Junli Hou

Isosmotic points and their ecological significance for juvenile Chinese sturgeon Acipenser sinensis.

Serum osmolality and ion concentrations were measured in juvenile Chinese sturgeon Acipenser sinensis at different salinities to determine the isosmotic point. Isosmotic and isoionic concentrations were calculated from the regressions for serum and ambient osmolality, with Na(+) , Cl(-) and K(+) as salinities 9·19, 8·17, 7·89 and 9·70, respectively. These values were consistent with the salinity of the habitat where juvenile A. sinensis occur in the Yangtze Estuary, suggesting that an isosmotic salinity is an important factor driving their habitat choice.

Effects of cryopreservation on exterior shape and interior structure of Chinese mitten crab (Eriocheir sinensis) embryos

In order to deeply understand the effects of cryopreservation on the configuration of embryos,we chose the Eriocheir sinensis as the object,and observed the exterior shapes and interior structure of different developmental stages embryos after treatment with cryoprotectants and cryopreservation by means of microscope,slice and electron microscopy.Results showed that:(1) Cleavage embryos swelled clearly after treatment with vitrifying solutions by two-step methods,exterior shape of the embryos had no significant difference compared to the control group by three-step equilibration methods,some yolk overflowed from the inner cells and cells were damaged seriously after cryopreservation.(2) Exterior shape of gastrula stage embryos was similar to the control group after treatment with two-step equilibration methods,surface of gastrula stage embryo treated with cryoprotectants crinkled and shaped reticulation structure by scanning electron microscopy(SEM),white gobbet appeared in cells of embryos and fringe of cell was coarse and protuberant by transmission electron microscopy(TEM).After cryopreservation,color of embryos was pink,cell became opaque,the brim of cell membrane was blurry and shaped floss,segmental yolk was disintegrated into granule,the surface of embryos was sunken and wrinkled.(3) Cell membrane of embryos broke off,ice holes of different size appeared inside embryos,visible vacuoles appeared inside cells by slice observation.Ice holes in cells were very clear and some vacuoles appeared,about 80% mitochondria dissolved,breach of cells was very obvious by TEM.Exterior shape of the original zoea stage embryos had no difference compared to that of the control group after treatment with cryoprotectants by microscope and SEM.After cryopreservation,above 95% tissues shaped dispersion,partial yolk was disintegrated into granule,cell membrane of embryos broke off,ice holes appeared inside embryos.Surface of 90% embryos was sunken and wrinkled,but the cuticle of 10% embryos retained slick and intact by SEM.The results implied that the original zoea stage of embryos was the appropriate stage for cryopreservation.

Secondary Production of Macrobenthos from Intertidal in the Changjiang Estuary and Its Impact Factors

Macrobenthos samples were collected from three sections in the intertidal zone of the Changjiang Estuary in August 2010,November 2010 and May 2011,and the parameters of the density,biomass,secondary productivity,and P/B value of the macrobenthos were measured based on the equation by Brey(1990).The foundings indicated that the total mean density of the macrobenthos was 637.83 ind m-2,total mean biomass in ash free dry mass(AFDW) was 6.71 g m-2,total mean annual secondary productivity was 6.91 g m-2 a-1,and total mean annual P/B value was 1.01 a-1,respectively.Three sections ordered by the total mean density,biomass,secondary productivity,and P/B value was Dongwang sand Buyu port Tuanjie sand.The secondary productivity was mainly influenced by Crustacea with six critical species,including Corbicula fluminea,Potamocorbula amurensis,Sinonovacula constricta,Stenothyra glabra,Bullacta exarata and Cerithidea sinensis,and the six species contributed 65.24% of the total.Based on the data of total mean annual P/B value(1.01 a-1),It was speculated that the average change of macrobenthos was year-generation,and community structure was instability and obviously influenced by the environment.The analyses of secondary productivity combination of variables indicated that the secondary productivity was not only impacted by the biomass and density but also by the total nitrogen and total phosphorus of water.The results of Principal Components Analysis(PCA) on the environmental variables showed that the environment in Tuanjie Sand was the most stable,Buyu Port was less stable,and Dongwang Sand was the most violent one.The relationship between environmental variables and the secondary productivity of community was analyzed using Canonical Correspondence Analysis(CCA),and Sa,TP,TOC and DO were found to be the key factors to the secondary productivity in Dongwang Sand macrobenthos communities;TN,TOC,Chla and DO in Buyu port.Furthermore,the habitat of Tuanjie Sand was the most stable,and all the environmental variables of this region rarely changed,so it was speculated that the physical factors were the key factors of the secondary productivity.

The role of temperature and salinity in the embryonic development of Striped Goby

With characteristics of a small body, omnivorousness, quick growth and strong reproductive capacity, gobies are advantageous for aquaculture and management in the laboratory, and are suitable for use as aquatic laboratory animals. They can also play an important role in the research of life sciences and toxicology evaluation. To better understand the biological characteristics and ecological requirements of Striped Goby (Tridentiger trigonocephalus), we examined the roles of temperature (17, 19, 21, 23 and 25°C) and salinity (0, 2, 4, 6, 8 and 10) in their embryonic development. Our results revealed there were many oil globules in Striped Goby oosperm. The rudiment of swim bladder formed before embryos were hatched. The eyes, mouths and alimentary tracts of embryos appeared early in development. Embryonic development accelerated with increasing temperatures tested. It was also accelerated with increasing salinities ranging from 2 to 6. Furthermore, we found the total hatch rate was inversely related to temperature, and it was significantly higher at salinity 4 than at 8 or 10. We determined the most effective statistical method for evaluating these results was the effective degree-day model. In conclusion, both temperature and salinity strongly affect the embryonic development of Striped Goby, and the optimal temperature and salinity ranges for incubation are 17–21°C and 2–6, respectively.