2015 Vol. 11 No. 4
We conducted a seasonal investigation on the community structure of macrobenthos in four typical wetlands in Macao from December 2012 to September 2013. A total of 66 species were identified, including 45 species of molluscs, 9 polychaetes, 8 crustaceans and 3 fishes. The macrobenthic species composition in wetlands was characteristized by brackish water species, freshwater species and estuarial low salinity species. Bottom-type species dominated in the life form composition, herbivorous and plankton feeders dominated in functional feeding composition. The species occurred in Lotus Flower Bridge Flat (46 species) most. Two-Way analysis of variance show that there was significant difference in species number among different seasons. Limnoperna fortunei, Angulyagra polyzonata, Bellamya purificat, Dendronereis pinnaticirris, Ilyoplax deschampsi and Trapezium liratum were the main dominant species. The descending order of macrobenthos density was autumn > summer>winter>spring. The descending order of biomass was autumn>spring>winter>summer. Shannon-Wiener species diversity and Pielou evenness indices were the highest in Lotus Flower Bridge Flat, but no significant difference was detected in the two indices among different seasons and sampling sites.
The distribution characteristics of zooplankton communities were discussed based on the survey data in the offshore waters of the Southern Yellow Sea and the East China Sea (23.5°N~35.0°N, 117.5°E~125.5°E) in summer, 2013. Seven phyla including 252 species (excluding 58 larval planktons) were identified. The zooplanktons were classified into six communities by cluster analysis with obvious ecological characteristics of of key species. Community Ⅰ was dominated by Centropages dorsispinatus, Sagitta enflata, Calanus sinicus, etc.; Community Ⅱ was dominated by C.sinicus, S.enflata, Temora turbinata, etc.; Community Ⅲ was dominated by C.sinicus and S.enflata; Community Ⅳ was dominated by T.turbinate, Diphyes chamissonis, Subeucalanus subcrassus, etc.; Community Ⅴ was dominated by Acartia pacifica and Labidocera euchaeta; Community Ⅵ was dominated by L.euchaeta, S.crassa and Pleurobrachia globosa. The distribution pattern of zooplankton in the Southern Yellow Sea and the East China Sea showed a higher agreement with water sphere. Difference in temperature and salinity in different water masses might be the main factor leading to the distribution pattern of zooplankton.
Based on the survey data in Qinzhou Maowei Gulf of Guangxi in wet and dry seasons in 2011, we analyzed the species composition and resources density of nekton in that area. The results show that there were 113 species of necton belonging to 86 genus, 54 families, 19 orders. Among them, 76 species of fish accounting for 67.26% of the total species belonged to 65 genus, 39 families, 13 orders. There were 29 species of crustacean accounting for 25.66% of the total species which belonged to 15 genus, 10 families, 2 orders. There were 7 species of cephalopoda accounting for 6.20% of the total species which belonged to 5 genus, 4 families, 3 orders. There was 1 species of merostomata accounting for 0.88% of the total species which belonged to 1 genus, 1 families, 1 orders. The necton mostly belonged to the fauna of Indian-Pacific. The fish all belonged to osteichthyes. The dominant fish species were warm-water (88.16%), then warm-temperate (11.84%), no cold-temperate. The dominant crustacean and cephalopoda species were warm-water, then eurythermal, warm-temperate, no cold-temperate. The resource density of nekton presented obvious seasonal variation, and the weight density was significantly higher in dry season (25 977.37 kg · km-3) than that in wet season (15 249.49 kg ·km-3), but individuality density was significantly higher in wet season (3 825 446 ind · km-3) than that in dry season (1 889 575 ind · km-3).
Based on the survey data collected from Shuidong Bay in April and October, 2013, we analyzed the species composition, spatial and temporal distribution and diversity of phytoplankton. A total of 69 species of phytoplankton belonging to four phylums were identified (59 species of Bacillariophyta, accounting for 85.51%;8 species of Pyrrophyta, accounting for 11.59%;1 species of Cyanobacteria and 1 species of Chrysophyta, accounting for 1.45%). The abundance of phytoplankton in autumn (203.10×104 ind ·m-3) was 8.87 times higher than that in spring (22.89×104 ind · m-3), and the abundances obtained from the sampling stations outside the bay and inside the bay in spring and autumn were high. Skeletonema costatum was the first dominant species in spring and autumn, and the dominances were 0.64 and 0.54, respectively. Shannon-Wiener diversity index (H′) and Pielou evenness index (J′) were higher in spring (2.38, 0.66) than in autumn (1.72, 0.43). Margalef richness index (D) was lower than 1.00 in the two seasons. It is concluded that the Shuidong Bay had been polluted.
We studied the effect of Cu2+ stress at different concentrations on the growth and physiological biochemical characteristics of Sargassum hemiphyllum by a semi-static test for 8 d. The results show that the relative growth rate (RGR) of thalli in the control increased initially and then decreased with time; on the 8th day, the RGR of thalli was higher than that in the control only when Cu2+ concentration was 0.05 mg · L-1. The physiological biochemical indices showed a fluctuation trend with time. On the 8th day, these indices of thalli at Cu2+ concentration of 0.01 mg · L-1 had no significant difference with the control; when Cu2+ concentration was 0.05 mg · L-1, the catalase (CAT) activity and malondialdehyde (MDA) content were significantly higher than those in the control, and the other indices recovered to the control level. However, in Cu2+ > 0.05 mg · L-1 groups, chlorophyll a (Chl-a), carotenoid (Car) and soluble protein (SP) were lower than those in the control; the other indices were higher than those in the control. Compared with 0.25 mg · L-1 Cu2+ group, 1.25 mg · L-1 Cu2+ group had more significant influence on biochemical indices except MDA. Therefore, appropriate concentration of Cu2+ (≤ 0.05 mg · L-1) had positive effect on the growth and physiological biochemical indices of S.hemiphyllum, but there was negative impact on the growth and the ability of resilience of thalli when the concentration of Cu2+ was extremely high (> 0.05 mg · L-1).
Vertebrae are usually used to determine age and growth for sharks. Recent studies have shown that vertebrae contain important information about feeding and trophic level. In this study, vertebrae of blue shark (Prionace glauca) were used to estimate stable isotope ratios of δ13C and δ15N which were -1.664‰~-1.308‰, 9.29‰~2.237‰, and 2.73~5.73, respectively. The vertebra samples were sub-sampled from the origin, middle and outer edge of centrum. The δ13C, δ15N, and TL between origin and middle, between middle and outer edge, and between origin and outer edge were not significantly different, indicating sub-sampling might be made at any of these positions. This results provide important information for further studies on trophic dynamics of pelagic sharks.
This study investigated the effects of parent-acclimation and heat-shock at gastrula stage on growth and development of sea cucumber (Apostichopus japonicus) larvae. The adult sea cucumbers were split into two groups: DA group and XP group, each with two treatments: control (C) and heat-shock (H). Gastrula larvae of H were heated at 26 ℃ for 45 min and then reared at 18 ℃ and 23 ℃ separately until metamorphosis. Results show that the specific growth rate at 23 ℃ was higher than that at 18 ℃ in the control, but the trend was opposite in heat-shock treatment. Since the 2nd day of auricularia, the maximum body length had been observed in heat-shock treatment for both DA and XP group, which was due to the ingestion of food. The setting rate of heat-shock treatment was significantly lower than that of the control due to the high rate of deformed individuals caused by heat-shock. Thus, high temperature-resistant sea cucumbers can be acquired via the following steps: first, obtain a certain number of high temperature-resistant juveniles by heat-shock at gastrula stage; then, culture these individuals in southern China until sexual maturity; finally, fix the high temperature-resistant properties by generation selection.
In order to provide references for developing high-density breeding of Litopenaeus vannamei, we established eight progeny populations based on eight different broodstock populations to investigate the growth and survival of the inbred and hybrid offspring of L.vannamei at different stocking densities (80 ind · m-2, 200 ind · m-2, 400 ind · m-2). The results show that stocking density had great effect on growth and survival of different populations (P < 0.05). At stocking density of 80 ind · m-2, the specific growth rate was 8.29~10.38 g · d-1[average (9.29±2.14) g · d-1] and the survival rate was 66.7%~96.7% [average (82.9±10.5)%], significantly higher than those at stocking density of 200 ind · m-2 and 400 ind · m-2 (P < 0.05). The growth and survival rate of L.vannamei reduced with increasing stocking density. Significant difference was found in growth and survival among different offspring of L.vannamei at three stocking densities. SIS♀×SIS♂ grew fast, higher than average values by 11.7%, 17.9% and 10.4% at stocking densities of 80 ind · m-2, 200 ind · m-2 and 400 ind · m-2, respectively. HD♀×YH♂ had higher survival rate which were higher than average values by 13.7%, 9.3% and 9.5% at three stocking densities of 80 ind · m-2, 200 ind · m-2 and 400 ind · m-2, respectively. YH♀×ZX♂ and YH♀×K♂ showed superior phenotype traits of growth and survival rate. It is suggested that SIS♀×SIS♂, HD♀×YH♂, YH♀×ZX♂ and YH♀×K♂ could be kept as breeding materials for next selective breeding.
To investigate the effect of low salinity stress on antioxidant function of juvenile Nibea albiflora, we set three levels of salinities (9, 16, 23) and salinity of 23 as the control; the tissues were sampled on the 0, 1st, 3rd and 7th day to measure the superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px) activities and total antioxidant capacity (T-AOC) in their liver, as well as malondialdehyde (MDA) in their liver and serum. The results show that SOD activity in liver increased first then decreased, and CAT activity showed a decrease-increase-decrease trend under low salinity stress. GSH-Px activities in liver increased significantly (P < 0.05), and the lower salinity was, the more dramatic the changes were. T-AOC in liver decreased after a significant increase (P < 0.05) at salinity of 16, but decreased significantly and maintained a low level at salinity of 9 (P < 0.05). MDA contents in liver and serum at salinity of 9 increased significantly (P < 0.05);MDA contents in liver fluctuated, and those in serum decreased slightly at salinity of 16. The results suggest that low salinity has significant effect on the antioxidant function of liver from N.albiflora; and N.albiflora is highly tolerated to low salinity but will consume energy reserve which leads to lower resistance even damage of fish when the stress is too strong.
Taking chicken (Gallus gallus) red blood cells as internal reference standard, we measured the genome size of Nibea albiflora by using flow cytometry. The relative area and integrated optical density (IOD) of 24 pairs of chromosomes were determined using fluorescence staining and microscopic image analysis software, and the physical length of each pair of chromosomes was estimated based on the IOD values. The genome size of N.albiflora was estimated as (595.70±24.08) Mb, and the DNA content was (0.61±0.02) pg. The genome of N.albiflora comprised 24 pairs of telocentric chromosomes, with the physical length ranging from (16.85±4.13) Mb to (31.95±4.23) Mb. The physical lengths of chromosomes were correlated linearly with the relative area and relative lengths. The results provide basic data for analysis of evolution rule of genome size in Sciaenidae and the forthcoming whole genome sequencing of N.albiflora, as well as for identifying and paring of chromosomes.
In 2011, there was an outbreak in a Plectropomus leopardus farm in Wenhui Town, Yandui Village, Hainan Province.The color of sick fish turned white and the tail fin festered. We isolated a Strain X11YD05 from sick P.leopardus which was proved to be pathogen by artificial infection and the LD50 was 1.67×105 cfu · g-1 in Epinephelus coioides using Karber method. To determine the molecular characteristics of X11YD05, we amplified the 16S rDNA, transmembrane regulatory protein (toxR), RNA polymerase δ70 factor (rpoD), actin-like cytoskeleton protein (mreB), topoisomerase (topA) and replication origin-binding protein (rctB) by PCR. Sequence analysis indicates that X11YD05 belonged to V.harveyi. Drug sensitivity test shows that X11YD05 was sensitive to norfloxacin, ofloxacin, ciprofloxacin, enrofloxacin and cotrimoxazole.
To investigate the effects of chronic external ammonia stress on growth, immunity and metabolism of juvenile GIFT tilapia (Oreochromis niloticus), we designed five concentrations of ammonia, including 0 mg · L-1(A0), 1.63 mg · L-1(A1), 3.25 mg · L-1(A2), 6.51 mg · L-1(A3) and 13.01 mg · L-1(A4). The results show that after 30-day feeding, the juveniles′ weight gain rate (WGR) and specific growth rate (SGR) decreased significantly with increasing concentration of ammonia. For immunity, the number of white blood cells (WBC) increased but that of hemoglobin (HGB) decreased with increasing concentration of ammonia. Serum albumin(ALB) concentration and superoxide dismutase(SOD) activities of A3 and A4 were significantly less than A0, while alkaline phosphatase (AKP) concentration of A4 was significantly less than A0. For metabolization, serum triglycerides(TG) concentration of A3 and A4 were significantly less than A0, while total cholesterol (TC) concentration of A1~A4 were significantly less than A0. Serum alanine transaminase(ALT) activities of A3 and A4 were significantly less than A1 and A2. Meanwhile, only aspartate transaminase (AST) activities of A4 was less than A0. It is revealed that the growth, nonspecific immunity and metabolism of juvenile GIFT tilapia would be inhibited under chronic ammonia stress; change of ammonia concentration in tilapia aquaculture should be paid more attention to.
To study the effects of dissolved oxygen levels on the growth, energy metabolism and oxidative stress of mullets (Mugil cephalus), we cultivated the healthy mullets at average body weight of (29.24±0.08) g for 40 d in a circulating water flow control system [(25±1)℃] at dissolved oxygen levels of (1.56±0.39) mg · L-1, (4.13±0.45) mg · L-1 and (7.22±0.46) mg · L-1, respectively. The specific growth rate (SGR), LD, SOD, T-AOC, ASOR and MDA in the plasma, muscle, lung and gill were measured; the oxygen consumption rate, ammonia excretion rate and O : N ratio were also determined. The results show that the weight gain increased with increasing dissolved oxygen content; the SGR was positively correlated with dissolved oxygen content which had significant effect on the growth of mullets. The oxygen consumption rate and ammonia excretion rate were the highest at dissolved oxygen level of 7.22 mg · L-1, while O : N value was the lowest. The contents of T-SOD, T-AOC and ASOR in liver were negatively correlated with SGR. It is revealed that since the increase of oxidative stress was conflict with rapid growth, the mullets will consumed more energy under oxidative stress, which leads to slow growth.
The morphology and histological structures of Polydora brevipalpa were studied by living observation, histological staining technique and scanning electron microscopy (SEM). The results show that: 1) The live worm was translucent and light brown, with black pigmentation on the palps. Prostomium was round, and four eyes were in trapezoidal arrangement. The setae on Chaetiger 5 were modified and enlarged; major spines of Chaetiger 5 were falcate, displaying a lateral tooth. Branchiae began from Chaetiger 7, and blood vessels flowed in the middle of the body and branchiae. Pygidium was disc-like with a dorsal incision. 2) The middle of the palps had food groove, where had a large number of cilia. Occipital tentacle was absent. Beginning from Chaetiger 7, the dorsal bands of cilia extended across the dorsum, between each pair of branchiae. The neurochaetae were replaced by bidentate hooded hooks.3) The body structure of P.brevipalpa was mainly composed of skin, muscle layer and digestive system. A lot of gland cells were concentrated in cuticular layers. The muscle system was highly developed and oblique muscle appeared. The villi on Epithelial cells of the digestive tube appeared densely and regularly which formed obvious striated border. Each segment had a pair of renal tubular, a pair of lateral vessel and a pair of glandular pouch. It is concluded that the boring mechansm of P.brevipalpa resulted from mechanical abrasion by modified chitinous setae on Setiger 5 and chemical action by a secretion.
We investgated the effect of desiccation on antioxidant enzyme activities of kuruma shrimp (Marsupenaeus japonicus). The results show that many shrimps died in the four treatment groups in 5 h after desiccation, and wet and low temperature improved the survival rate of shrimps significantly. Compared with the control, the activities of glutathione peroxidase (GPx), catalase (CAT) and superoxide dismutase (SOD) in hepatopancreas of the four treatment groups increased firstly and then decreased gradually, but GPx activities in the low temperature and dry (DG) and the normal temperature and wet (CS) groups decreased significantly at the beginning of the experiment (P < 0.05). The activities of glutathione S-transferase (GST) and peroxidase (POD) decreased significantly (P < 0.05). The contents of malondialdehyde (MDA) decreased firstly and then increased gradually. These results indicate that the response to oxidative stress of M.japonicus could be induced by desiccation. GPx, CAT, SOD and MDA were all sensitive to desiccation and could be regarded as monitor indices for desiccation in M.japonicus. It is beneficial to keep appropriate low and wet temperature during the transportation of M.japonicus without water, and the shrimps of average body weight of about 10 g would have a higher survival rate under such condition after 10-hour desiccation.
We inoculated the low-salt pickled fish with compound lactobacillus, fermenting and drying them to produce cured fish. The effects of compound lactobacillus on the microbial, nitrites and nitrosamines of salted fish were studied. Compared with the control (CK), the lactobacillus content maintained a high level at a state of dominant bacteria in maturation and storage process of salted fish, and the nitrites and nitrosamines of groups inoculated with compound lactobacillus (EG) reduced significantly (P < 0.05), which indicates that inoculating lactic acid bacteria had blocking effect on the formation of nitrites and nitrosamines in salted fish. Inoculating with lactic acid bacteria could improve the edible safety of salted-dried fish.
We isolated and characterized 15 polymorphic microsatellite markers in crimson seabream (Parargyrops edita) using high-throughput sequencing and polyacrylamide gel electrophoresis (PAGE), having obtained 0.12 Gbp spliced sequences of P.edita and searched 292 microsatellite sequences with suitable flanking regions from the spliced sequences. Then we designed 40 primer pairs in the microsatellite sequences for amplification by polymerase chain reaction (PCR), among which 15 primer pairs were clearly amplified and shown to be polymorphic. We found 2~16 alleles per locus (averagely 6.93). The observed and expected heterozygosities ranged from 0.268 to 0.979 and from 0.300 to 0.914, with an average of 0.568 and 0.640, respectively. No loci showed significant deviation from Hardy-Weinberg equilibrium after Bonferroni correction, except for three loci. These markers will be useful for analyzing the population genetic diversity characteristics of P.edita.