Abstract:Common carp (Cyprinus carpio L.) is an important economic fish species with very rich resources, which have been used to develop many carp varieties in China. Because of the significant differences in the genetic back- ground among varieties, quantitative trait loci (QTLs) detected from one variety are difficult to use directly in another variety. In addition, it is impossible to construct a genetic map and detect QTL markers affecting important traits in every variety. Thus, it is a good selection strategy to verify QTLs in one variety and identify shared QTL markers. The methods will save time and money and can be used to detect QTLs quickly in different varieties. Mirror carp (Cyprinus carpio L.) and Jian carp (Cyprinus carpio var. jian) are two important Chinese aquaculture varieties that play an impor- tant role in selective breeding. Significant differences in body shape, growth rate, and growth scale have been found between Jian carp and mirror carp. Thousands of QTLs affecting important traits have been detected recently in differ- ent mirror carp panels. However, the number of Jian carp QTLs is very limited. In this study, 89 microsatellite markers were selected to identify markers associated with mirror carp traits. These markers were located at overlaps or flanks of QTL interval peaks affecting body weight, standard length, body height, and body thickness based on a genetic map containing 992 microsatellite markers. As a result, 54 QTL markers and 83 preferred genotypes were identified by as- sessing the contribution of different genotypes on traits. In addition, a mapping population containing 94 Jian carp was analyzed using these 54 QTL markers. Forty markers were polymorphic in Jian carp, with a percentage of 74.07%, which was higher than that of randomly selected markers. Correlation analysis results indicated that 22 markers were shared QTLs between mirror carp and Jian carp, and 18 of the shared markers were significantly correlated with the same trait in the two carp. Thirty preferred genotypes were detected in Jian carp, which will be useful for a marker-associated selection breeding program. The QTLs shared between strains can be used to reduce the effort and cost of QTL mapping in new common carp varieties.

Abstract:The mud crab (Scylla paramamosain) is widely cultured on the southeast coast of China. Unfortunately, the crab industry has suffered significant economic losses in the past 10 years due to viral, bacterial, and parasitic diseases. Researchers have suggested that using immunostimulants would help establish a crab disease control strategy. However, little information on immune-enhancing proteins in crabs is available. In this study, a quantitative real-time reverse transcription-polymerase chain reaction (RT-PCR) analysis was carried out to investigate whether 11 reported genes, including metallothionein (Met), serine protease inhibitor (Spi), lysozyme (Lys), crustin (Cru), catalase (Cat), peroxide reductase (Per), prophenoloxidase (Pro), anti-lipopolysaccharide factor (Alf), Scylla serrata anti-microbial Scy2 pre- cursor, serine proteinase (Sek), and peroxinectin (Per) are associated with enhancing immunity in S. paramamosain treated with rhubarb polysaccharides for 4 days. The results indicate that the mean hemocyte mRNA expression values of Spi, Cat, Per, and Pro increased about 1.1-, 4.1-, 1.2-, and 2.1-fold, respectively. At the same time, the Spi, Cat, Per, Lys, and Alf genes in the hepatopancreas were significantly upregulated. Of these, Spi, Per, and Alf were upregulated 2.1-, 4.8-, and 1.7-fold, respectively. The Lys and Cat genes were only expressed in the experimental group. This result was different from our previous findings that five related immune-enhancing proteins, including hemocyanin, chy- motrypsin, cryptocyanin, C-type lectin receptor, and ferritin protein, were identified in S. paramamosain using proteo- mic and RT-PCR strategies. The discrepancy probably reflects differences between the two research approaches or an uni- dentified post-transcriptional mechanism in these related immune-enhancing proteins. Considering recent evidence that the Spi, Cat, Per, Pro, Lys, and Alf genes play significant roles in invertebrate immune defense, it seems likely that these six significantly upregulated genes in hemocytes and hepatopancreas may be related to enhancing the crab’s im- mune response. These results will help reveal the immune enhancement mechanism in S. paramamosain and will be important for immunological prevention of crab diseases.

Abstract:Comparative transcriptomics data have become one of the most important ways to study single nucleotide polymorphisms (SNP). We have identified 129 gene segments associated with growth. SNP is a third-generation mo- lecular marker and is useful for breeding rapidly growing species, such as the swimming crab, Portunus trituberculatus. We developed an efficient method to selectSNPs correlated with P. trituberculatus growth. Time-of-flight-mass spec- trometry was used for SNP typing, and the chi-square test was used for the correlation analysis. Nineteen gene segments were amplified based on comparative transcriptomics, and a total of 17 387 bp DNA fragments were amplified. SNP frequency was estimated to be 0.43/100 bp of DNA sequence, the conversion mutation rate was 80%, and the transver- sion mutation rate was 20%. The conversion ratio was far greater than the transversion ratio to comply with the princi- ple of “transition bias”. The G/T (C/A) rate was 20%, the A/T rate was 9.33%, the G/C rate was 10.67%, and the C/T (G/A), which is the most common gene mutation type, was 60%. The intron mutation frequency was 1.34/100 bp and that of exons was 0.17/100 bp, indicating that the exon mutation frequency was more conserved. Three SNP markers were significantly correlated with growth traits, and P-values of 10 SNPs were < 0.05. The chi-square test result re- vealed that comp58070-R31 was closely related to growth traits (P<0.01). A multivariate analysis of variance showed that comp58070-R31 was closely related to body weight, full carapace width, and carapace width (P<0.01). A signifi- cant correlation was detected between body length and body height(P<0.01). Loci comp46623-F49 and comp49193-R333 were significantly correlated with carapace width (P≤0.05). Observed heterozygosity of the P. trituberculatus SNPs was 0.162 8–0.833 3, and expected heterozygosity was 0.189 6–0.591 2, indicating less information content than that from microsatellite markers. These SNPs will be helpful for pedigree analysis, association studies, and marker-associated selection in this crab species.

Abstract:In the present study, two groups with different genetic backgrounds were obtained by intergeneric crossing Megalobrama amblycephala (♀)×Erythroculter ilishaeformis (♂). Our results show that fertilization rate (90.0%) and hatching rate (80.6%) in the intergeneric cross group were high. Hybrid A (96.2%) and hybrid B (3.8%) were obtained. The morphological characters of hybrid A were intermediate between those of the parents, and hybrid B had the same morphological characters as the M. amblycephala female parent. Relative DNA content of the hybrids was examined by flow cytometry. The results show that hybrids A and B were diploid and had the same DNA content as their parents. Two pairs of specific loci (TTF6 and TTF10) were screened by simple sequence repeat analysis. The results indicate that hybrid A inherited genetic material from both parents, whereas hybrid B only inherited maternal genetic material, indicating gynogenetic progeny. Hybrid A grew faster than either M. amblycephala or E. ilishaeformis, suggesting a clear growth advantage in earthen ponds. Our results provide basic data on a novel hybrid strain between Parabramis pekinensis and Erythroculter ilishaeformis. In addition, production of gynogenetic progeny can be applied to establish a pure line of M. amblycephala.

Abstract:We conducted a comparative study of hypoxia and high-ammonia resistance in Litopenaeus vannamei after 48 hours of stress in different mating combinations of the F1 generation at the juvenile and adult stages. We set up eight mat- ing combinations of inbred and hybrid L. vannamei with six different genetic backgrounds. The results show that the sur- vival rates of the YH♀× ZX♂, SS♀ × SS♂, and HD♀ × YH♂ juvenile shrimp mating combinations were 76.23%, 74.61%, and 74.38%, which were significantly higher than those of the other mating combinations (P<0.05). Survival rates of adult shrimp under hypoxic stress were 83.08%, 65.57%, and 71.12%. Thus, these adults could be used as candidates for hy- poxia-resistant breeding. Survival rates of the YH♀ × KN♂, HD♀ × YH♂, and YH♀ × ZK♂ juvenile shrimp mating combinations were 97.71%, 86.43%, and 80.01%, which were significantly higher than those of the other mating combina- tions (P<0.05). Survival rates of the adult shrimp under high-ammonia stress were 85.53%, 74.18%, and 69.23%. Thus, these adults could be used as candidates for high-ammonia resistant breeding. Hypoxia and high ammonia resistance of the HD♀× YH♂ mating combination was high, but the correlation between hypoxia and high-ammonia resistance in the dif- ferent mating combinations was not significant. We found that if a female parent originated from the YH group, its off- spring were also hypoxia resistant, suggesting that the hypoxia resistance trait is a maternal dominant genetic trait. Hy- poxic resistance decreased during the growth and development of the shrimp. The correlation between mating combina- tions of juvenile and adult shrimp for hypoxic stress and high-ammonia stress was highly significant (P<0.01). These re- sults suggest that the hypoxia and high-ammonia resistance traits of L. vannamei should be evaluated at the juvenile stage. This study lays the foundation for developing and culturing hypoxia- and high ammonia-resistant L. vannamei strains.

Abstract:Relatively high mortality has become a problem during Marsupenaeus japonicus culture in the summer in southern China. Thus, it is necessary to evaluate the thermal tolerance of M. japonicus. The upper thermal tol- erance trait (UTT) was determined to evaluate thermal tolerance of different sizes of M. japonicus. We combined the UTT with critical thermal methodology to compare thermal tolerance among three species, such as M. japoni- cus, Exopalaemon carinicauda, and Litopenaeus vannamei. We observed their behavior under gradually changing temperature and compared the lethal index. A correlation analysis revealed a correlation coefficient of −0.142 be- tween body weight and the UTT of M. japonicus. The UTT of juveniles (<0.01 g) was significantly higher than that of the group weighing 1–5 g (P<0.05). The three species responded differently to high temperature: tempera- tures for initial mortality and climax mortality of L. vannamei were highest, whereas those for E. carinicauda were the lowest. The mean UTT and critical thermal maximum of L. vannamei were highest, followed by those of M. japonicus and E. carinicauda (P<0.05). In conclusion, the thermal tolerance of M. japonicus was lower than that of L. vannamei but higher than that of E. carinicauda. These results are important data for a comprehensive un- derstanding of M. japonicus thermal tolerance and have practical applications for selecting high-temperature re- sistant strains.

Abstract:Thirty full-sib families including six maternal half-sib Acipenser gueldenstaedtii families were built using artificial insemination. The families were spawned on the same day, and a standardized procedure was used to produce the families during larval rearing to eliminate spawning age and common environmental effects on traits to increase precision of the estimate. Fifty individuals of each family were sampled randomly on days 150 and 410, and A. gueldenstaedtii body weight and body length were measured. The variance component and genetic parameters of body weight and body length were estimated with a multi-trait animal model using ASReml soft- ware. The heritability estimates on day 150 were 0.16±0.055 for body length and 0.18±0.058 for body weight. The heritability estimates on day 410 were 0.18±0.070 for body length and 0.094±0.049 for body weight. Heritabilities at different growth stages were low, suggesting that mass family selection is necessary for further selective breeding of A. gueldenstaedtii. The estimates of phenotypic and genetic correlation coefficients between the two traits at different stages were highly positive and were 0.91, 0.85, 0.62, and 0.57, respectively. A difference in the degree of correlation was observed between the two traits. A correlation analysis of genetic parameters would quantify the relationships between growth traits and facilitate planning of a multi-traits breeding program. These results suggest that growth traits of A. gueldenstaedtii could be improved by selecting either body weight or body length. The coefficients of variation for body weight at the two growth stages were 29.09% and 9.46% and both were higher than those for body length, which were 10.16% and 8.43%. These results indicate that the selection potential for body weight was higher than that for body length and provide a theoretical basis for the next A. gueldenstaedtii breeding program.

Abstract:We conducted a 90-day experiment in 12 flow-through tanks to evaluate the influence of stocking density on growth performance, muscle composition, and blood biochemical parameters in juvenile hybrid sturgeon [Acipenser baerii (♀)×Acipenser schrenckii (♂)]. Sturgeon (mean total length: 31.55±1.50 cm; mean body weight: 251.11±0.59 g) were randomly distributed into four different stocking density groups of G1 (5.50 kg/m3, 200 fish/pond), G2 (8.27 kg/m3, 300 fish/pond), G3 (11.01 kg/m3, 400 fish/pond), and G4 (13.80 kg/m3, 500 fish/pond). The results show that stocking density had significant effects on the growth and survival of juvenile hybrid sturgeon (P<0.05). Survival rates at the end of the experiment were 99.33%, 97.67%, 95.33%, and 92.80% in the G1, G2, G3, and G4 groups, respec- tively. Final body weight, specific growth rate, and condition factor decreased with an increase in stocking density, whereas the food conversion ratio showed the opposite tendency. Muscle moisture content increased significantly with the increase in stocking density, whereas crude muscle lipid content decreased significantly (P<0.05). However, no sig- nificant difference was observed in ash or crude protein content. Differences between treatments were detected for glu- cose, total protein, and hemoglobin. In conclusion, these results suggest that a high juvenile hybrid sturgeon stocking density could negatively influence growth, muscle composition, and blood biochemical parameters.

Abstract:The particle size, dispersion, and stability of a microencapsulated diet developed for the pearl oyster, Pinc- tada martensii, were measured in this study. An experiment was conducted to evaluate pearl oyster feeding and diges- tion, in which the experimental group (EG) was fed a microencapsulated diet, and the control group (CG) was cultured at sea. Survival rate, growth rate, biochemical components in the dried edible part, and digestive enzyme activities were measured and compared in the two groups after 45 days. The results showed good dispersion of the diet, a particle size < 48 μm, and that of about 80% of the particles were 28–48 μm. The settling velocity in 35 NaCl solution was (2.74±0.21) mm/s under static conditions. The nitrogen retention rates of the diet soaked in 35 NaCl solution for 120 min at 25℃ and the diet soaked in 35 NaCl solution for 60 min at 35℃ were (79.10±0.15)% and (80.85±0.72)%, respec- tively. No significant difference in survival rate was observed between the EG and CG, whereas the absolute and rela- tive growth rates of shell length, shell width, shell height, and total weight in the EG were significantly lower than those in the CG (P<0.05). The lipid component of the edible part was significantly higher in the EG than that in the CG (P<0.05). No significant differences were observed in the carbohydrate, protein, or ash components of the edible part between the EG and CG. The hepatopancreas of pearl oysters in the EG was saffron-yellow. Amylase, protease, and cellulase activities of the hepatopancreas of pearl oysters in the EG were not significantly different from those in the CG. A significant difference was observed in amylase activity between the two groups (P<0.05). These results suggest that this microencapsulated diet had appropriate particle size and stability and was absorbed and digested by the pearl oyster. Further studies should be conducted to optimize diet composition and farming protocols, which will be helpful for de- veloping indoor pearl oyster farming.

Abstract:We investigated nitrogen (N) and phosphorus (P) budgets in different grass carp (Ctenopharyngodon idellus) culture systems within a land-based enclosure. The experiment began in May and ended in October in 2011. Samples were collected periodically, and the enclosed area was 7 m × 7 m. N and P inputs and outputs were evaluated in grass carp monoculture(G), grass carp and silver carp (Hypophythalmichthys molitrix) polyculture (GS), grass carp and common carp(Cyprinus carpio) polyculture(GC), and grass carp, silver carp, and common carp (GSC1 and GSC2) sys- tems. N and P accumulation in water and sediment were analyzed. The results show that fish feed was the main N and P input source in all culture systems (85.54%–93.38% and 82.60%–84.26%). Other sources were the stocked animals, precipitation, and the initial water used. The N output sources in the different culture systems were the stocked animals, sediment accumulation, water accumulation, and absorption and volatilization by the enclosure cloth, which accounted for 62.80%–77.15%, 15.19%–27.60%, 5.04%–7.71%, 1.54%–2.14%, and 0.22%–0.30%, respectively. The P output sources were accumulation in sediment, accumulation in water, culture animals at harvest, and absorption by the enclo- sure cloth, which accounted for 76.46%–80.04%, 13.04%–15.14%, 4.09–9.79%, and 0.71%–1.61%, respectively. Ni- trogen accumulation in sediment from the GSC1 and GSC2 system was significantly lower than that in the G, GS, and GC systems (P<0.05), whereas P accumulation in sediment from the GSC1 and GSC2 systems was significantly lower than that in the G and GS systems (P<0.05). N and P accumulation in water from the GSC2 system was significantly lower than that in the G system (P<0.05). N and P utilization by the GSC2 culture system was significantly higher than that by the G, GC, or GSC1 systems (P<0.05). These results indicate that the GSC2 system (grass carp: 0.38 ind/m2, silver carp: 0.69 ind/m2, and common carp: 0.55 ind/m2) effectively reduced N and P accumulation and enhanced N and P utilization. Thus, the GSC2 system was an effective and clean grass carp polyculture mode.

Abstract:Common carp(Cyprinus carpio) is the main fish species cultured in ponds at high latitudes in northern China, where there are long and cold winters. Common carp reaches market size after a 5-month overwintering period in northeast China. Thus, it is critical to understand the effects of overwintering on the survival and growth of cultured fish. In this study, the growth of Songpu mirror carp (Cyprinus carpio var. songpu mirror) was monitored using passive in- tegrated transponders before and after overwintering. All fish were hatched at the same time and cultured under the same conditions. Morphological indices, liver and foregut histological structure, and biochemical composition of the viscera, muscle, and whole body were analyzed at 125 d (before overwintering), 170 d (beginning of freezing), and 325 d (after overwintering). Furthermore, the correlation between major energetic material at 325 d and overwintering body weight loss rate (WRL) was evaluated. The results showed that body weight (BW), condition factor (CF), visceral-somatic index (VSI), hepatosomatic index (HIS), and intestine-somatic index (ISI) decreased significantly over the entire overwintering period (125–325 d) (P<0.05). Significant degeneration of histological structures for the hepatic and foregut was observed during 125–325 d. Hepatic cells shrank, and the boundaries between hepatic cells were blurred. The abundant hepatic glycogen and lipid stores present before winter disappeared after winter. Foregut diame- ter, villus height, and muscle layer thickness decreased significantly after winter compared with those before winter (P<0.05), and the striated borders of the foregut were clearly atrophied. Visceral fat and hepatic glycogen contents were significantly attenuated at each sampling period (P<0.05). However, whole-body and muscle protein contents only de- creased significantly during 170–325 d (P<0.05). In addition, a significant negative correlation was detected between muscle protein content at 325 d and WRL (P<0.05), but no association was found between visceral fat at 325 d and WRL(P>0.05). Taken together, these results suggest that overwintering led to significant changes in the morphological indices based on common carp BW. Degeneration of the hepatic and foregut histological structures resulted from chronic hunger during the winter. The stages of consuming endogenous energy during the winter varied. Hepatic gly- cogen and fat were used initially during 125–170 d, whereas hepatic glycogen, fat, and protein were used for energy ex- penditure during 170–325 d. Muscle protein content after the winter could be useful as a reference indicator for WRL.

Abstract:The wild Modiolus modiolus resource has experienced a dramatic decline in abundance over the past few decades because of overfishing, declining seawater quality, and a lack of proper protection. The reproductive cycle and gonadal development of M. modiolus from the coast of Heishijiao, Dalian city were investigated from October 2013 to September 2014 to develop management strategies and optimize hatchery-based seed production. Specimens were col- lected monthly, and seawater column temperatures were recorded simultaneously. Shell size, total weight, tissue weight, and gonad weight of M. modiolus were measured to calculate fatness and the gonadosomatic index, and histological techniques were used to analyze the seasonal gonadal cycle. The histological analysis showed a unimodal gametogenic cycle with one spawning season (August–October) annually. Although shellfish gonadal development stages have no unified standard, M. modiolus gonadal development was divided into five stages according to previous studies: the pro- liferating stage, growing stage, maturing stage, spawning stage, and resting stage. Oogenesis was divided into the oogo- nial stage, early growth stage, middle growth stage, late growth stage, and mature stage, according to the oocyte devel- opmental characteristics and the proportions of different oocyte developmental stages in the follicle. Spermatogenesis of M. modiolus included five stages of spermatogonium, primary spermatocyte, secondary spermatocyte, spermatid, and spermatozoon. Spermatogonia were morphologically divided into types A and B. Type A spermatogonia distributed in all developmental stages, and their nuclear chromatin was arranged loosely. Type B spermatogonia occurred during the proliferating stage, and the nuclear chromatin was concentrated. Thus, types A and B spermatogonia were considered differentiated cells and stem cells, respectively. The peak gonadosomatic index of 32.25% and fatness of 38.43% were observed in January, and the maximum values for both occurred in August. The breeding season was from June to No- vember, when the average seawater temperature was 16.8–22.1℃. M. modiolus gonads matured by the end of May, but they did not spawn until August of the rainy season, indicating that the mature gonads of the parental shellfish only pro- vided a material basis for reproduction and that the reproductive process requires particular conditions for induction, such as temperature and salinity. The developmental rate of the male gonad was slightly faster than that of the female. Gonochorism existed, and the female to male ratio was 1︰1. These results provide basic information about M. modio- lus reproduction to help with natural resources protection, and will aid in developing a large-scale artificial breeding program.

Abstract:Invertebrates play an important role as a fishery resource. Catches of finfish have declined in recent years, yet invertebrate catches have continued to increase. However, little research has been done on the invertebrate commu- nity in the Yangtze River estuary and its adjacent waters. In this study, the characteristics of the invertebrate community dynamics in the Yangtze River estuary and its adjacent waters (30°45′–32°N and 122°30′–123°30′E) were investigated based on data collected from fishery surveys conducted in autumn 2009–2011. The relationships between the spatial and temporal variations in the invertebrate community and related environmental factors were also analyzed. The results indicate that 25 invertebrate species (14 crustaceans and 11 mollusks) were caught, and they belonged to 8 orders and 15 families, which was well below the number of invertebrates captured in the 1980s (31 species). The species replace- ment rates (R) from 2009 to 2010 and 2010 to 2011 were > 50%, indicating species succession and declining inverte- brate community stability. The dominant invertebrate species in the community were Portunus trituberculatus, Trachypenaeus curvirostris, Loligo japonica, and Charybdis bimaculata, and they presented a succession phenomenon during autumn 2009–2011. The individual and biomass densities of the invertebrate community showed an increasing trend with minimum values in 2009 (4.57 kN/km2 and 185.52 kg/km2, respectively) and maximum values in 2011 (73.46 kN/km2 and 233.11 kg/km2, respectively). The significant interannual variations (P<0.05) in invertebrate species diversity (Species richness, Shannon–Wiener index, and Pielou evenness) were lower in the estuary than those in Laizhou and Jiaozhou Bays. The invertebrate species were classified into two assemblages based on a two-way indica- tor species analysis, which showed clear interannual variations in the community. A redundancy analysis clarified that surface salinity and bottom temperature were the major factors affecting the invertebrate assemblage structure. In con- clusion, the variations in invertebrate community structure were embodied in the alteration of dominant species and diversity during autumn 2009–2011, and temperature and salinity were the primary limiting factors driving the spatial and temporal variations in the invertebrate community in the Yangtze River estuary and its adjacent waters.

Abstract:Antarctic krill (Euphausia superba Dana) is a keystone species in the Southern Ocean ecosystem. Biomass and distribution research is important to further understand the Southern Ocean ecosystem and its relationship with en- vironmental change. Krill biomass fluctuates annually in the Southern Ocean, and a relationship between extensive sea-ice cover during winter and subsequent high krill recruitment in the Antarctic Peninsula region has been suggested. Although many studies have investigated the effects of environmental factors (temperature, salinity, oxygen, and cur- rents) on krill, except bathymetry of the shelf break and the presence of Circumpolar Deep Water near the Antarctic Peninsula, few studies have demonstrated a clear relationship between other factors and krill. Based on a transection survey conducted in the waters near Prydz Bay during the 29th Antarctic Chinese Scientific Expedition, continuous hy- droacoustic surveying and net sampling were conducted to estimate krill biomass and study the effects of the marine environment on krill spatial-temporal distribution. The environmental factors included water temperature, salinity, chlorophyll concentration, and bathymetry. The hydroacoustic instrument used was the 38 kHz SIMRAD EK500 (Nor- way). The sampling net had a 15-mm mesh size. Environmental data were collected with the SBE-CTD911 instrument. The results showed that mean krill density in the survey area was 32.8 g/m2, and krill biomass was 9.34 million tons. The population age structure was mainly composed of the 2+ and 3+ recruitment groups, and the growing conditions during recruitment were the main reason for the annual changes in krill biomass. Krill aggregated primarily at the shelf break (70.50°E–75.50°E and 67°S–68.5°S) at 250–1000 m. A significant correlation (P<0.01; r=0.193) was found be- tween chlorophyll concentration and the spatial-temporal distribution of Antarctic krill. Temperature, salinity, and bathymetry did not correlate directly with the Antarctic krill spatial-temporal distribution(P>0.05). A significant nega- tive correlation was found between salinity and chlorophyll concentration (P<0.01, r=−0.23). The deep chlorophyll concentration maximum phenomenon (DCM) was found at 73°E and 67°S in the waters near Prydz Bay. The DCM may correlate with the winter residual water mass.

Abstract:Macrobenthic species diversity in the waters surrounding Zhelin Bay was studied based on the quantitative data of macrobenthos sampled in February, May, August, and December 2013. The results show that 89 macrobenthic species were sampled in 2013. Mean Margalef richness index, Shannon-Wiener index, and Pielou evenness index val- ues were 1.73, 1.84, and 0.88, respectively. One-way analysis of variance showed that the richness, diversity, and even- ness indices were not significantly different among seasons. The k-dominance curve of abundance showed that the sea- sonal trend in species diversity was winter > spring ?autumn > summer. An R-type cluster analysis showed that the rich- ness, diversity, and evenness indices could be classified as a cluster. The correlations between the diversity index and richness index, the diversity index and species number, and the richness index and species number were relatively high. A Q-type cluster analysis showed that the 28 sampling stations could be classified into three or five clusters.

Abstract:Seasonal bottom-trawl surveys were conducted in Haizhou Bay, China from March to December 2011. A total of 516 Conger myriaster stomach samples were analyzed to study their feeding ecology, including diet composi- tion, feeding type, feeding intensity, trophic niche, and trophic level. The results show that the prey items of C. myri- aster included more than 40 species, and fish, decapods, and cephalopods were the dominant prey groups. Syngnathus acus, Chaeturichthys stigmatias, Alpheus distinguendus, and Loligo sp. were the major prey species of C. myriaster. Benthic animals were the dominant C. myriaster prey type, followed by swimming animals. The diet composition of C. myriaster had clear seasonal and length variations, and fish and shrimp were the major prey groups throughout all four seasons, whereas cephalopods were the most important prey during autumn. Loligo sp. were the dominant prey group of the C. myriaster with anal length < 70 mm, whereas Callionymus beniteguri and A. distinguendus were the dominant prey groups of the 70–99 mm C. myriaster. Loligo sp., Syngnathus acus, and A. distinguendus were the dominant prey groups of the C. myriaster > 99 mm. Percent of empty stomach and mean stomach fullness index of C. myriaster varied seasonally. The lowest and highest percent of empty stomach occurred in summer and spring, respectively. The mean stomach fullness index was lower in spring and higher in autumn. The C. myriaster trophic level was 4.17, indicating that it was in a high trophic position in the Haizhou Bay food web. The feeding ecology of C. myriaster varied season- ally and ontogenetically, which was mainly due to variations of dominant prey species. These results will help with as- sessments of prey abundance and species changes and provide basic information for building a food web and under- standing the trophic dynamics in the Haizhou Bay ecosystem.

Abstract:Previous fish population studies were mainly based on short historical catch records. However, the short time-scale of such records and the almost complete overlap in time between the records and large-scale fishery exploita- tion are of limited use when assessing long-term variations in fish populations and distinguishing the relative impor- tance between natural and anthropogenic factors. Therefore, it is essential to develop long-term time series of fish stocks beginning when human impacts were minimal to understand the causes of variability in fish stocks (natural and/or anthropogenic). Well-preserved fish scales from sediment records are useful indicators for revealing the history of fish population dynamics over the last few centuries. Fish scale fossils discovered in sediment are primarily identi- fied by comparison with fresh fish material collected in the same area. Therefore, developing a fish-scale database is useful for identifying species from fish-scale fossils and reconstructing the population using a sedimentary-scale record analysis. The morphological structure of fish scales is stable and contains species-specific characters. These morpho- logical characters can be used to identify species from sedimentary records. Twenty-eight common fish species in the Yellow and Bohai Seas were chosen as study objects, and the morphological characters of their scales were described and compared. Distinguishable scale characteristics of different orders, families, and genera include: (1) overall scale shape; (2) appearance and manifestation of circuli; (3) position of the focus; (4) number and manifestation of radii; (5) appearance of the anterior, posterior, and lateral fields of the scale; (6) appearance and position of the lateral-line canal; and (7) appearance and number of ctenii. The results show that scales with a poorly defined focus and a trans- verse or wavy radii pattern were uniquely in Clupeiformes; the number and manifestation of radii were regarded as identifying features of different genera in Clupeiformes. Because of the intertwined patterns of the radii and ridges, dense small blocky shapes on the scale surface were unique in the scales of Gadiformes. Scales of Myctophiformes had a relatively small number (2–4) of radii and large arcs in the posterior field. A rectangular and oval shape with a nearly right angle in the anterior field was the most common character among scales in Perciformes and Scorpaeniformes, ex- cept in Chaeturichthys stigmatias and Pampus argenteus; the distribution of ctenii and the shape of the lateral-line canal were identifying features of different genera in Perciformes and Scorpaeniformes. An oblong shape with dense radii in the anterior field was a unique character in the scales of Pleuronectiformes. Distinguishable characters, including over- all scale shape, distribution of ctenii, and the shape of the lateral-line canal, were found in different genera of Pleu- ronectiformes. However, these families and genera are usually distinguished by combinations of the characters men- tioned above. This study provides basic information on identifying species for a scale sedimentary record analysis based on fish-scale morphology. This type of analysis is expected to improve the veracity of species identification and reli- ability of scale sedimentary record analysis by collecting fish scales of more species, quantifying scale morphological characters among close relatives, and studying the geographic variations of scales in inter-species. When combined with other biogeochemistry and productivity proxies, a scale sedimentary record analysis can be compared with changes in ocean productivity and help illuminate factors driving changes in ocean productivity, which is the ultimate goal of our ongoing work.

Abstract:As primary producers, phytoplankton play an important role in ensuring the laws of material recycling and energy flow in aquatic ecosystems. Phytoplankton abundance and community structure are indicators of the marine en- vironment. Thus, they influence fisheries resources through a bottom-up effect. The Qiansan Islets have been rich in fisheries resources for a long time, but over-fishing and environmental degradation have put tremendous pressure on this marine ecosystem in recent years. Thus, the local government conducted an artificial reef construction project beginning in 2005 to improve the marine environment and enhance fisheries resources. In this study, we used multivariate statistical analysis to compare phytoplankton community structure at different times (four seasons) and locations (artificial reef and control areas) to assess primary production in this region after constructing an artificial reef. Four cruise survey samplings were carried out at the artificial reef island and the adjacent waters around the Qiansan Islets in Haizhou Bay from September 2012 to August 2013. Eighty-five species in 35 genera and three phyla were identified, including 67 species of Bacillariophycophyta, 17 species of Pyrrophycophyta, and one species of Chryso- phycophta. Phytoplankton abundance values in spring and autumn (16.5  105 and 13.31  105 cells/m3, respectively) were significantly higher than those in summer and winter (6  105 and 3.8  105 cells/m3, respectively). The dominant species included Chaetoceros densus, Chaetoceros constrictus, Chaetoceros pseudocurvisetus, Coscinodiscus subtilis var. subtilis, Coscinodiscus debilis, Chaetoceros castracanei, Chaetoceros curvisetus, and Chaetoceros debilis. C. den- sus was the most dominant species in the spring. Phytoplankton community parameters (species number, abundance, chlorophyll a concentration, Margalef’s richness, Shannon-Wiener diversity, and the Pielou evenness index) were not significantly different (P>0.05) between the reef and control areas, except the Shannon–Wiener diversity and the Pielou evenness indices in spring, but significant differences were found among seasons (P<0.01). Environmental factors were also significantly different seasonally, but no differences were found between the reef and control areas. Multidimen- sional scaling and cluster analyses showed that phytoplankton community composition was very similar between areas but significantly different among seasons. The similar phytoplankton community structure was probably due to the close proximity of the reef to the control area, the small scale and deep water in the sampling area, the sampling sites’ close proximity to the island, and the short settling time of the artificial reef. A redundancy analysis showed that tem- perature, SiO3-Si, dissolved oxygen, PO4-P, BOD5, dissolved inorganic nitrogen, chemical oxygen demand, and trans- parency were the main factors influencing the phytoplankton community.

Abstract:A virus named FYL140220 was isolated from naturally infected Triplophysa siluroides in Leshan, Sichuan Province using epithelima popuasum cuprini (EPC) cells. The infected EPC cells showed circular shrinkage, necrosis, and desquamation, which formed significant plaque-lesion characteristics. Diseased tissue suspension filtered from bac- teria and EPC-grown virus were used to inoculate healthy Triplophysa siluroides. As a result, the infected T. siluroides developed similar clinical symptom to those described above and suffered 30% and 40% mortality, whereas the uninfected control EPC cells remained normal. Electron microscopy revealed icosahedral viral particles in the cells. The FYL140220 virus had an average diameter of (103 ± 7) nm, and the hexagonal shape was highly similar to that of other Iridoviridae viruses. DNA was extracted from the EPC-grown virus and naturally and artificially infected internal T. siluroides tissues for polymerase chain reaction (PCR) amplification of the conserved region of the ranavirus major capsid protein (MCP) gene, revealing a 500-bp fragment. The MCP homology and genetic evolution analysis showed that FYL140220 and other ranavirus strains formed a tight cluster and shared 99.8% identity with CGSV-G and 99.6% with RGV. Taken together, these results confirm that FYL140220 is a ranavirus. This is the first report on a natural ranavirus infection and mortality caused by this pathogen in cultured Triplophysa.

Abstract:The model purse seine was prepared following Tauti’s modeling law and actual cases. The dimensions of the model purse seine were: float line length, 80.9 m; maximum net height, 15.6 m; lead line length, 98 m; basic lead line weight, 0.663 kg/m; and float line buoyancy, 25 N/m. The same hanging ratio was used for the model net and the full-scale purse seine. The results show that the relationship between sinking depth (D) and time (t) for the middle sec- tion of the lead line was described by the formula: D=−0.0014t2 + 0.276t–0.6476 (R²=0.9953). Lead line weight, but not setting speed, had a significant effect on sinking performance, while the interaction effect caused by these two factors was significant on sinking depth. Lead line weight of 0.531–0.663 kg/m increased sinking depth significantly, whereas sinking speed showed a decreasing trend. Lead line weight of 0.663–0.759 kg/m decreased sinking depth slightly, whereas sinking speed improved significantly. A lead line weight of 0.663 kg/m resulted in a tendency that sinking speed increased as setting speed increased. As sinking time increased, tension on the lead line of 0–20 s fluctuations was needed to maintain a steady state. Constructing the mode net is an important part of a model test and is directly related to the model test results. In this study, we constructed a tuna purse seine model to better understand tuna purse seine performance.

Abstract:The Pacific oyster(Crassostrea gigas) is cultured worldwide, and the meat yield and shell shape (shell width and shell depth) are two of the most important economic traits of this species. The mapping population used in this study was an F1 full-sib family produced by mating a female parent from a second-generation strain selected for rapid growth in Japan with a male parent from a wild Chinese population. Eighty-three progeny were selected for linkage analysis in July 2009, and the meat yield, shell width, and shell depth traits were determined. The values for the shell width and shell depth traits were normally distributed, except meat yield, and these three traits were positively correlated. A genetic linkage map was constructed with 120 microsatellite and 66 single nucleotide polymorphisms (SNPs) from the F1 full-sib family. Based on the linkage map, PROC QTL 2.0 software was selected to perform a quantitative trait locus (QTL) analysis for the meat yield and shell shape (shell width and shell depth) traits under a four-way model using the maximum-likelihood method. The results show 13 related QTLs distributed on three linkage groups (LGs). Four QTLs were associated with meat yield on LG 1 and 3 and explained 0.25%–47.53% of the phenotypic variance. Three QTLs on LG10 were related to shell width and explained 0.71%–45.39% of the phenotypic variance. Six QTLs were identified for shell depth on LG10 and explained 3.37%–24.78% of the phenotypic variance. The results of the QTL linkage group and correlation analyses suggest that meat yield and glycogen content, and shell depth and shell width may have closely related genetic characteristics, and that the traits (meat yield and glycogen content, and shell depth and shell width) could be improved simultaneously when closely linked markers are used during breeding. These results provide a useful reference for further candidate gene research and molecular marker-assisted selection in the Pacific oyster.

Abstract:Thirteen polymorphic microsatellite markers were examined in four different Meretrix lamarckii geographi- cal populations to assess the naturally occurring Meretrix lamarckii resource. The four populations were sampled in Cangnan City, Zhejiang Province; Changle City, Fujian Province; Ningde City, Fujian Province; and Shantou City, Guangdong Province. Sixty-three alleles were found in the 13 microsatellite markers. Allele number per locus was 2–7, and the mean number of alleles was 4.87. Mean effective number of alleles, mean observed and expected heterozygosity, and mean polymorphism information content were 1.927–2.591, 0.437–0.562, 0.446–0.549, and 0.383–0.490, respec- tively. All of these genetic indices indicate medium genetic diversity in the four populations. The Hardy-Weinberg bal- ance test showed that most of the microsatellite sites in the four populations deviated from equilibrium(P<0.05). An unweighted pair group method with arithmetic mean cluster analysis indicated that the Cangnan population clustered with the Ningde population into one clade, and the Changle and Shantou populations were in a second group, which was consistent with their actual geographical locations. The Fst value was 0.230 9, suggesting that the genetic variation in the four M. lamarckii populations was 23.09%, which was high, and that the genetic differentiation level was high.

Abstract:Macroalgal photosynthesis is a major source of marine primary productivity and a crucial part of the ocean carbon cycle. Macroalgae effectively absorb inorganic carbon dissolved in the ocean and CO2 in the air to produce or- ganic carbon and release O2 through photosynthesis. Besides supporting the ocean ecosystem, photosynthetically pro- duced products are deposited in the sediment in the form of organics to complete the carbon sink. Proliferation of macroalgae results in a significant decrease in CO2 concentration, mitigates ocean acidification, strengthens the effect of ocean carbon sequestration, and mitigates climate change. These results provide a general description of the mechanism and potential of macroalgae to contribute to the carbon sink and present ways to enhance ocean carbon sink capacity. The results provide a basis for developing a macroalgal carbon sink effects study.