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1.
桑沟湾养殖海区沉积物-海水界面氮、磷营养盐的通量   总被引：15，自引：1，他引：14  
20 0 2年 5月和 7月分 4个航次对桑沟湾养殖海区海底沉积物进行了底质与间隙水营养盐(NH+ 4,NO- 3,NO- 2 ,PO3- 4)的分析 ,并使用Fick第一定理对该海区沉积物 海水界面营养盐的通量进行了估算。研究结果表明 ,各站点间隙水三氮和磷酸盐的平面分布和垂直分布有较大的差异。用 4个航次的数据估算全年由沉积物向上覆水扩散的NH+ 4的通量为 376 33μmol/m2 ·d ,NO- 3、NO- 2 和PO3- 4的通量分别是 33 0 2、6 4 1、10 .0 8μmol/m2 ·d。估算桑沟湾全年由沉积物扩散进入上覆水的总无机氮的量为 2 81 7t,可以满足该湾浮游植物初级生产需要的 2 8 73% ,释放的无机磷的总量为 4 16 2t,可以完全满足该湾全年浮游植物的需求。研究结果为桑沟湾海湾沉积物 海水界面氮、磷营养盐的通量建模提供了重要数据 ,结论可以运用到规模化养殖海湾养殖容纳量的进一步研究之中。  相似文献   

2.
桑沟湾海带养殖容量的研究   总被引：23，自引：5，他引：23  
首次对桑沟湾的海带养殖容量进行了调查研究。采用了无机氮作为估算桑沟湾海带养殖容量的关键因子，通过无机氮的供需平衡估算海带养殖容量。结果显示，海底沉积物中释放的无机氮为该湾无机氮的主要来源，而由海水交换所带入的无机氮次之。海带生长期间海水交换周期为３９ｄ，比８０年代中期延长了近１倍。桑沟湾在海带生长期间由海水交换、陆地径流、动物排泄和海底沉积物中释放所进入该湾的无机氮总供应量为１２２８ｔ；而浮游植物  相似文献   

3.
基于海流、波浪、水环境和沉积环境指标的实测资料,探讨了桑沟湾贝类养殖水域沉积物再悬浮的动力机制,并估算了一次大的动力过程作用下桑沟湾沉积物中氮、磷营养盐的释放量。结果表明,(1)在小风速(≤5.0m/s)条件下,波浪在海水-沉积物界面产生的切应力量值与底流切应力大致相当;在较大风速(5.0～11.8m/s)条件下,波浪切应力比底流切应力高出一个量级;(2)当风浪较小(风速≤3.6m/s)时,随底层流速的周期性变化,底层水体浊度变化并未呈现出明显的规律性,二者相关系数值仅为0.22,这说明底流作用只会引起沉积物的水平输运,对沉积物再悬浮的贡献相对较小,沉积物再悬浮的动力主要来自波浪扰动;(3)据估计,桑沟湾贝类养殖水域沉积物再悬浮的临界波浪切应力在0.04N/m2左右,对应的风速约为8m/s;(4)据估算,一次大的动力过程作用下桑沟湾沉积物中无机氮和活性磷酸盐的最大释放量,春季分别为10.24t和1.71t,这相当于全湾水体中无机氮平均含量增加9.54μg/L,活性磷酸盐平均含量增加1.59μg/L;夏季分别为11.04t和0.95t,相当于全湾水体中无机氮平均含量增加10.28μg/L,活性磷酸盐平均含量增加0.88μg/L;(5)贝类养殖使桑沟湾生物沉积作用加强,而沉积物再悬浮造成的内源释放,又对桑沟湾的水产养殖产生反馈作用。  相似文献   

4.
以桑沟湾扇贝和海带两个养殖海区的柱状沉积物为研究对象,采用连续提取法将沉积物中磷的赋存形态分为交换态磷（Ex-P）、铁结合态磷（Fe-P）、自生磷（Au-P）、碎屑磷（De-P）和有机磷（Or-P）,并分析了各形态磷的垂直分布特征;利用沉积物年代序列测定的结果,结合桑沟湾水产养殖历史,探讨了近200年来桑沟湾养殖海域沉积物中磷形态的含量变化情况,并进一步分析了该区域的生物有效磷。结果表明,柱状沉积物中上层各形态磷的含量高于底层,表明养殖活动使桑沟湾表层沉积物中的磷含量增大。各形态磷的含量在贝壳沉积区内变化幅度均较大,Or-P是沉积物中磷的主要形态;扇贝养殖区沉积物中的总磷（TP）、Or-P和海带养殖区沉积物中的TP、Or-P在沉积时间序列上分布基本一致,其含量变化与各时期工业生产和海水养殖活动密切相关;两个区域柱状沉积物中潜在生物有效性磷占总磷的百分比为61.2%和71.0%。沉积物中Ex-P的含量对该海域的初级生产力的影响较大。  相似文献   

5.
本研究初步估算2011—2020年九龙江总氮、总磷污染物入海通量,分析年际通量变化和月际通量的空间变化,探讨了可能的影响因素。结果表明,2011—2020年间九龙江总氮和总磷的入海通量呈现递减趋势,但仍具有较高养分通量的特点,总氮和总磷的入海通量排放主要受到畜禽养殖和化肥施用等人为活动的影响。2018年九龙江北溪的总氮通量最高,西溪的总磷通量最高,南溪最低。入海通量的空间差异主要与径流量有关,北溪的畜禽养殖和西溪的化肥施用是导致养分入海的主要因素,九龙江氮磷污染物入海与水产养殖关系较小。本研究对九龙江-厦门湾提出有关污染物总量控制措施建议,为当地政府做好重点河流污染物总量控制提供参考。  相似文献   

6.
2012年5月27～29日对桑沟湾贝类养殖、贝藻混养、藻类养殖等区域水-气界面区pCO2等参数的连续走航和贝类养殖区的日变化观测,讨论了桑沟湾不同养殖区域水-气界面区pCO2的分布特性及机制。结果显示,在该航次水质及气候条件下,桑沟湾养殖区域叶绿素偏高,溶解氧始终处于过饱和状态,最高达140%,强烈的浮游藻类光合作用消耗大量无机碳,水-气界面始终是大气CO2的汇。其中贝类养殖区pCO2低于贝藻混养区,低于藻类养殖及湾外近海区域。当然,这还不足以说明这一海区水-气界面可能是大气CO2的汇区,需要精细的航次计划做全面观测,例如养殖区域沉积的大量颗粒有机物在某些特定条件下的再悬浮、降解对水气界面CO2的贡献以及实际意义上的埋藏通量究竟有多大等。  相似文献   

7.
本研究分析了桑沟湾表层沉积物的粒度、总有机碳(TOC)、总氮(TN)、碳和氮稳定同位素(δ13C和δ15N)的时空分布特征,估算了贝藻生物沉积对近海沉积物有机质的贡献。结果显示,桑沟湾沉积物成分组成以粉砂为主,且粒径分布与海水养殖和水动力学条件密切相关;TOC、TN的季节变化和平面分布均呈相似性,数值上总体表现为春季最高,秋季最低,季节差异不大,在贝藻、鱼贝和贝类养殖区域出现较高值;而δ13C和δ15N的季节变化和平面分布有较大差异。从相关性分析可以看出,TOC和TN呈极显著正相关(r=0.955, P<0.001),表明桑沟湾表层沉积物的TOC和TN具有同源性。根据对δ13C和C/N的综合分析表明,贝类生物沉积、海带(Saccharina japonica)和土壤有机质是桑沟湾沉积物有机质的主要来源。采用三元混合模型估算得到贝类生物沉积贡献率为67.52%,土壤有机质贡献率为26.47%,海带贡献率为5.97%。研究表明,海洋贝藻生物沉积对近海碳埋藏具有显著影响。  相似文献   

8.
为研究不同养殖活动对海–气界面CO_2交换通量(F)的影响,于2014年5月采用走航式CO_2分压仪对中国北方典型的多营养层次混合养殖海域—桑沟湾养殖区的表层水CO_2分压(pCO_2)进行了大面调查,并通过数据计算桑沟湾海区的F值。在调查过程中,选择在网箱养殖区、贝类养殖区、藻类养殖区等区域内进行24 h定点连续观测。探讨了春季桑沟湾海–气界面CO_2的交换通量及其主要影响因素。大面调查结果显示,桑沟湾内海水中pCO_2总体变化趋势是由湾内向湾外递减,网箱养殖区海水中pCO_2远远高于其他区域。在大面调查中,贝类、藻类、贝藻混养、网箱养殖区的F值分别为(–1.02±0.83)、(–15.40±1.28)、(–4.32±1.41)、8.14 mmol/(m~2·d)。定点连续监测显示,藻类、贝类、网箱养殖区的pCO_2 24 h平均值分别为(320±14)、(330±10)、(413±37)μatm。研究表明,光合作用是海–气界面CO_2交换通量的主要影响因素之一,不同养殖区之间的海–气界面CO_2交换通量差异显著。影响各养殖区海–气界面CO_2交换通量日变化规律的影响因子与走航调查结果一致。养殖活动是影响海–气界面CO_2交换通量的主导因素。  相似文献   

9.
为研究季节变化和养殖活动对桑沟湾表层海水二氧化碳分压(pCO_2)的影响,尤其是海带(Saccharina japonica)养殖活动对表层水pCO_2的影响,本研究分别在海带收获前(2015年5月)、后(2015年8月)采用走航式二氧化碳分压仪对中国北方典型的贝藻筏式养殖海域——桑沟湾养殖区表层水pCO_2及有关环境参数进行了大面调查,探讨了季节、养殖模式以及海带收获前、后表层水pCO_2的变化规律及影响因素。调查结果显示:(1)春夏两季桑沟湾湾内表层海水中pCO_2的平均值分别为(346.78±13.85)μatm(1 atm=101325 Pa,1 μatm=10~(-6) atm)和(351.50±8.00)μatm;湾外自然海域pCO_2值分别为(353.42±0.71)μatm和(358.05±2.01)μatm,均小于大气中pCO_2。(2)pCO_2的平面分布特性为:由湾底向湾外递减并在外海空白区升高,两个季节最低值都出现在海带养殖区,最高值都出现在贝类养殖区。(3)春季表层海水pCO_2与水温相关性不显著(P0.05),而与叶绿素a(Chl a)、溶解氧(DO)显著相关(P0.05),反映了生命活动对pCO_2影响较大;夏季,养殖海带已收获,表层海水pCO_2与水温、溶解无机碳(DIC)、Chl a、DO显著相关(P0.05)。(4)桑沟湾养殖区以及外海自然海域表层水pCO_2都低于大气中pCO_2,表现为二氧化碳(CO2)的汇区。藻类养殖区表层水pCO_2远低于自然海域,表现为CO2的强汇区;贝类养殖区表层水pCO_2略高于自然海域,表现为CO2的弱汇区,贝藻混养区则介于二者之间。春季海带的光合作用是影响表层水pCO_2的主要因素之一,养殖活动对海区表层水pCO_2的影响使得桑沟湾pCO_2表现出不同于自然海域的特性。夏季养殖活动减少导致物理因素的影响开始显现。  相似文献   

10.
2003 年8~11 月对桑沟湾进行了两次生态环境的调查研究,测定了其扇贝、海带和牡蛎养殖区3个站位的表层沉积物中有机碳、总氮、总磷的含量,并且通过沉积物水界面交换室内培养实验得到了沉积物水界面有机碳、总氮、总磷的交换量与时间的动力学关系,利用连续函数和非线形拟合技术计算了沉积物水界面有机碳、总氮、总磷的交换速率。其交换速率变化范围TOC 为22 .96~172. 41 mg/m2·d,TN为1 .71~10. 83 mg/m2·d,TP为1. 22~7 .66 mg/m2·d。总体趋势是相同站位的交换速率为8月高于11月,不同站位的交换速率为扇贝和牡蛎养殖区高于海带养殖区。  相似文献   

11.
The environmental processes associated with variability in the catch rates of bigeye tuna in the Atlantic Ocean are largely unexplored. This study used generalized additive models (GAMs) fitted to Taiwanese longline fishery data from 1990 to 2009 and investigated the association between environmental variables and catch rates to identify the processes influencing bigeye tuna distribution in the Atlantic Ocean. The present findings reveal that the year (temporal factor), latitude and longitude (spatial factors), and major regular longline target species of albacore catches are significant for the standardization of bigeye tuna catch rates in the Atlantic Ocean. The standardized catch rates and distribution of bigeye tuna were found to be related to environmental and climatic variation. The model selection processes showed that the selected GAMs explained 70% of the cumulative deviance in the entire Atlantic Ocean. Regarding environmental factors, the depth of the 20 degree isotherm (D20) substantially contributed to the explained deviance; other important factors were sea surface temperature (SST) and sea surface height deviation (SSHD). The potential fishing grounds were observed with SSTs of 22–28°C, a D20 shallower than 150 m and negative SSHDs in the Atlantic Ocean. The higher predicted catch rates were increased in the positive northern tropical Atlantic and negative North Atlantic Oscillation events with a higher SST and shallow D20, suggesting that climatic oscillations affect the population abundance and distribution of bigeye tuna.  相似文献   

12.
In this experiment, a feeding trial was performed to determine the effects of fructooligosaccharide (FOS) on growth performance, digestive enzyme activity and immune response of Japanese sea bass, Lateolabrax japonicus juveniles (initial weight 38.3 ± 0.5 g), and the fish were examined following feeding with six levels of FOS (0, 0.5, 1, 2, 4 and 6 g/kg) for 28 days. Significant enhancement of weight gain (WG) and specific growth rate (SGR) was found in fish fed 1 g/kg FOS incorporated diets (p < .05), while the feed conversion ratio (FCR) in the 1, 2 g/kg FOS groups reduced significantly compared with the control (p < .05). Besides, the crude lipid in the 4, 6 g/kg FOS groups increased significantly compared with the control (p < .05). On the other hand, the erepsin and lipase activities significantly elevated in intestine of fish fed 2 g/kg FOS (p < .05) and the lysozyme activity in serum of fish fed 2 g/kg FOS were significantly higher than that in the control (p < .05). Moreover, the alkaline phosphatase activities in serum of fish fed 0.5, 1, 2 g/kg FOS were significantly higher than in control (p < .05). Regression analysis showed that the relationships between dietary FOS levels and either SGR, FCR, erepsin or lysozyme activities were best expressed by regression equations, and the optimal inclusion levels are 1.37, 1.80, 3.06, 3.11, 1.93 and 1.80 g/kg for SGR, FCR, erepsin, lipase, lysozyme and total superoxide dismutase activities, respectively. Overall, this study revealed that FOS incorporated diets could beneficial for L. japonicus culture in terms of increasing the growth, digestion and immune activities. Under the present experimental condition, the optimal supplementary level of FOS in the diet of L. japonicus is 1–3 g/kg.  相似文献   

13.
Previously, we reported 10 PEGE types of 85 tilapia Streptococcus agalactiae(GBS), which shifted from Streptococcus iniae in China, by using PEGE method. Presently, larger and more representative tilapia GBS were isolated, for the ?rst time in China, to characterize their serotypes and genetic diversities more precisely than had done before. 168 GBS strains were distributed in ?ve provinces of China, in which Guangdong, Guangxi and Hainan were the major ones, holding36.9%(62/168), 37.5%(63/168) and 19.6%(33/168), respectively. Serotypes, Ia, Ib and III, were observed in these strains and the most predominant one was Ia(95.2%), which mainly distributed in Guangdong, Guangxi and Hainan. Ia initially occurred in 2009, it shoot up to 32.1% in 2010,but decreased to 16.1% in 2011 before went up to 45.2% in 2012. Ib sporadically occurred during2007–2011, III onlyoccurred in 2012. 14 different PFGE types, including 4 new types(N, O,P and Q), were observed, in which B, D, F and G were the predominant types, holding 83.9%(141/168) of the total GBS strains. Ia corresponded to 11 PFGE types(A–H, N–P), in which type D predominated(51%). Ib represented 3 genotypes(I, J and Q) and III harbored only 2genotypes(N and F). Type N and Fsynchronously presented in Ia and III. In summary, the genetic diversity of tilapia GBS varied by serotypes and changed with geographical locations and years.Although Iastillpredominated, new rareserotypeIII alreadyoccurred in China.  相似文献   

14.
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15.
Growth hormone (GH) and reproduction: a review   总被引：5，自引：0，他引：5  
Interaction between growth and reproduction occurs in many vertebrates and is particularly obvious at certain stages of the life cycle in fish. Endocrine interactions between the gonadotropic axis and the somatotropic axis are described, the potential role of GH being emphasised. A comparative analysis of these phenomena in mammals, amphibians and fish, suggests a specific role of GH in the physiology of puberty, gametogenesis and fertility. It also shows the original contribution made by studies on the fish model in this field of investigations.  相似文献   

16.
Two gonadotropins (GtH; Qa and Qb) were purified by gel filtration and ion exchange chromatography from the pituitaries of Indian walking catfish (Clarias batrachus). The presence of GtH during purification was assessed by in vitro oocyte maturation and in vivo steroidogenic activity, and their identities were determined by elution profiles, molecular weight, biological activities and yield. The molecular weights of Qa and Qb were 37 and 42 kDa, respectively, and composed of distinct subunits (Qa: 20 and 14 kDa and Qb: 26 and 18 kDa). Polyclonal antibodies raised against Qa immunostained Qa, Qb and pituitary GtH cells. A competitive Qa‐ELISA was developed whose sensitivity was 6.25 ng mL?1 (1.25 ng well?1) with intra‐ (3.5%) and inter‐ (12.4%) assay coefficients of variation. Displacement curves parallel to the standard were obtained with plasma and pituitary extracts of catfish, Qb and carp GtHII. The assay was validated by measuring the plasma Qa levels after LHRH treatment and in relation to ovarian growth in the female catfish during different reproductive phases. Based on the results, Qa and Qb corresponded to fish LH and FSH respectively. The findings will increase the knowledge of the mechanisms controlling fish reproduction and identification of sensitive phases in fish in captivity for hormonal manipulation.  相似文献   

17.
Tetrahymena is a protozoan parasite, which infects guppy, Poecilia reticulata Peters, and causes substantial economical losses in commercial farms worldwide. Studies of guppy infected by Tetrahymena require standardized infection protocols. The LD50 for Tetrahymena infection of guppies by intraperitoneal (IP) injection was calibrated, and the level obtained was 946 parasites per fish. Guppy infection with Tetrahymena by immersion, imitating the natural route of infection via the integument, was studied under normal or stress conditions. Exposure to cold and netting (CNI) and to cold only (CI) followed by immersion exposure to 10 000 Tetrahymena per mL resulted in 22.5% and 19.2% mortality, respectively, as compared to 14.2% and 10% in groups that were netted only (NI) or non‐stressed (I). Histopathology revealed that immersion infection resulted in a systemic infection. Lysozyme levels, measured 3 weeks after infection, were significantly higher in the CNI group (288 μg per mg protein) compared with CI‐, NI‐ and I‐treated groups (94.5, 64 and 62.3 μg mg?1, respectively). There was no evident parasite immobilization activity in body homogenates, suggesting no development of acquired immunity. Re‐infection by IP injection revealed no increase in protection in any of the treatment groups, mortality range of 56.3–75%, higher than in the non‐exposed control (40.6% mortality).  相似文献   

18.
Plasma estradiol-17 (E2), testosterone (T), 17,20-dihydroxy-4-pregnen-3-one (DHP) and 17,20,21-tri-hydroxy-4-pregnen-3-one (20-S) levels were measured by radioimmunoassay (RIA) in white perch (Morone americana) and white bass (M. chrysops) that were induced to undergo final oocyte maturation (FOM) with human chorionic gonadotropin (hCG). Plasma DHP levels increased in females of both species in association with oocyte germinal vesicle migration (GVM) and germinal vesicle breakdown (GVBD) and decreased thereafter. Plasma 20-S levels also increased with oocyte GVM in white bass, but were several-fold lower than DHP levels. Circulating E2 and T levels were greatest during GVM and GVBD in both species and decreased to low levels during oocyte hydration and ovulation. Follicles from white perch and white bass which received a priming injection of hCG in vivo, produced both DHP and 20-S in vitro after exposure to hCG and their oocytes underwent GVBD. Ovarian incubates from unprimed fish of either species produced only E2 and T and their oocytes did not complete GVBD. Oocytes from unprimed bass, but not perch, matured when follicles were exposed to hCG in vitro. Both trilostane and cycloheximide blocked in vitro production of DHP and 20-S and oocyte GVBD by white perch follices. DHP and 20-S were equipotent inducers of FOM in the GVBD bioassay. None of several other structurally-related steroids tested were effective within a physiological range of concentrations. These results indicate a role for DHP and 20-S in the control of FOM in white perch and white bass.  相似文献   

19.
Changes in heart rate, ventilatory activity and oxygen consumption were determined in trout (Salmo gairdneri) and brown bullhead catfish (Ictalurus nebulosus) during exposure to a steadily increasing concentration of waterborne cyanide selected to produce death in 8–9 hours for each species. The lethal cyanide concentration for the bullheads was an order of magnitude higher than for trout. Trout developed an immediate and gradually increasing bradycardia throughout the exposure period. Cyanide produced tachycardia in the bullhead followed by a gradual onset of bradycardia as the concentration of cyanide was raised. Pericardial injection of atropine (a muscarinic cholinergic antagonist) indicated that bradycardia in the trout was due initially to increased vagal tone but later due to the direct effect of cyanide on the heart. Hyperventilation in the trout persisted throughout the exposure period, although the rate and amplitude fluctuated and was variable between individual fish. During the last hour of exposure (highest cyanide concentration), ventilation was characterized by rapid, shallow breaths followed by a sudden respiratory arrest. The bullheads exhibited hyperventilation during the first 3 hours of exposure followed by a gradual, linear drop in ventilation rate and amplitude until death occurred. Cardiac and ventilatory responses in both species were attributed to stimulation of central and peripheral chemoreceptors by cyanide. Evidence is presented which suggests the initial response in the bullheads was due, at least in part, to gustatory stimulation by the cyanide. Oxygen consumption of the trout remained above pre-exposure levels for the majority of the test period. Oxygen consumption in the bullhead paralleled the changes in heart and ventilatory rates. Whole-body lactate levels of fingerlings of both species during cyanide exposure were measured to estimate the extent of anaerobiosis. Whole-body lactate levels were much greater in the bullheads than the trout, indicating a higher capacity for anaerobiosis, possibly due to a greater fuel supply. Overall, the trout responded to cyanide in a manner similar to that produced by environmental hypoxia whereas the bullheads experienced a gustatory stimulus which masked the hypoxia-like response.  相似文献   

20.
Protein and amino acid composition of the mantle of juvenile O ctopus vulgaris (Cuvier, 1797) during fasting for 27 days were determined. Average protein content of octopus mantle was of 711.19 ± 46.80 g kg?1 DW, and it decreased with increasing fasting days. The non‐essential amino acids content was higher (486.18 ± 11.08 g kg?1 protein) than essential amino acids (425.82 ± 9.15 g kg?1 protein) at the start of the experiment (unstarved animals). The results suggest that the amino acid profile of the mantle where the most abundant amino acids are Arg, His, Lys, Gly, Leu and Pro could indicate a prolonged fasting condition (>20 days) or poor nutrition of O . vulgaris. This study supports the idea of using mantle for metabolic needs of starved O . vulgaris suggesting that the degradation pathway of amino acids to pyruvate and tricarboxylic acid cycle intermediates was favoured contrary to the degradation pathway of ketogenic amino acids. Special considerations should be taken concerning Thr, Ile, Ser, Ala, Asx (Asp, Asn), Glx (Glu, Gln) (because of their fast intake) and Lys and His (due to their stable contents) during a prolonged period of fasting.  相似文献   

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