genetic diversity of 6 cultured GFP populations collected in China, and 2 wild populations from Viet Nam. The wild populations were included as a reference so that the genetic diversity of the introduced cultured GFP populations could be evaluated. We used six polymorphic primer pairs to estimate genetic diversity. Results showed that the number of alleles per locus ranged from 6 to 19. The mean observed heterozygosity (0.364 ± 0.090) was less than the expected heterozygosity (0.893 ± 0.016); highly significant deficiencies in heterozygotes were detected (100%). The polymorphism information content (PIC) of 8 populations at 6 loci was greater than 0.5 (varying from 0.616 to 0.912). Pair-wise genetic differentiation (FST) varied from 0.006 to 0.129 among the eight populations. The dendrogram based on genetic distance showed six populations distributed on the same major branch, suggesting that they have closely genetic distance and two populations (ZJC and GDB) distributed on the other branch, so they also have closely genetic distance. The results of study provide a baseline assessment of genetic diversity in some populations in China and Viet Nam that will be useful for the development of breeding programmes in the future.

High-throughput sequencing analysis of gut contents was used to study the feeding habits of two filter-feeding fish, namely silver carp Hypophthalmichthys molitrix and bighead carp Hypophthalmichthys nobilis, in mesotrophic Lake Qiandao and eutrophic Lake Taihu. Silver carp feed primarily on phytoplankton, with a feeding preference for Chlorophyta, in Lake Qiandao and rely on phytoplankton in Lake Taihu. Bighead carp feed more on zooplankton in Lake Qiandao and on phytoplankton in Lake Taihu. With increasing levels of algae, bighead carp feed more on phytoplankton. The dietary shifts suggest that bighead carp would be useful in controlling nuisance algae in lakes.

Using multi-mesh gillnets and trawls, the fish communities in Dianshan Lake at 6 stations from Oct. 2009 to Jul. 2010 were investigated seasonally to reveal the biodiversity and its spatial and temporal distribution patterns. The long-term changes in their structural characteristics were then analyzed to identify the main influencing factors and several measures for lake restoration were put forward. Thirty six species, belonging to 9 family and 30 genera, were collected, amongst which, the order Cypriniformes accounted for 61.1% of the total species number. In terms of importance value, Cypriniformes was the predominant group, Coilia nasus the dominant species, while Cyprinus carpio and Rhinogobius giurinus were the subdominant taxa. The community types did not differ among stations, but between seasons. There were no significant differences between seasons and among stations in species diversity, but richness differed both spatially and seasonally. Along with the process of eutrophication and the drastic reduction of the area colonized by macrophytes from 1959 to 2009–2010, the fish diversity declined markedly, and species numbers of herbivores and piscivores declined proportionately more than those of invertivores, omnivores, and planktivores. The decline of potamophilus and river-lake migratory fish was more marked than those of sedentary, river-sea migratory, and estuarine fishes. Eutrophication concomitant with sharp reduction of macrophyte area and overfishing may be the main reasons for the decline in fish diversity in Dianshan Lake.

The temporal and spatial distributions of zooplankton communities in the upper, middle, and lower reaches of the Xin’anjiang Reservoir, Zhejiang, China, were investigated monthly, between 2009 and 2010. Silver carp (Hypophthalmichthys molitrix) and bighead carp (Aristichthys nobilis) dominated the pelagic fish community of this large, deep reservoir. Cladocerans were distributed evenly throughout the reservoir. Rotifers were mainly found in the upper reaches, while copepods tended to assemble in the lower reaches. The Pearson correlation analysis and stepwise multiple regression were used to identify the major physicochemical gradients influencing community variations. Zooplankton community distributions were influenced by water temperature, dissolved oxygen, phosphorus, nitrogen, and silicon. Excess nutrients, in particular silicon, stimulated rotifer growth. Based on these findings, it is possible to use rotifer density as a bioindicator of eutrophic status in deep reservoir ecosystems.

A 924 bp segment of the mitochondrial control region ( d -loop) was sequenced and analyzed in 334 specimens of Sinibrama macrops from 13 sites in Qiantang River Basin, China. Haplotype diversity ( h = 0.724 ± 0.063) and nucleotide diversity ( π = 0.00263 ± 0.00027) were lowest in Shengzhou population which had been separated from mainstream of Qiantang River Basin by seawater. The results of pairwise Fst values and average genetic distance revealed significant divergence between Shengzhou and other populations. No geographic clustering was observed in haplotype network, suggesting that there were gene flow among populations except Shengzhou. Pairwise mismatch distributions and Tajima's d -test showed demographic history of Shengzhou population was different from others. Base on the analysis of mitochondrial control region, the differentiation of Shengzhou population was considered to be the result of the transgression and regression in the last interglacial period.

Chinese fisheries production (including total wild fisheries and aquaculture) went through a substantial increase from 4.3 million metric tons in 1978 to 12.4 million metric tons in 1990, and then on to 47.48 million metric tons in 2008. A similar increase was observed in lake fisheries over the same period. Lake fisheries developed from wild fisheries to stock-enhanced fisheries, and most recently, to a wide range of culture systems including intensive aquaculture. Decades of pursuing high production, with less attention paid to environmental and biological concerns, has resulted in issues related to the sustainability of the fisheries resources and the health of the lake ecosystems. Chinese lakes are now facing declining fisheries resources, eutrophication, reduced biodiversity, and increasing alien species invasions, which individually and jointly challenge lake fisheries management and policy making. However, economic prosperity and improving awareness of environmental protection and food-safety concerns have provided a new opportunity for management of lake fisheries in China.