Predicting impacts of climate change on the biogeographic patterns of representative species richness in Prydz Bay-Amery Ice Shelf

The research on the biological ecology of the Prydz Bay-Amery Ice Shelf in East Antarctica is inadequate under the increasing threat from climate change,especially for Antarctic fish and krill.The Dynamic Bioclimatic Envelope Model(DBEM)has been widely used in predicting the variation of species distribution and abundance in ocean and land under climate change;it can quantify the spatiotemporal changes of multi population under different climate emission scenarios by identifying the environmental preferences of species.The species richness and geographical pattern of six Antarctic representative species around Prydz Bay-Amery ice shelf were studied under RCP 8.5 and RCP 2.6 emission scenarios from 1970 to 2060 using Geophysical Fluid Dynamics Laboratory(GFDL),Institut Pierre Simon Laplace(IPSL),and Max Planck Institute(MPI)earth system models.The results showed that the species richness decreased as a whole,and the latitude gradient moved to the pole.The reason is that ocean warming,sea ice melting,and human activities accelerate the distribution changes of species biogeographical pattern,and the habitat range of krill,silverfish,and other organisms is gradually limited,which further leads to the change of species composition and the decrease of biomass.It is obvious that priority should be given to Prydz Bay-Amery ice shelf in the planning of Marine Protected Areas(MPAs)in East Antarctica.

Dietary Leucine Requirement of Juvenile Japanese Seabass(Lateolabrax Japonicus)

A 56-day feeding trial was conducted to examine the dietary leucine requirement of juvenile Japanese seabass in sea- water floating net cages （1.5 m × 1.5 m × 2.0 m）. Six isonitrogenous （crude protein 40%） and isoenergetic （gross energy 20 kJ g-1） diets were formulated to contain different concentrations of leucine （0.9%, 1.49%, 2.07%, 2.70%, 3.30% and 3.88% of dry matter）. Crys- talline L-amino acids were supplemented to simulate the whole body amino acid pattern of Japanese seabass except for leucine. Three groups （30 fish individuals each, 8.0g±0.20g in initial weight） were fed to apparent satiation at 5：00 and 17：30 every day. During the experimental period, the water temperature ranged from 26 to 32℃ and salinity from 26 to 30, and the dissolved oxygen was maintained at 7mgL-l. The results showed that weight gain （WG）, nitrogen retention （NR）, feed efficiency （FE） and protein efficiency ratio （PER） were significantly increased when dietary leucine was increased from 0.90% to 2.70% of dry matter, and then declined. WG was the highest when fish were fed D4 containing 2.70% of leucine. No significant differences were observed in body composition among dietary treatments （P 〉 0.05）. Considering the change of WG, the optimum dietary leucine requirement of juve- nile Japanese seabass was either 2.39% of dry matter or 5.68% of dietary protein.

Dietary guaiacol improves the growth of juvenile abalone,Haliotis discus hannai Ino

We conducted a preliminarily study on the effects of dietary guaiacol on growth performance of abalone, Haliotis discus hannai Ino. Seven semi-purified diets were formulated with graded levels of guaiacol （0, 5, 10, 50, 100, 500, and 1 000 mg kgl）. Abalone （initial weight： 0.29 ± 0.01 g; initial shell length： 8.55 ± 0.27 mm） were fed with these diets in a re-circulated water system for 152 days. Guaiacol significantly improved the specific growth rate （SGR） （P〈0.05）; excessive dietary guaiacol （1 000 mg kg1） led to significantly high mortality （P〈0.05）, and lipid content in the soft body increased significantly after dietary guaiacol （P〈0.05）. Activities of catalase and phenoloxidase （PO） in the viscera were significantly stimulated by dietary guaiacol （P〈0.05）. Broken-line analysis based on SGR indicated that the minimum dietary guaiacol for the optimal growth of juvenile abalone is 15.43 mg ·kg^-1.

A Comparative Study on the Buoyancy of Resting Eggs from Different Artemia Populations, with Emphasis on Its Relationships with Habitat Salinity and Biometric Characters of Resting Eggs

The buoyancy of Artemia resting eggs is a feature with both biological and economic importance.Since the buoyancy of resting eggs is dependent on the specific weight of the eggs or salinity of ambient water,we suppose that habitat salinity may exert a selection pressure on resting egg buoyancy,and thereby lower habitat salinity may result in better floating capacity of resting eggs and vice versa.In this study,we compared the floating capacity of resting eggs from 25 Artemia populations.The results showed that the floating capacity of resting eggs varied greatly among different populations.The minimum salinity to float some eggs varied from 0 to 180.The salinity at which all resting eggs floated varied from 80 to 320.The FS_(50)(salinity with 50%eggs floating)of Zhundong and Yuncheng population was not detectable(over 50%eggs floating in distilled water),that of Kyêbxang Co population was 4.3,while the maximum value found in Dabancheng population was 234.5.In terms of the‘apparent specific weight’of resting eggs,18 populations exhibited a single-peak distribution pattern,while the other 7 populations showed a multiple-peak or non-peak distribution.Negative correlations were found between FS50 and chorion thickness,and between FS_(50) and the volume percentage of the chorion in eggs,supporting a previous standpoint that shell thickness was a determinative factor for the floating capacity of resting eggs.A positive correlation was determined between FS50 and habitat salinity.The hypothesis that habitat salinity may cause a directional selection on the buoyancy of resting eggs seems to be true.

Effects of vitamin C deficiency or excess on growth performance, anti-oxidative response and fatty acid composition of juvenile abalone Haliotis discus hannai Ino

A 240-day feeding trial was conducted to investigate the effects of dietary vitamin C on growth performance,anti-oxidative response,and fatty acid composition of juvenile abalone Haliotis discus hannai Ino(initial body weight:0.93±0.00 g).Three semi-purified experimental diets were formulated containing 0.00,94.52,and 9649.58 mg/kg of vitamin C supplied as L-ascorbyl-2-monophosphate.The results show that there was no significant difference in weight gain ratio,daily increment in shell length,and survival rate among the three treatments.Adding dietary vitamin C(9649.58 mg/kg)significantly increased the activities of superoxide dismutase(SOD),glutathine peroxidase(GPX),glitathione-S-transferase(GST),glutathione reductase(GR),alkaline phosphatase(AKP),and lysozyme in viscera(P<0.05).In muscle,activities of phenoloxidase,catalase,SOD,GST,GR,and AKP were increased in the treatment with 9649.58 mg/kg of dietary vitamin C(P<0.05).The highest concentrations of ascorbic acid in viscera and muscle were found in the group with 9649.58 mg/kg of dietary vitamin C(P<0.05).The contents of crude protein and crude lipid in the soft body were significantly increased in the 9649.58 mg/kg group(P<0.05).Dietary vitamin C supplementation significantly decreased the contents of saturated fatty acids(14:0,16:0,and 18:0),and increased the composition of 18:2n-6 and 22:6n-3 in the soft body of abalone(P<0.05).Therefore,although there were no significant effects on the growth performance,dietary vitamin C supplementation improved the anti-oxidation and immune responses,increased specific unsaturated fatty acid(i.e.,16:1,18:1n-7,18:1n-9,18:2n-6 and 22:6n-3),and decreased specific saturated fatty acid(i.e.,14:0,16:0 and 18:0)contents in the soft body of abalone.

Modelling the variation of demersal fi sh distribution in Yellow Sea under climate change

Climate change can aff ect fi sh individuals or schools,and consequently the fi sheries.Studying future changes of fi sh distribution and abundance helps the scientifi c management of fi sheries.The dynamic bioclimate envelope model(DBEM)was used to identify the“environmental preference profi les”of the studied species based on outputs from three Earth system models(ESMs).Changes in ocean conditions in climate change scenarios could be transformed by the model into those in relative abundance and distribution of species.Therefore,the distributional response of 17 demersal fi shes to climate change in the Yellow Sea could be projected from 1970 to 2060.Indices of latitudinal centroid(LC)and mean temperature of relative abundance(MTRA)were used to represent the results conducted by model.Results present that 17 demersal fi sh species in the Yellow Sea show a trend of anti-poleward shift under both low-emission scenario(RCP 2.6)and high-emission scenario(RCP 8.5)from 1970 to 2060,with the projected average LC in three ESMs shifting at a rate of-1.17±4.55 and-2.76±3.82 km/decade,respectively,which is contrary to the previous projecting studies of fi shes suggesting that fi shes tend to move toward higher latitudes under increased temperature scenarios.The Yellow Sea Cold Water Mass could be the major driver resulting in the shift,which shows a potential signifi cance to fi shery resources management and marine conservation,and provides a new perspective in fi sh migration under climate change.

The Fish Microbiota:Research Progress and Potential Applications

The gut microbiota plays an important role in host health and disease.Our understanding of the fish microbiota lags far behind our knowledge of that of humans and other mammals.Nevertheless,research has highlighted the importance of the microbiota in the health,performance,and various physiological functions of fish.The microbiota has been studied in various fish species,including model animals,economic fish,and wild fish species.The composition of the fish microbiota depends on host selection,diet,and environmental factors.The intestinal microbiota affects the nutritional metabolism,immunity,and disease resistance of the fish host,while the host regulates the intestinal microbiota in a reciprocal way through both immune and non-immune factors.Improved and novel gnotobiotic fish models have been developed,which are important for the mechanistic study of host–microbiota interactions in fish.In this review,we discuss recent progress in fish microbiota research.We describe various aspects of this research,including both studies on fish microbiota variations and fundamental research extending our knowledge of host–microbiota interaction in fish.Perspectives on how fish microbiota research may benefit fish health and industrial sustainability are also discussed.

开展陆生与水产养殖动物营养感知研究的展望

饲料在动物生长和健康中扮演着重要的角色,然而决定饲料表现的内在机一直是一个所谓的“黑箱”。直到近年来,研究证明营养素能够作为信号分子被细胞和机体感知,并在调控基因表达和代谢活动中起着至关重要的作用。多条分别感知不同营养素的信号通路被发现,营养感知信号调节也已在临床医学中被广泛用于药物开发与疾病控制。然而,在陆生和水产养殖动物中,对主要营养素(蛋白质、糖脂等)的营养感知和代谢调控的研究仍处于起步阶段。因此,我们针对未来在动物营养学中开展营养感知研究可能的研究主题和应用场景提出设想和建议。

Polysaccharides in Sipunculus nudus: Extraction Condition Optimization and Antioxidant Activities

Marine organisms constitute unlimited resource of bioactive substances due to their high biodiversity and represent a valuable source of new compounds. This study optimized the alkali-extraction conditions and antioxidant activities of soluble polysaccharides from the body wall of Sipunculus nudus. The effects of solid-liquid ratio, extraction duration, extraction temperature, and alkali concentration on the yield of S. nudus polysaccharides(SNP) were examined, according to which the optimal combination of extraction parameters was obtained by an orthogonal test. The relative influencing importance of different extraction parameters on the yield of SNP followed the order as solid-liquid ratio > extraction temperature > alkali concentration > extraction duration. The highest extraction yield, 1.98%, was achieved under an optimal extraction condition: temperature 60℃, solid-liquid ratio 1:6 g mL^(-1), duration 5 h, and alkali(Na OH) mass fraction 6%. The in vitro antioxidant activities examination showed that extracted SNP under this optimized condition had strong power in reducing certain hydroxyl and superoxide radical scavenging abilities. The promising results showed that extracted SNP could be a potent natural antioxidant.

Proline with or without Hydroxyproline Influences Collagen Concentration and Regulates Prolyl 4-Hydroxylase α(I) Gene Expression in Juvenile Turbot(Scophthalmus maximus L.)

This study was conducted to investigate the effect of dietary proline(Pro), and Pro and hydroxyproline(Hyp) in combination on the growth performance, total Hyp and collagen concentrations of tissues, and prolyl 4-hydroxylase α(I)(P4H α(I)) gene expression in juvenile turbot feeding high plant protein diets. A diet containing 50% crude protein and 12% crude lipid was formulated as the basal and control, on which other two protein and lipid contents identical experimental diets were formulated by supplementing the basal with either 0.75% Pro(Pro-0.75) or 0.75% Pro and 0.75% Hyp(Pro+Hyp). Four groups of fish in indoor seawater recirculating systems, 35 individuals each, were fed twice a day to apparent satiation for 10 weeks. The results showed that dietary Pro and Hyp supplementation had no significant effect on growth performance and feed utilization of juvenile turbot(P > 0.05). Total Hyp and collagen concentrations in muscle were significantly increased when dietary Pro and Hyp increased(P < 0.05), and fish fed diet Pro+Hyp showed significantly higher free Hyp content in plasma than those fed other diets(P < 0.05). The expression of P4 H α(I) gene in liver and muscle was significantly up regulated in fish fed diet Pro-0.75 in comparison with control(P < 0.05); however the gene was significantly down regulated in fish fed diet Pro+Hyp in muscle in comparison with fish fed diet Pro-0.75(P < 0.05). It can be concluded that supplement of crystal L-Pro and L-Hyp to high plant protein diets did not show positive effects on growth performance of juvenile turbot, but enhanced total collagen concentrations in muscle.

Recent progress in the understanding of the gut microbiota of marine fishes

As the significance of the gut microbiota has become increasingly realized,a large number of related studies have emerged.With respect to the gut microbial composition of fish,the predominant gut microbes and core gut microbiota have been reported by many researchers.Our understanding of fish gut microbiota,especially its functional roles,has fallen far behind that of terrestrial vertebrates,although previous studies using gnotobiotic zebrafish models have revealed that the gut microbiota performs a significant role in gut development,nutrient metabolism and immune responses.Given that environmental factors of marine habitats are very different from those of freshwater habitats,a distinct difference may exist in the gut microbiota between freshwater and marine fish.Therefore,this review aims to address the advances in marine fish gut microbiota in terms of methodologies,the gut microbial composition,and gnotobiotic models of marine fish,the important factors(host genotype and three environmental factors:temperature,salinity and diet)that drive marine fish gut microbiota,and significant roles of the gut microbiota in marine fish.