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1.
This note reports the histological studies of gonad of the mullet. The fishes werecollected from the Huanghua and the Beitang of Cyclic changes of the gonads in mulletwere studied in the adu1t and young fishes. Qil globule formation in the oocytes began at stage Ⅱ to Ⅲ of gonad development(usually at the end of stage Ⅱ). When the oil globules fromed a ring in the periphery ofthe nucleus, the gonads entered stage Ⅲ. The oil globules extended from center to outerregion and combined with each other, at last there was only one golden oil globule in theegg. There is no vesicle in the mullet. Yolk formation in the oocytes begen in the winter. The volume of the ovary andthe size of eggs attained a maximum at the end of April or at the beginning of May.  相似文献   

2.
For most aquacultured animals, the unsaturated fatty acids of marine microalgae have the effects of raising their rates of hatchability, survival and growth and the essential nutrients for the cultured animals such as fish and shrimp. Japanese and ROK scholars have reported that the algal powder added into the fish and shrimp bait may act as coagulating and anti-collapsing agents, and is especially effective if it is used in the water lacking minerals and vitamins[1]. Japanese scholars have p…  相似文献   

3.
In most fish,reproduction is seasonal or periodic under the suitable conditions.In turbot(Scophthalmus maximus)farms,one of the most economically important marine flatfish species,changes in daylength could cause changes in the spawning time.In this study,to characterize the regulation of reproductive physiology following light signals,three melatonin receptors(Mtnr)investigated in turbot were named sm Mtnr1,sm Mtnr2,and sm Mtnr1 c.Distinct expression profiles demonstrated that Mtnr m RNAs were concentrated in the brain(as detected in the hypothalamus(Hy)and mesencephalon(Me)),gonad and eye.The most abundant Mtnr1 and Mtnr2 m RNA expression levels were detected in the central nervous system at the beginning of the breeding season,suggesting that Mtnr1 and Mtnr2 may play vital roles in the regulation of turbot gonadal development.In addition,the melatonin profiles gradually increased and reached to the highest level at the spawning stage,indicating that melatonin is a potent hormone in the regulation of fish oocyte growth and maturation.The results of this study suggested that melatonin is the primary factor that transduces the light signal and regulates the physiological functions of turbot seasonal reproduction.Moreover,the results of this study may establish a foundation for further research seeking to identify fish melatonin receptors involved in the gonadal development and gamete maturation.  相似文献   

4.
The ultrastructural changes of the oogenesis in Capitella capitata are described. The developing oocytes undergo obvious ultrastructural changes during the process of oogenesis, which include: the formation or differentiation of endoplasmic reticulum, Golgi complex, endocytotic pits, vesicles and the surface of the cell. The evidence demonstrates that these changes are connected with the process of yolk synthesis which occures largely within the ovary by means of autosynthesis and heterosynthesis. The results show that the Golgi complex and the endoplasmic reticulum within both the oocytes and the follicle cells are involved in the yolk synthesis and transformation of probable yolk precursors. In summary, the similarities of oogenesis in the sibling species of Capitella suggest that there is a very close evolutionary relationship between them.  相似文献   

5.
The reproductive ecology of the mudskipper Boleophthalmus pectinirostris was investigated during the spawning season in the Funing Bay, Fujian, China. The fish burrows were basically Y-shaped and had two openings onto the mudflats. Part of the intersection at the center of the burrow was dilated to form a "spawning chamber". The dissolved oxygen concentrations (0.40~0.65 mg/dm3)of water 15 cm deep inside the burrows were much lower than those (5.96~6.19 mg/dm3) of intertidal pool water. Water temperatures inside the burrows were much lower than those of intertidal pools. Field investigations indicated that eggs were laid on the inner wall and ceiling of the spawning chamber by means of filamentous attachments, and a male stayed inside the burrows to guard it. Field investigations also suggested that fish of both sexes constructed mud burrows by themselves but that the spawning chamber was made only in the male burrow. The male attracted a female to his burrow for mating and spawning. There was no water in the spawning chamber, and thus the eggs were exposed to the air in the chamber. Changes in spawning readiness and gonadosomatic index indicated that synchronization of spawning was related to the semi-lunar periodicity, and this is the first report of this relationship in the mudskippers.  相似文献   

6.
Whitespotted conger Conger myriaster is a commercially important species in the seas around China, Korea and Japan. The coastal waters of China serve as an important feeding ground for congers, but the spatio-temporal variations in the fishery and biological characteristics of the population have been rarely evaluated and less well understood in this area. We studied the growth, spawning and feeding characteristics of C. myriaster on the basis of samples collected from October 2016 to April 2017 in the Yellow Sea and East China Sea. A total of 529 specimens were collected, with ages ranging from 1 to 6 years and total length ranging from 132 mm to 834 mm.The parameters of von Bertalanffy growth equation L_∞ and k were 1 026 mm and 0.226 a~(–1), respectively; the sex ratio was 88:0(female: male) in the East China Sea and 2.67:1 in the South Yellow Sea; the development stage of ovary ranged from peri-nucleolus stage to secondary yolk globule stage, and the testis of two males was at midmeiotic stage; Crustacean was the major prey for conger of small length, and food source shift to fish with somatic growth. The results showed substantial differences from previous studies in Japan and Korean waters, as well as from China seas in the 1980 s, suggesting potential spatiotemporal changes in the biological characteristics of C.myriaster. This study may improve current understanding of the fishery biology of C. myriaster in the Yellow Sea and East China Sea.  相似文献   

7.
Gracilaria tenuistipitata vahang et Xia is cultivated at two different salinites(21,33) in the laboratory for 4 weeks,The daily growth rate is determined.The total agar yield and fractional agar composition are analyzed.Results show that algae grow faster in low salinity.The total agar yield is higher under high salinity conditions than under low salinity conditions.Among the eight fractions extracted,the yields of cold water extract and 40% ethanol extract are about the highest.In low salinities the yields of autoclaved extract and 60% ethanol extract are higher,while the yield of cold water extract is lower relative to high salinities.  相似文献   

8.
Iranian nesting populations of the critically endangered hawksbill turtle(Eretmochelys imbricate) are some of the most important in the Indian Ocean. In this study, four of the most important hawksbill nesting grounds in the Persian Gulf, situated within three Iranian marine protected areas, were surveyed during nesting season,including Nakhiloo, Ommolgorm and Kharko Islands and the mainland beaches of the Naiband Marine-Coastal National Park(NMCNP). We present GIS maps of these key nesting grounds and describe sand texture of key nesting zones, along with conservation recommendations. About 9.2(28.3%) out of 32.5 km of all shores surveyed in this study were used by nesting hawksbill turtles follows: Nakhiloo: 1.4 km(52% of potential nesting area);Ommolgorm: 1.94 km(40%); Kharko: 3.4 km(28%), and NMCNP: 2.46 km(18.9%). The average nesting density was calculated as 131 nests/km at Nakhiloo, 76 nests/km at Ommolgorm, 7 nests/km at Kharko, and 15 nests per km at NMCNP. Highest nesting density was observed in Nakhiloo and Ommolgorm. It is thought that high hawksbill nesting density in these islands seems likely a result of limiting adequate nesting shores rather than the size of population, and also low density in Kharko and NMCNP more related to past and current pressures and low population density. With the exception of Ommolgorm Island, sands at the nesting grounds were well sorted.Grain size indicated that female hawksbill turtles in the Iranian Persian Gulf nest in sands that are generally mixed, with mean grain size ranging from coarse sands(0.4Φ;～0.5–1 mm) to fine sands(2Φ;～0.25 mm). We provide and discuss conservation recommendations and suggestions for future.  相似文献   

9.
The ovary is an excellent system for studying stem cell renewal and differentiation, which is under the control of ovarian somatic cells. In order to understand oogenesis in Fugu rubripes (Temminck et. Schlegel) as a marine fish model of aquaculture importance, we established cell lines called TSOC1 and TSOC2 from a juvenile ovary of this organism. TSOC1 is composed of spindle epithelial-like cells, while the other is cobblestone-like cells. Therefore, TSOC1 and TSOC2 appear to consist of ovarian somatic cells. Growth requirement condition was investigated including temperature, concentration of FBS and pH. Significant fluorescent signals were observed after TSOC1 and TSOC2 cells were transfected with pEGFP-N3 vector, indicating its potential utility for genetic manipulation such as gene function studies. It is shown that these cell lines are effective for infection by the turbot reddish body iridovirus and flounder lymphosystis disease virus as evidenced by the appearance of cytopathic effect and virus propagation in the virus-infected cells, and most convincingly, the observation of viral particles by electron microscopy, demonstrating that TSOC1 and TSOC2 are suitable to study interactions between virus and host cells. It is believed that TSOC1 and TSOC2 will be useful tools to study sex-related events and interactions between primordial germ cells and oogonia cells during oogenesis. Therefore, establishment of ovary cell lines from Fugu rubripes seems to be significant for those research areas.  相似文献   

10.
Quasi-3D Numerical Simulation of Tidal Hydrodynamic Field   总被引：2，自引：0，他引：2  
Based on the 2D horizontal plane numerical model,a quasi-3D numerical model is establishedfor coastal regions of shallow water.The characteristics of this model are that the velocity profiles can be ob-tained at the same time when the equations of the value of difference between the horizontal current velocityand its depth-averaged velocity in the vertical direction are solved and the results obtained are consistent withthe results of the 2D model.The circulating flow in the rectangular area induced by wind is simulated and ap-plied to the tidal flow field of the radial sandbanks in the South Yellow Sea.The computational results fromthis quasi-3D model are in good agreement with analytical results and observed data.The solution of the finitedifference equations has been found to be stable,and the model is simple,effective and practical.  相似文献   

11.
In recent years, fish invasion has become one of the main reasons for the decline of native fish stocks. Pseudorasbora parva is considered one of the major invasive species worldwide. The present study investigated the fish resources of the Chabalang Wetland (Lhasa, Tibet) during diff erent seasons in 2009 and 2013. Four hundred and twelve individuals were subsampled to estimate age, growth, and feeding habit of P . parva . Furthermore, food relationships between P . parva and the native Schizothoracinae fish were also examined. The results revealed a significant shift in species composition and community structure characterized by the disappearance of native fish and outbreak of non-native fish. The percentage of nonnative P . parva in the fish collections significantly increased from 33.64% in 2009 to 64.08% in 2013. The standard length (SL) ranged from 22.00 to 78.71 mm, and their age was 1–5 a. The von Bertalanff y function was used to model the observed length-at-age data as L t =112.19(1–e^-0.1495 ( t +0.8012)) for females and as L t =123.12 (1–e^-0.1500 ( t +0.7132)) for males. The results indicated that P . parva in Tibet has lower growth and mortality rates compared with that from the native ranges. Ninety-seven prey taxa belonging to 9 prey categories were identified in the gut of 38 P . parva . P . parva can be considered a generalized and opportunistic predator, competing with the native fish, especially Schizothorax o’connori , Schizopygopsis younghusbandi younghusbandi , and Ptychobarbus dipogon , for Bacillariophyta and Chironomid larvae. This is an important reason for the decline in native fish population.  相似文献   

12.
Oxidative hair dyes containingρ-phenylenediamine(PPD)are reported to induce an allergic reaction by promoting oxidative stress when absorbed through the skin.Despite the associated risk,these hair dyes remain popular owing to their convenience and sharpness of color.This makes it important to minimize the cytotoxicity and oxidative stress induced by PPD-containing hair dyes.Ecklonia cava extract has been evaluated in different studies for its protective effects against external stress in fibroblasts and keratinocytes.Our study was aimed at using in-vitro and in-vivo models to investigate the extract’s effects on cytotoxicity of and oxidative stress induced by PPD-containing hair dyes.Analysis of CIEL*a*b*Color space was first used to determine the range of E.cava extract that would not interfere with the coloring ability of the dye upon addition.Subsequently,the set ranges of E.cava extract(5% and 7%)were added to the hair dye and their toxicity assessed by evaluating the viability of fibroblasts and keratinocytes.The effects on developmental phenotypes and induction of oxidative stress by hair dye were evaluated and compared with those of hair dyes containing different contents of E.cava extract using an in-vivo zebrafish model.Our results showed that E.cava extract in hair dye could significantly decrease the cytotoxicity and levels of oxidative stress caused by hair dyes containing PPD in both in-vitro and in-vivo models.These results suggest that the addition of 7% E.cava extract to 250μg/mL hair dye does not interfere with the coloring ability of the dye while showing significant protective eff ects against the hair dye.The study proposes that the use of E.cava extract as an adduct to hair dyes containing PPD reduces the cytotoxicity and oxidative stress induced by these hair dyes.  相似文献   

13.
The method of acoustic backscattering measurement from different parts of fish using the focus array of transducer developed recently is described in this paper. The results of the measurements of several kinds of flsh are given in this paper, indicating that the backscattering from fish is closely relative to the anatomy of fish. Its application in forming backscattering model of fish and that in using this model to obtain the information of fish kinds by the echoes from fish sonar are discussed.  相似文献   

14.
Reservoirs are important artificial ecosystems that modify the hydrological and ecological characteristics of a river. Knowledge of the basic characteristics of fish assemblages in reservoirs is a first step toward the development of effective conservation policies. We used the information collected over a 10-year period (2006-2015) to assess the structure of the fish assemblages in the Three Gorge Reservoir (TGR) in a river-dam gradient. Three fish zones were detected in TGR. Species richness was the highest in the upper zone and lowest in the lower zone. The riverine zones were dominated by rheophilic species Coreius guichenoti and Pelteobagrus vachelli. The transitional zones were dominated by Coreius heterodon and Rhinogobio cylindricus. The lacustrine zones were dominated by eurytopic species Hypophthalmichthys molitrix, Aristichthys nobilis, Hemiculter bleekeri and Cyprinus carpio. For the functional characteristics, fish assemblages in riverine and transitional zones were dominated by insectivorous species, equilibrium strategists and rheophilic species (e.g., Coreius heterodon and Coreius guichenoti). In lacustrine zones, the fish assemblage was dominated by habitat generalists common to lakes and reservoirs (e.g., Hemiculter bleekeri, Hypophthalmichthys molitrix, Aristichthys nobilis). Moreover, 18 exotic species (e.g., Protosalanx hyalocranius, Ictalurus punctatus, Megalobrama amblycephala, Tilapia) were collected in TGR, most of which only existed in the lacustrine zone. The results highlight the importance of freely flowing riverine reaches for conserving native fish in the upper Changjiang River and adaptive management strategies for fisheries in TGR.  相似文献   

15.
Effects of copper toxicity and salinity shock on selective group of juvenile pompano Trachinotus ovatus were investigated.The fish were exposed to different Cu2+ concentrations of 0(blank),0.02(C1),0.05(C2),0.10(C3),and 0.15 mg·L–1(C4)at a salinity of 10‰ or 40‰ for 96 h,with the salinity of 29‰ as the control.The results showed that the effects of the acute salinity stimulation to survival rates of pompano between control(29‰)and lower or higher salinity for 96 h were not significant(p0.05).However,the survival rates in each treatment were decreased with the increase of Cu2+ concentration.The dominant factor influencing body moisture of the fish was salinity,and there was no sign that body moisture was correlated with exposure to Cu2+.The gill lamellas in high level of Cu2+ concentration(C4 treatments)were abnormal under the salinity of 40‰ and extremely curly under the salinity of 10‰.Hemorrhage in gill was observed in the two C4 treatments.Under transmission electron microscope,pillar cells in gill lamellas appeared deformed and ruptured in some areas of the epithelia in the higher concentration of Cu2+,resulting in the death of the fish due to the destruction of gill tissue,elevation of the arithmetic mean distance from water to blood,the decrease of oxygen diffusion capacity,and other physiological functions.These findings indicate that the pompano might suffer much more pressure when encountered with Cu2+ pollution and low salinity.  相似文献   

16.
Extensive oedometer tests and physical tests have been conducted on remoldod and reconstituted marine soils with different initial water contents and liquid limits. The oedometer test data can be well fitted with a straight line in the bilogarithmin In(1 e)∽lg p plot. The initial effective stress corresponding to the initial void ratio is determined by extrapolation of the bilogarithmic compression line. This new way of extrapolating oedometer test data to the initial void ratio overcomes the difficulty of measuring the residual effective stress of soils in the remolded state. The initial stable compression line of ocean floor deposits under different deposition environments corresponds to the compression line at the sensitivity equal to one. This initial stable compression line obtained in this study is consistent with the available compression line at the sensitivity equal to one which is proposed based on the experimental data of remolded undrained strength and the theoretical concept of Cam-clay critical state line.  相似文献   

17.
An attenuation depth is defined for remote sensing purposes as a depth above which 90% of the arising light leaving the water surface is originated.The deeper the attenuation depth,the more information of water is detectable by remote sensing,then the more precise information of water is extracted.Meanwhile,the attenuation depth is helpful to know water layer (by its thickness) from which remote sensing will be able to extract information.A number of investigators are using the moderate resolution imaging spectroradiometer (or MODIS) for remote sensing of ocean color.It is necessary to have a rough idea of the effective attenuation depth of imagery in each of the spectral bands employed by the MODIS.The attenuation depth is directly determined from MODIS data.Though analyzing the spectral distribution of the attenuation depth on 7 August 2003 and the seasonal variation of the attenuation depth (551 nm) in the Bohai Sea indicated that:the spectral distribution of the attenuation depth for the spectral range between 400 to 700 nm is single-peak curve,and it''s similar and difference in different regions is consistent with other scholars'' results of zoning,moreover,it supports the Bohai Sea is Case 2 water; the maximum attenuation depth shifts toward longer wavelengths,liking the red shift,with increase of turbidity of water,just like the maximum attenuation depth in the outside of the northwest coast of the Bohai Sea and the Bohai Strait is at 531nm,in the central of the Bohai Sea is at 551nm,in the region controlled by the Huanghe (Yellow) River,the region impacted by the old Huanghe River,the western side of the Liaodong Bay and the eastern side of the Liaodong Bay is at 555 nm; the seasonal change of the attenuation depth is the largest in the summer,followed by the fall,and the ranking of winter and spring in different regions is distinct.The attenuation depth in different regions is dissimilar:the order of the attenuation depth in different regions from small to big is the region controlled by the Huanghe River or the eastern side of the Liaodong Bay,the western side of the Liaodong Bay,the region impacted by the old Huanghe River,the central of the Bohai Sea or the outside of the northwest coast of the Bohai Sea,the Bohai Strait (except at 412 nm and 645 nm),in which between the region controlled by the Huanghe River and the eastern side of the Liaodong Bay (and between the central of the Bohai Sea and the outside of the northwest coast of the Bohai Sea) it varies in different seasons and different bands.  相似文献   

18.
Vast declines in Zostera marina seagrass beds demand effective methods of rehabilitation. In this study, we developed a practical method by reducing salinity to induce seed germination followed with recovering salinity to facilitate seedling production of Z. marina. The results showed that Z. marina seeds collected from natural seawater(salinity 30) were induced to germinate at reduced salinities. Percent germination(GR) was higher and mean-time-to-germinate(MTG) was shorter at lower salinities. The highest GR and shortest MTG occurred at salinity 0(deionized freshwater). After germination in freshwater, seeds could develop into seedlings at salinities5–30 and continue the growth. Viability or development of germinated seeds was not significantly different during the 40 d of post-germination incubation at salinities 5–15 after 1–20 d of germination in freshwater. However,during the process of translating germinated seeds from salinity 0 and 5 to salinity 30, reducing the gradients of post-germination acclimation facilitated more seeds forming seedlings in less time. On average, after 60 d of static incubation, including 20 d in freshwater for germination followed with immediate shift to salinity 5 and increasing to salinity 30 at increment of 5 every two days until cultivation at constant salinity 30, 33% of Z. marina seeds produced healthy seedlings. The results indicate that the salinity-manipulation based method of artificial germination and seedling production is practical and effective in supporting rehabilitation of Z. marina bed.  相似文献   

19.
In order to evaluate the involvement of the thyroid gland in reproduction, thyroid functioning was described in female cultivated Japanese eel (Anguilla japonica) in progressive stages of sexual maturation induced by chum salmon pituitary homogenate (SPH) treatment. Serum thyroid hormones, thyroxine (T4) and triiodothyronine (T3) were also measured in each stage. Thyroid gland activity (epithelial cell height) was high before SPH injection (previtellogenic stage), further increasing at the early vitellogenic stage, thereafter decreasing to late vitellogenic and migratory nucleus stages. The profiles of both T3 and T4 changed during vitellogenesis, being high during previtellogenic and early vitellogenic stages, and subsequently declining, thus mimicking thyroid gland activity. These results suggest that the thyroid has relation with eel ovarian development during artificial maturation.  相似文献   

20.
The impact of Stokes drift on the mixed layer temperature variation was estimated by taking into account an advective heat transport term induced by the Stokes drift in the equation of mixed layer temperature and using the oceanic and wave parameters from a global ocean circulation model （HYCOM） and a wave model （Wave Watch III）. The dimensional analysis and quantitative estimation method were conducted to assess the importance of the effect induced by the Stokes drift and to analyze its spatial distribution and seasonal variation characteristics. Results show that the contribution of the Stokes drift to the mixed layer temperature variation at mid-to-high latitudes is comparable with that of the mean current, and a substantial part of mixed layer temperature change is induced by taking the Stokes drift effect into account. Although the advection heat transport induced by the Stokes drift is not the leading term for the mixed layer temperature equation, it cannot be neglected and even becomes critical in some regions for the simulation of the upperocean temperature.  相似文献   

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