2011 Vol. 7 No. 5
In base of the data of 4 comprehensive investigations on the ecological environment in Beibu Gulf during 1998.1~1999.5, we analyzed the seasonal species composition and diversity of planktonic Copepods during El Niño/La Niña, exploring the relation between them and marine hydrology. The results reveal that 122 species of Copepod are identified, among which 32 species occurred yearly. The species of Copepod are found relatively more in spring (82) and summer (84), while less in autumn (52) and winter (67). Among the 13 dominant species in 4 seasons which are mostly eurythermal and euryhaline, 12 species are seasonal species except Canthocalanus pauper. The meso-copepods, the dominant species in winter and summer, are affected by El Niño. The macro-copepods, which take relatively high proportion in autumn and spring, are influenced by La Niña. The Copepods in the area was dominated by wide-temperature and wide-salt species. The diversity of the planktonic Copepods in Beibu Gulf is relatively high. Water temperature and salinity may affect the community diversity of Copepods in summer, but the impact is not obvious in the other 3 seasons.
From April to July, 2008, by setting up 31 survey stations within the closed fishing area for bottom trawl fishery in Lüsi fishing ground (32°~34° N), we conducted 4 investigations to study the species composition and biomass distribution of fish eggs in that area. Altogether fish eggs of 12 species were found. The dominant species are Scomber japonicus (April), Ilisha elongata (May), Engraulis japonicus (June and July).The average biological density of fish eggs vertically is 1.71 ind·m-3 (2.06 ind·m-3 in April, 2.77 ind·m-3 in May, 0.566 ind·m-3 in June and 1.35 ind·m-3 in July), while the average biological density horizontally is 6.675 ind·min-1 (12.484 ind·min-1 in April, 6.916 ind·min-1 in May, 1.977 ind·min-1 in June and 5.323 ind·min-1 in July). The fish eggs in Lüsi fishing ground distribute more in the north than in the south.
We used LC-MS-MS to investigate the biodegradation capacity of 7 PAEs by activated sludge. The results reveal that first-order kinetics equation can describe the degradation process of PAEs, and the degradation rate constants decrease with the increase of the molecular weight and initial concentration of PAEs. The degradation capacity of activated sludge is enhanced when several kinds of PAEs existed simultaneously. Temperature and pH affect the degradation directly, and the optimal conditions for the biodegradation are 36.7 ℃ and pH 7.6.
We studied the variation in contents of carbon (C), nitrogen (N) and heterotrophic bacteria in the intensive shrimp ponds in Shanwei Red Bay of Guangdong Province, and analyzed the effects of C and N on heterotrophic bacteria, so as to provide theoretical references for a reasonable regulation for water quality during culture period. The results show that carbon content gradually reaches the maximum during pre- and mid-culture periods but declines to stability in late period; the nitrogen content is relatively low during pre- and mid-culture periods but reaches the maximum in later period; the content of heterotrophic bacteria peaks in mid-culture period for 56 d and later period for 98 d, but reaches the lowest point after 70-day culture. The heterotrophic bacteria show a very significant positive correlation to TIC and TC. In late culture period, the heterotrophic bacteria show a very significant negative correlation to C/N (TOC/TN).Mainly carbon limits the propagation of heterotrophic bacteria in mid and late culture periods. Thus, addition of carbon in the ponds can promote propagation of heterotrophic bacteria, absorption and transformation of inorganic nitrogen, and reduce the concentration of inorganic nitrogen, finally improve the efficiency of material recycling.
In March 2008, taking 4 families established in 2006 as parents, we successfully established 9 families of pearl oyster Pinctada fucata, which were cultured under the same conditions, by incomplete diallel cross method. One-year continuous measurement for the growth traits (shell height, shell length, shell width and total weight) of the 9 families was conducted. Significant difference of those 4 growth traits is observed among different families and at different growth stages (P < 0.05). The order of the growth rate of shell height, shell length, shell width and total weight is as follows, respectively: F11>F4>F9>F3>F6>F12>F2>F7>F5, F11>F4>F3>F9>F12>F2>F6>F7>F5, F6>F11>F3>F9 >F4>F12>F2>F5>F7, F11>F12>F9>F3>F7>F2>F4>F5>F6. F11, F4 and F9 grow faster in shell height; F11 grows faster in shell length; F11, F3 and F9 grow faster in shell width; F11, F12 and F9 grow faster in total weight (P < 0.05). The growth rate of the 4 traits shows significant difference at different growth stages. From October to December, the growth rate of shell length, shell width and shell height isobviously faster, while from March to May, the growth rate of total weight is. The growth rate of 4 traits shows significant difference among the 9 families at fast growth stage but not at slow one. F11 is selected as the best family for its satisfactory growth traits, which provides excellent genetic materials for the breeding selection, as well as references for the breeding strategies of P.fucata families.
With SKW-3 instrument, we determined the oxygen consumption (OC) of gill tissue in vitro and of per unit respiratory area gill tissue in vitro of juvenile Trachinotus ovatus to investigate the effects of temperature, salinity and pH on them. The results reveal that with the increase of temperature, salinity and pH, the OC of gill tissue in vitro and of per unit respiratory area gill tissue in vitro of juvenile T.ovatus increase. Under the conditions of water temperature 27 ℃, salinity 28 and pH 8.5, the OC of gill tissue in vitro reaches the maximum value but then declines gradually; under the conditions of water temperature 27 ℃, salinity 23 and pH 8.5, the OC of per unit respiratory area gill tissue in vitro has the same situation as above. Water temperature, salinity and pH have significant effects on the OC of gill tissue in vitro (P < 0.05); temperature and salinity have very significant effects on the OC of per unit respiratory area (P < 0.01); pH has significant effect on the OC of per unit respiratory area (P < 0.05). There is no significant difference in the effects of salinity 18 and 33 on the OC of gill tissue in vitro of juvenile T.ovatus (P> 0.05).
To determine the suitable temperature and salinity for hatching, the embryos of Nibea japonica were hatched at different temperatures and salinities. The result indicates that at salinity of 30, the fertilized eggs can be hatched within 14~28 ℃ and the optimal temperature for hatching is 18~20 ℃. The hatching time (H) and temperature (T) are power function relative.The hatching time shortens with rising temperature. All fertilized eggs of N.japonica hatch within the salinity of 14~45, suspend or semi-suspend within the salinity of 25~32 at 18 ℃, and the suitable salinity for hatching is 26~32. The total length of newly hatched larvae, which in low salinity group is significantly longer than that in high salinity group (P < 0.05), is significantly affected by salinity.
Using electron microscopy, we studied the ultrastructure of peripheral blood cells of Cromileptes altivelis. Six types of cells (erythrocyte, granulocyte, monocyte, lymphocyte, thrombocyte and plasma cell) were detected under the electron microscope. Erythrocyte is round or oval with visible mitochondria and a few vesicles. According to the size, shape of particles and form of nucleus, granulocytes can be divided into 4 types: Ⅰ-type granulocyte, Ⅱ-type granulocyte, Ⅲ-type granulocyte and Ⅳ-type granulocyte. Monocyte is round with smooth surface and vacuoles, occasionally holding out pseudopodia. Lymphocyte has a few organelles and little cytoplasm which only forms a thin layer around the nucleolus. Thrombocyte is rich in heterochromatins which distribute zonally along the nuclear membrane. There are many vacuoles at various sizes and a small amount of mitochondria. Rough endoplasmic reticulum distributes hierarchically around the nucleolus in plasma cell. In addition, erythrocytes could be seen to be phagocytized by eosinophils and thrombocytes gathered in groups.
We compare and study the genetic diversity and structure of DNA control region of 4 Misgurnus anguillicaudatus populations by using PCR and DNA sequencing. The results show that the sequence of mitochondrial DNA control region is 918~920 bp.Among 32 sequences, a total of 56 polymorphic loci were detected, including 32 transitions, 19 transversions, 5 transitions-transversions and 36 haplotypes. The key sequences of extended terminal associated sequences (ETAS), central domains (CSB-A, B, C, D, E and F) and conserved sequence blocks (CSB-1, CSB-2 and CSB-3) were discovered. The haplotypic diversity (Hd), average genetic distance (Pi) and average number of pairwise differences (K) is 0.992, 0.012 and 10.698, respectively. The average Kimura 2-parameter distance, Fst value, Nm value and AMOVA reveal great genetic differentiation among the 4 M.anguillicaudatus populations. The NJ phylogenetic tree constructed on nucleotide sequence indicates that the 4 populations form into 2 monophyletic lineages, and cross and cluster among one another except Fanxian population.
We used TPA model of texture analyzer to test the hardness, adhesiveness, springiness, chewiness, gumminess and cohesiveness of muscle of Litopenaeus vannamei during frozen storage. At -18 ℃ and -50 ℃, the hardness, chewiness, gumminess and cohesiveness of shrimp muscle slowly declined with storage time, but the springiness did not change significantly while adhesiveness increased. The results indicate that frozen storage of shrimp ensures its long shelf life but leads to a decline in textural characteristics in general. The lower the temperature for frozen storage is, the better it is for maintaining the textural characteristics of shrimp muscle.
We conducted a static bioassay test to investigate the acute toxicity of compound trichloroisocyanuric acid to larvae of Penaeus semisuicatus. The concentration of TCCA in the experiment for nauplius and zoea is 0 mg · L-1, 0.5 mg · L-1, 1.0 mg · L-1, 1.5 mg · L-1, 2.0 mg · L-1, 2.5 mg · L-1 and 3.0 mg · L-1; that for mysis and post larvae is 0 mg · L-1, 1.0 mg · L-1, 1.5 mg · L-1, 2.0 mg · L-1, 2.5 mg · L-1, 3.0 mg · L-1, 3.5 mg · L-1 and 4.0 mg · L-1; each concentration has 3 replicates. The results show that the 24 h LC50 and 48 h LC50 with 95% confidence interval for nauplius are 1.47~1.78 mg · L-1 and 1.34~1.46 mg · L-1, respectively;those for zoea are 1.67~1.78 mg · L-1 and 1.23~1.36 mg · L-1, respectively;those for mysis are 2.05~2.25 mg · L-1 and 1.58~1.79 mg · L-1, respectively;those for post larvae are 3.14~3.38 mg · L-1 and 2.59~2.78 mg · L-1, respectively. The safe concentration (SC) for nauplius, zoea, mysis and post larvae is 0.30 mg · L-1, 0.22 mg · L-1, 0.34 mg · L-1 and 0.55 mg · L-1, respectively. The results provide references for safe medication in larvae rearing for P.semisuicatus.
The noble scallop Chlamys nobilis, a warm water marine bivalve, is nutrient-rich, delicious and succulent. It grows fast and yields well, having short culture circle and good economic returns. The paper reviews the achievement in the culture of C.nobilis, including reproductive development, growth, artificial seedling, genetic breeding as well as development and application of genetic markers. The problems in its artificial breeding and culture are also analyzed; the ideas and strategies for future development are put forward.